Maybe more details/background over your inquiry.
Who are you? manufacturer, engineering company, end user or third party?
Which (geographical) region are you referring to?
Which type of valves?
Otherwise AI can answer your question, like below
Quote
The requirement for third-party presence, review, or approval during the pressure testing of valves (such as ball, gate, and globe valves) depends on the specific standards and codes being followed.
For instance, ISO 5208:2015 outlines the procedures for pressure testing of metallic valves but does not explicitly mandate third-party involvement12. However, certain industry practices or specific project requirements might necessitate third-party verification to ensure compliance and quality assurance.
It’s always a good idea to check the specific requirements of the project or contract, as well as any additional standards that might apply, such as those from the American Petroleum Institute (API) or the American Society of Mechanical Engineers (ASME).
Unquote
My comments (I am not AI):
Third party = assuming this is Notified Body (NoBo) such as TUV, Bureaue Veritas, etc.
Object of testing: Prototype and/or Production valve
Then:
- Safety valves --> always to be witnessed by NoBo representative. Prototype of safety valve need to be send to ASME for its initial validation testing (usually this for VR ASME stamp qualification for fairly new workshop)
- Prototype valve (both control and manual valves)--> PED/CE marked to be witnessed by NoBo as well. Some end user also mandate such requirement for their representative to witness (and also audit) prototype valve.
- Production valves --> unless stated otherwise, then manufacturer self (assuming possess ISO 9001 qualification and purchase ASME standard? this I am not entirely sure) can perform the testing on their own and issue 3.1. certificate.
Otherwise means: 3.2. certificates required; certain local (country) regulation is applicable, specific requirement (very severe acute product) that end user imposed to be witness, etc.
I might miss some details, but then the question is also general.
Regards,