A FlexEJ guide to common applications and media used in our primary industries
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Application & Media Guide
These pages give a broad overview of the main media groups and the materials that work well with them. FlexEJ has access to very comprehensive compatibility data and will be pleased to advise on specific media.
WATER
Water Applications
Water is a ubiquitous media and present in just about all domestic, commercial and industrial settings. Selecting the most appropriate expansion joint for water applications requires a variety of factors to be considered including the temperature, contamination and intended use of the water.
Potable Water and Food Use
Potable water service requires an approved EPDM rubber which has passed rigorous testing by a recognised body – WRAS for example. The certification may be for the product as a whole or for the material in contact with the potable water. For foods, a specific food related approval such as FDA will be required. An approval for potable water does not normally extend to food products or processing, .
Rubber expansion joints with WRAS product approval are Elaflex RedBand, Elaflex RedSpot and with FDA product approval Elaflex WhiteBand.
Rubber expansion joints with WRAS approved materials are routinely designed and manufactured by Safetech.
Metal expansion joints with WRAS product approval are FlexEJÂ Copper End.
Metal expansion joints in stainless steel may be designed and manufactured by FlexEJ and are listed by DWI.
Waste, Sewer and Swimming Pool
These applications tend to be low temperature and are best suited to a Chloroprene CR rubber compound. This compound is resistant to contaminants such as oils, oily anti corrosion agents, weak acid or alkalis and is a robust solution where the water chemistry may not be fully known. Rubber bellows are a very good selection for these services where high chlorides could pose a corrosion risk with stainless steel bellows.
Rubber expansion joints with Chloroprene lining are Elaflex BlackBand.
Safetech also routinely designs and manufactures in Chloroprene allowing customers to specify any diameter or length of expansion joint.
Heating & Hot Water
Prolonged exposure to temperatures over 60°C appx will cause rubber to harden over time. Long term reliability can be assured by using a high quality EPDM rubber and conforming to DIN4809. For long term operation above 100°C and for any steam service, a metal bellows should be considered and certainly applied above 130°C. (EPDM is a term that is applied to any rubber mixture containing it, the quantity/quality needs to be high to ensure good performance).
Rubber expansion joints with DIN4809 product approval are Elaflex ROTEX.
Metal expansion joints suited to high temperature water and steam applications are FlexEJ HVAC Metal range.
Sea Water
This application is normally considered clean and is very well suited to a Chloroprene lined rubber expansion joint.
Stainless steel bellows should be avoided in marine and saline environments as there is a high risk of chloride attack. If a metal bellows is needed then bellows manufactured from a high Nickle alloy such as 625 should be specified. Such expansion joints are designed and manufactured
by FlexEJ.
Sea water applications are often very large diameter, found on the intakes to desalination, power or process utility plants. Safetech manufactures very large diameter rubber expansion joints specifically for these applications in Chloroprene.
Cooling Water
EPDM is often specified for this application but it is rarely the best choice unless the water is entirely free of oily contaminants. (If clean then consider as a hot water application as above.)
In process plants or on systems with high levels of anti corrosion additives a Nitrile bellows would be the best choice. Nitrile is immune to attack from oily contaminants, hydrocarbons and aromatics and has an operating temperature limit of about 90°C.
Rubber expansion joints with Nitrile liners are Elaflex YellowBand.
Rubber expansion joints with Nitrile liners are routinely designed and manufactured by Safetech.
Marine
The use of rubber expansion joins on ships requires the product to be type approved; Elaflex holds a wide range of approvals for their range from DNV, LR, ABS and BV.
Fire resistance is an important factor for any expansion joint on engine service and Elaflex offers a specific fire resistant bellows and an additional fire cover which can be used with any of the rubber bellows.
Rubber expansion joints with Nitrile liners and fire resistant to ISO 15540 are Elaflex YellowSteel and YellowSteel HNBR.
OILS & FUELS
Oils & Fuels
This is a very wide group of applications and is broadly suited to Nitrile rubber bellows. For more arduous media either FKM or HNBR may be required. Metal expansion joints are very well suited to any of these applications.
Oils, fuels with <50% aromatic content
Petroleum based media, E85 fuel, natural gas, mineral oils, hydraulic oils, oil contaminated water.
Rubber expansion joints with Nitrile liners are Elaflex YellowBand.
Rubber expansion joints with Nitrile liners and fire resistant to ISO 15540 are Elaflex YellowSteel and YellowSteel HNBR.
>50% aromatic content, aggressive media
Fuels with high aromatic content, bio diesel, hot oils, Benzene, aromatic / chlorinated hydrocarbons
Rubber expansion joints with Viton liners are available from Safetech.
Low temperatures
In low ambient temperatures rubber becomes less compliant and the spring rate of the bellows will increase. Harsh, cold environments such as found in Siberia require low temperature rubber formulations for applications such as drilling muds and aviation fuels.
Rubber expansion joints with Low Temperature Nitrile liners are Elaflex YellowBand LT.
Stainless steel metal bellows perform exceptionally well in low temperatures and are routinely used on cryogenic services such as LNG. Below -40°C a metal bellows must be used.
Metal expansion joints in stainless steel may be designed and manufactured by FlexEJ to suit your exact application.
Large diameters, higher pressures
Many large refinery, petrochemical and industrial processes require larger diameters and higher pressures than can be catered for by a standard product.
Safetech also routinely designs and manufactures in Nitrile allowing customers to specify any diameter or length of expansion joint.
FlexEJ can design and manufacture high pressure and large diameter metal expansion joints for any large scale process.
Grease, oily compressed air
For non aggressive applications it is possible to use Chloroprene rubbers which are well suited to contaminated wastes, greases, compressed air.
Rubber expansion joints with Chloroprene lining are Elaflex BlackBand.
Fire rated applications
Fire resistance is an important factor for any expansion joint on engine service and Elaflex offers a specific fire resistant bellows and an additional fire cover which can be used with any of the rubber bellows.
Rubber expansion joints with Nitrile liners and fire resistant to ISO 15540 are Elaflex YellowSteel and YellowSteel HNBR.
GASES
Gases
Gases fall into three main applications groups – ambient, high temperature and hydrocarbon.
Air, Compressed & Combustion
Air applications are usually benign if oil free. Compressed air is best handled by a Chloroprene rubber which will tolerate oily contamination. Combustion air similarly is suited to a Chloroprene rubber. Although most often clean, the external environment – an engine compartment for example – could be an issue. Metal bellows should be considered with care as they are susceptible to flow induced vibrations which can cause very premature failure.
Rubber expansion joints with Chloroprene lining are Elaflex BlackBand.
Safetech also routinely designs and manufactures in Chloroprene allowing customers to specify any diameter or length of expansion joint.
Steam
Rubber compounds suffer from rapid hardening if exposed to steam long term and should be avoided in this application. Metal bellows are ideal for steam applications and can be applied on all service temperatures. Liners must be used for steam applications to protect the bellows from flow induced vibration and to lower the bellows material temperature.
The FlexEJ HVAC Metal range can be applied to 180°C and the FlexEJ Industrial Metal range to 300°C. Above this, FlexEJ will design and manufacture for specific applications to any desired temperature.
Exhaust and Flue Gas
Characterised by very high temperatures, vibrations and corrosive combustion compounds these are amongst the most challenging applications for expansion joints. Liners must be used in these applications to protect the bellows from flow induced vibration and to lower the bellows material temperature. High Nickel alloys such as 625 are typically selected although care must be taken to protect these materials from corrosion.
The FlexEJ Industrial Metal range may be used up to 300°C. Above this, FlexEJ will design and manufacture for specific applications to any desired temperature.
Hydrocarbons, Natural Gas and LPG
Nitrile rubber bellows are very well suited to these applications at moderate pressures and temperatures.
Rubber expansion joints with Nitrile liners are Elaflex YellowBand for Natural Gas and Elaflex OrangeBand for LPG.
ABRASIVES
Chemicals & Abrasives
Bellows compatibility is critical in these applications. Given details of the service we will be able to advise a suitable material selection
Chemicals
A CSM or FKM rubber compound is suited to this group of services. Metal bellows may also be applied successfully if the exact chemical composition is known at the outset.
Rubber expansion joints with CSM lining are Elaflex GreenBand.
Rubber expansion joints with Viton liners are available from Safetech.
The FlexEJ Industrial Metal range may be applied with media compatible with stainless steel up to 300°C. For other media and higher temperatures, FlexEJ will design and manufacture for specific applications to any desired temperature.
Abrasives, Slurries and Carbon Black
Metal bellows are very thin and careful design is needed to ensure the media does not abrade the inside of the convolutions. Specific rubber BR/NR compounds bellows are reasonably tolerant of abrasive flows although not so of sharp, cutting solids.
Rubber expansion joints with BR/NR lining are Elaflex BlueSpot. These bellows may be fitted with a stainless steel liner for additional protection.
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Frequently Asked Questions
A. Yes, FlexEJ has full design capability for engineered metal expansion joints and can work to any recognised standard – typically EJMA, B31.3/Appendix X, EN14917 plus PED and/or other customer specifications. Engineered rubber expansion joints are typically designed to meet the FSA guidelines plus PED and/or other customer specifications For technical assistance please contact us or use the Live Help link on this page.
A. Do use FlexEJ’s new Bellows Finder available on our Expansion Joints page to find recommended expansion joints by media (application) such as waters, oils, acids, etc, as well as by bore size, length, end type and more. Generally speaking, any of our HVAC bellows (rubber or metal) might be suitable for general purposes whereas our high-quality Elaflex ranges are recommended for more specific requirements you may have. And metal expansion joints can generally be designed and built to accommodate any media and temperature range, environment and pressure ranges you are likely to encounter. Do call us or use LIVE CHAT for more direct advice.
Please visit our full FAQ page to see all our frequently asked questions.