What is L-Grade stainless steel?
What is L-Grade stainless steel?
(OP)
Hi Guys,
What is the L-Grade S.S?
Why is it unnecessary to ask PMI testing for L-Grade S.S?
I am totally layman and need your guys help.
Thanks in advance,
What is the L-Grade S.S?
Why is it unnecessary to ask PMI testing for L-Grade S.S?
I am totally layman and need your guys help.
Thanks in advance,





RE: What is L-Grade stainless steel?
RE: What is L-Grade stainless steel?
RE: What is L-Grade stainless steel?
It is thus imperative to perform PMI (Positive Material Identification) to segregate low carbon grade SS from relatively higher grade of carbon containing SS.
RE: What is L-Grade stainless steel?
Unless you have need for "H" grade,(high carbon) material you should make of point of only using "L" grade materials to minimize the risk of a mixup. In many parts of the world the price premium for "L" over standrad material is $0.02/lb or less. Further, almost all of the "L" grade material manufactured has sufficent mechanical properties to be dual certified as 304/304L and used at the stanrd 304 strength levels.
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RE: What is L-Grade stainless steel?
For castings the price differential becomes very huge as we need to use virgin grade raw materials to get the C right. We have no converter facilities.
RE: What is L-Grade stainless steel?
If a steel mill is charging more than a few cents/pound premium then either you are being gouged, or the material is not being made via and oxygen decarb process (I would say AOD, but that is trademarked). Blowing the carbon down is trivial in a refined steel. In the US (and from sources in Europe) we often get 304L/316L with carbon in the range of 0.012-0.016.
I have seen stainless foundries that used AOD to refine heats before casting. This let them use lower cost, higher carbon feedstock.
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Rust never sleeps
Neither should your protection
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RE: What is L-Grade stainless steel?
RE: What is L-Grade stainless steel?
To sum up, L-Grade SS is good for intergranular corrosion resistance but not good for strength application like pressure containing parts owing to the low carbon.
The main purpose of PMI is for alloy composition identification but not for carbon. So mill certificate is necessary to make sure the carbon content is less than .03%.
Thanks again.
RE: What is L-Grade stainless steel?
For newer alloys (lean duplex, 6% Mo, super ferritics) the spec minimum strengths are very close to reality.
The time that you NEED "L" grade material is when you will be using material with welds that are not annealed. If there are no field welds and all fabrication welds are annealed then there are no sensitized welds to worry about.
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: What is L-Grade stainless steel?
Also a general note on "L" grade stainless- if it is weld metal, up to .04%C is allowed in most cases.
RE: What is L-Grade stainless steel?
RE: What is L-Grade stainless steel?
Regards,
Mike
RE: What is L-Grade stainless steel?
We find that there is zero premium regionally for using dual grade material (304/304L or 316/316L dual certified). That's all we use, unless we need H grade material in which case we specify and segregate it.
And there's a lot more to working with L grade material than merely buying L grade material in the first place. Keeping carbon out of the HAZ of piping during welding is critical, which means good cleanliness and materials control during welding and fitting, no grease pencils, being careful with tape used to cover openings for purging etc.
RE: What is L-Grade stainless steel?
Recent PMI requirements by Engineer/Owners have effectively prohibited the use of such PMI equipment on our current projects because of the arc burn produced.
RE: What is L-Grade stainless steel?
Best regards,
ct