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1 1/4 Cr - 1/2Mo YIELD STRENGTH

1 1/4 Cr - 1/2Mo YIELD STRENGTH

1 1/4 Cr - 1/2Mo YIELD STRENGTH

(OP)
I am trying to design a TEMA BEM fixed tubesheet exchanger per ASME Sec. VIII, Div.1 with the following criteria:

Design Temp. = 1150°F
Metallurgy = 1 1/4Cr - 1/2Mo [plate (SA-387-11 Cls. 2), tubes (SA-213-T11), & Forgings (SA-182-F11 Cls 2)]

The problem I am running into is trying to interpret ASME Sec. II part D, Table Y-1.  Although the material is allowed up to 1200°F, yield stresses are only listed up to 1000°F.  However, I need the yield strength of the tubes, tubesheets, and shell cyl. at 1150°F to complete the UHX tubesheet calculations.

How can I find the values for yield strength at 1150°F?  Does the code mention how to procede and if so where is it referenced?

Your help is greatly appreciated.

RE: 1 1/4 Cr - 1/2Mo YIELD STRENGTH

Why are you even contemplating using these materials at that design temperature? The material is in the high temperature Creep regime for design; yield strength is not germane to the design. You truly need to reconsider materials selection.

RE: 1 1/4 Cr - 1/2Mo YIELD STRENGTH

Per Part UHX 13.3 "When a yield strength value is not listed in Table Y-1,one may be obtained by using the procedure in UG-28(c)(2) Step 3"

Regards,

Mike

RE: 1 1/4 Cr - 1/2Mo YIELD STRENGTH

(OP)
Thanks for your help.  Unfortunately, I can't change the material at this stage (budget quote).  I tried to suggest alternates, but the customer is not interested at this time.

RE: 1 1/4 Cr - 1/2Mo YIELD STRENGTH

Agree with Standweld, I'm not sure why you're using this material either.

Allowable stress around 1,900 at your design temperature?  Save yourself and your customer some time and take a look at another material.

347/347H comes to mind.

-TJ Orlowski

RE: 1 1/4 Cr - 1/2Mo YIELD STRENGTH

Agree with Stanweld et al; this is out of the range for 1¼Cr-½Mo.   

RE: 1 1/4 Cr - 1/2Mo YIELD STRENGTH

bam-bam.....

Another teeny tiny point....

A TEMA BEM for 1100+ degrees F ???/?  I don't think so....

TEMA BEM is good to a maximum of ~ 300F

Aside from your client's poor choice of materials, he has a very poor choice of HX design.

Ya, ya I know.....you are running out of time and you have to bid the spec.....your boss is an MBA...

   

RE: 1 1/4 Cr - 1/2Mo YIELD STRENGTH

MJC
         From your reply it would appear that you have come across the same "numpties" out there with MBA's. It's a pity they have the ultimate say in decision making as they tend to get it wrong on the majority of times.

RE: 1 1/4 Cr - 1/2Mo YIELD STRENGTH

Certainly the wrong material and wrong design.

But anyhow, I remember seeing the fixed plate design dwgs   for the clinch river liquid sodium HX ( never commissioned), and as I recall, the tubes were twisted, en masse, to allow some flexibility for thermal expansion, shell vs tubes, during transients. Exactly how is your design going to accomodate differential expansion during transients?

A beter design would be similar to "header type" heaters, with tubeside fluid distributed / accumulated in internal headers, and the tubes  able to move slightly  relative to each other , also add  thermal sleeves at the header to shell connection. Tubing would be T23 or T91/92, but if T23 tubes are used, the tube stub at the header would need to be another alloy ( non bainitic) if teh heder wall thickness was greater than 1" .

RE: 1 1/4 Cr - 1/2Mo YIELD STRENGTH

I have personally designed a similar unit some years ago, similar metallurgy, similar temperatures, as specified by the customer. Not my preference, certainly, but it can be done.

Regards,

Mike

RE: 1 1/4 Cr - 1/2Mo YIELD STRENGTH

Afterthought: that WAS before Part UHX was introduced.

RE: 1 1/4 Cr - 1/2Mo YIELD STRENGTH

DSB123 & MJCronin,

Its not all bad with MBAs.  As a failure analyst I thank them daily for my job security.   

RE: 1 1/4 Cr - 1/2Mo YIELD STRENGTH

brimstoner;
 careful now- it would be an MBA who would decide to outsource your job overseas.

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