ASME B31.4 vs B31.8

[suraiya]

I know B31.4 is meant for liquid pipeline transportation, whereas B31.8 is for gas transmission.
Apart from this distiction, I would really appreciate if someone can tell me what are the major differences between these codes.

 

[Cockroach]

Volume transfered per unit time as a function of compressability. Liquid is not compressable, gas is, pump setups and compressor stations along the pipeline.

Also there are special considerations for gas transfer measurement governed by AGA Report Number 3. The code does apply to liquids, gases independently BUT NOT two phase flow.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[grampi1]

B31.8 has requirements for the more dangerous gas service that are not contained in B31.4. For example B31.4 uses 0.72 everywhere. B31.8 will alter the design factor based on class location. B31.8 has more stingent toughness requirements that are not in B31.4.