Flange Connections
- Scope
Flanging is used extensively for process lines that require periodic dismantling. Plastic flanges and factory flanged valves and fittings in PVC and CPVC are available in a full range of sizes and types for joining to pipe by solvent welding.Gasket seals between the flange faces should be an elastomeric full flat faced gasket with a hardness of 50 to 70 durometer A. LD can provide full face gaskets in various materials and from 1/2" through 12" range having a 1/8" thickness.When it is necessary to bolt plastic and metal flanges, use flat face metal flanges not raised face, and always use recommended torques shown in the table below. - Pressure Rating
As with all other thermoplastic piping components, the maximum non-shock operating pressure is a function of temperature. Maximum pressure rating for LD flanged valve is 150 psi@22 degree. - Sealing
The sealing surfaces are slightly raised from faces of flanges so that when the bolts are tightened the faces will be pulled together generating a force in the water way area to improve sealing. - Alignment
The sealing surfaces are slightly raised from faces of flanges so that when the bolts are tightened the faces will be pulled together generating a force in the water way area to improve sealing. - Installation Tips
Installing and maintaining your flange and flanged valve is simple, but small mistakes can lead to big problems. The method for mating two flanges together is as follows:
- Make sure that all the bolt holes of the mating flanges match up. Don't force or twist the flange and pipe to achieve this.
- Use flat washers under bolt heads and nuts.
- Insert all bolts.(Lubricate bolts.)
- Make sure that the faces of the flanges and gasket mate snuggly tight fit prior to tightening of the bolts. Lose fit between two flange faces and gasket, might cause crack or damage to flange,valve and piping.
- The bolts on the plastic flanges should be tightened by pulling down the nuts diametrically opposite each other using a torque wrench. (See diagram below.) Complete tightening should be accomplished in stages. The final torque values are shown in the table below. Uniform stress across the flange will prevent leaky gaskets. E If the flange is mated to a rigid and stationary flanged object, or to a metal flange, the adjacent plastic pipe must be supported or anchored to eliminate excessive stress on the flange joint.
