- Mating flanges should be of the same type and correctly aligned.
- Fasteners should be selected to ensure that they do not exceed their elastic limit at the required tension.
- Do not re-torque elastomer bound compressed non-asbestos gaskets after exposure to elevated temperatures. (They may well have hardened and are at risk of cracking.
- Ensure that fasteners show no signs of corrosion, which might affect their load bearing capacity.
- Fasteners and/or gaskets should never be re-used.
- Good quality gaskets should always be procured from reputable suppliers only.
- Gaskets should be stored in a cool dry place, away from heat, humidity, direct sunlight, ozone sources, water, oil and chemicals. They should also be stored flat (i.e. not hung on hooks).
Simple Torque settings
Joint Size Range of Torque
| in. (mm) | ft/ib | N/m |
|---|---|---|
| 3 (76) | 45-60 | (61-81) |
| 4-24 (102-610) | 75-90 | (102-122) |
| 30-36 (762-914) | 100-120 | (136-163) |
| 42-48 (1067-1219) | 120-150 | (163-203) |
Bolt Tightening
Gaskets should be tightened evenly in at least three, or even four stages using an opposed-pattern as illustrated here.
Be aware that “cross-talk” exists between bolts during the tightening process so that as one tightens and the gasket compresses, another bolt may loosen. Therefore, a final pass around all of the bolts at the end is suggested to ensure that all remain tight.
