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API 5LX Pipe in high temp service

API 5LX Pipe in high temp service

API 5LX Pipe in high temp service

(OP)
We ordered 36" std wt A106 grade B pipe for a nominal 40 psig, 300F steam line replacement, but were substituted API 5L X42 pipe in place of this.  This grade falls under the tables in ASME, but the allowable stress table is terminated at 400F.  Problem being, this line is a turbine exhaust line, whereby, steam temperature can approach 550F during startup and shutdown (accounts for less than 0.1% of total operating time).  Can the tables be extrapolated beyond the 400F cutoff for X42?  There are allowances for this in the code for certain grades, but I am not familiar with the limitations on this.  Does anybody know what property of X42 pipe warrants the temperature limit and what the implications could be in operating beyond this limit?

RE: API 5LX Pipe in high temp service

tersla..

You state:  "This grade falls under the tables in ASME, but the allowable stress table is terminated at 400F."

Are you referring to ASME B31.1 Power piping Code ?

In my opinion, this should be the "code of record" for this work and the B31.1 temperature limitations of  API 5L X42 must apply.

Was there some specific reason that your purchasing department substituted this material ?

-MJC

   

RE: API 5LX Pipe in high temp service

(OP)
Thanx for your prompt reply MJCronin.  This falls under ASME B31.3 (Actually in Canada so CSA B51-03 prevails which refers to B31.3).  Purchasing did not do the substitution, it was done by the vendor.  A106 Grade B is in tight supply for this size (36" std wt) right now and they felt that 5L X42 had superior tensile strength and was a valid substitution.  They did not receive our consent,however.

RE: API 5LX Pipe in high temp service

Yield stress varies with temperature, but 5L allowable stress maximum is 20 ksi at 400ºF.

5L X42 [b]CANNOT[b] be used above 400ºF under B31.3.

"I think it would be a good idea."
- Mahatma Gandhi (1869-1948),
when asked about Western civilization  

RE: API 5LX Pipe in high temp service

Seamless, 36" API 5LX pipe is in similar tight supply so I assume that your Supplier also provided welded pipe. Since the supplier did not meet the contract, you have recourse to resolve your problem - shove it back to him and hit him in the pocket book. If welded pipe is acceptable, A-671 or A-672 should have been ordered.

If you're under the gun and facing liquidated damages or other losses and your contract with the Supplier does not include financial remedy, explore recertification of the pipe to API 5LB or A-671/A672.  

RE: API 5LX Pipe in high temp service

(OP)
Thanx all for your comments.  Stanweld, I did not entertain having the pipe re-certified.  We will explore this option as we would miss the outage window if new material was ordered.  And yes, welded pipe was supplied.

RE: API 5LX Pipe in high temp service

No claim to add anything new here and definitely not an expert on the detail.  Just interested in the question and why the vendor substituted.  
I visited a pipe mill several years ago.  At the time they were making API 5L B, X42, and various similar low carbon specs.  My understanding was that the only difference was what name they dialled into the automatic paint sprayer and what was written on the order.  It was cheaper to manufacture to a minimum higher spec than keep changing it.  My understanding is that X grades are dependent on both metallurgy and manufacture for their strength.  Hence, they are used only when it is necessary and when their use can be strictly controlled - on a pipeline.  I am not saying you can do it but what is the technical reason for limiting to 400F?  You are not going to get X grade properties, which have been determined at air temperatures, but would it not just fall back to B grade?  What has the pipe mill got to say?  Another factor is manufacturing processes have changed over the last 30 years and the Codes might not have caught up with the best.  e.g.  HFI cf old ERW. (Although not much help with the present question).  The mill / supplier may be looking at it from a real material vs Code wording point of view. i.e.  The manufacture may not have high temp properties for X42 but might for the B.  To him it might well be the same thing but we as users need it in writing. Again not much help if you are dealing with an insurer who is only looking at the code.

After saying all that, there is one thing I can say for sure.  The original spec of A106B seamless at 36" Std seamless was an error.  It does not exist.  Its the sort of "mistake" people let graduate trainees make to bring them back to earth or to show how clever they are compared to the new boy.  The pipers equivalent of tartan paint.  
It would have been more helpful if the vendor had told you as soon as he got the order.  I'd be looking to kick his butt for that reason as well as substituting, either correctly or incorrectly, without asking permission to change the order.  It's not the first time I have come across similar smart ass "I know better" arrogance.  A polite 60 second phone call - "thanks for the order but..." would have prevented the problem without embarrassing you and probably have won him the next order.
I'd be looking to follow Stanweld on getting it recertified. Hopefully, its a technicality rather than a technical problem for your service.  

RE: API 5LX Pipe in high temp service

(OP)
4Pipes, I will try to answer all points raised above.
-Indeed, 36" A106B does not exist (my ignorance), that is why the engineer in charge (I am merely the operator of the line) changed the spec to API5L B, which still meets code.
-X42 has allowances for up to 1.35% Mn, whereas, 5L B is lower (not sure on the magnitude here).
-The pipe mill graded the pipe as X42, yet the Mn content in the MTR shows 1.47% (pipe does not even meet X42 spec).  I have no idea what property the increased Mn adds, but it seems to be the common denominator for a temperature limit on piping.
-X42 is prohibited above 400F.  Local codes dictate line must be designed for maximum temperature the line can possibly see.  This line can see 540F during startup and shutdown.
-agreed, a phone call would have avoided all this mess.

We decided to take the hit on the timeline and reject the pipe.  Suddenly, the supplier says "we can have grade B here in 10 days".  Now we may meet original timeline after all.  Funny how a little pressure squeezes out some action.  This supplier is in danger of losing all business from us ($1 Bn expansion starting in October) and are now scrambling hard.

RE: API 5LX Pipe in high temp service

tersla,
What you are experiencing is the "one-size-fits-all" method of modern steel making. The manganese content of X42 can be increased to 1.50 max when the carbon content is suitably lowered per Table 2A and 2B footnote a.
Normally pipe mills dual stamp or triple stamp pipe 5LB, 5LX-42 and A-53.

Manganese enhances strength and toughness.

I will also wager that the X42 pipe purchased would also meet X60 pipe; take a good look at Table 3B.  You need to be very careful how you order pipe, especially when used in sour service; a number of owners had ordered X42 without chemistry and mechanical controls and regretted it greatly.  

T

RE: API 5LX Pipe in high temp service

Tersla:
I had similar case as you. I needed 6" A53-B pipe, instead, I received triple stamp pipe A106-B/A53-B/API5L X42 pipe. Based on the pipe MTR's doc, the pipe's actual yield strength is from 42kips to 59kips.

1. From the manufacturer's point of view, the material properties are similar. So, it has typically triple or quadruple stamp (with API5L-B) pipe to help fabrication and inventory. And, the Pipe Sales will substitute it automatically based on the material, but not on your application condition.

2. The issue is API5L X42 pipe have a temperature limitation of 400 deg-F per ASME B31.3. Instead, A106-B/A53-B/API5L-B could be up to 750 deg-F.

3. The API5L X42 pipe has the same allowance stress as A106-B and A53-B. But, the high yield strength pipe may have potential problem of welding cracking and hydrogen embrittlement.

In my case, the X42 pipe is still OK since the service temperature of the application was about 200 deg-F. For your case at 550 deg-F service temperature, you may want to use Grade B pipe only. It could be triple stamp A106-B/A53-B/API5L-B pipe. I believed the 36" pipe is a critical header for the system, and it will be really bad if something happened because of it.

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