Minimum Gasket width for ASME APP 2 designed Flanges.

[DK44]

For Girth Flanges of Heat Exchangers designed to ASME Sec VIII Div 1 App2,

1. ASME Sec VIII Div 1, gives Recommended minimum gasket contact widths for sheet and composite gaskets at Table 2-4.

2. This code does not provide rules to check minimum required width of gaskets.

3. Whereas Process Equipment Design by Brownell & Young gives a formula to check the minimum gasket width as Ab * Sa / (Pi * y * (Gkt OD + GKT ID)). This formula is not in code. But many follow it probably as a good design practice.

4. PV Elite also follows B & Y method and compares it with ASME Table 2-4. Many times it does not meet code (2-4) requirements. In such cases, is it required to increase the width to suit code vales for contact width. Then the flange may become not optimised.

5. But ASME Sec VIII Div 2 gives the minimum vales at Table 4.16.2 which are less than Div Table 2-4 values.

6. Minimum Peripheral Gasket widths are followed as per TEMA RCB 4 and for Shell sizes > 584 mm it is 12.7 mm. PV Elite gives a warning many times on comparing with Table 2-4 as stated above.

Request the experts to throw some light on the above subject for guidance.

 

[SnTMan]

DK44, 1,2 & 3: Agreed
4. Table 2-4 recommended widths need not be applied to metallic gaskets, regardless of software messages.
5. No comment, I have no knowledge of Div 2.
6. TEMA widths are good practice, and are applied generally to metallic gaskets, composition gaskets may need to be wider. Again, software messages may not apply.

Regards,

Mike

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

 

[Vikko]

1. ASME tab 2-4 and ASME 2-5(a)(3) are not mandatory, and only valid for sheet (of any material I suppose) and plastic
2. yes, width is very important factor, look at:
- table 2-5.2 (basic width b0) and also table 2-5.1
- 2-3 : b0 basic gasket width
- 2-3 : b effective gasket width
- 2-3 : G diameter of location of gasket reaction
=> gasket width, which has consequences on the contact surface area, which has effects on diameter G and reaction arm hG, so it is very important, increasing the gasket arm will make the gasket reaction moment to increase, with all due consequences. Also the width has direct effect on the contact surface are, which has direct effect on the bolt load in both operating and seating condition Wm1, Wm2: more the contact surface area is, and more force is required to seat and compress.
3. I do not have this.
4. I do not have this.
5. I do not know very well Div 2, the method are different: ASME VIII Div 1 is Taylor Forge methoid (also EN 1591 has another different method for flange calc).
6. you shall follow TEMA only if it is required by customer specification (TEMA then has to verify everything with ASME VIII Div. 1).