This was an interview question. Ask many people what a welding engineer does and the answer will often be simple:

“A welding engineer writes WPS.”

That answer is correct. But it is dangerously incomplete. A Welding Procedure Specification (WPS) is only one part of the story. The real work of a welding engineer is much bigger than producing documents.

A welding engineer turns design requirements, material behaviour, welding metallurgy, process control, welder competence, inspection requirements and acceptance criteria into a welded joint that is fit for service.

In other words: A welding engineer makes sure that a weld is not just made, but engineered.

Start with the load, not the weld

Imagine a component that must be fabricated. In service, that component will experience an applied stress of 200 MPa. The first question is not: Can we weld it?

The real question is:

Can we produce a welded joint that will safely carry that stress, in that material, under that loading condition, in that service environment, for the required design life?

That is where welding engineering begins. Because welding is not only about joining two pieces of metal. It is about producing a joint that can perform safely under real service conditions.

• A weld may look neat and still fail.
• A weld may pass visual inspection and still contain internal imperfections.
• A weld may have enough strength for static loading but perform poorly under fatigue.
• A weld may meet dimensional requirements but have poor toughness, excessive hardness, lack of fusion, high residual stress or an unsuitable metallurgical structure.

This is why weld quality must be built into the process before welding starts. It cannot be added at the end by inspection.

Welding is a special process

Welding is commonly treated as a special process because the final quality of the joint cannot always be fully verified by inspection of the completed product alone.

• A radiograph may find volumetric imperfections.
• Ultrasonic testing may detect internal planar imperfections.
• Visual testing may identify surface condition and profile.
• Hardness testing may reveal unacceptable hard zones.
• Impact testing may confirm toughness.

But none of these controls can replace proper welding engineering before production begins.

The quality of a welded joint depends on decisions made long before the welder strikes an arc.

Those decisions include:

1. Material selection
2. Filler metal selection
3. Joint design
4. Welding process selection
5. Heat input control
6. Preheat and interpass temperature
7. Welding sequence
8. Consumable control
9. Welder competence
10. Inspection and acceptance requirements

This is why ISO 3834 is important. It provides quality requirements for fusion welding of metallic materials and is applicable to both workshop fabrication and site installation.

The WPS is not paperwork

The WPS, is one of the most familiar documents in welding. But a WPS should never be treated as ordinary paperwork. A WPS is the controlled instruction for making the weld. It tells production how the weld shall be made, using defined parameters and controlled conditions.

A typical WPS may include:

1. Welding process
2. Parent material
3. Material thickness range
4. Joint type and preparation
5. Welding position
6. Filler metal
7. Shielding gas or flux
8. Current and voltage
9. Travel speed
10. Heat input or arc energy
11. Preheat temperature
12. Interpass temperature
13. Welding technique
14. Number of runs
15. Post weld heat treatment, where required

In the ISO system, ISO 15609 defines the content and structure of the WPS. For arc welding, ISO 15609-1 is the relevant part.

A good WPS gives the welder a controlled method. But the WPS alone is not enough. It must be supported by evidence. That evidence is the WPQR.

The WPQR proves the method

In ISO terminology, the qualification record is commonly called the Welding Procedure Qualification Record, or WPQR. In many industries, people also use the term PQR. The purpose is the same:

The WPQR proves that the proposed welding procedure can produce a joint with the required properties. A test weld is made using the proposed welding conditions. The test weld is then examined and tested.

Depending on the material, application standard and project requirement, testing may include:

1. Visual testing
2. Radiographic testing
3. Ultrasonic testing
4. Magnetic particle testing
5. Penetrant testing
6. Tensile testing
7. Bend testing
8. Impact testing
9. Hardness testing
10. Macro examination

This is where assumption is replaced by evidence.

The message is simple: Do not assume the weld is acceptable. Prove it.

ISO 15614-1 is widely used for welding procedure qualification testing for arc and gas welding of steels and arc welding of nickel and nickel alloys. It defines the test conditions and the range of qualification for production welding applications.

The welder must also be qualified

A qualified WPS does not automatically mean that every welder can make the production weld.

• This is a common misunderstanding.
• The WPS controls the method.
• The WPQR proves the method.
• The welder qualification proves the person.

A project can have a properly qualified procedure and still produce unacceptable welds if the welder is not qualified or competent for the required process, material, position, thickness range or joint type. That is why welder qualification is separate from procedure qualification. ISO 9606 is commonly used for welder qualification. For steel welding, ISO 9606-1 is the relevant part within the ISO welder qualification framework.

In simple terms:

The procedure may be qualified, but the hand that applies it must also be qualified.

Standards give structure, but judgement gives meaning

A welding engineer does not work by guesswork. The work is guided by standards, specifications, drawings, application codes, client requirements, regulations and engineering judgement.

In the ISO system, the following documents are commonly involved:

These documents provide structure. But they do not replace engineering judgement.

For example, ISO 5817 gives quality levels for weld imperfections, but whether a particular imperfection is acceptable still depends on the governing application standard, contract requirement, stress condition, consequence of failure and service environment.

This is why welding engineering is not only about knowing standards. It is about knowing how to apply them.

Inspection does not create quality

Inspection is important. But inspection does not create weld quality. Inspection only confirms whether the weld meets the specified requirements.

Quality is created by:

1. Correct design
2. Correct material selection
3. Correct filler metal selection
4. Qualified welding procedures
5. Qualified welders
6. Controlled welding parameters
7. Controlled consumables
8. Suitable equipment
9. Effective supervision
10. Appropriate inspection and acceptance criteria

ISO 17637 supports visual testing of fusion welded joints. ISO 5817 gives quality levels for imperfections in fusion welded joints. However, inspection and acceptance must always be applied in line with the relevant application standard, client specification and service requirement.

A small imperfection in a lightly loaded static structure may be acceptable. The same imperfection in a fatigue sensitive, pressure retaining or safety critical component may be unacceptable. That is the difference between inspection and engineering judgement.

The welding engineer is the technical bridge

The welding engineer sits between design, production, inspection, quality, procurement, subcontractors and the client.

The role is to translate engineering requirements into controlled fabrication practice.

That may include reviewing:

1. Drawings
2. Material certificates
3. Welding specifications
4. WPS documents
5. WPQR records
6. Welder qualifications
7. Consumable certificates
8. Heat treatment requirements
9. Inspection and test plans
10. NDT reports
11. Non conformity reports
12. Repair procedures
13. Subcontractor welding documentation

The welding engineer also answers the questions that determine whether production is technically compliant:

• Can this WPS be used for this material?
• Does this WPQR cover this thickness?
• Does the welder qualification cover this position?
• Is this filler metal suitable?
• Is preheat required?
• Is the heat input acceptable?
• Is post weld heat treatment required?
• Is this imperfection acceptable?
• Can this weld be repaired?
• What evidence is required for compliance?

These are not administrative questions. They are engineering decisions. They affect safety, quality, structural integrity, cost, programme and reputation.

So, what does a welding engineer do?

A welding engineer ensures that a welded joint is:

1. Suitable for the intended loading condition
2. Made from compatible materials
3. Welded using an appropriate process
4. Controlled by a qualified WPS
5. Supported by suitable WPQR evidence
6. Deposited by a qualified welder
7. Managed under an effective welding quality system
8. Inspected using appropriate methods
9. Accepted against the correct criteria
10. Fit for service in its intended environment

That is the job. Not just paperwork. Not just WPS writing. Not just box ticking.

Frequently Asked Questions

1. What does a welding engineer do?

A welding engineer ensures that welded joints are designed, produced, inspected and accepted in a controlled way so that they are fit for service. The role connects material selection, welding process selection, WPS development, WPQR qualification, welder qualification, inspection requirements and acceptance criteria.

2. Is a welding engineer only responsible for writing WPS?

No. Writing or reviewing a Welding Procedure Specification is only one part of the welding engineer’s role. A welding engineer also considers materials, filler metals, heat input, preheat, interpass temperature, welding sequence, welder competence, inspection methods, defect acceptance and compliance with project or code requirements.

3. What is a WPS?

A WPS, or Welding Procedure Specification, is a controlled document that tells the welder how a weld shall be made. It normally includes the welding process, parent material, filler metal, joint preparation, welding position, current, voltage, travel speed, heat input, preheat, interpass temperature and post weld heat treatment where required.

4. What is the difference between WPS and WPQR?

The WPS gives the instruction for making the weld. The WPQR provides the evidence that the welding procedure has been tested and can produce a weld with the required mechanical and quality properties. In simple terms, the WPS controls the method, while the WPQR proves the method.

5. Is PQR the same as WPQR?

In many industries, the terms PQR and WPQR are used in a similar way. In ISO terminology, WPQR means Welding Procedure Qualification Record. In ASME terminology, PQR means Procedure Qualification Record. Both refer to the qualification evidence supporting a welding procedure, although the exact requirements depend on the applicable code or standard.

6. Why must a welding procedure be qualified?

A welding procedure must be qualified to prove that it can produce a joint with the required properties. A test weld is made using the proposed welding conditions and then examined and tested. This may include visual testing, non destructive testing, tensile testing, bend testing, impact testing, hardness testing and macro examination, depending on the application.

7. Does a qualified WPS mean any welder can use it?

No. A qualified WPS proves that the welding method can work when correctly applied. The welder must also be qualified to show that they have the skill to make the weld under the required conditions. The WPS qualifies the method, while the welder qualification qualifies the person.

8. What standard is used for welder qualification?

In the ISO system, ISO 9606 is commonly used for welder qualification. For steel welding, ISO 9606-1 is commonly applied. The exact part of the standard depends on the material being welded.

9. What standard is used for welding procedure qualification?

ISO 15614-1 is commonly used for welding procedure qualification testing for arc and gas welding of steels and arc welding of nickel and nickel alloys. Other parts of ISO 15614 apply to other materials and welding processes.

10. What standard defines the content of a WPS?

ISO 15609 defines the content requirements for Welding Procedure Specifications. For arc welding, ISO 15609-1 is the relevant part.

11. What is ISO/TR 15608 used for?

ISO/TR 15608 is used for grouping metallic materials for welding purposes. Material grouping helps determine the range of qualification when developing and applying welding procedures.

12. What is ISO 3834 used for?

ISO 3834 provides quality requirements for fusion welding of metallic materials. It helps manufacturers control welding quality through proper planning, competent personnel, qualified procedures, inspection, equipment control, consumable control and documentation.

13. What is ISO 14731 used for?

ISO 14731 defines welding coordination tasks and responsibilities. It is often used to describe the responsibilities of welding coordination personnel, including welding engineers or responsible welding coordinators.

14. What is ISO 17637 used for?

ISO 17637 is used for visual testing of fusion welded joints. Visual testing is one of the most important inspection methods, but it does not replace other NDT methods where internal or surface breaking imperfections must be assessed.

15. What is ISO 5817 used for?

ISO 5817 gives quality levels for imperfections in fusion welded joints. It helps define acceptance levels, but the actual acceptance requirement must still be linked to the application standard, contract specification and service condition.

16. Does inspection create weld quality?

No. Inspection does not create weld quality. It only confirms whether the weld meets specified requirements. Weld quality is created through correct design, suitable materials, qualified procedures, qualified welders, controlled parameters, proper supervision and effective quality management.

17. Why can a weld look good but still fail?

A weld can look good externally but still contain internal imperfections, poor fusion, poor toughness, excessive hardness, unsuitable microstructure or high residual stress. This is why welding quality cannot rely on appearance alone, especially for critical applications.

18. Why is welding called a special process?

Welding is often treated as a special process because the final quality of the weld cannot always be fully verified by final inspection alone. The process must be controlled before, during and after welding to ensure the joint achieves the required properties.

19. What does fit for service mean in welding?

Fit for service means the welded joint is suitable for its intended loading condition, environment and design life. A fit for service weld must have acceptable strength, toughness, soundness, geometry, metallurgical condition and inspection evidence for the application.

20. Why is engineering judgement important in welding?

Standards provide rules and structure, but they do not remove the need for engineering judgement. A welding engineer must understand the material, loading condition, environment, defect risk and consequence of failure before deciding whether a weld, procedure or imperfection is acceptable.

21. What is the main difference between a welding engineer and a welder?

A welder makes the weld. A welding engineer defines, qualifies, controls and verifies the technical route used to make the weld. The welder applies the qualified procedure, while the welding engineer ensures that the procedure, materials, inspection and acceptance criteria are technically suitable.

22. Why is weld acceptance not just about finding a table in a standard?

Acceptance depends on the application. A small imperfection may be acceptable in a lightly loaded structure but unacceptable in a fatigue sensitive, pressure retaining or safety critical component. The welding engineer must understand the consequence of the imperfection, not just the acceptance table.

23. What documents does a welding engineer normally review?

A welding engineer may review drawings, material certificates, WPS, WPQR, welder qualifications, filler metal certificates, inspection and test plans, NDT reports, heat treatment records, repair procedures, subcontractor documents and non conformity reports.

24. Why is a welding engineer important in fabrication?

A welding engineer protects the integrity of the welded product by ensuring that welding is properly planned, qualified, controlled, inspected and accepted. Without welding engineering control, a weld may be produced without enough evidence that it can perform safely in service.

25. What is the simplest way to describe welding engineering?

Welding engineering is the discipline that turns molten metal into a controlled, qualified, traceable, inspectable and serviceable joint. It ensures that the final weld is not just joined, but engineered.

Read more

Welding Imperfections and Classification – Part 1: Cracks

Welding Imperfections and Classification – Part 2: Cavities

Welding Imperfections and Classification – Part 3: Solid inclusions

Welding Imperfections and Classification – Part 4: Lack of Fusion and Penetration

Welding Imperfections and Classification – Part 5: Imperfect Shape and Dimensions

Welding Imperfections and Classification – Part 6: Miscellaneous imperfections