Expansion joints with two or more arches (convolutions) may be manufactured to accommodate movements greater than those of which a single arch type joint is capable of.
Length of the joint is dependent on the number of arches.
Spool arch type joints are available in many standard pipe sizes with fluoroplastic liners of TFE and/or FEP.
These liners are fabricated as an integral part of the expansion joint during manufacture and cover all wetted surfaces in the tube and flange areas.
Fluoroplastic provides exceptional resistance to almost all chemicals within the temperature range of the expansion joint body construction.
Filled arch-type expansion joints may be supplied with a bonded-in-place soft rubber filler to provide a smooth interior bore.
Filled arch design reduces possible turbulence and prevents the collection of solid materials that may settle from the solution handled and remain in the archway. Filled arch joints also have a seamless tube so the arch filler cannot be dislodged during service.
Reducing expansion joints are designed and manufactured in order to allow the connection of different diameter pipes.
Unusual applications of rubber expansion joints may require the specification of: protective shields, protective cover or fire cover. These three types of covers, when manufactured of metal, have one end which is bolted to or clamped to the mating pipe flange. The other end is free, designed to handle the movements of the expansion joint.
Protective shields should be used on expansion joints in lines that carry high temperature or corrosive media. This shield will protect personnel or adjacent equipment in the event of leakage or splash. Wrap around protective shields of fluoroplastic impregnated fiberglass are the most common. Protective covers of expanded metal are used to prevent exterior damage to the expansion joint.
Fire covers, designed oversize, are insulated on the I.D. to protect the expansion joint from rupture during a flash fire. They are normally installed on fire water lines.
Sun covers protect the elastomer against UV radiation.
When possible, it is not recommended to insulate over elastomeric expansion joints.
Protection / Spray shield have some insulating properties. The containment of system temperatures can accelerate the aging of the product and makes required external inspections difficult.
Consists of a sleeve extending through the bore of the expansion joint with a full face flange on one end. Constructed of hard rubber, metal or fluoroplastic it reduces frictional wear of the expansion joint and provides smooth flow, reducing turbulence.
This type sleeve should not be used where high viscosity fluids, such as tars, are being transmitted. These fluids may cause packing-up or caking of the arch area, which reduces movements and in turn may cause premature expansion joint failure.