Valve Testing API 598
Valve Testing API 598
(OP)
Why do valves with the same pressure class get tested at slightly different pressures because the body material is different? (API 598)
F316 and A105N for example
F316 and A105N for example





RE: Valve Testing API 598
Looking at table 3, for check valves, other test pressures, note that the pressure references b below the table that includes 110% of the maximum allowable pressure at 100 degree F for steel, alloys and stainless. Type 316 stainless steel is rated for less pressure in each Class rating that A105.
RE: Valve Testing API 598
Different metals have different strengths. Castings are the same thickness. Therefore a casting made of A105 for example would be able to hold a higher pressure than one made of 316. Most people are unaware of that because the majority of valve manufacturers only make castings out of a few metals. The manufacturers test to API 598 using the pressures for the lowest strength metal that they produce.
RE: Valve Testing API 598
For the very technical minded: http
For less technical: http://en.wikipedia.org/wiki/Tensile_strength
Heather's focus: Alloy Valves Duplex Valves Super Duplex Valves Monel Valves Inconel Valves Titanium Valves & 6 Moly Valves
RE: Valve Testing API 598
RE: Valve Testing API 598
James Chan
RE: Valve Testing API 598
RE: Valve Testing API 598
For example:
Class 150 A105 has a 100° rating of 285 psi so:
Shell: 450 psi (you round up to the next 25 psi increment)
Closure: 325 psi
Class 150 F316 has a 100° rating of 275 psi so:
Shell: 425 psi
Closure: 325 psi