y ceramic slurry pumps

Rubber expansion joints - Tubes International

Rubber expansion joints – general information

Rubber compensators are widely applied in a variety of industrial pipelines, in power plants, in heating networks (heat transfer stations) and sanitary installations (sewage treatment plants and pumping stations, water treatment stations and machines). Basically, they are mounted near components that produce vibrations (pumps, engines, turbines, compressors etc.). They absorb different movements: axial, lateral and angular that result from thermal expansion of the pipelines or misalignment. They dampen vibration and noise and absorb the energy of pressure variations.

Working pressure up to 25 bar, working temperature from -40°C to 150°C depending on material and medium. Nominal diameter range from DN15 to DN1000. Most of compensators is fitted with swivel flanges put on the fold of the bellow. Some compensators are fitted with fixed flanges, threaded connections or other connections mounted with worm drive clamps. Flange material: zinc-plated steel, stainless steel and acid-resistant steel, aluminium. Flanges PN 10/16, PN25, ANSI 150 lb. and other. Accessories: inner PTFE liner, tie rods, vacuum supporting ring or spring, thermal protective cover.

Expansion joints are constructed of a rubber bellow reinforced with synthetic or steel cord and connectors to mount them into a pipeline (usually steel flanges). The expansion joints are classified by bellow material and application into several types:

• EPDM, CR, IIR rubber expansion joints designed for cold and hot water (industrial water, seawater, potable water), acids, bases and other slightly aggressive chemicals. They are not suitable for oils, fats and hydrocarbons;
• EPDM rubber anti-vibration hump connectors with threaded pipe unions for water systems;
• NBR or HNBR rubber expansion joints designed for oils, substances containing fat, petroleum products, some hydrocarbons, natural gas;
• white NBR rubber expansion joints designed for food substances, containing fats and oils, alcohol;
• conductive NBR rubber expansion joints for LPG (propane-butane);
• CSM rubber expansion joints, for chemicals and natural gas;
• FPM (Viton) fluorocarbon rubber expansion joints for chemicals and hot petroleum products;
• NR/BR rubber expansion joints (natural rubber/polybutadiene) for highly abrasive substances in the form of water suspension, slurry, sludge as well as dust and powder. They are not suitable for oils, fats and hydrocarbons;

List of products:

FAQ – Rubber expansion joints:

Which type of elastomer is best for rubber expansion joints for hot water?

EPDM rubber is normally used in expansion joints for hot water. It has great temperature resistance, even up to +130C (with peaks up to +150C) depending on the type of expansion joint.

It shows considerable longevity undergoing only slow weathering. In addition, it is resistant to weak acid and base solutions, technical alcohols, esters and ketones, and seawater.

Can rubber expansion joints operate in vacuum conditions?

Yes. Rubber expansion joints can operate in vacuum conditions. However, the value of vacuum depends on the type and diameter of the expansion joint. As the diameter increases, the value of a permissible operating vacuum in rubber expansion joints decreases. So, when the rubber expansion joints, especially those with larger diameters, are to withstand such operating conditions, they are additionally equipped with internal vacuum support rings and spirals made of acid-resistant steel. As a result, the rubber expansion joints, even those with larger diameters, can operate in vacuum conditions which are close to full vacuum.

Which rubber expansion joints offer high resistance to chemically aggressive media?

Bellows in rubber expansion joints can be made of different materials, suitable for the medium flowing through. These can be, for example, CSM rubber (Hypalon) or FPM rubber (Viton). Both of them are resistant to a wide range of chemicals and different types of petroleum products. However, rubber expansion joints with additional, PTFE (Teflon) bellow lining have the highest chemical resistance to very aggressive compounds and substances. This lining is 1 to 3 mm thick and covers the entire inner surface of the rubber expansion joint in such a way that the flowing medium does not come into contact with the rubber of the bellow, which has lower chemical resistance. The rubber expansion joints lined with PTFE have excellent resistance to almost all types of chemically aggressive substances. Apart from the lining, the expansion joint can also be equipped with internal vacuum rings made of PTFE, which allow operation in negative pressure conditions.