Hello team,
I am designing safety valve for the first time , i need to calculate the thickness of bonnet flange also the body that connects to the bonnet can you please suggest wich standard should i refer
You are not designing the entire relief valve from scratch are you? The relief valve is designed structurally by a compentent experieced engineer which these days would use FEA analysis, and it is purchased from the manufacturer.
Yes you have to learn sometime but I don't really think you would design a one-off relief valve and actually put it into service. Manufactured relief valves have taken years and years of evolution to get where they are today and have been proven over time. But anyway the attached is an old BP oil specification for relief valves that refers to the two main industry standards to follow in the design is ASME Boiler and Pressure Vessel Code and API 526 (See Section 5.0), among other design requirements. There should be specification on wall thickness requirements in one of those standards.