JimCasey, thanks for your response, I need to clarify that the valve I mentioned is a new vavle that has not been in comercial use. Firstly we performed pressure test strictly as per API 598 and found no leakage, after 6 months on site after the valve was installed on line the pressure test was...
by the way, this C.S ball valve with DN300,600# applied for Natrual Gas pipeline was tested as per API598, in order to find crack during test in future we intend to test valves with 600# as per API6D, which reqiures much longer duration of pressure.
Most of the cracks appear on 600# valve...
We have processed 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. Believe us we did do all that need to do to prevent such thing, we wonder if the crack appear after pressure test...
