Invar or Ni36

[pbrown]

Hi,

I have been trying to find mechanical properties and availability of Ni36 pipe and fittings without much success.

We are wondering whether to use this for cryogenic pipework to B31.3 instead of ss304.

Any info. would be apreciated

 

[Metma]

Dear pbrown,
last month we had the same matter for a cryogenic line in a LNG plant, for which we considered whether to use a high Ni alloy or a SS304.
In particular we have taken 9%Ni (ASTM A353 and A553) and 36%Ni (Alloy 36) into consideration:
-pipes are available for both materials (at Eisenbau & Kraemer); just to give an idea the price of Alloy 36 pipe is about four times the price of 9%Ni pipe;
-no fittings availability up to now;
-9% Ni is listed in B31.3;
-Alloy 36 neither is listed nor is considered in a Code Case, so design in accordance with B31.3 is more onerous: in particular, due to the shortage of mechanical properties (even by vendor), allowable stresses at different temperatures can not be determined.

In conclusion we have discarded Alloy 36 and we are still looking for 9%Ni fitting.
Regards.

 

[EdStainless]

Unless you are working below LN (LH or LHe) don't go for 36Ni. We have supplied it to NASA, but how many other LH lines are there that need it?

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Plymouth Tube

 

[unclesyd]

There is a lot of information on Invar piping systems for LNG in Japan mainly by Osaka Gas.
I believe that the pipe was made by Sumitomo Metals and the fabrication procedures were developed by Osaka Gas and Kawasaki Heavy Industries.
Osaka Gas has an Invar LNG line in service since 2001.