The purpose of a fire-safe valve is to prevent or hinder flammabel fluid (liquid or gas or gases formed from liqid phase)to pass, at least for a given time and at least during that periode not in critical amounts, a closed valve during overheating of the pipeline , caused by fire or similar events.
When you should use a firesafe valve is given by a sensible risk analysis. When you are required to use one is dependent on any rules, regulations and laws concering the special process, plant, pipeline, vessel or contraption you have.
In addition to this comes the regulations given by the protection of surroundings or requirements from for instance your insurance company.
Check if firesafe tested type or only firesafe design without test of actual type is required.
A firsafe valve does not necessarily need to be much higer in price than a good non-firesafe for the same purpose.
What code should I review in th US to determine if I need to use firesalve? I know API 607 covers the valve itself but what standard governs the use of fire safe valve?
Start with your contracts. Then consider terms in 29 CFR 1910.119. PSM includes requirements for "preventing or minimizing the consequences of catastrophic releases of toxic, reactive, flammable, or explosive chemicals. These releases may result in toxic, fire or explosion hazards."