Pressure Release sound effects, royalty-free and cleared for commercial work. 3 libraries carry this tag, most of them filed under Ambience and Mechanical.
Recordists here also tag Steam, iceland and valve, which is worth a look if nothing below fits.
Natural air pressure and industrial pipe sound effects captured in Iceland, featuring authentic hissing, whistling, and mechanical resonance from geothermal sources.
Historic steam engines come alive through authentic sound effects, featuring both raw recordings and designed elements, capturing mechanical rhythms, hisses, and industrial machinery movements.