High Temperature Bolting for B16.5 Flange

[sgtpickles]

Hello

I am looking for a little technical advise regarding a high temperature bolting application. This applies to both bolting on vessels (ASME BPV VIII-1) and process piping (ASME B31.3). The design temperatures in the areas for concern are in the range of 1200 F to 1500 F with an internal pressure of 90 psi.

My question is with regard to bolt selection for standard 600# or 900# RFWN or Lap Joint B16.5 flanges. Unfortunately we are committed to these flanges and changing to another style, i.e. grayloc, is not possible.

The only published allowable stress values for bolting in B31.3 (Table A-2) at 1500 F is A193 B8C, B8M, B8T, or A320 B8. All material being class 1. Unfortunately, all these materials are "low strength" bolting materials (30 ksi yield at room temp). Paragraph 309.2.1 in B31.3 does not allow these bolts to be used in any B16.5 flanges above 300#. Similarly, ASME B16.5 has the same restriction in Paragraph 5.3.4.

B16.5 does allow the use of ASME Section II materials for bolting - so this opens up a few more options from Table 3:

SB-572 UNS N06002 (Hastelloy X)
SB-408 UNS N08800 and N08810 (Incoloy 800/800H)
SB-572 R30556 (Haynes 556)

Originally, I was thinking of using Incoloy 800HT (UNS N08811) which would be dual certified for N08800 and N08810, but the coarse grain structure and low yield strength would likely leave me no better off than B8s.

Both in talking with Flexitallic, and looking at pages 54-55 in their "Gasket Design Criteria" Handbook, they recommend ASTM B637 N07718 (Inconel 718) up to 1400 F and ASTM B446 N06625 (Inconel 625) up to 1500 F. However, the published allowable values in Table 3 of Section II stop at 1150 and 1200 F for these materials. (As a note, Table 1B allows for grade 2 N06625 to be used up to 1600 F).

Does anyone have experience with high temperature B16.5 flanges? Our vessel (heater) manufacturers are both reputable vendors, and have originally shown regular B7s on their drawings (only suitable in ASME up to 1000F). When we questioned it and asked them to choose a suitable material for our approval, they did not have any better suggestions.

Can someone point me towards some handy references or resources that could be of some benefit? Am I stuck with one of the two suitable options in Table 3, i.e. N06002 or R30556?

Thanks in advance.

 

[rneill]

There is a table in the book "An Introduction to the Design and Behavior of Bolted Joints" by Bickford that lists the following materials as extreme temperature bolting:

Inconel X-750, max 1500 F
Waspaloy, max 1600 F
Rene 41, max 1600 F

However, when I check Section II it lists the max temp for Inconel 750 as 800 F (not sure why there is such a discrepancy between Bickfords data and Section II). Apparently Waspaloy is UNS N07001, and Rene 41 is UNS N07041 but I was unable to find either of these in Section II.

Sorry I couldn't be more help

 

[gr2vessels]

I can give you a hint;- if you open the section II, Table D, perhaps a pdf version, look up the bolting column and the maximum operating temperature column. Eg. page 368/369 shows bolting up to 1650F.
Cheers,
gr2vessels

 

[sgtpickles]

Thanks, actually the bolting on page 368/369, line 28, is SB-572 UNS N06002 (Hastelloy X). Table 3 in Section II Part D also lists a couple other materials (see my first thread) for temperatures at or above 1500 F.

So are you suggesting that I must stick to those published materials in Table 3, i.e. the ones listed above? Or does anyone have experience with other materials or have suitable documentation available to allow using a material recommended by Bickford or Flexitallic, etc.

 

[rneill]

Regarding the advice from Flexitallic, that material is listed in Section II but not at the temperatures Flexitallic indicated it was suitable to. Since these materials are explicitly addressed by Section II, I don't think you can use them outside of these limits regardless of what other data or information you are able to obtain.

With regards to materials not listed in Section II then these would be "unlisted" materials and I think you then have an opportunity to do some work and obtain data on their properties, apply the code rules for determining the allowable stress values and then take responsibility for using these materials with the stress values thus obtained.

Normally, if at all possible, we like to use code listed materials unless these are unavialable.

Both ASME Section VIII Div 1 and ASME B31.3 have rules regarding the use of unlisted material.