Stress Relief of Flush-Type Clean Out Fitting

[andrewleong]

Does a stainless steel flush-type clean out fitting requires thermal stress relief?

According to clause 5.7.4.1, all flush-type clean out fitting require thermal stress relief.

While Appendix D section 3.7 - 650-I-33/99 also states that stress relief is required regardless of the material used.

However under Appendix S, clause S.3.3.2 indicates that thermal stress relief requirements of 5.7.4 are not applicable for stainless steel.

Could anyone clarify on the above?

Many thanks.

 

[fegenbush]

Stainless steel flush-type clean out fittings do not require stress relief per S.3.3.2.

650-I-33/99 in Appendix D references Section 3.7.4 (in 1999). This is equivalent to 5.7.4 in the 11th Edition 3rd Addendum.

 

[andrewleong]

Thanks for the reply.

Yes, i understand that 650-I-33/99 section 3.7.4 is equivalent with 5.7.4.
That's why it contradict with S.3.3.2.

Am i correct that the statement "regardless of the material used" of Appendix D 650-I-33/99 only applied to all materials other than stainless steel?

 

[Duwe6]

Correct. The specific requirements of Appendix S for stainless steel override the general requirements of Appendix D.

This difficulty came from 'expanding' 650 to encompass austenetic stainless steels, in adition to the ferritic carbon steels that it was originally written for.

 

[fegenbush]

"Am i correct that the statement "regardless of the material used" of Appendix D 650-I-33/99 only applied to all materials other than stainless steel?"

Yes, that is my interpretation.

If you would like to submit a technical inquiry, you can email me a file and I will see that it is addressed at the committee meeting in April. (mfegenbush<at>caldwelltanks<dot>com).

 

[IFRs]

I agree with Mr. Fegenbush. Appendix D is often a source of controversy due to its nature.

 

[andrewleong]

Thanks all for the comment .
Appreciate very much.