Pressure vessel and pressure pipe welds are impacted by long-term alternating loads, high temperature and high pressure, corrosive media, radiation embrittlement and other external factors, the combined effect of which causes easy formation of fatigue cumulative damage, resulting in the weld structure. Residual strength is reduced, and the magnetic parameters are effective in the characterization of the weld microstructure damage extent - state of fatigue and remaining life.


● Hydrogenation reactor,

● Spherical tank,

● Storage tank,

● Gas cylinder,

● High pressure pipeline, etc.


● Magnetic structurescope (coercimeter) MC-04H-2

● Magnetic analyzer MA05

Standard welded joint of pipeline. Measurement principles.

Current fatigue state frequently is not correspond to remaining service life. It can be both better and worse, depending on combination of metal operation factors. Metal often is in extreme fatigue state, and still has no fatigue macro defects (cracks, etc.). Coercimetric control monitors such states quite well, and allows passing in diagnostic practice from search of fatigue macro defects to their prevention!

The measurements of Нс in the point of each "hour" on the weld itself and in both weld-adjacent zones are made.

The results of coercimetric monitoring are presented as a color map and a graph which enables to detect stress concentration areas and make prompt and effective assessment of weld fatigue degradation and remaining life. The worse is the condition of metal, the "more red" are zones on the diagram of the welded joint. For estimation of the dynamics of accumulation of fatigue changes, it is convenient to use a gistogram showing distribution of coercivity values. Gistogram changes from the beginning to the end of the metal lifetime.

Petrochemical refi nery pressure vessel. Circular welded joints Fatigue state of the base metal and welded joints

Coercimetry non-destructive evaluation technology was used for rapid collection of coercive force values of 12 levels of circular welded joints and heat affected zone of petrochemical refinery pressure vessel.

Coercimetry is especially important for multi-million decision on further running or decommissioning of industrial facility at the end of design service life.