Allowable stress for 904L pipe materials

[sbnz]

Hi all,

I am designing a pressure piping system where the pipe material is SS to ASTM A 240, TP 904L (UNS N08904). I was trying to decide the corresponding pipe spec and the allowable stresses as per B 31.1 - but am completely confused without any joy.

I noticed ASTM A 312 standard covers pipes to material TPXM-15/ UNS N08904. However B31.1 does not list that type under spec A 312 nor does AutoPipe in its library. From some lirterature on net it appears ASTM B673 & B674 could be appropriate pipe standards for 904L material. Again, B 31.1 doea not list the grade under B673 - and Autopipe does not have any pipe spec for "B" series.

Expecting some of you might have used this piping material in past and will be able to throw some light.

regards,

 

[MJCronin]

sbnz...

You state that your specification for "pipe material is SS to ASTM A 240, TP 904L (UNS N08904)"

I believe that A240 is a plate/strip material spec...... are you fabricating large pipe from plate ?

If so, another whole new set of rules apply under ASME B31.1/B31.3 !!!!!

ASTM describes this spec as:

"ASTM A240 / A240M - 08 Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications"

What, exactly, are you doing ???

-MJC

 

[stanweld]

904L is not listed in B31.1. Because 904L is used for its corrosion resistance, I would suggest that you redesign per B31.3.

 

[ytse]

First, you cannot use A240 for pipe. Para 123.1.1 (B) of B31.1 stated:
"A material conforming to a specification for which
allowable stresses are not listed in Appendix A is acceptable provided its use is not specifically prohibited by this Code Section and it satisfies one of the following
requirements:
(B.1) It is referenced in a standard listed in
Table 126.1. Such a material shall be used only within
the scope of and in the product form covered by the
referencing standard listed in Table 126.1."
Since A240 is spec for plate, you cannot use this material for pipe.

However, you already know, 904L pipe is available in ASTM B673. Since B673 is listed in Table 126.1, this is acceptable per para 123.1.1(B).

As for the allowable stress, para 102.3.1(C) stated:
"The basis for establishing the allowable stress values
in this Code Section are the same as those in the
ASME Boiler and Pressure Vessel Code, Section II, Part
D, Appendix 1...."

So, all you need to do is refer to the table in Section II part D, for the allowable stress for the B673 material.

 

[sbnz]

Thanks all for the comments/responses.

MJC - exactly what we are doing is exactly what I stated - using pipes made from SS ASTM-240, Tp-904L (UNS N08904). You can get this pipe directly from the pipe suppliers and have been in use in corrosive (specially marine) atmosphere- so we do not have to roll pipes out of plates in our yard.

ytse, I exactly did what you suggested - estimated the all stress from 1st principle as per Appendix-D of Sec-II.

ASTM B673 lists this material for pipe manufacturing, but B31.1 does not show this type under material grades - I am still baffled why.

Thanks all once again.