If pipe material is specified as ASTM A312 TP316/316L does it mean:
a) the material must meet the requirements for both 316 and 316L
or
b) material that meets the requirements for either 316 or 316L is acceptable?

The meaning of the specification as "ASTM A312 TP316/316L" is important because per B31.3 the allowable design stress is different.

For example, at 700°F,
ASTM A312 TP316 has an allowable stress of 16,300 psi
and
ASTM A312 TP316L has an allowable stress of 12,900 psi.

When analyzing a piping system whose material is specified as ASTM A312 TP316/316L which allowable stress should I use?

To be conservative, I could use the lower allowable stress but that requires a thicker wall pipe (at considerable extra cost!). Thanks for any advice.

It normally means either could be bought and installed. In this case you must limit stresses to the lower value.

This is usually clarified in the project documents. In this case I would say its dual certified and must meet both requirements, *not* a choice of either, but thats based on my experience. You should check your project documentation and materials selection people to be certain.

Dear John

Usually if your material is Dual 316/316L this is special ordered and have both corrosion resistance of 316L and mecanical behaviour of 316. you can use stresses of A312 TP 316 but be careful above 1000°F carbone content have to be highter than 0.04% for A312 TP 316 to use B31.3 values which may not be compatible with dual steel chimical composition.


best regards,

Laetitia