Sealing and expansion joints

Sealing depends on three things: the material of the gasket, matched to the fluid and the temperature, the geometry of the seating face, and the tightening applied, worked crosswise and to torque. Neglect any one of the three and a brand-new assembly will leak.

The O-ring works by controlled compression in a properly sized groove: NBR for mineral oils, EPDM for hot water, steam and brake fluid, FKM for hydrocarbons and high temperatures, silicone for food applications. The flat gasket is chosen on the flange rating and the thickness. The metal and graphite spiral-wound gasket is reserved for flanges under pressure and temperature, where it takes up creep.

• Rubber or stainless steel expansion joints absorb thermal movement, vibration and slight misalignment: they protect pumps and pipework, provided they are installed free of tension and twist.
• An O-ring is not reused once it has been dismantled: it has taken the shape of its groove.
• On a flange, the tightening torque is checked again once the line is up to temperature.

We cut flat gaskets from sheet, to a template or from the part itself, and supply complete kits.