Back again don't know which one applies to pipe but at least a starting point. I did have one for piping but like everything else is misfiled/lost. We used the wire and bar.
The Japanese have done a lot of work with Invar 36 on cryogenic piping.
UNS K93600, K93601
ASTM B 388, B 753
DIN 1715
S.E.W. 385
Werkstoff Nr. 1.3912
AFNOR NF A54-301