Visual Testing in Refining: What It Finds, What It Misses, and What Governs It
What VT is actually used for in refining
Every refinery inspection starts visual: external corrosion under insulation evidence, support and foundation condition, and internal vessel entry examinations that decide what the rest of the scope becomes.
How VT works
Visual testing is the examination every other method is deployed against: direct or remote observation under controlled lighting and access, judged against written acceptance criteria. It finds the majority of reportable conditions in most programmes — weld profile, corrosion, mechanical damage, coating breakdown, leakage evidence — and it decides where volumetric examination is worth performing.
What VT will not do
What VT will not do: see beneath the surface, quantify wall loss, or substitute for a volumetric method where the code requires one. Its weakness is human rather than physical — inconsistent lighting, inadequate access, and acceptance criteria applied from memory rather than from the document.
The refining assets this applies to
Crude and vacuum units, cokers, reformers, hydrotreaters, the piping circuits between them, fired heaters, exchanger trains, and the tank farm at the end of it.
The damage mechanisms driving the examination
Corrosion is the governing story — sulphidic and naphthenic attack on hot circuits, aqueous corrosion in overheads, corrosion under insulation everywhere insulation exists — with wet H2S cracking, high-temperature hydrogen attack and creep in specific services.
What governs acceptance
API 510 (vessels), 570 (piping) and 653 (tanks) govern in-service inspection, with ASME Section V supplying method rules and Section VIII / B31.3 the acceptance criteria. Operator contractor-approval gates site access above the codes. On the method side: ASME Section V Article 9; AWS D1.1 for structural acceptance; API 510/570/653 for in-service external and internal examination; ASME B31.3 for process piping. An examination that is technically sound but performed outside the governing regime is not an examination anyone will accept, which is why the code family matters as much as the technique.
How Atlantis delivers VT in this sector
Atlantis mobilises examination teams to your site under Atlantis procedures with ASNT Level III oversight — we do not claim a depot or laboratory in every market, and say so plainly. What you receive is the examination performed to a qualified procedure, findings evaluated against the acceptance criteria your contract names, and records structured to survive a client audit years later.
Visual Testing services · VT training and certification · Refining programme consulting · Refining NDT training · scope a VT examination.
VT in other sectors
Petrochemical · LNG · Offshore · Pipeline · Marine & Shipbuilding · Aviation & Aerospace.