sgtpickles
Mechanical
- Jan 25, 2008
- 7
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.
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.
