gasket 2

[mielke]

we are designing a custom flange with a sheet gasket and are thinking about widening the gasket surface. I know that we will need to increase the force on the gasket to provide the same pressure, since we are increasing the area.

and therefore it seems that the wider the gasket the more force and bolt torque required. it does not seem to be optimal to go to a wider gasket but are there any benifits of going to a wider gasket that i am missing?

 

[muld0020]

A wider gasket will help in larger diameter flanges. If you do not have enough width even though you torque the studs all the way down you may get a leak. I think the width is a parameter determined by the gasket material you are using. I would not worry about the torque in your case since you probably have small bolts/studs if you are using a sheet gasket with a relatively low design pressure. If you have high pressure I would look at a SS winding.

I would use the following rule of thumb for compressed non-asbestos sheet gasket width

ID < 24" = 3/4"
24"< ID < 36" = 1" Wide
36"< ID < 60" = 1-1/4" Wide
ID > 60" 1-1/2" Wide

I would also use a confined joint for a design pressure over 300 psi

 

[mielke]

thanks muld0020 we're testing it at 100psi our ID is about 25" and we have 1" gasket and thinking about changing to 1 3/8". we are having sealing difficulties.

 

[muld0020]

Thickness of the gasket will also affect things. Not knowing your service/design is hard to comment, but if you are using a 1/8" thk gasket it will require more bolt loading than a 1/16" thk gasket. Generally the "m" and "y" for 1/8" thk compressed gaskets are larger than 1/16" thk...thus your Wm1 and Wm2 will increase (assuming ASME App. 2 calcs).

There are also a wide range of compressed gaskets out there, you might be able to keep the design and switch to a different material with a better m and y value for your flange. An interesting gasket we used once for a leaking flange was Garlock 3760 multi-swell, the gasket swells in contact with water or oil.

 

[TJOrlowski]

If your contact surfaces are out of flat in opposite directions (assuming non-lap flanges), it may be causing your leak. And as muld0020 pointed out, a thicker gasket may not be the solution.

Thermoseal & Flexitallic both have equivalents of the 3760 multi-swell sheet.

-TJ Orlowski