A-182 F-53 super duplex STAINLESS
A-182 F-53 super duplex STAINLESS
(OP)
An UT thickness inspection crew took thickness readings on a A-182 F-53 super duplex 8" reducer. At the time of inspection, the material wasn't known. The crew calibrated to S/S and achieved a reading of .138". I knew that wasn't correct. I had them calibrate to C/S due to the fact of the material being magnetic and achieved a reading of .375". At that time they achieved proper readings on same. Why is the material called S/S yet has a carbon make up? Is it because of it's corrosion inhibitor factor?
API-510 cert # 32890





RE: A-182 F-53 super duplex STAINLESS
Your assumption is not correct. The F-53 is a super duplex stainless steel that contains ferrite/austenite. You need to have a calibration standard for this material. You just got lucky because the ferrite in this material responded like ferrite in carbon steel. You need to have a calibration gage made out of F-53 duplex ss.
RE: A-182 F-53 super duplex STAINLESS
API-510 cert # 32890
RE: A-182 F-53 super duplex STAINLESS
The "duplex" in duplex stainless means that it has the best characteristics of both the carbon and "stainless" worlds.
From what you have said, I believe that you consider the word "stainless" to mean an austenitic (non-magnetic)material.....Not true
The current meaning of "stainless" as I understand it, simply means that it has a certain minimum percentage of chrome and can be of austenitic, ferritic or martensitic structure.
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-MJC
RE: A-182 F-53 super duplex STAINLESS
How do you know that the 0,375" reading is accurate when, in response to metengr's sound (no pun intended)advice to obtain a piece of the same material of known thickness from which to calibrate, you are still "working on it"? Or perhaps there is a typo somewhere in your description?
I am not saying that the figure of 0,375" is neecesarily wrong (or the 0,138" right), but something is definitely amiss when by recalibrating for carbon from stainless (nominally a maximum velocity change of about 20 - 25% with mild steel at 5960 m/s and 410 stainless at 7390 m/s)your UT crew gave you a reading variation of 0,138" to 0,375", i.e. some 270%!
I would be more worried about what that UT crew is up to than anything else!
Nigel Armstrong
Karachaganak Petroleum
Kazakhstan