Your interpetation of B31.1 para 122.1.7(B)(B.1)

I know this is a piping code, but I posted this question here because it applies to Boiler External Piping.

In the above mentioned paragraph, it states:  "The stop valve or cock shall comply with the requirements of (C.5) below."

para (C.5) states: ..."valves or cocks shall be bronze, cast iron, ductile iron or steel."

Question:  since
only the stop valve is mentioned, does that mean I can use a stainless
check valve per para 107.1 as long as the material is listed in table
126.1?
Not so fast. The Code does not provide card blanch for materials to be
used in any environment or service just because materials are listed in
Table 126.1. The reference to C.5 applies to low temperature/pressure
boilers and if a stop valve is installed of the permitted materials, the
check valve should be close to the same material. Why would you want to
install a stainless steel check valve? Galvanic corrosion could be a
problem.

Have you heard of stress corrosion cracking in
austenitic grades of stainless steel at around 160 deg F and higher in
oxygenated, treated water?
From the original1Check Valve.com
.