Normal Fluid Service and Severe Service

[gwelch123]

We are doing the required 5% RT on Normal Fluid service and we also have Class I Fluid Service with 100% RT.

My question is does the 100% RT go toward the 5% on normal or is it separate? I have conflicting answers on this subject.

Thanks

 

[JohnBreen]

What Code are you designing the system to?

 

[gwelch123]

B31.3

 

[JohnBreen]

In B31.3, what is Class I fluid service?

Appendix M and paragraph 300.2 list and define Normal fluid service, Category D fluid service, Category M fluid service and High Pressure fluid service.

Chapter VI (inspection. Examination and Testing) references those categories and severe cyclic conditions. No mention there about a "Class I fluid service". ???

If the Code of record is ASME B31.3 Process Piping, design it to B31.3 rules.

 

[bvi]

The title of the post is severe cyclic, which requires 100% RT or UT. However, many people misclassify systems as severe cyclic. But if it is in fact severe cyclic, the 100% RT or UT requirements only apply to those portions of the system that are severe cyclic, that is, where the calculated stress due to thermal expansion and other displacement loading is over 80% of the allowable (+ more than 7000 cycles). The 5% part and the 100% parts are treated entirely seperately with respect to examination.

 

[gwelch123]

B31.3 here....Okay so if you are postweld heat treating pipe (carbon steel) and 100 % RT after PWHT shouldn't the X-ray tech automatic assume it's graded severe? I mean any 100% RT and PWHT is automatic graded sever on X-ray right?

Again please let me know where I can find the answer

 

[stanweld]

No, not necessarily. Many Owner's specify 100% RT examination for specific systems to normal service acceptance criteria under Table 341.3.2. It has been my experience that when examination to Severe Cyclic Conditions is to be performed, it is specifically stated either by the Owner or the Engineer.