am working for a company that wants me to setup a Chart. It is so they can give to contractors to tell them what maximum valve class they are allowed to use for hydrotest purposes. Example:Such as Socket Weld Valve 800 class bolted bonnet API trim #8 is good to a maximum hydrotesting pressure of 1400 psi temp range 35 F to 120 FAnd being that valves are not my area of knowlegde I need some help to setup this chart. The pupose of this chart is to ensure safety when using hydrotest tree of the right pressure rating.It is a common misunderstanding that valves legally can be used above the allowable operating pressure/temperature clearly stated by the norm the valves are produced and tested after.If you ask the producer he will give you the relevant pressure temperature curve according to the correct class.The misunderstanding occurs because the valve body is normally tested (at a given temperature) at a pressure about 1,5 times higher than allowable operation pressure (variations according to class, norm (European, Asian, US and others) and type). The body test is done with valve open.The seat thightness test is made at max operating pressure, or at about 1.1 times this (again variations, and factories might allow higher, but again according to type).

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