Rerate Pressure vessel from 1968 2

[daniel1978]

I try to rerate vessel from 1968 to raise temperature and reduce pressure , i use compress software and i have problem with allowable stress.so my question are which stress i should use to rerate vessel new or old? any othere standard i have too review during Rerating?

 

[metengr]

I would try to locate the allowable stress values from the 1968 edition of the ASME B&PV Code. You can request from the National Board of Boiler and Pressure Vessel Inspectors for a nominal fee a copy of the stress values for the specific material.

 

[weldstan]

If the new temperature does not exceed 650F and the material is carbon steel or low alloy steels, the design allowable stress was 1/4 of the specified minimum tensile strength of the ASME materials. specification used.

 

[loilfan]

For a pressure/temperature re-rate use the old Code. You can use the new Code for alterations where you can show that the techniques/properties that you are using have improved since it was originally built. For example, NDT methods, joint efficiency, material strength, etc. This only applies if new metal is being added which would not be the case here.

If in doubt, use the more conservative Code.

 

[DanTh3Man]

If you are worried about it find the allowable stress values from each edition of the code and use the smaller value.