Rubber Expansion Joint Advantages Compared to Metal Expansion Joints
Rubber expansion joints, also referred to as elastomeric expansion joints, have many advantages compared to metal expansion joints. Below are just a few to highlight:
Minimal face-to-face dimensions
Minimal face-to-face dimensions in rubber expansion joints offer untold economies compared with costly bends or loops. The relative cost of the pipe itself may be less or no more than a rubber expansion joint, however, total costs are higher when considering plant space, installation labor, supports, and pressure drops.
Rubber expansion joints are relatively light in weight, requiring no special handling equipment to position, contributing to lower installation labor costs.
Low movement forces required
The inherent flexibility of rubber expansion joints permits almost unlimited flexing to recover from imposed movements, requiring relatively less force to move, thus preventing damage to motive equipment.
Reduce fatigue factor
Compared to steel, the inherent characteristics of natural and synthetic elastomers are not subject to fatigue breakdown or embrittlement and prevent any electrolytic action because of the steel-rubber interface of joints and mating flanges.
Reduced heat loss
Rubber expansion joints reduce heat loss, giving long maintenance-free service. The added piping required for loops contributes to higher operating costs after going on stream due to increase in heat losses.
Corrosion, erosion resistant
A wide variety of natural, synthetic, and special purpose elastomers and fabrics are available to the industry. Materials are treated and combined to meet a wide range of practical pressure and temperature operating conditions, corrosive attack, abrasion, and erosion. Standard and special sizes of rubber expansion joints are available with PTFE/TFE/FEP liners, fabricated to the configurations of the joint body, as added insurance against corrosive attack. Fluoroplastics possess unusual and unique characteristics of thermal stability, non-sticking surface, extremely low coefficient of friction, and resistance to practically all corrosive fluids and forms of chemical attack.
Elastomeric expansion joints are supplied with flanges of vulcanized rubber and fabric integrated with the tube, making the use of gaskets unnecessary. The sealing surfaces of the expansion joint equalize uneven surfaces of the pipe flange to provide a fluid and gas-tight seal. A ring gasket may be required for raised face flanges.
Elastomeric expansion joints significantly reduce noise transmission in piping systems because the elastomeric composition of the joint acts as a dampener that absorbs the greatest percentage of noise and vibration.
Greater shock resistance
The elastomeric type expansion joints provided good resistance against shock stress from excessive hydraulic surge, water hammer, or pump cavitation.