Can the inspection method for the butt joint seam of the heat tracing tubes in pressure vessels be changed from MT to PT? The material is S30408
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A horizontal vessel is equipped with a heating coil; its design pressure is 0.8 MPa, the design temperature is 290°C, and the medium used is steam. The material used for the connection is S30408, while the material of the flange is S30408Ⅱ. The welding methods for heat tracing pipes mainly include the butt welds between the pipes, as well as the butt welds between the pipes and the flanges. The butt joints of the heat tracing pipes specified by the design institute are required to undergo MT testing and must meet Grade I standards. The question now is: Is it possible to change the flaw detection method from MT testing to PT testing so as to achieve grade I compliance? I need experts’ advice! !
Can’t stainless steel be detected with magnetic powder, right? It needs to penetrate.
Which design institute are you from? Stainless steel cannot be used for MT; only PT can be used
MT is only applicable to ferromagnetic materials, while S30408, as an austenitic stainless steel, is a non-ferromagnetic material; so cannot it be used with MT?
MT is only applicable to ferromagnetic materials, while S30408, as an austenitic stainless steel, is a non-ferromagnetic material; so cannot it be used with MT?
The last edit to this post was made by wanlirn on 2021-10-27 at 09:54. It’s definitely a typo – the wrong technical specifications for design were used; they forgot to make the correction here. Just talk to him about it and he’ll fix it right away; it’s a simple mistake
It’s not a matter of whether to make changes or not; for welds made of austenitic stainless steel, PT should be used instead of MT. The surface inspection method chosen in the design was incorrect. Using 100% PT directly is the correct approach
Can S30408 be used for MT? Did I misread it?
The design institute made a mistake; have the designers prepare the changes and then implement them. It has nothing to do with technical issues – what’s important is following the proper procedures and clarifying responsibilities.
Stainless steel should undergo PT; it seems the designer forgot to make the changes
Austenitic stainless steel can only be tested by PT