SB-622 Tube manufacturer hydrotest

[payaam2000]

Dear All

In ASME section II , part B , SB-622 which is related to "specification for seamless nickle and mickle cobalt alloy tubes" it has been mentioned as follows:

Each tube shall be tested by the manufacturer to an intenal pressure not to exceed 1000 psi ....

as per SB-622 , this sentence is included for a range of different materials and different thicknesses of tube (such as hastelloy c2000, c22, c278 inconel 686 and etc.)

my question is that "why the range of tube hydrotest is limited in the code while hydrotest pressure should be depended on material allowable stress and thickness as a common practice"

thank

 

[metengr]

You are only looking for gross defects from manufacture and you are not proving the design pressure of the tube in service. Looks like 1,000 psi was an acceptable value to the ASTM committee members to evaluate if through-wall flaws are present and would result in leaks.