An internal audit checklist for fabrication shops is a structured list of checks and records to sight that tests whether a shop really follows its own quality system, from contract review to final documentation. It turns the requirements of ISO 9001, the ISO 3834 welding quality standard and customer codes into questions an auditor can answer with objective evidence, and it makes audits repeatable between auditors and between years.
This guide gives a ready-to-use checklist organised by process area, a way to plan and run the audit, a grading scheme for findings and a corrective-action method. Weld-specific checks refer to preheat, cooling-rate and carbon-equivalent controls, supported by the preheat temperature calculator and the carbon equivalent calculator.
- An internal audit tests practice against the shop’s own system and the applicable standards.
- Every finding needs objective evidence: a record, a measurement or something observed on the floor.
- Audit by process and sample across jobs, welders and dates, not only by document.
- Grade findings consistently and close each one with a root cause and a check that it worked.
- Auditors should be independent of the area they audit.
What Is an Internal Audit Checklist for a Fabrication Shop?
Internal audit is a first-party review testing whether shop practice matches the documented quality system and applicable standards.
A checklist is the working tool of that review. It lists what to check, what evidence proves the check passed and which requirement the check comes from. It does not replace auditor judgement: it ensures that every process is looked at and that findings are tied to evidence. Shops that fabricate pressure equipment, structural steel or machinery typically build the checklist from three sources: the management system standard, the welding quality standard and the contract requirements for the job being audited.
The audit is first-party because the shop audits itself. A second-party audit is performed by a customer on a supplier, and a third-party audit is performed by an independent certification body. The internal audit is the cheapest of the three and the one that should find problems before the others do.
Why Do Fabrication Shops Need Internal Audits?
Internal audits are required by the management system standard and expected by customers and certification bodies. ISO 9001 (Quality management systems: Requirements) calls for internal audits at planned intervals to show whether the system conforms and is effectively implemented. ISO 19011 (Guidelines for auditing management systems) describes how to plan and conduct them and how to judge auditor competence.
For shops that weld, the welding standard sets the content. The ISO 3834 series (Quality requirements for fusion welding of metallic materials) defines what a manufacturer must control at comprehensive, standard or elementary level, including requirements review, personnel, equipment, procedures, inspection and non-conformance handling. Structural steelwork supplied in Europe also needs factory production control under EN 1090-1, and a working audit programme is the usual evidence that this control is effective. Where customers specify ASME Section IX or AWS D1.1, those codes add procedure and welder qualification rules the audit should check.
The practical reasons are simpler: audits find drift. Welder qualifications lapse, calibration labels go out of date, a revised drawing is not reaching the floor, and a consumable is stored loose. Each is cheap to fix when found internally and expensive when found by a customer, a failed weld test or a field failure.
How Do You Plan and Run an Internal Audit?
An internal audit follows seven steps from programme to verified closure:
- Define the audit scope, criteria and frequency in an audit programme based on risk and past results.
- Select auditors who are competent and independent of the area being audited.
- Prepare the checklist from the standards, the contract requirements and previous findings.
- Hold an opening meeting, then observe work and sample records across jobs, welders and dates.
- Record objective evidence for each check and grade any finding as major, minor or observation.
- Hold a closing meeting and issue a report with owners and response dates.
- Track each corrective action to verified closure and report results to management review.
Frequency is set by risk. Many shops cover every process at least once a year, audit high-risk processes such as special processes and NDT more often, and bring forward an audit when a customer complaint, an internal failure or a process change signals trouble. The auditor should not audit their own work, which is why small shops often swap auditors between departments or use an external auditor for the internal programme. Related technical guides are collected in the Welding Metallurgy category and the Materials Testing category.
On the day, work from evidence. Ask the person doing the job to explain it, then ask to see the record. Trace one job end to end, from the order through the material certificate, the welding procedure, the welder’s qualification, the inspection and the final document pack. A single job traced in depth often exposes more than ten records examined in isolation.
Quick Reference: Internal Audit Checklist by Area
The tables below are a starting checklist. Adapt the items to the shop’s scope and to the code and class named in the contract. Each row gives the check, the evidence to sight and the usual basis. Mark each item conforming, non-conforming or not applicable, and note the evidence reference.
What should be checked in contract and requirements review?
| Check | Evidence to sight | Basis |
|---|---|---|
| Customer specification, drawings and code reviewed before acceptance | Signed review record dated before start | ISO 9001, ISO 3834 |
| Execution class, welding quality level or code stated | Order or specification page | EN 1090-2, ISO 5817 |
| Special requirements captured: impact tests, NDT extent, PWHT, hardness limits | Job traveller or inspection and test plan | Contract, code |
| Subcontracted work identified and the subcontractor approved | Approved supplier list, subcontract order | ISO 3834 |
What should be checked in document control?
| Check | Evidence to sight | Basis |
|---|---|---|
| Current drawing revision at the workstation matches the master | Drawing register against floor copy | ISO 9001 |
| Obsolete documents removed or marked | Floor walk, revision stamps | ISO 9001 |
| Procedures and forms controlled and approved | Document list with revision and approval | ISO 9001 |
What should be checked in purchasing and materials?
| Check | Evidence to sight | Basis |
|---|---|---|
| Material certificate type and content match the order | Certificate against purchase order, such as EN 10204 type 3.1 | EN 10204, contract |
| Heat or batch number on the plate matches the certificate | Mark on the material against the certificate | Traceability requirement |
| Traceability marks transferred when material is cut | Offcut and part marks on a sample job | ISO 3834, contract |
| Carbon steel and stainless steel stored and handled separately | Storage areas, tooling segregation | Shop procedure |
| Welding consumables match the procedure, are stored and handled as the manufacturer directs | Store, ovens, issue log | ISO 3834, manufacturer data |
What should be checked in welding coordination and personnel?
| Check | Evidence to sight | Basis |
|---|---|---|
| Responsible welding coordination named and competent | Appointment letter, training record | ISO 14731, ISO 3834 |
| Each welder’s qualification is valid for the process, material, thickness and position in use | Qualification certificates, maintenance records | ISO 9606-1, ASME IX |
| Welder identification system links each weld to a welder | Weld map, stamp or log | ISO 3834 |
| NDT personnel hold a valid certification for the method used | Certificates and level | ISO 9712 |
What should be checked in welding procedures?
| Check | Evidence to sight | Basis |
|---|---|---|
| Each procedure specification is supported by a qualification record | WPS linked to WPQR or PQR | ISO 15609-1, ISO 15614-1, ASME IX |
| The job parameters fall within the qualified range | Job record against WPS range | Procedure standard |
| The procedure specification is available to the welder at the work | Copy at the station | ISO 3834 |
| Preheat, interpass and heat-input limits are stated and controlled | WPS, temperature record | Procedure standard |
Preheat and cooling limits on the procedure come from the steel’s composition and thickness, and the weld cooling time t8/5 calculator and the explanation of t8/5 cooling time show how the cooling time between 800 and 500 °C is calculated.
What should be checked during production?
| Check | Evidence to sight | Basis |
|---|---|---|
| Fit-up inspected before welding | Fit-up record or hold point signature | Inspection and test plan |
| Preheat measured with a calibrated device before welding | Temperature log, indicator or contact thermometer | WPS |
| Interpass temperature controlled and recorded | Log for a sample weld | WPS |
| Weld repairs follow a repair procedure and are re-inspected | Repair record and re-inspection report | ISO 3834, code |
| Weld area protected from wind, moisture and contamination | Floor observation | Shop procedure |
What should be checked in equipment and calibration?
| Check | Evidence to sight | Basis |
|---|---|---|
| Welding machines and their meters verified or calibrated on schedule | Calibration certificates, status labels | ISO 17662 |
| Measuring tools, temperature devices and gauges calibrated | Calibration register | ISO 9001 |
| Holding ovens for consumables work and are checked | Temperature records | Manufacturer data |
| Action taken when an instrument is found out of tolerance | Impact assessment on earlier work | ISO 9001 |
What should be checked in inspection, NDT and testing?
| Check | Evidence to sight | Basis |
|---|---|---|
| Inspection and test plan followed, with hold points signed | Completed plan on a sample job | Contract, ISO 3834 |
| Visual inspection performed before other NDT | Visual report | ISO 17637 |
| Acceptance criteria match the specified quality level or code | Report against the specification | ISO 5817, code |
| NDT performed to a written procedure, with reports traceable to the weld | Procedure, reports, weld map | Method standard |
| Hardness and impact tests done where specified, using suitable methods | Test reports, laboratory records | Specification |
Where hardness or toughness checks apply, auditors can refer to the guide to hardness testing methods, the comparison of Vickers, Brinell and Rockwell hardness and the Charpy impact testing guide to confirm that the method named in the report suits the requirement.
What should be checked in heat treatment and non-conformance records?
| Check | Evidence to sight | Basis |
|---|---|---|
| Post-weld heat treatment follows a procedure and the chart is on file | Furnace chart, thermocouple placement record | Code, specification |
| Furnace and temperature recorders are calibrated | Survey and calibration records | Code, ISO 17662 |
| Non-conforming product is identified, segregated and dispositioned | Non-conformance reports, quarantine area | ISO 9001, ISO 3834 |
| Records are complete, legible and retained for the required time | Final document pack for a completed job | Contract, ISO 9001 |
The reasons and limits for stress-relief heat treatment are covered in the article on stress-relieving heat treatment.
How Should Audit Findings Be Graded?
Findings are usually graded as major, minor or observation. ISO 19011 does not fix the grades, so each shop defines them in its audit procedure and applies them consistently; certification bodies use similar classes.
| Grade | Meaning | Illustrative example | Typical response |
|---|---|---|---|
| Major | Requirement not met, systemic or likely to affect product | Welders working on a code job without a valid qualification | Immediate containment and root-cause action |
| Minor | Isolated lapse that does not affect product | One missing signature on a fit-up record | Correction and action within an agreed time |
| Observation | No requirement breached, but a risk or improvement was seen | Consumable oven readings are legible but not trended | Consider; no formal response required |
Whatever the grade, every finding needs three things: the requirement, the objective evidence and the location. A finding that says that records are poor is not usable; one that cites the missing qualification renewal for a named welder, the job number and the requirement is.
How Do You Close a Corrective Action?
A corrective action is closed only when the root cause is removed and the removal is shown to have worked. The sequence is:
- Contain. Stop or segregate affected work and assess earlier jobs that could share the problem.
- Correct. Fix the specific instance, such as renewing the qualification or re-calibrating the instrument.
- Find the root cause. Ask why the lapse could happen, using a simple method such as five whys, until the answer is a gap in the system rather than a person.
- Define the corrective action. Change the process, for example a qualification expiry list reviewed monthly by the coordinator.
- Implement with an owner and a date.
- Verify effectiveness. After a defined period, re-check a sample to confirm that the problem has not recurred.
Closing a finding when the correction is done but the cause is untouched is the commonest reason that the same finding comes back next year.
What Are Common Audit Mistakes?
- Auditing documents only. Procedures that look perfect can differ from what happens at the bench. Observe the work.
- Auditing your own area. Lack of independence weakens the result and the credibility of the programme.
- Ticking boxes without evidence. A tick with no record reference cannot be verified later.
- Sampling the easy jobs. Sample across jobs, welders and dates, and include difficult or recent work.
- Treating the checklist as the audit. Follow a lead when something looks wrong, even if the checklist has no line for it.
- Closing without verification. Check that the corrective action worked, not just that it was done.
- Blame instead of cause. Findings should lead to system fixes, or people will stop reporting problems.
Key Terms
- Internal audit
- A first-party review by the organisation of its own system to test conformity and effectiveness.
- Audit criteria
- The set of requirements, such as standards, procedures and contract terms, against which evidence is compared.
- Objective evidence
- Records, measurements or observations that can be verified and support an audit finding.
- Non-conformity
- The failure to meet a stated requirement.
- Corrective action
- Action taken to remove the cause of a non-conformity so that it does not recur.
- Root cause
- The underlying system-level reason that allowed a non-conformity to occur.
- Traceability
- The ability to link a finished weld or part to its material, procedure, welder and inspection records.
Frequently Asked Questions
How often should a fabrication shop carry out internal audits?
ISO 9001 requires internal audits at planned intervals rather than a fixed period. Many shops cover every process at least yearly, audit higher-risk processes such as NDT and special processes more often, and add an audit after a major failure or process change.
Who can carry out an internal audit?
Any competent person who is independent of the area being audited. In small shops, staff from one department can audit another, or an external auditor can run the internal programme. ISO 19011 gives guidance on auditor competence and impartiality.
What should an auditor check first on a welding job?
Trace one job end to end: the order and specification, the material certificate, the welding procedure, the welder’s qualification, the inspection and NDT reports, and the final document pack. This shows how the system works together and where records break.
What is the difference between an internal audit and a certification audit?
An internal audit is carried out by the shop on itself to find and fix problems. A certification audit is carried out by an independent body to decide whether the shop meets a standard such as ISO 9001 or ISO 3834. Internal audit results are normally reviewed by the certification body.
Does ISO 3834 require a separate internal audit programme?
Audit requirements in most shops come from the management system, usually ISO 9001, which requires internal audits at planned intervals. Confirm what the edition of ISO 3834 and your certification body expect, because requirements can differ by edition and scheme.
How many records should be sampled during an audit?
No fixed number applies. Sample size is a judgement based on risk and the volume of work. Sample across jobs, welders and dates, and extend the sample if a failure is found to learn whether it is isolated or systemic.
What is the difference between a major finding and an observation?
A major finding is a breach of a requirement that is systemic or could affect product. An observation is not a breach but a risk or an improvement point. Grades are defined in the shop’s own audit procedure.
Conclusion
A good internal audit checklist for a fabrication shop covers each process from contract review to the final document pack, names the evidence that proves each check and ties every item to a requirement. Plan the audit by risk, trace jobs end to end, grade findings consistently and close each one with a root cause and a verified result. Adapt the checklist to the code, class and edition that apply to the project. For the welding-specific requirements behind many of these checks, the next step is the guide to the ISO 3834 welding quality system, which sets out the quality levels and responsibilities the audit should test.
About This Guide
This guide was prepared by the MetallurgyZone technical team from the sources listed under Standards and References. Verify requirements against the standard edition, material specification and contract applicable to your application.
Standards and References
- ISO 9001, Quality management systems: Requirements, International Organization for Standardization (iso.org).
- ISO 19011, Guidelines for auditing management systems, ISO.
- ISO 3834 (Parts 1 to 5), Quality requirements for fusion welding of metallic materials, ISO.
- ISO 14731, Welding coordination: Tasks and responsibilities, ISO.
- ISO 9606-1, Qualification testing of welders: Fusion welding, Part 1: Steels, ISO.
- ISO 15609-1, Specification and qualification of welding procedures for metallic materials: Welding procedure specification, Part 1: Arc welding, ISO.
- ISO 15614-1, Specification and qualification of welding procedures for metallic materials: Welding procedure test, Part 1: Arc and gas welding of steels and arc welding of nickel and nickel alloys, ISO.
- ISO 17662, Welding: Calibration, verification and validation of equipment used for welding, including ancillary activities, ISO.
- ISO 17637, Non-destructive testing of welds: Visual testing of fusion-welded joints, ISO.
- ISO 5817, Welding: Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding excluded): Quality levels for imperfections, ISO.
- ISO 9712, Non-destructive testing: Qualification and certification of NDT personnel, ISO.
- EN 10204, Metallic products: Types of inspection documents, CEN.
- EN 1090-1, Execution of steel structures and aluminium structures: Requirements for conformity assessment of structural components, CEN; and EN 1090-2, Technical requirements for steel structures.
- ASME Boiler and Pressure Vessel Code, Section IX, Welding, Brazing, and Fusing Qualifications, ASME (asme.org).
- AWS D1.1/D1.1M, Structural Welding Code: Steel, American Welding Society (aws.org).