m & Y factors for 13 Cr-Mo 44 Metal Grooved Gasket

[Awais Arshad]

Hello,

I am in a fix these days while designing a modified U-tube bundle for a heat exchanger on ASME VIII-I and TEMA ‘R’. Originally, exchanger had a 13 Cr-Mo 44 metal grooved gasket. Now while I am modifying the tube-bundle due to updated process requirements, I need to evaluate the exchanger for:

1. Existing Girth flange

2. New Required tube-sheet thickness

For Girth Flange evaluation, I need m & Y factors for gasket. In ASME Section VIII Div.1 Table 2-5.1 (Mandatory Appendix-2), I am unable to find m & Y factors for 13Cr-Mo44 material metal grooved gasket. Since existing gasket material is 13 Cr-Mo 44, what value for m and Y should I use?

Regards,
Awais

 

[r6155]

You need to think of an alternative to five of those listed in Table 2-5.1
is it soft aluminum? : NO
Is it copper or brass?:
......?
......?
......?
Try a minimum effort to understand.

Regards

 

[CuMo]

Check if a Flex Pro gasket with stainless steel core and graphite facings is suitable for the process / chemically compatible.

And if yes - the values are typically m = 2.0 and y = 17.2 MPa

https://flexitallic.com/wp-content/uploads/site//1/Flexpro_PN_Rev3.pdf

https://flexitallic.com/wp-content/uploads/2022/05/Flexpro-Kammprofile-Brochure.pdf

Consult also your best gasket supplier.

 

[SnTMan]

Awais Arshad, it appears 13Cr-Mo44 is similar in composition to 1 1/4 Cr - 1/2 Mo material in Sec II, Part D. If so, and assuming an unfaced gasket, I would interpret that per Table 2.5-1 it is classified as "Iron or Soft Metal", m = 3.75, Y = 7600 (52).

I would not follow this interpretation blindly however. You should be able to evaluate the flange design using this and higher values as well. Existing flange design should jive, or not.

A faced gasket, as per CuMo could be a good way to go. And yes, consult with your supplier.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Krausen]

Why not use a Kammpro style gasket (grooved metal, graphite faced)? You can get the exact m & y values from gasket manufacturers (Lamons, Flexitallic, etc), as the VIII committee is unable (or unwilling) to provide m & y values for Kammpro style gaskets in the code. These are the best type of gaskets for heat exchangers in general. Your m & y values will be lower compared to just a grooved metal gasket & will save you money on your shell girth flange design as a result

 

[VFK]

Consider galvanic corrosion risk if introducing graphite (most noble material). Other soft facing for kammprofile is PTFE.
If you stick to the original gasket construction, suggest you ask a reputable gasket manufacturer for the recommended m/y values.

 

[CuMo]

On the other side - with PTFE - the temperature limits shall be carefully examined.

 

[Awais Arshad]

@CuMo, @SnTMan, @r6155, @Krausen, @VFK, many thanks for the responses. From a cumulative understanding developed from your inputs, I opted for flexitallic PN type kammprofile gasket and took m and Y factors avaiable in their brochure.

Further, I checked SS type flange for Hydrogen Induced SCC at elevated temperatures from Nelson Curve and found it resistant to such problems at my working temperature.

@CuMo, your lead was a great support!