Processed a strict pressure test on a C.S ball valve with DN300,600#, during the test there's no leakage. While 6 months later on site customer find a crack with 20mm length.

Spring seated check ball used in a low volume low flow (130 cubic in./min max) hydraulic device.

The calculation of Ag defined in ASME B16.34 sections 6.4.1 and 6.4.2 as it pertains to ball valves. Specifically, we are discussing section 6.4.2 and the bolts between the adapters and body.

Any acceptable for bolted body joints on ball valves per ASME B16.34? I note that some other standards state that coarse threads be used.

What's a Maximum Allowable Operation Pressure for ball valves since I haven't find this parameter in API 6D and ASME B16.34.

A ball valve will be forced open/closed by the force of the liquid flowing through it. (i.e. when the valve is nearly closed the force of the flow will "snap" it closed, and similar for opening.)

A david brown 995 recently i had replaced a supply line to my frontend loader valve that blew in the process .

WOG is an old acronym for Water Oil Gas. Others can provide some additional details.