Minimum seating stress 1

[APH]

How do you calculate minimum seating stress on a die-cut gasket between 2 flanges. Gasket material is Nitrile 60 durometer. I don't know the "K" (spring constant value) of the rubber. Can I calculate the seating stress based on the compression set data.

Thanks
APH

 

[nagarajh]

The sealing stress is a function of gasket type, material and flange surface finish, thickness, size and number of bolts, operating pressure, temperature, type flowing fluid, etc. I would suggest you contact the gasket manufacturer and give them the details of your design and they can give you good recommendations. Sorry I couldn't be of any more help.

 

[tothepoint]

Minimum and maximum compressive stress for unreinforced elastomer gaskets are as follows:
Minimum = 500 psi
Maximum = 1,500 psi

When I am determining assembly bolt torque for such elastomers, I usually shoot for 1,000 psi stress. Below 500 psi you may not get sufficient conformability from the elastomer (depends upon surface finish and flatness), and stresses higher than 1,500 you're going to experience fracturing of the elastomer.

 

[Cockroach]

I ran across a similar calculation for gasket pressure as a result of bolt torque in an old Crane Manual. The manual was circa 1965 or so, quite old now but the mathematics is still applicable.

As expected, when you need something a guy can never find it. Let me grope around the office and see if it is retrievable!

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[APH]

Cockroach,

Thanks!!

APH