Asme B31

[Malcolm Clulow]

Does anyone know anything about ASME B31.5 and ASME B31.3 with regard to classifying the minus 25 glycol as Type M fluid Service?

[US Iceman]

Hi Malcolm,

It has been a long time since I have looked at the ASME piping codes. From what I remember the M service classification only appeared in B31.3 (Process Piping).

B31.5 is strictly for Refrigerant Piping.

Although the use of glycol could be considered a secondary refrigerant, the last version of B31.5 I saw did not have these classifications.

My impression is that B31.3 would be used for all process piping, including the use of glycol.

B31.5 would be used for volatile (phase change) refrigerants only.

I understand in the more current version of B31.5 some of the material charts from B31.3 were used (or referenced in B31.5).

I do not have copies of the piping codes, so I am providing this from memory. Some times it does not work too well, but I hope this helps you.