Test pressures JIS rated valves

[CarlosEstinos]

Hello All,
I am currently inspecting some valves that my company wishes to ship. They are JIS 16K rated globe valves. I have a few queries regarding the test pressure that would normally be used on this type of valve.
The valves have been supplied with test certificates detailing that they have been hydrostatically tested to 38 bar(body) and 23 bar(seat).
I am trying to conclude whether the test pressures are correct for this type of valve, as i have seen similar JIS 16K rated valves tested at pressures of 24Bar(body) and 18 bar (seat).
My understanding of a JIS 16k valve is that they have a pressure rating of 16kg/cm^2. So a normal test specification would be 1.5 × 16kg/cm^2 (body pressure) and 1.1 × 16kg/cm^2 (seat test pressure) .
I've been advised two contradictory bits of information from valve suppliers, one stating that the test pressures should only be calculated from the rated pressure rating of the valve, the other is saying it should be the maximum working pressure by which you calculate the test pressures.
Which Japanese standard details the maximum working pressures of JIS rated valves? And can anyone shed any light on what would be deemed as a suitable test specification. As i cant calculate how 38 bar has been used for the body test and 23 for the seat, I'm assuming the max working pressure has been used to calculate these test pressures.
The European PN system, say a PN20 valve for example would be tested at 1.5 × 20 (Body) & 1.1×20 (seat). The ANSI systems takes into account the mechanical properties of the material as detailed in B16.34 these are detailed as the rated pressure ratings at a certain temperature range.
Any help on the matter would be greatly appreciated.
Thanks in advance
Carlos

 

[gerhardl]

Hello Carlos,

Any valve, tested in/at a certain standard and with a certificate giving test pressure will tell you exactly what is described on the certificate, not more, not less. One way out is to contact the issuer of the certificate stating that your QA-system requires that they clarify test procedures, if this is not described in detail.

On the other side: comparisons and reasoning from one test system to another (EN, JIS, AISI or others) will lead you no way, as one system is 'a system to itself' not normally directly based on other systems.

Third way is of course to test pressure all valves once more at a qualified testing company, or ask the end user if excisting certificates are acceptable within their system.