Comparison of seamless vs. welded tubes

Osama · **Joined:** Thu Apr 02, 2009 9:38 am **Posts:** 59

Dear Sir,

Service is gas to gas on both shell side and tube side

Design Pressure is 33 kg/cm2g, Design Temperature is 450 deg. C.

Recommended matrl is seamless SA 213 T11

There is one opinion from client to use SA 249 316L Welded tubes.

Can we use welded tubes.

akonrad · **Posted:** Tue May 12, 2009 2:49 pm

Sure you can, why couldn't uou? What in particular raises your concern?

dr.chris · **Posted:** Tue May 12, 2009 4:38 pm

Osama,

You are comparing "apples" to "oranges". You are comparing a 1.25Cr-0.5Mo tube with a 316L tube. Talk to a metallurgist to resolve your dilemma.

Now, if you want to compare seamless vs. welded tubes of the "same material" like say SA-213-TP316L vs. SA-249-TP316L, one of the difference is that seamless tubes have higher allowables stresses than welded tubes. This means that at the same design conditions, seamless tube would be thinner than welded tubes. You can check the allowable stress in ASME Section II Part D.

Also see this link for other comparisons of seamless vs welded tubes... http://www.obcorp.com/WorkArea/download ... px?id=1432

sanjeev_shukla70 · **Joined:** Wed Apr 18, 2007 2:05 pm **Posts:** 260

Welded tube is not a preferred option in case of 'U' Tube exchangers.

For MOC, you need to consult metallurgist as already pointed out by Dr Chris.

Regards

Osama · **Joined:** Thu Apr 02, 2009 9:38 am **Posts:** 59

Sir,
Actually SA 213 T11 Smls Vs SA 250 T11 Welded are being compared.

I have understood from Dr.Chris reply, higher allowable stresses are being taken care off in SA 213 T11.

Moreover that SA 213 T11 will be thinner in thickness from SA 250 T11
This means if compromise on above two important points than in general one can go for welded tubes?

Please confirm above point
Best regards
Osama

Osama · **Joined:** Thu Apr 02, 2009 9:38 am **Posts:** 59

Also in addition to my last post reply, i forgot to ask that are there any mechanical test differences between these materials.

akonrad · **Posted:** Wed May 13, 2009 1:40 pm

Osama,
I think you are getting different answers because it's not clear who is asking:
1. A manufacturer who has a design supplied by the client and considers some substitutions
2. A designer who wants to make a cheapest (or otherwise optimal) design
3. A designer who wants to utilise some stock material
4. A material supplier who wants to sell the right stuff for the purpose

and the best answer can be different depending on the case.

lordsteel · **Joined:** Wed Aug 10, 2011 4:20 pm **Posts:** 18

I think it mostly depends on the wall thickness you will choose in such two kind of material.
and compare the costs, it will be the best way to help you and your clients to make the decision in material here.

shmulik · **Joined:** Wed Jun 02, 2010 9:28 pm **Posts:** 31

There is significance for welded tubes If only one side of a heat exchanger contains a lethal substance. See at ASME VIII - 1, UW-2 (a)(3).

Indeed it seems that someone tries to utilize a stock material…

Anyway, I wouldn’t go for a 316L material as its strength at the temp. of 450 ºC is on borderline (316 with no 'L' could meet temp. requirement much better).
Don’t forget to consider limiting notes as well.

Comparison of seamless vs. welded tubes

Who is online