A-182 F-53 super duplex STAINLESS 2

[retthib]

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

 

[metengr]

retthib;
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.

 

[retthib]

Yes we are working on that, just was wondering why with a material name S/S we achieved a more accurate reading calibrated to C/S. I figured it was due to the carbon content, but thanks for clearing that up.


API-510 cert # 32890

 

[MJCronin]

retthib,

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.

http://www.alleghenyludlum.com/pages/products/xq/asp/G.2/qx/ProductLine.html

http://www.matweb.com/search/datasheettext.aspx?matguid=59b6c05b82cb41cfb102bd8dc6cb3a52

http://www.thefabricator.com/MetalsMaterials/MetalsMaterials_Article.cfm?ID=1550

-MJC

 

[ndeguy]

retthib,

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