B31.3 ERW

[BCbrad]

Good day,

I have been asked to supply reasons why SA53B - ERW pipe should not be used for hot oil (550F)applications. System max pressure is 125psi. As far as I can tell, the code does not show a reason to exlude it from this application, however the longitutal seam now has a .85 multipier for min. thickness calculations.

Any one had any experience with this?

 

[stanweld]

At the operating parameters stated, I would have no problem using ERW pipe from a reputable manufacturer.

Beside the .85 efficiency factor, ERW seams may have flaws that could be severe enough to result in leakage or rupture. When properly tested and inspected, the probability of such flaws inducing failure is highly remote, especially at your stated operating conditions.

 

[BCbrad]

Would it be reasonable to request random RT along the seam, especially where there may be higher levels of human traffic with in the piping system?

 

[blacksmith37]

The advantage of ERW is that you know where it will fail and where to look for flaws- the seam. The best mills will perform UT and EMI of the weld seam (RT no help). Also ,metallography to verify fiber orientation and seam recrystallize. Do not permit subcritical seam HT. Flattening tests, etc.(I generally do not trust mill certs, witness is best). I expect much of this is still in API 5CT. Or, you could just go smls for limited quantities.

 

[PAN]

We should consider how to find a reputable manufacturer...

In my previous project, reject rate of UT was highly increased after sending a resident inspector at the mill...

 

[Duwe6]

What diameter? Critical issue. At 2"NPS and above, the A-53 ERW seams are 100% NDE'd [usually eddy current, might be UT]. No NDE below 2". 1.5" & under, we buy A-106 [smls] for Process, Steam, and especially Hot Oil service. Cheap insurance.

As for corrosion allowance; Are you planning on prolonged 'down time' [months]? Temp is way too high for Corrosion-Under-Insulation, not high enough for serious scaling, and the oil inside is a metal preservative. Won't corrode much on OD, none on ID, while in-service.

 

[BCbrad]

The pipe size in use is 2" - 12" NPS STD. On occasion 14". The majority of the pipe run is 8".


The systems rarely have downtime longer than 1 week and that may happen once per year during a maintenace shut down. The

 

[Duwe6]

Buy SA-53-b ERW, paint it the high-temp silver, RT/UT at least 5% of the buttwelds, keep a welding inspector 'prowling' during all fabrication, support it at proper intervals, and run it for 100+ years.