Alloy 20 Pipe

[Hectorex]

My client requires 12” Alloy 20 Pipe to ASTM B474 Class 3, single welded employing ER320LR filler, 100% radiographed. I have an offer for 12” Alloy 20 Pipe to ASTM B464, no addition of filler metal 100% radiographed and hydro tested at 500 psi.

Service – Sulphuric Acid 93-98%

Would you consider this an acceptable substitution?

Apologies if this is not the corrcet forum!

Thanks for your help.

 

[metengr]

How can you offer 12" pipe to ASTM B464 when the scope below for ASME SB 464 limits the pipe size to 6"?

Excerpt from the Scope of ASME SB 464;

The pipe covered is nominal pipe sizes up to and
including NPS 6, with the nominal wall thicknesses given
as Schedules 5S, 10S, and 40S and nominal pipe sizes up
to and including NPS 2, also including Schedule 80S. Table
2 of Specification B 775 is based on Table A1 of ANSI....

 

[Hectorex]

I have an offer of 12” Alloy 20 Pipe to ASTM B464, no addition of filler metal 100% radiographed and hydro tested at 500 psi. This has not gone to my client yet!

SB464 also states "Pipe having other dimensions may be furnished provided such pipe complies with all other requirements of this standard".

My original question still stands. Thanks

 

[metengr]

The acceptance of the pipe will be based on your client approval, not what is said or thought here. Having said that, I don't have a copy of B 474, and that is what is necessary to run a side by side comparison with SB 464 before a client would accept a substitution.

 

[pradipgoswami]

Hectorx,

B464 pipes(autogeneous welds-No Filer Metal) could not be a substitute to B-473 pipes (Welded with filer metals) due to the reasons stated below:-

-Addition or deletion of filler metal is an essential variable as per ASME Sec-IX, QW-404.14. So if the P.O calls for B-473 pipes B-464 is not the acceptable substitute on technical grounds.

-Integrity of pipes welded with filler metals are far superior that pipes welded autogenously (no filler).

-Addition or deletion of filler metal for alloy -20 could seriously affect corrosion resistance. ER320LR filler matches alloy-20 base metal chemistry. Following welding & with solution anneal heat treatment, weld properties may equal to or may be superior to base metal (to be proven by required test. This may not be the case in autogeneously welded pipes.

As per ASTM B-464,such pipes are restricted to 6 NPS max, with schedule 5S, 10S, 40S, and the application is restricted to general corrosion resisting and low or high temperature service. While for B-474 pipes there're no such restriction.

Sulfuric acid is highly corrosive. Though acids with 93-98% concentration is less corrosive than acids in 40-70% range, a change of piping spec may be difficult to accommodate by your client, since any leak of Sulfuric acid is considered to be a major health and safety issue , in North America. However if the piping is for low pressure and low velocity service, then the deviation may get accepted also.

You may still approach your client if the proposed alternative is the last option and see their replies.

Thanks.





Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario, Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299