Visual testing is the most widely used NDT method in KSA shutdowns, and the most underestimated. It does not require an expensive instrument, it does not produce a digital record by default, and it tends to be the first thing skipped on tight schedules. It is also the method on which every other NDT result eventually depends, because a weld that fails VT does not move forward to UT, RT, or PAUT. Get VT wrong and the whole inspection record on that weld is suspect.
This guide is for QA/QC managers, inspection contractors, and shutdown leads commissioning visual testing on KSA oil-and-gas plant. It covers the code framework, the procedure conditions that get audited, the direct-versus-remote split, and the acceptance criteria that decide every repair call.
The code framework: where VT requirements actually come from
VT does not sit on a single code. It pulls from the same family of codes the rest of the inspection record references, and the procedure must name them explicitly.
Codes that drive VT procedures in KSA
ASME Section V is the source for the underlying VT method requirements, defining direct VT conditions, remote VT conditions, lighting, distance, and angle. It is the method-of-examination reference, not the acceptance reference.
ASME Section VIII Division 1, API 570, API 653, and AWS D1.1 are the acceptance-criteria references. Each names what counts as a defect on the equipment class it covers. The same surface condition can be acceptable under one criterion and rejectable under another, which is why the procedure must name the applicable acceptance code for each scope.
ISO 17637 is the European equivalent for visual testing of fusion welds and shows up on projects with European EPC heritage. The lighting and distance requirements are broadly similar to ASME V but the procedure should reference one or the other, not both at once.
This is the same logic we set out for higher-level methods in the NDT methods and standards guide: name the standard, do not assume it.
The four conditions that get audited
A VT procedure that names the code without naming the conditions is incomplete. Four conditions are audited on every Aramco-grade shutdown:
- Lighting. Minimum 1000 lux at the examination surface for direct VT under ASME V. Procedures should describe how the inspector confirms this on site (typically a calibrated light meter taken to the surface) and how the reading is recorded.
- Distance. Within 24 inches (610 mm) of the surface for direct VT under ASME V. Greater distances require remote VT with appropriate aided viewing.
- Angle. No less than 30 degrees from the surface plane under ASME V. The angle requirement is the one most often skipped on awkward geometries and is the one auditors check on retrospective record reviews.
- Surface preparation. Cleanliness sufficient for the criteria to be applied. A weld surface obscured by scale or slag is not VT-ready, and an inspector who proceeds anyway is recording an unreliable result.
On an audit, the question is not whether the inspector knew the lighting requirement. It is whether the lighting meter reading is in the record, whether the distance and angle are documented, and whether surface preparation is signed off. Procedures should make the evidence trail explicit.
Direct versus remote VT
Direct VT, with the inspector close to the surface, is the baseline. Remote VT, with cameras, borescopes, drones, or other aided viewing, is the alternative where the geometry, the access, or the safety case rules out direct viewing.
Remote VT is not direct VT performed at a distance. It is its own method requiring its own procedure, its own equipment calibration, its own resolution check, and often its own qualification. The lighting and angle requirements from direct VT do not transfer directly because the camera optics change the relationship between viewing condition and surface evidence.
Common applications for remote VT on KSA refining and petrochemical work include the internal surfaces of pressure vessels and storage tanks, congested piping where access is restricted, elevated and confined-space inspection where worker entry is undesirable, and rapid screening of fired-heater coils and similar assets. The same integrity logic applied to higher-level methods in the PAUT and conventional radiography trade-off guide applies to direct-versus-remote VT: the choice should be driven by what evidence the asset and the schedule allow, not by what is easier on the day.
Acceptance criteria: the procedure decides, not the inspector
A VT report that records a finding without referencing the acceptance criterion is not a complete record. The criterion is what determines whether a surface condition is a defect, an imperfection, or a feature, and the criterion sits in the code, not in the inspector's judgement.
Common acceptance frameworks on KSA work include ASME Section VIII Division 1 Appendix 6 and ASME Section IX for pressure vessel welding, API 570 for in-service piping with its damage-mechanism context, API 653 for tank bottom and shell welds, and AWS D1.1 for structural welds. The procedure should name the applicable criterion for each scope, the inspection report should reference it for each finding, and the integrity engineering response should sit on the API 510 and pressure vessel integrity logic or its piping and tank equivalents.
A VT finding without an acceptance-criterion reference is a personal opinion. The whole point of the procedure is to turn personal opinion into auditable evidence against a named standard.
Where VT sits in a shutdown inspection programme
VT is the first NDT method performed and the most frequent NDT method repeated. On a typical shutdown weld inspection programme, VT is performed before any higher-level method, after every higher-level method that opens or modifies the weld surface, and again at the final hold point before the equipment is returned to service.
Sizing the VT workload against the rest of the inspection programme is a planning problem treated in the shutdown staffing guide. Mismatching VT capacity to higher-level NDT capacity is one of the recurring causes of mid-shutdown re-mobilisation, because the VT bottleneck slows down every method that depends on it.
The inspector certification side of VT runs on the same SNT-TC-1A and ISO 9712 schemes treated in the ASNT NDT Level II training guide. VT Level II is one of the most common NDT credentials in KSA, partly because of the workload it underpins.
How IES approaches visual testing
IES treats VT as the foundation of every inspection record, not as a tick-box ahead of the "real" NDT work. Our non-destructive testing service line covers VT alongside MT, PT, UT, and RT under procedures that name the code, the conditions, and the acceptance criteria for each scope. To discuss a shutdown VT programme or wider NDT scope, contact our team, or see the NDT methods and standards reference for how VT sits alongside the higher-level methods on a typical KSA inspection programme.
Questions buyers ask us
Visual testing is the systematic visual examination of welds, components, and equipment for surface conditions, dimensional features, and visible defects. It is performed under defined lighting, distance, and angle conditions, by an inspector certified for the method, against acceptance criteria from the applicable code. VT is the most widely used NDT method because almost every higher-level NDT requires a clean VT pass first.
ASME Section V requires a minimum of 1000 lux (100 ft-candles) at the examination surface for direct visual testing, with the inspector positioned within 24 inches of the surface and at an angle of no less than 30 degrees from the surface plane. The lighting requirement is audited, the distance is audited, and the angle is audited. Procedures should describe how the inspector confirms each condition on site, not just declare it.
Direct VT is performed by the inspector standing within close distance of the test surface and viewing it directly. Remote VT is performed using cameras, borescopes, drones, or other aided viewing where the inspector cannot stand directly in front of the surface. Remote VT requires its own procedure, equipment calibration, and resolution checks, because the standard lighting and angle requirements do not transfer directly.
Acceptance criteria are set by the applicable code, not by the inspector. ASME Section VIII Division 1 has its own criteria for pressure vessel welds, API 570 for piping in service, API 653 for storage tanks, and AWS D1.1 for structural welds. The VT procedure names the code and the acceptance criteria explicitly, and the inspection report references the criteria for each finding. A finding that is not against a named criterion is not a defect, even if it looks like one.
Almost every higher-level NDT method assumes a credible VT result first. A weld that fails VT does not progress to UT, RT, or PAUT. A VT pass that should have been a fail leaks downstream into every other inspection record on that weld. Operators audit VT procedures, lighting evidence, and inspector qualification because the integrity of the rest of the inspection record depends on getting the visual call right.
