Strength material than ASTM A194 B16

[abbver98]

I had to analyse an existing product that doesn't met the ASME code.The bolting section isn't enough 35 cm2 in spite of 38 cm2 required by the stress analysis (10 bolt B16 D1&quot. I can't increase the number of bolts nor the diameter. I can only change the material. ASTM A194 B16 has an allowable stress at room temperature of 25 ksi. It works also at 482°C and the stress analysis is ok. Do you know other bolting material having allowable stress higher that ASTM A194 B16 at room temperature and at 482°C commonly avalaible in commerce.
Regards,

 

[PAN]

You are talking about ASTM A193-B16. ASTM A194 is the specification of nut.

Please describe more about your application. Is this for pressure vessel design/flange bolting?

 

[abbver98]

Excuse me it's ASTM A193.
Yes It's for flange bolting of pressure vessel.

 

[prex]

I'm afraid that your only choice is Inconel 625... prex
motori@xcalcsREMOVE.com

http://www.xcalcs.com

Online tools for structural design

 

[abbver98]

I found 3 spec that match my inquiries :
*SA-479 XM-19 with ASR of 26.2 ksi and 1150°F VIII-1 limit but not enough strength.
*(SA-437 B4B is slight equivalent to XM-19).
*SB-637 (Alloy 718) has a good ASR of 37.0 ksi 1150°F VIII-1 limit. I don't know if it's available in commerce and how the cost is.

 

[abbver98]

To prex,
What is the exact spec. of the Inconel 625 acco. to ASTM ?
Do you have experience whith such alloy.
I'm looking for SB-637 (Alloy 718) now. What do you think ?

 

[abbver98]

Ok I found it.
It seems that the Alloy 718 is very hard to be machined.
With 625 alloy stress analysis is ok and it's avalaible in our supplier.
Are there any requirements for the bolting made from 625 ?
Had to be machined or rolled ? Any help !

 

[abbver98]

I don't know which nut I had to use.
I know that it had to be less strength that the stud.
Do someone have opinion ?
Thanks in advance

 

[prex]

Have no experience with 625 bolting. However I suppose that you will machine it, as this is simpler for small quantities, and that the nut will be made with the same material. prex
motori@xcalcsREMOVE.com

http://www.xcalcs.com

Online tools for structural design

 

[JamesJennings]

One concern with using the various Inconel alloys is galvanic compatability. Inconel is very noble, so you need to worry about the environment and Inconel's effects on the materials that it contacts.