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Carbon Steel Contaimination of Stainless Steels

Carbon Steel Contaimination of Stainless Steels

Carbon Steel Contaimination of Stainless Steels

Contamination of stainless steels by contact with carbon steels has been a issue for years.  I do not fully understand contamination of the external surfaces of components that are not heated or welded.

First of all what is the main source of the contamination from the carbon steel.... carbon or iron.

Types of conatimination I inquirying about are:
Resting parts on carbon steel surfaces during fabrication
CS grinding particles
Machining of tube holes with carbide drill bits (rolled only joints)
Handling: forks on forklift, crane hooks, clamps, plate rollers, storage in CS plate racks  

If this is so serious why doesn't ASME, API, NBIC address?  Is this left up to the end user to determine?
I understand there are types of cleaning, I don't want to discuss that. I want to further understand why this is an issue, again the contamination I am concerned with is not at any welded area, which is also not addressed by ASME?

Sorry about the length of the post, I will appreciate your feedback,


RE: Carbon Steel Contaimination of Stainless Steels

The contamination is iron, which can oxidize to iron oxide (rust).

Resting parts on a surface really isn't a problem.  You need a force, which means carbon steel dies, tooling, etc. that contacts the stainless part during fabrication.

Grinding particles for sure is a problem.

The problem during machining is not with carbide tools, rather with steel bits (HSS, cobalt steel, etc.).

Forks, hooks, etc. is possible with high force, high temp, and long time, but is not very likely.

RE: Carbon Steel Contaimination of Stainless Steels

The standards don't address this issue probably because it is purely a 'housekeeping' problem and can happen anywhere down the supply chain.  It's great to see the lovely, passivated pipe arrive on site having travelled half the world and then watch the installation crew set about it!  Reminds me of that TV programme Destroyed In 60 Seconds.  Another difficulty for the standards is whether the contamination is a cosmetic or an integrity concern.

Steve Jones
Materials & Corrosion Engineer

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