Solehah: Welding Inspection Technology Course

Introduction to the subject
Welcome to Welding Inspection Technology course. This subject introduces you to the major tools in welding inspection technology tools The aim of the subject is to provide students with the necessary knowledge and skills to success in the weld inspection program by imparting all the knowledge which is fundamental to the welding and inspection field. Student should be able to recognize the duties, work ethics and responsibilities of a welding inspector. The subject aims to provide the all necessary knowledge related to welding and inspection such as duties and responsibilities, destructive test, non-destructive test, imperfections and weld defects, codes and standard as well as new and advance testing method and their implementation in industry. In addition this program explains the duties and responsibilities of a welding inspector; fusion welding processes, typical weld defects, types of steel, carbon-manganese, low alloy and stainless steels, hardening of steels, weldability, heat treatment, parent metal defects, visual inspection, testing parent metals and welds, destructive tests, NDT techniques, welder and procedure approval, codes and standards, outline of safe working practices, practice in examination questions, continuous and end-of-course assessment. There are eight (8) Modules in this subject. Module 1 provides a general introduction and an overview of welding inspector rules and responsibility. Welding inspectors need to have the ability to understand/interpret the various QC procedures and also have sound knowledge of welding technology. Module 2 provides the terms and terminology of weld types, welding joint, joint preparation method, welding position, weld terminology and weld zone terminology. Module 3 provides how welds are inspected and what discontinuities and defects are common in fusion welding process. Module 4 provides a specification code and standard for API 1104 writing bodies. The standard fall into six (13) major categories. Module 5 focus on welding inspection tools, method and recording. Inspection may be carried out by the use of the eye alone or can be enhanced by using optical systems such as magnifiers and other visual examination aids. A detailed report has carried out for plate and pipe visual inspection T –fillet inspection process and macro specimens defect inspection process. The reports need to evaluate and proper sentencing as are particularly appropriate for major industry project. Module 6 provides a most widely used welding methods in industries and research organizations of welding process such as Oxy Acetylene, SMAW, GMAW, GTAW and SAW. Module 7 provides flame, thermal and metal cutting operations. Module 8 provides weld symbol information on the welding assembly drawings. Module 9 provides the knowledge and interpret the material identification and designation to check compliance with relevant normative documents focus on the development of the detailed project plan. Texts, References and other Resources Textbooks The textbook below is an integral part of the subject, and sections of the textbook are set as required reading for most topics. Main Textbook: 1. Welding Inspection Slides (AWS) 2. Welding Inspection Notes (AWS) 3. Course Notes: 1. https://vle.unikl.edu.my/course/view.php?id=27177
Additional Notes
1. Welding: Principles and Application, 8^th Edition, Jeffus, Larry F, Delmar USA (2017) 2. Modern Welding Technology, 3^rd Edition Howard B. Cary (1994) 3. Welding Principles and Practices, 5^th Edition Edward R Bohnard (2018) 4. Welding Skills, 3rd Edition B.J Moniz & R.T Miller (2004) 5. A Quick Guide to Welding and Weld Inspection, Steven E. Hughes (2009) 6. Welding of Pipelines and Related Facilities, API STANDARD 1104 (19^th Edition) 7. Welding Essential, Willian Galvery, Frank Marlow All notes and questions are referred to the text book. You are required to read the following text book for additional sources and information. How to use this study guide This study guide has been designed to assist you in studying this subject. The study guide clearly defines the number of topics covered by the subject, the objective(s) of each topic, specific text and reference materials for each topic, the amount of work you have to do for each topic, and the sequence of study. The guide gives you a clear idea of the contents of the subject and the amount of work you are expected to do to achieve the subject’s objectives. It is NOT meant to be a complete set of lecture notes for the subject. To study this subject, you need not only this study guide, but also the resources listed in the section “Texts and references”. The layout of each Module in the study guide is as follows: Aim: This outlines the general concepts and techniques to be covered in the Module. Study Methodology: This outlines the study process that is recommended for the particular Module. Reading list: This gives you the details of the relevant texts that you have to study for the topic. Study notes: This provides the main content of each topic, which will assist you in your reading. Tutorial questions: This section gives you the coursework requirements and tutorial questions that you should attempt in order to evaluate your learning A detailed study program is shown on the following page

Learning Schedule

	Topic	Relevant Assessments
WEEK 1	1. Introduction to the course 1.1 Briefing session 2.1 Study guide reference 3.1 Text book reference 4.1 Assessment method 5.1 Grading assessment 6.1 VLE guideline 2. Welding Inspection – Overview 1.1 General; 2.1 Specific duties of in visual inspections; 3.1 Tasks Before, During and After welding; 4.1 Welding inspector’s tools & equipment; Outcome(s): CLO 2, 3	· Discussion Question 1 · Discussion Question 2
WEEK 2	3. Welding Inspection – Overview (Continuation) 1.1 Quality Assurance & Control in weld inspection; 2.1 Personnel qualifications and qualification levels; 3.1 Summary; Outcome(s): CLO 2, 3	· VLE – True and False – Multiple Question – Missing words (Discussion Question 3)
WEEK 3	4. Weld Terminology 1.1 Types of joint; 2.1 Types of weld; 3.1 Types of joint preparation; 4.1 Edges preparation tools Outcome(s): CLO 2, 3
WEEK 4	5. Weld Terminology 1.1 Welding terminology; 2.1 Welding zone terminology; 3.1 Welding position Outcome(s): CLO 2, 3
WEEK 4	6. Welding Processes 1.1 General; 2.1 Oxy-Fuel welding (OFW); 3.1 Shielded Metal-Arc Welding (SMAW) ; 4.1 Flux-cored Arc Welding (FCAW); Outcome(s): CLO 2, 3
WEEK 5	7. Welding Processes (Continuation) 5.5 Gas Metal Arc Welding (MIG/MAG); 5.6 Gas Tungsten Arc Welding (TIG/TAG); 5.7 Plasma Arc Welding (PAW); 5.8 Submerged Arc Welding (SAW); Outcome(s): CLO 2, 3	Group / Individual exercise
WEEK 6	8. Welding Processes (Continuation) 6.9 Electro-slag Welding (ESW); 6.10 Friction-Stir Welding (FSW); 6.11 Friction Welding (FW); 6.12 Electron Beam Welding (EBW). Outcome(s): CLO 2, 3	Group / Individual exercise
WEEK 7	9. Flame and Thermal Cutting 7.1 General 7.2 Flame cutting processes 7.3 Electric arc cutting processes 7.4 Gouging processes: flame, electrode. Outcome(s): CLO 1, 3	Group / Individual exercise
WEEK 8	10. Materials Identification & It’s Weldability 8.1 Materials type and their weldability; 8.2 Guidelines for the welding of steels and alloys. Outcome(s): CLO 1, 3	Group / Individual exercise
WEEK 9	11. Welding Discontinuities, Defects and Imperfections 9.1 Stress: residual stresses, etc.; 9.2 Distortions: warping, etc.; 9.3 Imperfections: Discontinuities; 9.4 Surface and sub-surface defects; 9.5 Internal defects: Lack of sidewall fusion, etc.; 9.6 Cracks: surface, internal; 9.7 Laminations, laps. Outcome(s): CLO 2, 3	Group / Individual exercise
WEEK 10	12. Welding Discontinuities, Defects and Imperfections 10.1 Stress: residual stresses, etc.; 10.2 Distortions: warping, etc.; 10.3 Imperfections: Discontinuities; 10.4 Surface and sub-surface defects; 10.5 Internal defects: Lack of sidewall fusion, etc.; 10.6 Cracks: surface, internal; 10.7 Laminations, laps. Outcome(s): CLO 2, 3	Group / Individual exercise
WEEK 11	13. Code and Standard 11.1 Understanding the use of API1104; 11.2 Inspection requirements; 11.3 Acceptance criteria. 11.4 Universal codes.
WEEK 12	14. Welding Inspection practice 12.1 Plates, pipes, fillets, bend and fracture; 12.2 Structures; 12.3 Thump print, evaluation, sentencing and reports; 12.4 Macro specimens. Outcome(s): CLO 1	Group / Individual exercise
WEEK 13	Test
WEEK 14	15. Welding Inspection practice (Plate) 13.1 Plates, pipes, fillets, bend and fracture; 13.2 Structures; 13.3 Thump print, evaluation, sentencing and reports; 13.4 Macro specimens. Outcome(s): CLO 1	Group / Individual exercise
WEEK 15	16. Welding Inspection practice (Fillet) 13.1 Plates, pipes, fillets, bend and fracture; 13.2 Structures; 13.3 Thump print, evaluation, sentencing and reports; 13.4 Macro specimens. Outcome(s): CLO 1	Group / Individual exercise
WEEK 16	Presentation	Group / Individual exercise
WEEK 17	Revision for final examination
	Test	MC Questions
	Assignment	Narrative/Case Studies
	Revision for final examination	MC & Narrative
120 hrs

Chapter 1 – Overview of Welding Inspection

Reading:

1. Study Guide Chapter 1: Welding Inspection An Overview

2. Students Slides: Welding Inspection Technology (Chapter 1)

3. Books: A Quick Guide to Welding and Weld Inspection, Steven E. Hughes (2009)

Additional References:

1. Welding Inspection Notes https://vle.unikl.edu.my/mod/resource/view.php?id=428465

2. Welding Inspection Slides https://vle.unikl.edu.my/mod/resource/view.php?id=428424

1.1 Introduction

A qualification in welding inspection can open doors to rewarding and varied careers anywhere in the world. Requiring a high level of skill and knowledge, welding inspection is an excellent career choice for anyone wishing for a transition from a general engineering or welding background into a more specialised and prestigious role.

2.1 Specific duties in welding inspector

Welding Inspectors are employed to assist with the quality control (QC) activities that are necessary to ensure that welded items will meet specified requirements and be fit for their application. Prior to starting a job assignment, the welding inspector should determine:

a. What code, standard, or specification applies;

b. What inspections should be conducted;

c. When inspections should be conducted;

A Welding Inspector should also ensure that any inspection aids that will be needed are:

§ In good condition

§ Calibrated – as appropriate/as specified by QC procedures

3.1 Stages of welding inspection

Extent of examination and when required should be defined in application standard or by agreement between the contraction parties. For high integrity fabrications inspection required throughout the fabrication process:

a. Before Welding (Before assembly & After assembly)

b. During Welding

c. After Welding

4.1 Conditions for Visual Inspection

Where access is restricted for direct visual inspection, the use of a mirrored boroscope, or a fibre optic viewing system, are options that may be used usually by agreement between the contracting parties.

5.1 Aids to Visual Inspection

· Illumination

· Inspection Lenses

· Optical viewing

· Access

6.1 Summary of duties

It is the duties of a welding inspection personnel to ensure all the welding and associated actions are carried out in accordance with the specification and any application procedures.

A welding Inspection Personnel must:

§ Observe:

§ Record:

§ Compare:

7.1 Repairs

When a defect is identified during the inspection, three main options exist, depending upon the severity of the defect and A repair procedure should be in place detailing what actions are required. The component being welded. The component can be scrapped, it can be given a concession or it can be repaired.

8.1 Personnel qualification and qualification levels

ISO 9606 is an international standard that is agreed to be used for the Welder Certification that provides a set of technical rules for a systematic qualification test of the welder and enables such qualification to be uniformly accepted independently of the type of product, location and examiner of examining body.

9.1 The Welding Inspector

When an inspection record is required it may be necessary to show that items have been checked at the specified stages and that they have satisfied the acceptance criteria.

10.1 Examination Records

Welding Procedures are the guidelines used to perform a weld. They are designed to provide a record of the welding variables used and the inspection results obtained during the procedure qualification test. Welding procedures are usually divided into two categories, the Procedure Qualification Record (PQR) and the Welding Procedure Specification (WPS).

For individual inspection reports, BS EN 970 lists typical details for inclusion such as:

§ Name of manufacturer/fabricator

§ Identification of item examined

§ Material type and thickness

§ Type of joint

§ Welding process

§ Locations and types of all imperfections not acceptable

§ Name of examiner/inspector and date of examination

11.1 Components Of A Weld Procedure

Items to be included in the procedure can be some of the following:

· Parent Metal

· Welding Process

· Joint Design

· Welding Position

· Thermal Treatment

12.1 The typical types of inspection and testing for each sample for Welding Procedure Qualification are:

· Inspection and Testing for Fillet Welds (Tee Joints)

· Inspection and Testing for Groove welds (Butt Joints)

Discussion Questions

Discussion 1

1. List four (4) other areas that would generally be covered by a NDT inspection standard for welds?

2. List other desirable characteristic that all welding inspector should possess?

3. List five (5) other areas of knowledge with which a proficient welding inspector should be familiar with?

Discussion 2

1. Give three main attributes, which all welding inspectors must possess.

2. Give six main duties of a welding inspector during welding.

3. List six tools and accessories used for welding inspection

4. Welding poses a range of hazards to your health. List 5 main safety precautions conscious for welding inspector before welding inspection activities.

5. Give the three main responsibilities of a welding inspector:

6. Which standard should be used for welding inspector should refer for welder certification?

7. Give six main duties of a welding inspector before welding.

8. How to Become a Certified Welding Quality Assurance Inspector

9. A code of practice for visual inspection should include before, during and after welding activities. What are the factors to be taken when conducting visual inspection on welds?

10. Give six main duties of a welding inspector after welding

Discussion 3

1. Why are welding codes (including standards and specifications) used?

2. Where do welding codes come from?

3. Who determines which code to use for an application?

4. What are some of the most common welding codes?

5. Where does the qualification and certification cycle begin?

6. What happens now that a WPS exists?

7. How can a PQR be developed?

8. Now that an approved WPS exists, are we ready to test welders?

9. What do these documents look like?

10. Can a common qualification and its welding procedure specification test be described?

11. Where can one find pre-qualified welds?

12. What positions may be used to produce the weld in Figure 1?

13. What type of weld testing is required for qualification?

14. What are the visual examination’s criteria?

15. If the visual examination is good, what other testing is needed?

16. Is the welder certified now that he has passed the welder performance qualification?

17. What is a certified welder?

18. If I am a qualified welder, can I weld everything?

19. Who is responsible for the qualification of welders?

20. What is the duration of a standard qualification?

VLE questions list for Chapter 1:

Types of questions	Total questions	Week	Time	Durations
Multiple choice	60	3		2 hours
True and false	50	3		1.5 hours
Missing words 1	30	2		1 hour

Chapter 2 – Weld Terminology

Reading:

1. Study Guide Chapter 2: Welding Terminology

2. Students Slides: Welding Inspection Technology (Chapter 2)

3. Books: A Quick Guide to Welding and Weld Inspection, Steven E. Hughes (2009)

Additional References:

1. Welding Inspection Notes https://vle.unikl.edu.my/mod/resource/view.php?id=428465

2. Welding Inspection Slides https://vle.unikl.edu.my/mod/resource/view.php?id=428424

2.1 Weld Joint Design

The term weld joint design refers to the way pieces of metal are put together or aligned with each other. The five basic joint designs are butt joints, lap joints, tee joints, outside corner joints, and edge joints.

Some of the factors that affect the selection of a specific weld joint design include welding process, edge preparation, joint dimensions, metal thickness, metal type, welding position, codes or standards, and cost.

2.2 Weld Types.

The purpose of a welded joint is to join parts together so that the completed weldment can withstand the stresses. The forces acting on a weld cause stresses. Forces cause stresses in five ways: tensile, compression, bending, torsion, and shear. Weld types include fillet weld, groove weld, surfacing weld, plug weld, slot weld, flash weld, seam weld, upset weld, projection weld.

2.3 Joint Edge Preparation.

The area of the metal’s surface that is melted during the welding process is called the faying surface. The faying surface can be shaped before welding to increase the weld’s strength; this is called edge preparation. The edge preparation may be the same on both members of the joint, or each side can be shaped differently. Reasons for preparing the faying surfaces for welding include the following:

· Codes and standards

· Metals

· Deeper weld penetration

· Smooth appearance.

2.4 Edge Preparation Tools

Two major techniques are used for edge beveling and welding preparation: large semi-stationary machines and angle grinders. The former creates very precise, clean angles at various bevel depths. Machining should be the first choice in edge preparation, mainly because it avoids thermal distortion to the material that is to be welded. Some of edge preparation tools:

· Grinding

· Oxyacetylene cutting

· Machining

2.5 Welding Terminology

The base metal is the metal or alloy that is to be welded. An electrode is a component of the welding circuit that conducts electrical current to the weld area.

· A weld bead is a weld that results from a weld pass. A weld pass is a single progression of welding along a weld joint

· A crater is a depression in the base metal that is made by the welding heat source at the termination of the weld bead.

· Joint penetration is the depth of the weld metal from the weld face into the joint.

· Weld reinforcement is the amount of weld metal in excess of that required to fill the joint.

· Root reinforcement is reinforcement on the side opposite the one on which welding took place.

· Face reinforcement is reinforcement is on the same side as the welding.

· The root face is the portion of the groove face within the joint root.

· The root opening is the distance between joint members at the root of the weld before welding. The root opening must be accurate so that excess welding is not necessary.

· Weld width is the distance from toe to toe across the face of the weld

· The weld toe is the point where the weld metal meets the intersection of the base metal and weld face. The toes are the points where the base metal and weld metal meet.

· The weld face is the exposed surface of the weld, bounded by the weld toes on the side on which welding was done. The face may be either concave or convex.

· The weld root is the area where filler metal intersects the base metal and extends the furthest into the weld joint.

· The actual throat is the shortest distance from the face of a fillet weld to the weld root after welding.

· The effective throat is the minimum distance from the face of a fillet weld to the weld root after welding. The effective throat is the minimum distance, minus convexity between the weld face and the weld root.

· A weld leg is the distance from the joint root to the weld toe. The weld leg is the size of a fillet weld made in lap or T.

· A joint root is the portion of a weld joint where joint members are the closet to each other. A joint root may be either a point, a line, or an area.

· A root bead is a weld bead that extends into or includes part or all of the joint root.

· A root pass is the initial weld pass that provides complete penetration through the thickness of the joint member.

2.6 Welding Microstructure Zone Terminology

A weld joint can be divided into four different microstructure zones. They are the weld metal (WM) or fusion zone, weld interface (WI) or fusion line, heat affected zone (HAZ), and unaffected parent metal (PM) zone or unaffected base metal zone (BM).

The WM is a mixture of the filler rod, flux, and parent metal that has completely melted during the fusion process.

The WI is a narrow boundary that separates the weld metal and the HAZ. This zone separates the fusion zone and heat affected zone.

The HAZ is the region that experiences a peak temperature that is well below the solidus temperature while high enough that can change the microstructure of the material

The BM zone surrounding the HAZ is likely to be in a state of high residual stress, due to the shrinkage in the fusion zone

2.7 Introduction to Welding Position

The American Welding Society has defined the positions of welding to include:

i. Flat. In a flat position, a weld is performed along largely a horizontal access and from above the joint. It is the easiest type of weld to perform.

ii. Horizontal. In the horizontal position, the weld’s axis is the horizontal plane. Horizontal welding is often used for fillet or groove welds.

iii. Vertical. With a vertical position, the weld’s axis is largely in a vertical or upright position. It is typically more complicated to perform than flat and horizontal welding.

iv. Overhead. In this the most complicated of the four, welding is performed from the underside of the joint.

ASME has defined the four basic welding position

· 1 = Flat Position or down hand. (1F/PA,1G/PA)

· 2 = Horizontal Position (2F/PB,2G/PC)

· 3 = Vertical Position. (3F/PF,3G/PG)

· 4 = Overhead Position. (4F/PD,4G/PE)

In addition there are letters that designate the type of weld you will do in that position. For example:

· F = Fillet Weld

For a fillet weld made in the flat position, the number/letter designation is 1F (F for fillet).

· G = Groove Weld

The 1G position refers to a groove weld that is to be made in the flat position.

2.7.1 Plate Welding Position

Because of gravity, the position in which you are welding affects the flow of molten filler metal. Use the flat position, if at all possible, because gravity draws the molten metal downward into the joint making the welding faster and easier. Horizontal welding is a little more difficult, because the molten metal tends to sag or flow downhill onto the lower plate. Vertical welding is done in a vertical line, usually from bottom to top; however, on thin material downhill or downhand welding may be easier.

2.7.2 Pipe Welding Position

The 1G and 5G horizontal and 2G vertical positions refer to the pipe position. 1G, 2G, 3G and 4G plate are applicable in the fabrication and installation of tanks, vessel, structural, shipbuilding and aeronotics. 1G, 2G, 5G and 6G pipe are applicable in the fabrication and installation of piping and pipelines for industrial plants, oil and gas industry, chemical plants and other industry which uses piping and pipelines. 6GR is applicable mainly in the fabrication and installation of offshore structure and other structure that have the TKY configuration.

Discussion Question (Source: Welding Skills, 3rd Edition B.J Moniz & R.T Miller (2004)

1. What factors must be considered when determining the type of joint to use in welding any structural unit?

2. What is fillet weld and which joints are suitable to use for fillet weld? Why fillet welds are easy compare to other welding process? Describe the application in lap joint.

3. In what type of joints are groove weld made and how to prevent excess welding in groove weld?

4. What is plug weld, when and why we should decide to use?

5. When is a surfacing weld used?

6. Why are grooved butt joints better for welding thick plates than square butt joints?

7. How T-joints does obtained in welding joint? What are the basic types of T-joints?

8. Describe a double fillet lap joint.

9. Describe a corner joint. Lists three types of corner joint. Which type of corner joint is the strongest?

10. What is the toe of a weld? Describe how weld to is located.

11. What is the root of a weld?

12. What are some of the basic principles that contribute to good joint geometry?

13. When are double bevel T joints normally used?

14. Which butt joint requires the least amount of preparation before welding?

15. What is reinforcement of the weld?

16. How is the root opening size determined?

17. Why is proper groove angle required?

18. What is weld leg? How is the size of a weld leg determined in fillet weld?

Chapter 3 – Weld Defects and Discontinuities

Reading:

1. Study Guide Chapter 3: Weld Defects and Discontinuities

2. Students Slides: Welding Inspection Technology (Chapter 3)

3. Books: A Quick Guide to Welding and Weld Inspection, Steven E. Hughes (2009)

Additional References:

1. Welding Inspection Notes https://vle.unikl.edu.my/mod/resource/view.php?id=428465

2. Welding Inspection Slides https://vle.unikl.edu.my/mod/resource/view.php?id=428424

3.1 Introduction

Most defects encountered in welding are due to an improper welding procedure. Once the causes are determined, the operator can easily correct the problem. Defects usually encountered include incomplete penetration, incomplete fusion, undercutting, porosity, and longitudinal cracking.

3.2 Definition

Classification of imperfections according to BS EN ISO 6520-1:

This standard classifies the geometric imperfections in fusion welding dividing them into six groups:

1 Cracks.

2 Cavities.

3 Solid inclusions.

4 Lack of fusion and penetration.

5 Imperfect shape and dimensions.

6 Miscellaneous imperfections.

Defect

A flaw or flaws that by nature or accumulated effect render a part or product unable to meet minimum applicable acceptance standards or specifications. The term designates reject ability

Discontinuity

An interruption of the typical structure of a material, such as a lack of homogeneity in its mechanical, metallurgical, or physical characteristics. A discontinuity is not necessarily a defect. Discontinuity becomes defect when the total length, number or depth exceeds the minimum acceptance criteria of the applicable codes and standards.

3.3 Weld Defects / Imperfections

In conducting visual inspection on welds, defects / imperfections can be encountered and they are grouped by the following five headings:

Root defects
Contour defects
Surface irregularities
Surface crack

3.4 Cracks

Cracks can be classified as either hot or cold types. Hot cracks develop at elevated temperatures. They commonly form during the solidification of the weld metal. Cold cracks develop after the solidification of a fusion weld as a result of residual stresses. Cold cracks in steel are sometimes referred to as delayed cracks. They are often associated with hydrogen embrittlement. Hot cracks propagate between the grains (grain boundary or intergranular), while cold cracks propagate both between the grains and through the grains (transgranular). Cracks may be longitudinal or transverse with respect to the weld axis. Longitudinal cracks in the weld metal and the heat-affected zone occur parallel to the axis of the weld. Transverse cracks are found perpendicular to the weld axis. Figure illustrates the common types of cracks and presents the crack terminology established by the American Welding Society (AWS).

A crack may be defined as a local discontinuity produced by a fracture, which can arise from the stresses, generated on cooling or acting on the structure. It is the most serious type of imperfection found in a weld and should be removed. Cracks not only reduce the strength of the weld through the reduction in the cross section thickness but also can readily propagate through stress concentration at the tip, especially under impact loading or during service at low temperature.

Types of crack:

Longitudinal.
Transverse.
Radiating (cracks radiating from a common point).
Crater.
Branching (group of connected cracks originating from a common crack).

These cracks can be situated in the:

Weld metal.
HAZ.
Parent metal.
Fusion zone
Centerline

Exception: Crater cracks are found only in the weld metal.

Depending on their nature, these cracks can be:

Hot (ie solidification or liquation cracks).
Precipitation induced (ie reheat cracks present in creep resisting steels).
Cold (ie hydrogen induced cracks).
Lamellar tearing.

Preventive Action

1. Remove contaminants from the joint (rust, grease, moisture, etc.) prior to welding.

2. Apply and maintain required preheat.

3. Do not allow the base material to cool too quickly.

4. Maintain filler metal control requirements.

5. Use correct filler metal type for the joint.

6. Apply proper bead size and sequencing to eliminate excessive distortion and/or stress in the base material.

3.5 Hydrogen induced cracks / Cold Cracking

Hydrogen induced cracking occurs primarily in the grain-coarsened region of the HAZ, and is also known as cold, delayed or underbead/toe cracking. Underbead cracking lies parallel to the fusion boundary, and its path is usually a combination of intergranular and transgranular cracking. The direction of the principal residual tensile stress can, for toe cracks, cause the crack path to grow progressively away from the fusion boundary towards a region of lower sensitivity to hydrogen cracking. When this happens, the crack growth rate decreases and eventually arrests.

3.6 Lamellar tearing

Lamellar tearing occurs only in rolled steel products (primarily plates) and its main distinguishing feature is that the cracking has a terraced appearance. Lamellar tears are cracks which form in the Heat Affected Zone (HAZ) of a weld when the strain imposed by the shrinkage of the weld exceeds the through thickness ductility of the parent material. Lamellar tearing only occurs in rolled materials, principally structural and pressure vessel steels

3.7 Cavity

Weld metal porosity is a cavity-type of welding defect formed by gas entrapment during solidification as a result of contamination by certain gases, such as hydrogen, oxygen, or nitrogen.

3.8 Solid Inclusion

Inclusions are solid materials trapped in the weld metal or at the interfaces of the weld metal. The foreign materials that are often entrapped include tungsten, flux, oxide, and slag. Inclusions may be encountered in welds produced with most arc welding processes but are most common in the flux shielded processes, such as shielded metal arc welding, flux cored arc welding, and submerged arc welding.

3.9 Incomplete Fusion / Lack of fusion

Is a lack of union between the weld metal and the parent metal or between the successive layers of weld metal. Incomplete fusion, illustrated schematically in Figure 26, is a discontinuity in which fusion failed to occur between the base metal and the weld metal or the adjoining weld beads. Failure to obtain fusion may occur at any point in a groove or fillet weld, including the root.

3.10 Lack of Penetration

Lack of penetration is the difference between actual and nominal penetration. If the weld joint is not of a critical nature, ie the required strength is low and the area is not prone to fatigue cracking, it is possible to produce a partial penetration weld. In this case incomplete root penetration is considered part of this structure and not an imperfection. This would normally be determined by the design or code requirement

3.11 Porosity

Porosity is a cavity-like discontinuity that forms when gas is entrapped in solidifying weld metal or in a

thermal spray deposit. The discontinuity is generally spherical, but it may be elongated. Porosity defect occurs due to the entrapment of gas bubbles by the freezing dendrites during the cooling of molten pad.

This type of weld discontinuity occurs on the surface or in the subsurface of the weld. The various types of porosity are described below followed by a discussion of the causes of porosity.

3.12 Imperfect Shape and Dimensions

3.12.1 Undercut

Undercut is often present as a shape discontinuity at the weld toe which only constitutes a defect if it exceeds the specification limits. It is usually found at the side wall or face of a groove, at the edge of a weld or layer, or at the toes of the cover pass, resulting in a reduction of base metal thickness at the point of undercut. In fillet welds, it tends to reduce the size and strength of the weld, as well as promoting stress concentrations at the toes.

3.12.2 Excess weld metal

Excess weld metal is the extra metal that produces excessive convexity in fillet welds and a weld thickness greater than the parent metal plate in butt welds. This feature of a weld is regarded as an imperfection only when the height of the excess weld metal is greater than a specified limit.

3.12.3 Excess penetration

Projection of the root penetration bead beyond a specified limit can be local or continuous. Note that the maintenance of a penetration bead having uniform dimensions requires a great deal of skill, particularly in pipe butt welding. This can be made more difficult if there is restricted access to the weld or a narrow preparation. Permanent or temporary backing bars can be used to assist in the control of penetration.

3.12.4 Overlap

Overlap exists when unfused weld metal protrudes beyond the weld toe or root. This surface discontinuity forms a severe mechanical notch parallel to the weld axis, which usually renders the weld unacceptable. Overlap is usually caused by incorrect welding procedures, inappropriate selection of welding materials, insufficient travel speed, or improper preparation of the base metal prior to welding.

3.12.5 Spatter

Globules of weld or filler metal expelled during welding and adhering to the surface of parent metal or solidified weld metal. Spatter defects occur due to scattering of metal around the vicinity of a weld. It causes poor surface finish. Spatter is caused by arc instabilities during metal transfer which can cause molten metal droplets to be generated from the arc and weld pool. Spatter in itself is a cosmetic imperfection and does not affect the integrity of the weld. However as it is usually caused by an excessive welding current, it is a sign that the welding conditions are not ideal and so there are usually other associated problems within the structure ie high heat input.

Discussion

How can weld joint design be adjusted to prevent throat cracks?
How do crater cracks form?
How can crater cracks be prevented?
What causes toe cracks?
How can toe and root cracks be prevented?
What are the two main types of porosity?
What can be done to reduce porosity in a weld?
What are slag inclusion?
How can slag inclusions be prevented in multiple pass welds?
What causes tungsten inclusions?
Which process more likely to produce incomplete fusion: SMAW or GMAW in short circuiting mode, and why?
What causes incomplete penetration?
What is overlap, and how can it be prevented?
What is melt through, and how can it be prevented?
Why are arc strikes detrimental to medium carbon or low alloy steels?

VLE questions list for Chapter 2:

Types of questions	Total questions	Week	Time	Durations
Multiple choice	100	4		2 hours
True and false	50	5		1.5 hours
Missing words	200	4 & 5		2 hour

Chapter 4 – Code and Standard (API 1104)

4.1 Introduction

4.2 Contents in API 1104, 19^th Edition 1999

API standards are published to facilitate the broad availability of proven, sound engineering and operating practices. These standards are not intended to obviate the need for applying sound engineering judgment regarding when and where these standards should be utilized. API 1104 contains 13 sections and two appendices:

1. General

2. References Publication

3. Definition Of Terms

4. Specifications

5. Qualification Of Welding Procedures For Welds Containing Filler-Metal Additives

6. Qualification Of Welders

7. Design And Preparation Of A Joint For Production Welding

8. Inspection And Testing Of Production Welds

9. Acceptance Standards For Nondestructive Testing

10. Repair And Removal Of Defects

11. Procedures For Nondestructive Testing

12. Automatic Welding

13. Automatic Welding Without Filler-Metal Additions

4.3 Section 1 - General

This standard covers the gas and arc welding of butt, fillet, and socket welds in carbon and low-alloy steel piping used in the compression, pumping, and transmission of crude petroleum, petroleum products, fuel gases, carbon dioxide, and nitrogen and, where applicable, covers welding on distribution systems. This standard also covers the procedures for radiographic, magnetic particle, liquid penetrant, and ultrasonic testing as well as the acceptance standards to be applied to production welds tested to destruction or inspected by radiographic, magnetic particle, liquid penetrant, ultrasonic, and visual testing methods.

4.4 Section 2 - References Publication

Code – A body of laws arranged systematically for easy reference and use. Because a code has a legal status, it is definition mandatory, and use words such as shall, will, and must to express certain conditions and requirements, and to verify that those requirements are being met. Examples of codes includes AWS D1.1, D1.5.

Standard – Is establish for use as a rule or basis of comparing in measuring quality, quantity, content, relative value. Examples AWS A30, Standard Welding Terms and Definition.

Specification – Is detailed description of the parts of a whole. A statement of particulars as to actual or required size, quality, performance, terms. Thus, a specification describes all technical information for a material, product, system or service and indicates hot to determine that the requirements have been met. Examples AWS Filler Metal Specification A5.1 through A5.32.

4.5 Section 3 - Definition of Terms

The definition of welding terms used in this API 1101 standard are as defined in AWS A3.0, Standard Welding Terms and Definitions, with additions and modifications.

4.6 Section 4 – Specification

This section calls for good judgement, sound engineering, suitable operating practices and attention to safety. A welding equipment, both gas and arc, shall be of a size and type suitable for the work and shall be maintained in a condition that ensures acceptable welds, continuity of operation and safety of personnel

4.7 Section 5 - Qualification of Welding Procedures for Welds Containing Filler Metal Additives

A welding procedure is an activity undertaken according to a set of specific instructions provided in a welding procedure specification. The quality of the weld shall be determined by destructive test.

4.8 Section 6 - Qualification of Welders

Welders must pass a qualification test to show that they can use a given welding procedure. The test should employ the same manipulative techniques that welders will use in production

4.9 Section 7 - Design and Preparation of a Joint for Production Welding

The purpose of this section is to establish requirements for production welding and fabrication. It requires constant attention to the specific of the welding procedure which is why it must be performed only by welders who have qualified for that procedure

4.10 Section 8 – Inspection and Testing For Production Welds

The company may dictate what kind of inspection will occur, when, how often, and may require that inspector demonstrate the effectiveness of the inspection procedure being used and their ability to use those procedure.

4.11 Section 9 ‑ Acceptance Standards For Nondestructive Testing

NDT testing does not hurt the serviceability or function of a part. When performing a nondestructive examination, the inspector may find imperfections or discontinuities which may not require rejection of the part

4.12 Section 10 – Repair and Removal of Defects

The company must authorize repair of defects in the root and filler beads, but need not authorize repair cover pass defects. Two conditions require a qualified repair welding procedure: when the repair employs a welding process different from that of the original weld, and when a previously repaired area is repaired again

4.13 Section 11 – Procedures for Non Destructive Testing

Some of the technologies involved in nondestructive testing of welds especially radiography and ultrasound. They have similar applicability to welding. Just as welding and destructive testing require the writing of qualified procedures

4.14 Section 12 – Automatic Welding

Welding procedures for a given welding process vary with the level of automation involved. The process involved SAW, GMAW, GTAW, flux core and plasma arc

4.15 Section 13 – Automatic Welding Without Filler Metal Additions

This section discuss about Automatic welding without filler‑metal additions shall be done using the flash butt welding process.

Tutorial

Section 4 – Specification

1. Filler metals are classified by the American Welding Society (AWS) and ASME according to their chemical composition and assigned a corresponding Filler Number or F-No. The type of filler metal must be specified by manufacturer. The AWS has set up the following AWS classification numbers for steel oxyacetylene gas welding rods (OAW).

a. What does the “RG-65” filler material classification designate?

b. API 1104 Table 1 Section 5 divides filler metals into nine groups based on electrode characteristic and the process that employ those electrodes. List the characteristic and the classifications of the filler metal as shown in Table 1

Section 5 – Qualification of Welding Procedures for Welds Containing Filler-Metal Additives

1. Why is a clamp required for Qualification of Welding Procedure, when the pipe nipples for the WPS will have been cut from the same length of pipe and hence the dimension fit up will be very good; whereas, the field fit ups are from pipes that will vary in dimension, quality, etc.? Which clause should we referred to this statement?

2. Nick-break specimens prepared in this manner from welds made with certain automatic and semiautomatic processes may fail through the pipe instead of the weld. The sample shall be broken by:

a) Pulling with a tensile machine

b) Supporting at each end and striking the middle;

c) Supporting one end and striking the other end with a hammer

d) The exposed area of the fracture shall be at least 3/4 in. (19 mm) wide.

i. Is it the intent of the code to specifically rule out other methods of causing fracturing through the weldment?

ii. What is the alternative method for testing specimens that may fail in the pipe instead of the weld? Stated the instruction qualifying procedures for semiautomatic and automatic welding process. What the acceptance criteria stated in the procedures?

iii. Discuss the acceptance criteria for acceptance of root and face bend test.

iv. Identify the preparation and acceptance criteria for side bend test

v. Sketch the nick break test specimen and how to prepare the nick by referred to the standard.

3. Can a fillet weld procedure qualified using a non-bevel lap fillet to complete a 45 degree single bevel fillet weld?

4. Acceptable process in API 1104 Clause No 5.3.2.4 is a joint specification design. What are the factors must be consider when choosing a weld joint design?

5. According to API 1104 Clause No 5.8.1 is a preparation for fillet welded joint test specimen. The base metal is the metal or alloy that is to be welded. An electrode is a component of the welding circuit that conducts electrical current to the weld area. Sketch and describe weld toe, actual throat, joint root, effective throat, weld root, weld face and weld leg in fillet weld to identify its various part.

Section 6 – Qualification of Welders

1. For multiple qualification, a welder must pass two different types qualification test of weld joints. It allows a welder to weld in all positions, on all wall thickness, joint designs and fittings.

a. Identify the clause of this procedure.

b. Does a specific procedure for the branch weld in a multiple qualification test of welders need to be in place when doing the multiple qualification?

c. Describe the two tests within the limits of the essential variables.

d. Is there a standard procedure and welder qualification report template that is offered pre-printed from API?

Section 7 – Design and Preparation of a Joint for Production Welding

1. Acceptance Criteria is a document necessary in performing weld and NDT inspection. In one acceptance criteria, “excess weld metal” or “crown” or “reinforcement” of a butt weld must not exceed 1.6 mm (1/16 inch) above the base metal surface. To solve this problem, stripper beads is required. Describe the minimum height of weld crown. Why both beads shall not be started at the same location?

Section 8 – Inspection and Testing of Production Welds

1. Rights of inspection and testing of production welds, Radiographic Test Methods, is it permissible to radiograph welds joining API 5LX-60 pipe with wall thickness of 0.312" and 0.375" using gamma radiography?

2. Production weld may be inspected by using non-destructive testing provided that the method can produce indications of imperfections that can be accurately interpreted and evaluated. This section states that" Non-destructive testing may consist of radiographic inspection or method specified by company"

a. Is Automated UT substituted for RT is required in Welder Qualification program to a qualified welding procedure?

b. Stated the acceptance criteria for imperfections discovered by destructive testing.

c. Who should determine the frequency of inspection?

Section 9 - Acceptance Standard for NDT

1. In accordance to API 1104, the acceptance standards presented in this section apply to imperfections located by radiographic, magnetic particle, liquid penetrant, and ultrasonic test methods. They may also be applied to visual inspection.

a. Listed the NDT testing method of acceptable standard for imperfections. Described how those methods encountering an imperfection in weld material.

b. Define the terms “Imperfections” as stated in Section 9.1.

c. How does the inspector determine the disposition of particular imperfections?

d. Describe how the Acceptance Standards in Section 9 applies to imperfections detected by visual inspection.

2. In accordance to API 1104, an Acceptance Standard for Radiographic Testing (RT) are based on negative images.

a. Describe the radiographic test method and how it is used to inspect weld imperfections.

b. An Inadequate Penetration without High-low (IP) and, an Acceptance Standard for Inadequate Penetration Due to High-low (IPD) are joint root conditions where the weld metal does not extend entirely through the thickness of a groove weld joint.

i. What is the causes of Inadequate Penetration without High-low (IP)?

ii. How does radiographic image appear for this imperfections?

iii. What is the imperfections condition of IP and IPD of groove weld joint?

c. An Acceptance Standard for Inadequate Cross Penetration (ICP) shall be considered as a defect when the length of an individual indication of ICP exceeds 50mm.

i. How does Inadequate cross penetration occurs between the weld joint?

ii. What is the causes of Inadequate Penetration without High-low (IP)?

iii. How does radiographic image appear for this imperfections?

d. Incomplete Fusion (IF) is a discontinuity and surface imperfection between the weld metal and the base metal that is open to the surface.

i. How Incomplete Fusion does occurs between the weld metal and weld beads?

ii. What is the causes of Incomplete Fusion (IF)?

iii. How does radiographic image appear for this imperfections?

iv. How can a notch cause incomplete fusion?

e. In accordance to API 1104, Incomplete fusion is defined as a surface imperfection between the weld metal and the base material that is open to the surface.

i. When they should be considered as a defect?

ii. Sketch the example of Incomplete Fusion at Root of Bead

f. Internal Concavity (IC) is acceptable, as long as the density of the radiograph negative image showing internal concavity does not exceed of the thinnest adjacent base metal.

i. How Incomplete Fusion does occurs between the weld root and weld surface?

ii. What is the causes of Internal Concavity (IC)?

iii. How does radiographic image appear for this imperfections?

g. Burn-Through (BT) is a characterized by visible root reinforcement in a joint welded from one side or a hole in the weld bead where excessive penetration has caused the weld puddle to be blown into the pipe.

i. How Burn-Through (BT) collapse in root area of the weldment?

ii. What is the causes of Burn-Through (BT)?

iii. How does radiographic image appear for this imperfections?

h. API 1104 breaks Slag Inclusions (SI) into two main groups. Acceptance criteria for slag inclusion depend on the outside diameter of the pipe

i. What are Slag Inclusions (SI)?

ii. Names two types of Slag Inclusions (SI)

iii. What is the causes of Slag Inclusions (SI)?

iv. How does radiographic image appear for this imperfections?

v. How can slag inclusion be prevented in multiple pass welds?

i. Porosity is defined as gas trapped by solidifying weld metal before the gas has a chance to rise to the surface of the molten puddle and escape. It takes many shapes on a radiograph.

i. How can porosity form in a weld, and not be seen by the welder?

ii. Which welding process can cause porosity to form?

iii. How is piping porosity formed?

iv. What type of porosity has been distinguish by API 1104?

v. How does radiographic image appear for this imperfections?

vi. What are the factors of acceptance and rejection of individual porosity?

vii. Which section should be apply when cluster porosity cannot be proven?

viii. What type of porosity indicate in root pass?

ix. Porosity may or may not be visible to the naked eye. Occasionally porosity can be found in the face of the weld or sometimes the face may appear porosity free, but deep inside the weld porosity may exist. Define what is porosity?

x. Sketch the medium size of the gas pocket for maximum distribution wall thickness less than or equal to 0.500 inch (12.7mm)

j. Cracks are fracture-type discontinuities. They can be readily identified by their sharp tip and their high ratio of length and width to the displacement of the opening. Cracks occur in weld and base metals when localized stresses exceed the ultimate strength of the metal.

i. How longitudinal or transverse crack should occurs between the weld joint?

ii. Why cracks is most critical imperfection?

iii. List the characteristic of cracks.

iv. What type of cracks may acceptable without repair in API 1104?

v. How does radiographic image appear for this imperfections?

k. In accordance to API 1104, cracks including crater and star cracks shall be considered a defect if they are: -

l. Undercut consists of a groove melted into the base metal adjacent to the weld toe or root and left unfilled by weld metal. Undercut may often be seen only in metallographic tests in which etched weld cross sections are examined under magnification.

i. What is undercut, and described how undercut is measured?

ii. How does internal and external undercut appear in weldment?

iii. What is the cause of undercut?

iv. How does radiographic image appear for this imperfections?

3. API 1104 is the standard used to entirely voluntary and is intended to apply to welding of piping used in the compression, pumping, and transmission of crude petroleum, petroleum products, and fuel gases and, where applicable, to distribution systems. Refer to the standard and ANSWER the following:

a. In accordance to API 1104, an individual or scattered porosity shall be considered a defect should the size of the pore is:

b. Is it correct to interpret that the spacing of the larger acceptable sized of porosity, be spaced such that the distance is similar?

Section 10 – Repair and removal of defects

1. In accordance to API 1104, repair and removal of weld defect is a commonly used technique in which the cracked material is removed by arc gouging and the element is welded to re-join the material on either side of the crack

i. Accordance to section 10.1.2. Describe two conditions that require a qualified repair welding procedure

ii. Accordance to section 10.1.1, what is the acceptable value for cracks after evaluation and repaired? And what types of cracks are permitted?

2. A qualified repair procedure must include the minimum requirements listed in 10.2.1 through 10.2.6. Destructive testing is necessary to demonstrate that the procedure is adequate.

i. Accordance to section 10.2.1, what is the method of exploration of the defect?

ii. Accordance to section 10.2.3, what type of inspection should be used to confirm completion removal of the defect?

iii. Accordance to section 10.2.4, why it is necessary to used preheat and interpass heat treatment after repairing the weld defect?

Discussion Question.

1. Which welding process may be done in common application in industry for the permitted process?

2. Which NDT may be done in common application in industry for the permitted technique?

3. API 1104 applies to the welding of pipe and fittings that conform to which specification?

4. Atmospheres for shielding an arc may consist of ____________:

5. Which of the following represent changes in essential variables for a manual welding procedure?

6. A welding procedure test is being performed on 3 inch schedule 80 pipe (0.300” wall). What is the total number of specimens required for testing?

7. For procedure qualification, the exposed surfaces of each nick-break specimen shall ____________

8. What is the criteria to test fillet-welded joints for qualification of a welding procedure?

9. The bend test shall be considered acceptable if:

10. The exposed surfaces of each fillet-weld-break specimen shall show:

VLE questions list for Chapter 2:

Types of questions	Total questions	Week	Time	Durations
Multiple choice	100	4		2 hours
True and false	50	5		1.5 hours
Missing words	200	4 & 5		2 hour

Chapter 5 – Weld Inspection Practice (ISO 5817)

5.1 Introduction

Methods of weld testing and analysis are used to assure the quality and correctness of the weld after it is completed. This term generally refers to testing and analysis focused on the quality and strength of the weld.

• To ensure development of quality weld by collecting qualitative and quantitative data.

– Qualitative - Non destructive tests

– Quantitative - Hardness, tensile strength, ductility, toughness, fracture toughness

• To asses suitability of welding for specific application.

Stages of Inspection

- Before Welding – Cleaning, Edge preparation

- During Welding - Selection of input parameters, welding speed

- After Welding – Removal slag, Peening, Pwht

Types of weld inspection

- – Destructive

o • Physical damage to w/p and welded join.

o • Quantitative data obtained

- – Non Destructive

o • Without Physically damaging the workpiece and joint

o • Qualitative data is obtained

5.2 Visual Inspection

Visual examination of the test weld is a requirement for welder qualification and generally precedes preparation and testing of samples for mechanical testing. If the visual examination reveals that the weld contains imperfections that exceed the limits given in 6.4, rejection is automatic and no additional testing need be performed.

5.3.1 Visual Inspection (VT)

Visual inspection is often the most cost-effective method, but it must take place prior to, during and after welding. Visual examination of the test weld is a requirement for welder qualification and generally precedes preparation and testing of samples for mechanical testing. Before the first welding arc is struck, materials should be examined to see if they meet specifications for quality, type, size, cleanliness and freedom from defects. Grease, paint, oil, oxide film or heavy scale should be removed. The pieces to be joined should be checked for flatness, straightness and dimensional accuracy.

During fabrication, visual examination of a weld bead and the end crater may reveal problems such as cracks, inadequate penetration, and gas or slag inclusions. Among the weld defects that can be recognized visually are cracking, surface slag inclusions, surface porosity and undercut.

5.3.2 Conditions for Visual inspection

The conditions for visual inspection can are affected mainly by the following:

i. Lightning

ii. Angle and distance of viewing

Light

It is essential that their is adequate illumination (lighting) present during inspection and that the access and angle of viewing are suitable. BS EN 970 states that the minimum light conditions shall be 350 lux. (500 lux similar to normal shop).

Angle and Distance

BS EN 970 states that viewing conditions for direct inspection shall be within 600mm of the surface and the viewing. For general visual inspection of welds there is generally an optimum viewing range of 150 – 500 mm where inspection can comfortably be carried out. It should be remembered that it is very good practice to carry out visual inspection using a variety of viewing angles as some imperfections particularly mechanical damage can only be identified when viewed in reflected light.

5.3.3 Visual Inspection Tools

To visually inspect and evaluate welds, adequate illumination and good eyesight provide the basic requirements. In addition, a basic set of optical aids and measuring tools, specifically designed for weld inspection can assist the inspector. Listed below are some commonly used tools or methods with VT of welds:

· Optical Aids

o Lighting

o Mirrors

o Magnifiers

o Borescopes and Fiberscopes

· Mechanical Aids

o Steel ruler

o Vernier scale

o Combination square set

o Thickness gauge

o Levels

· Weld Examination Devices

o Inspector’s kit

o Bridge cam gauge

o Fillet weld gauge

§ Adjustable fillet weld gauge

§ Skew-T fillet weld gauge

§ The weld fillet gauge

§ Hi-lo welding gauge

§ Digital pyrometer or temperature sensitive crayons

5.4 ISO 5817

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

5.5 Visual Inspection Report Form

The requirement for examination records/inspection reports will vary according to contract and type of fabrication and there may not always be a need for a formal records. When a records is required it may be necessary to show that items have been checked at the specified stages and that they have been checked at the specified stages and that they have satisfied the acceptance criteria, The form of this record will vary possibly a signature against an activity on an Inspection Check List or Quality Plan or an individual report for an item. Typical lists details for inclusions as:

a) Name of the component manufacturer

b) Examining body, if different

c) Identification of the object examined

d) Material

e) Type of joint

f) Material Thickness

g) Welding process

h) Acceptance criteria

i) Imperfections exceeding the acceptance criteria and their location

j) Extent of examination with reference to drawing as appropriate

k) Examination devices used

l) Result of examination with reference to acceptance criteria

m) Name of examiner/inspector and date of examination

When it is required by contract to produce and retain permanent visual records of a weld as examined, photographs, accurate sketches or both should be made with any imperfections clearly indicated.

5.6 Fillet Welded Tee Joint

In this type of connection one plate element "T"'s into another. The joint can be made with fillet, partial penetration, or full penetration welds. Fillet welded joints such as 'T', lap and corner joints are the most common connection in welded fabrication. In total they probably account for around 80% of all joints made by arc welding.

To assess a Fillet welded T Joint for sizes and visual acceptance of the weld and joint, several guidance should be considered.

1) Firstly, the plate reference number must be recorded in the top left hand corner of the report sheet, then thickness of the plate is measured and then entered in the top right hand corner of the report sheet in the boxes provided.

2) Secondly, both fillet weld leg lengths must be measured to find both maximum and minimum leg lengths in both Vertical and Horizontal legs. These values are entered in the boxes provided on the report sheet. Use the gauge as shown below:

(i) Fillet Weld Leg Length:

The gauge may be used to measure fillet weld leg lengths of up to 25mm, as shown on left.

(ii) Fillet Weld Leg Length:

The gauge may be used to measure fillet weld leg lengths of up to 25mm, as shown on left.

3) Thirdly, the maximum and minimum throat thickness is measured and entered in the boxes provided on the report sheet. These values are measured as shown below:

5.7 Macro-examination

Macro-etching is the procedure in which a specimen is etched and evaluated macrostructurally at low magnifications. It is frequently used for evaluating carbon and low alloy steel products such as billets, bars, blooms and forgings as well as welds. Macro-examinations are also performed on a polished and etched cross-section of a welded material. During the examination, a number of features can be determined including weld run sequence, important for weld procedure qualifications tests.

5.7.1 Micro-examination

This is performed on samples either cut to size or mounted in a resin mould. The samples are polished to a fine finish, normally one-micron diamond paste and usually etched in an appropriate chemical solution prior to examination on a metallurgical microscope. Micro-examination is performed for a number of purposes, the most obvious of which is to assess the structure of the material. It is also common to examine for metallurgical anomalies such as third phase precipitates, excessive grain growth, etc.

No.	DEFECT	SIZE	ACCEPT / REJECT / REFER
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Comments:
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Signature: ……………………………………………		Date: ……………………………………………

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Chapter 6 – Welding Process

6.1 Oxy Fuel Arc Welding (OAW)

The oxyacetylene welding process uses a combination of oxygen and acetylene gas to provide a high temperature flame. The high temperature flame melts the metal faces of the work-pieces to be joined, causing them to flow together. A filler metal alloy is normally added and sometimes used to prevent oxidation and to facilitate the metal union.

6.2 Shielded Metal Arc Welding (SMAW)

SMAW is manual arc welding in which the heat for welding is generated by an electric arc established between a flux-covered consumable metal rod called the electrode and the work. For this reason, the process is also called stick electrode welding. The combustion and decomposition of the electrode creates a gaseous shield that protects the electrode tip, weld puddle, arc, and the highly heated work from atmospheric contamination.

6.3 Flux Cored Arc Welding (FCAW)

Flux Cored Arc Welding (FCAW) uses the heat generated by a DC electric arc to fuse the metal in the joint area, the arc being struck between a continuously fed consumable filler wire and the workpiece, melting both the filler wire and the workpiece in the immediate vicinity. The entire arc area is covered by a shielding gas that protects the molten weld pool from the atmosphere. FCAW is a variant of the MIG process and, while there are many common features between the two processes, there are also several fundamental differences.

6.4 Gas Metal Arc Welding (GMAW)

The complete name for GMAW is gas metal arc welding as shown in Figure 11. Slang and trade names are often applied, such as MIG for metal inert gas (aluminum and magnesium are typical when only an inert gas is used) or MAG for metal active gas [carbon steel and stainless-steel welding when carbon dioxide (CO2) and/or oxygen (O2) is added to the inert gas]. Some slang names relate more specifically to the part of the process like CO2 or wire welding.

6.5 Gas Tungsten Arc Welding (GTAW)

The necessary heat for Gas Tungsten Arc Welding (TIG) is produced by an electric arc maintained between a non consumable tungsten electrode and the part to be welded. Consequently, GTAW is commonly known as TIG (tungsten inert gas) welding. The heat-affected zone, the molten metal, and the tungsten electrode are all shielded from the atmosphere by a blanket of inert gas fed through the GTAW torch. Inert gas is that which is inactive, or deficient in active chemical properties. The shielding gas serves to blanket the weld and exclude the active properties in the surrounding air. GTA welding is efficient for welding metals ranging from sheet metal up to 1/4 in.

6.6 Plasma Arc Welding

If a high voltage is applied between the electrode and the workpiece while the plasma gas is flowing, the gas is ionized and becomes conductive, then a plasma arc is generated. Since the plasma arc is restricted by the nozzle, it had higher energy density, compared to MAG and TIG and can be used as a heat source of ultra high temperature (above 20,000°C) having high heat concentrating performance.

6.7 Submerged Arc Welding

The controlled welding current provides the heat to fuse the filler rod, parent metal and flux which is supplied from flux hopper. The flux forms a slag than deposited the weld metal and floats on the surface as a protective cover against oxidization of the steel. The wire speed controlled by a wire feeder to adjust the deposition rate according to different heat input. The infused flux is collected by vacuum for recycling and thus keeping the working area air clean.

Discussion Question

SMAW

1. SMAW is manual arc welding in which the heat for welding is generated by an electric arc. What is the factors to successful for Smaw welding?

2. The size of the electrode generally depends on the thickness of the section being welded, and the thicker the section the larger the electrode required. What is the application of electrode for AWS E7024?

3. Name three types generic of flux covering of consumable electrodes for Smaw welding process.

4. The flow of electrons through the circuit is the welding current, measured in Amperes (I). What types of defects will appear when amperage too high?

5. Arc voltage is the voltage required to maintain the arc during welding and is usually between 20-40V. What types of defect will appear when arc voltage too low?

6. What are the most common stick electrodes? And give the examples.

7. What do AWS E7018 stick electrode classifications mean?

8. What function does the flux surrounding a stick electrode serve?

9. What are the two methods of striking an arc?

10. What are the two primary kinds of beads? How are they made?

FCAW / GMAW

1. Sketch the FCAW-G and FCAW-S process schematics and label and highlight the differences.

2. Describe the three main modes of metal transfer used with the GMAW process.

3. Describe how bird nesting can be eliminated.

4. Describe the crater filling technique.

5. Describe the use of the following GMAW and FCAW machine controls: wire-feed speed control, voltage control, slope control, inductance control.

6. List five items necessary for the constant voltage power source and constant speed wire feeder to function properly to sustain the welding arc.

7. Describe the indicator you will have if the proper arc length (voltage) is set when a spray arc mode of metal transfer is being used.

8. List the safety concerns for GMAW that are different than those for the SMAW and GTAW processes.

9. List the types of metal that can be welded with the GMAW process.

10. List the four causes of incomplete penetration and fusion when welding aluminum with the GMAW process.

Chapter 7 – Welding Cutting Process

Cutting of metals implies severing or removal of metal. Cutting is the process of separating metals, i.e., a metal piece is separated or split into two parts. Cutting of metals is an everyday practice in industry.

When it comes to cutting metal, several processes are available today. Two of the most widely used thermal cutting technologies are oxyfuel and plasma. Although oxyfuel is a tried-and-true method, plasma is a more versatile – and less expensive – alternative with an equally good performance record.

7.1 Flame Cutting

The process often called Flame Cutting is known by many names, such as Oxy Acetylene Cutting, Oxy Fuel Gas Cutting, Oxygen Burning, Steel Burning and other terms too numerous to mention. It is an oxygen cutting process wherein the severing of metals is effected by means of the chemical reaction of oxygen with the base metal at elevated temperatures, the necessary temperature being maintained by means of a gas flame obtained from the combustion of a fuel gas (such as acetylene, hydrogen, propane, etc.) and oxygen.

7.2 Thermal Cutting

The thermal processes and the oxy-fuel gas process in particular share two disadvantages. First, heat changes the structure of metal in a "heat-affected zones" adjacent to the cut. This may degrade some metallurgical qualities at the cut's edge, requiring pre-treatment or trimming. Secondly, tolerances may be less accurate than a machined cut, except for laser cutting.

7.3 Plasma cutting

Plasma is defined as a gas which has been heated to an extremely high temperature and ionized so that it becomes electrically conductive. The plasma arc cutting and gouging processes use this plasma to transfer an electric arc to the workpiece. The metal to be cut or removed is melted by the heat of the arc and then blown away. By forcing the plasma gas and electric arc through a small orifice, the torch delivers a high concentration of heat to a small area.

Discussion

1. What principle makes possible the cutting of metal by OFC?

2. How does a cutting torch differ from a welding torch?

3. What determines the oxygen and acetylene pressure that must be used for cutting?

4. What is the benefits to facilitate an even cut?

5. How can it be determined that the cut is penetrating through the metal?

6. What is the position of the torch when cutting round stock?

7. What is the possible steps to making a bevel angle cut with cutting torch?

8. Describe the operation for piercing small holes with a cutting torch.

9. Describe the operation for cutting cast iron, assuming a good grade of iron?

10. How is the torch held when cutting cast iron?

11. What types of metals can be cut by Plasma Arc Cutting?

12. What type of electrode is used in the Air Carbon Arc Cutting processes?

13. What does the term “washing” mean when using Air Carbon Arc Cutting?

14. What are some of the precautions that should be observed before engaging in any cutting operation?

Chapter 8 – Weld Symbol

8.1 Introduction

The use of welding symbols enables a designer to indicate clearly to the welder, important detailed information regarding the weld. The information in the welding symbol can include details for the weld such as length, depth of penetration, height of reinforcement, groove type, groove dimensions, location, process, filler metal, strength, number of welds, weld shape, and surface finishing. All of this information would normally be included on the welding assembly drawings.

It is important to study and understand each part of the welding symbol. Figure 1 is a table showing basic weld symbols that are used with the AWS welding symbol to direct the welder in producing the proper weld joint. The arrow of the welding symbol indicates the point at which the weld is to be made. The line connecting the arrow to the reference line is always at an angle.

Figure 1 shows the basic components of welding symbols, consisting of a reference line with an arrow on one end. Other information relating to various features of the weld are shown by symbols, abbreviations, and figures located around the reference line. A tail is added to the basic symbol as necessary for the placement of specific information.

8.2 Indicating Types Of Welds

Welds are classified as follows: fillets, grooves, flange, plug or slot, spot or protecting, seam, back or backing, and surfacing. Each type of weld has a specific symbol that is used on drawings to indicate the weld. A fillet weld, for example, is designated by a right triangle. A plug weld is indicated by a rectangle. All of the basic symbols are shown in Figure 2.

8.3 Weld Location

Welding symbols are applied to the reference line at the base. All reference lines have an arrow side (near side) and other side (far side). Accordingly, the terms arrow side, other side, and both sides are used to locate the weld with respect to the joint. The reference line is always drawn horizontally. An arrow line is drawn from one end or both ends of a reference line to the location of the weld. The arrow line can point to either side of the joint and extend either upward or downward. If the weld is to be deposited on the arrow side of the joint (near side), the desired weld symbol is placed below the reference line, Figure 3A.

FIGURE 3 Designating weld location. American Welding Society

8.4 Location Significance Arrow

In the case of fillet and groove welding symbols, the arrow connects the welding symbol reference line to one side of the joint. The surface of the joint that the arrow point actually touches is considered to be the arrow side of the joint. The side opposite the arrow side of the joint is considered to be the other (far) side of the joint.

Discussion

1. What is meant by the arrow side of the welding symbol?

2. What is meant by the other side of the welding symbol?

3. Indicate the meaning of the following welding symbols.

4. What type of weld do these symbol indicate?

5. These symbols represent for what weld specification?

6. These symbol represent for what weld specifications?

7. Draw completed welding symbols including necessary information, to describe the following welds.

Indicates flare vee groove weld joint

8. What do these welding symbols mean?

9. What do these welding symbols represent?

10. Identify the parts of the master welding symbol shown

1
2
3
4
5
6
7
8
9
10
11
12
13

Chapter 9 – Material Identification

9.1 Introduction

During welding inspection, the inspector should verify the conformance of the base material and filler metal chemistries with the selected or specified alloyed materials. This should include reviewing the certified mill test report, reviewing stamps or markings on the components.

9.2 Material type and weldability

A welding inspector must understand and interpret the material designation to check compliance with relevant normative documents. For example materials standards such as BS EN, API, ASTM, the WPS, purchase order, fabrication drawings, quality plan/contract specification and client requirements.

A commonly used material standard for steel designation is BS EN 10025 – Hot rolled products of non-alloy structural steels.

9.3 Material condition and dimensions

The condition of the material could have an adverse effect on the service life of the component so is an important inspection point. The points for inspection must include:

 General inspection.

 Visible imperfections.

 Dimensions.

 Surface condition.

There are four grades of rusting which the inspector may have to consider:

Rust Grade A: Steel surface largely covered with adherent millscale with little or no rust.

Rust Grade B: Steel surface which has begun to rust and from which mill scale has begun to flake.

Rust Grade C: Steel surface on which the mill scale has rusted away or from which it can be scraped. Slight pitting visible under normal vision.

Rust Grade D: Steel surface on which mill scale has rusted away. General pitting visible under normal vision.

Chapter 10 – Documents Related to Welding Inspection

10.1 Introduction

It is essential for the welding inspector to have an opportunity to study all applicable documents before the start of the job. This pre welding effort provides the welding inspector with information about the upcoming inspection. Some of the information that can be gained from this document review includes the following:

• Part size and geometry

• Base and filler metals to be used

• Requirements for hold points

• Processing details

• Processes to be used

• Specification for nondestructive inspection

• Extent of inspection

• Acceptance/rejection criteria

• Qualification requirements for personnel

• Procedure and welder qualification

• Materials control requirements

10.2 Drawing

Drawings describe the part or structure in graphic detail. Drawing dimensions, tolerances, notes, weld and welding details, and accompanying documents should be reviewed by the inspector. This gives the welding inspector some idea of the part size and configuration.

Dimensions provided on a blueprint have two basic functions:

· To provide the sizes needed to fabricate the parts.

· To indicate locations where the individual components of each part should be placed.

Welding details shown on drawings or other documents include locations, lengths and sizes of welds, joint configurations, material call-outs, specification of non-destructive examination, and special processing requirements. Some materials require special techniques such as preheating. The welding inspector should be aware of this before the start of any welding.

10.3 Codes

The welding inspector will often inspect work according to some code. Several organizations including AWS and ASME have developed codes for various areas of concern. AWS has published nine codes, each of which covers different types of industrial welding applications:

· AWS D1.1 Structural Welding Code—Steel

· AWS D1.2 Structural Welding Code—Aluminum

· AWS D1.3 Structural Welding Code—Sheet Steel

· AWS D1.4 Structural Welding Code—Reinforcing Steel

· AWS D1.5 Bridge Welding Code

· AWS D1.6 Structural Welding Code—Stainless Steel

· AWS D1.8 Structural Welding Code—Seismic Supplement

· AWS D1.9 Structural Welding Code—Titanium

· AWS D9.1 Sheet Metal Welding Code

Many codes are issued by professional organizations such as the American Welding Society (AWS) and the American Society of Mechanical Engineers (ASME) and trade associations like the American Petroleum Institute (API).

They are known as consensus standards. Committees of senior engineers and scientists within these organizations establish and update these codes.

With so many different sections involved, it is imperative that the welding inspector understand where each specific type of information can be found. It should be noted that Section II, Part C, is essentially identical to the AWS Filler Metal Specifications; ASME adopted the AWS specifications almost in their entirety. If the inspector specializes in a certain area, then only the section covering the topic concerned needs to be reviewed

10.4 Standard

A standard is treated as a separate document classification; however, the term standard also applies to numerous types of documents, including codes and specifications. Other types of documents considered to be standards are procedures, recommended practices, groups of graphic symbols, classifications, and definitions of terms.

Some standards are considered to be mandatory. This means the information is an absolute requirement. A mandatory standard is precise, clearly defined and suit-able for adoption as part of a law or regulation. There-fore, the welding inspector must make judgments based on the content of these standards. These mandatory standards use such words as “shall” and “will” because their requirements are not a matter of choice. Codes are examples of mandatory standards because they have legal status.

Another common standard used by certain welding inspectors is the American Petroleum Institute’s API 1104, Standard for Welding of Pipelines and Related Facilities. As the name implies, this standard applies to the welding of cross-country pipelines and other equipment used in the transportation and storage of petroleum products. This standard covers the requirements for qualification of welding procedures, welders and welding operators. It applies to gas and arc welding of butt and T-joints in pipe used in the compression, pumping, and transmission of crude petroleum, petroleum products, and fuel gases. API 1104 also includes requirements for the visual and radiographic inspection of these welds.

The American Society for Testing and Materials (ASTM) produces many volumes of specifications covering numerous materials and test methods. These standards include both metal and nonmetal products for many industries. As their name implies, they are also involved in the details of methods for evaluating these materials. These specifications are widely recognized by both buyers and suppliers. The result is a better under-standing of the requirements for particular materials and test methods. When a specific material or test is required, it is easier to communicate the necessary information if the specification exists and is readily available.

10.5 Specifications

The final document classification to be discussed is the specification. This type is described as, “a detailed description of the parts of a whole; statement or enumeration of particulars, as to actual or required size, quality, performance, terms, etc.” A specification is a detailed description or listing of required attributes of some item or operation. Not only are those requirements listed, but there may also be some description of how they will be measured.

Other organizations that have developed specifications for their particular industries are API and AWS. API specifications govern the requirements for materials and equipment used by the petroleum industry.

The American National Standards Institute (ANSI) is a private organization responsible for coordinating national standards for use within the United States. ANSI does not actually prepare standards. Instead, it forms national interest review groups to determine whether proposed standards are in the public’s interest. If the consensus is reached for the general value of a particular standard, then it may be adopted as an American National Standard. However, adoption of a standard by ANSI does not, of itself, give it mandatory status.

Other industrial countries also develop and issue standards on the subject of welding. There is an International Organization for Standardization (ISO). Its goal is the establishment of uniform standards for use in international trade and exchange of services. ISO is made up of the standards-writing bodies of more than 80 countries and has adopted or developed over 4000 standards. ANSI is the designated U.S. representative to ISO. ISO standards and publications are available from ANSI.

The American Welding Society (AWS) publishes numerous documents covering the use and quality control of welding. These documents include codes, specifications, recommended practices, classifications, methods and guides. AWS publications cover the following subject areas: definitions and symbols; filler metals; qualification and testing; welding processes; welding applications; and safety.

10.6 Control of Materials

Materials for welded fabrication are often ordered with the stipulation that they meet a particular standard or specification. To demonstrate this compliance, the sup-plier can furnish documentation that describes the important characteristics of the material. This documentation for metals is sometimes referred to as an “MTR,” which is the abbreviation for Material (or Mill) Test Report, or “MTC,” which is the abbreviation for Material (or Mill) Test Certificate.

When material ordered to some specification arrives at the fabrication site, the inspector may be responsible for reviewing the accompanying MTRs. This review can aid in determining whether or not the material meets all the applicable requirements of that specification. Normally, the material will be physically identified as to its type, grade, heat number, etc. This identification may be painted, stenciled, or otherwise noted in some conspicuous location on the material’s surface. The inspector should compare that identification with the information contained on the MTR to ensure that the proper documentation has been provided and that the material is actually that which was ordered.

For a material control program to be successful there must be some system whereby the received material can then be traced through the various fabrication steps. The goal is to be able to trace each piece of material used in some fabricated component all the way back to the MTR, and therefore, its manufacturer. Positive Material Identification (PMI) is finding its way into the industry. Those using PMI do not rely on MTRs solely for material identification. There have been instances where Notarized MTRs have been wrong. In some critical applications such as chemical plants and refineries the material is checked 100% to verify its chemistry.

A short, specific alphanumeric code can be assigned to a specific group of material to simplify the operation while still maintaining traceability. When material of a given type, grade, heat, etc., is received, it is assigned some code such as A1, A2, A3, …, D1, D2, etc. The material information is then listed on a log sheet and associated with its proper alphanumeric code. Once this relationship is established, the specific code is all that is needed to trace that material through the fabrication steps.

10.7 Alloy Identification

Alloy identifications are usually developed by industry associations such as the Society of Automotive Engineers (SAE), American Iron and Steel Institute (AISI), and the Copper Development Association (CDA). Alloy identification systems were created to assist those working within a particular industry, and often with little regard to industries outside their sphere of influence. The Unified Number System (UNS) was developed in 1974 to help interconnect many nationally used numbering systems that are currently supported by societies, trade associations, and individual users and producers of metals and alloys. The UNS is a means to avoid confusion caused by the use of more than one identification number for the same material, or the same identification numbers appearing for two or more entirely different materials.

The standard practice initiated by the Unified Numbering System aids the efficient indexing, record keeping, data storage, retrieval and cross referencing of metals and alloys. The system is not, however, a specification regarding form, condition, quality, etc., of the materials covered. It is for basic identification purposes only.

10.8 Typical Steel Specification

The welding inspector is sometimes required to compare actual material properties with the requirements of the specified material specification. ASTM has developed numerous material specifications; those referring to metals contain much the same types of information. To become familiar with what type of information is pro-vided as well as how it is presented; a typical steel specification will be discussed.

For this example, the ASTM specification A 514, Standard Specification for High Yield Strength, Quenched and Tempered Alloy Steel Plate, Suitable for Welding, will be used to illustrate some of the details which may be included in a typical steel specification.

Scope. This statement explains exactly what is to be described by the specification. That is, it defines the limits of the specification’s coverage.

Applicable Documents. This is a listing of other documents which may be referred to within the text of the specification.

General Requirements for Delivery. Here, there is a statement regarding the required condition of the material if ordered to comply with this specification. Steel specifications will normally refer to ASTM A 6 rather than including all of those requirements in each individual specification.

Process. The approved method(s) of producing this product are listed.

Heat Treatment. For alloys requiring heat treatment, the details of that treatment will be stated.

Chemical Requirements. This section refers you to a table which lists the actual chemical composition requirements. It is important to note that several grades will usually be listed, and each grade has a separate required chemical composition.

Tensile Requirements. This paragraph refers to a table which defines the required tensile values for the alloy. Required tensile values are usually different for various thickness ranges.

Brinell Hardness Requirements. For materials requiring Brinell hardness testing, the extent and requirements are stated.

Test Specimens. Any information relating to the location, preparation and treatment of test specimens is stated here.

Number of Tests. The number of test specimens required to show compliance is stated.

Retest. This paragraph describes what procedures will be followed if any of the test specimens fail

Marking. A statement is made regarding how this material will be identified.

Supplemental Requirements. Any additional details which may be required by the purchaser are stated. These are not considered to be requirements unless so stated by the purchaser in the purchase order.

10.9 Typical Filler Metal Specification

The welding inspector may also be required to review welding filler metal properties to check for compliance with the applicable specification. One of these specifications, AWS A5.1, Specification for Covered Carbon Steel Arc Welding Electrodes, will serve as an example of the type of information provided as well as a description of the meaning of that information.

Some of the important features of this specification are described below.

Scope. This describes the coverage of the specification.

Section A—General Requirements

Classification. The basis for classification is stated. Reference is made to various tables which list these classifications, based on type of current, type of covering, welding position, chemical composition, and mechanical properties.

Acceptance. States that electrodes will be accepted if they comply with the requirements of AWS A5.01.

Certification. States that the manufacturer must certify that his product meets all of the requirements of this specification.

Retests. If any test fails, two retests must be conducted and each must pass.

Method of Manufacture. Any method of manufacture which produces a product in accordance with this specification is satisfactory.

Marking. States what minimum identification must be visible on the outside of each package.

Packaging. Describes suitable packaging, including standard sizes and configurations.

Rounding-off Procedures. Explains how tensile data will be rounded to the nearest 1000 psi.

Section B—Required Tests and Test Methods. Describes the various chemical and mechanical tests which may be required to judge the acceptability of a filler metal with this specification. Tests include chemical composition, all-weld-metal tensile, impact, sound-ness, transverse tensile, longitudinal guided bend, and fillet weld tests.

Section C—Manufacture, Packaging, and Identification. Details the specification requirements for these features.

Section D—Details of Tests. Describes the actual details of performing the various tests used to measure the suitability of a filler metal to meet this specification. It also describes which of those tests are required for each classification.

Appendix. Contains additional descriptive information about certain requirements found in the main body of the specification. Includes information related to the actual care and use of electrodes complying with this specification.

10.10 Qualification of Procedures and Welders

Part of every major welding project, whether completed in the shop or field, is the qualification of welding procedures and welders, or welding operators. It is one of the most important preliminary steps in the fabrication sequence. Too often projects are begun without the bene-fit of proven welding procedures and personnel. This can result in excessive reject rates in production due to some unsuspected deficiency in the technique, materials or operator skill.

During the performance of this qualification testing, the welding inspector may become involved. Individual company structures will dictate the degree of involvement in this process. Some codes require that the weld-ing inspector witness the actual qualification welding and testing. Consequently, the welding inspector should be aware of the various steps in the qualification of welding procedures and welding personnel.

Most codes place the burden of responsibility for qualification on the fabricator or contractor. Therefore, welding qualifications are statements by the company verifying that the welding procedures and personnel have been tested in accordance with the proper codes and specifications and found to be acceptable.

The welding inspector may also become involved with these qualifications from a document review standpoint. One of the responsibilities may be to review both welding procedure and welder qualification forms to deter-mine if they are in accordance with the code and job specifications. Experienced welding inspectors realize that numerous problem spots can be detected and corrected prior to welding if this review is done carefully. Further, most codes give the welding inspector the authority to request that welders be prequalified in the event they continue to produce substandard work.

10.11 Procedure Qualification

The very first step in the qualification process is the development of the welding procedure. This must pre-cede both the welder qualification and the production welding because it will determine if the actual technique and materials are compatible. In general, the welding procedure qualification is performed to show the compatibility of:

· base metal(s),

· weld or braze filler metal(s),

· process(es), and

· techniques.

Before we can evaluate the skill of welders to make a joint, we must first define the joint itself and the process to make it. To do this we must develop a welding procedure specification (WPS). There are three general approaches to procedure qualification. These include prequalified procedures, actual procedure qualification testing, and mock-up tests for special applications. The mock-up tests may be used to supplement the other more standard methods of procedure qualification.

A video that does a little bit of a deep dive into Prequalified Welding Procedure Specifications, mainly focusing on Clause 3 of AWS D1.1 Structural Steel Welding Code

https://www.youtube.com/watch?v=yIqsLJxrCsQ

Solehah

Selasa, 11 Ogos 2020

Welding Inspection Technology Course

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