Magnetic Particle Testing in Fabrication & Welding: What It Finds, What It Misses, and What Governs It
What MT is actually used for in fabrication & welding
In-process MT on fit-ups, tack repairs and completed structural welds catches surface defects while rework is cheap.
How MT works
MT magnetises a ferromagnetic component and applies iron particles, which gather at the flux leakage a surface-breaking or near-surface discontinuity creates. It is fast, inexpensive per square metre, and unusually good at what it does: finding cracks in steel that a visual examination would miss.
What MT will not do
What MT will not do: work on non-magnetic material at all — no stainless austenitics, no aluminium, no nickel alloys — and it finds nothing meaningfully below the surface. Coatings degrade sensitivity, and flaws parallel to the flux direction are invisible, which is why examination in two directions is standard practice rather than diligence.
The fabrication & welding assets this applies to
Structural steel, pressure vessels and pipe spools, skids and modules — everything examined before it ever enters service.
The damage mechanisms driving the examination
Construction defects rather than degradation: lack of fusion and penetration, porosity and slag, cracking from restraint or hydrogen, and dimensional non-conformance.
What governs acceptance
AWS D1.1 for structural steel, ASME Section VIII and IX for pressure equipment and procedure qualification, B31.3 for process piping, plus customer specifications that routinely tighten all three. On the method side: ASME Section V Article 7; AWS D1.1 for structural work; ASTM E1444 in aerospace and general industry; ASTM E709 as the practice reference. 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 MT 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.
Magnetic Particle Testing services · MT training and certification · Fabrication & Welding NDT training · scope a MT examination.
MT in other sectors
Refining · Petrochemical · LNG · Offshore · Pipeline · Marine & Shipbuilding.