FAQ

If you have any questions you would like to ask us directly please use the Contact Us form or call us on 01384 881188 or use the LIVE HELP facility for an immediate response to anything you require.

Please see our frequently asked questions and answers below. Use may also use the form to ask a new question about FlexEJ's products and services.

Please use the Contact Us form or call us on 01384 881188 or use the LIVE HELP facility for an immediate response to anything you require.

Technical - Bellows & Expansion

A: Yes, our Elaflex ERV-R rubber bellows have WRAS, DVGW and ACS approval for drinking water. Our MRCA copper ended metal expansion joints also have WRAS approval. For technical assistance please contact us or use the Live Help link on this page.

A: Yes, our MRCA copper ended metal expansion joints have WRAS approval. Our Elaflex ERV-R rubber bellows also have WRAS, DVGW and ACS approval for drinking water. For technical assistance please contact us or use the Live Help link on this page.

A: To identify an existing expansion joint we need to know: nominal bore, overall length and flange type plus service, temperature, pressure and required movement if known. Try our Flange Finder to help identify the flange and you can send us a picture of the existing part using the Contact us form. For technical assistance please contact us or use the Live Help link on this page.

A: To design or select a rubber bellows or metal expansion joint we need to know: nominal bore, end type, service, temperature, pressure and required movements. You may also specify in addition your requirements for external hardware – tie rods, hinges, gimbals - internal liner, external cover and instrumentation. Material selections should also be specified to suit the service and associated system piping. For technical assistance please contact us or use the Live Help link on this page.

A: Yes, we can normally accommodate any combination and also different nominal bores. A selection of common flanges are shown in our Flange Finder. For technical assistance please contact us or use the Live Help link on this page.

A: Our ranges have many approvals and certification, a summary for the Elaflex range of high quality rubber bellows can be found here. The individual product data sheets for rubber bellows also show the certification and approvals. We can also provide specific material certification for all items if requested at time of PO. For technical assistance please contact us or use the Live Help link on this page.

A: Standard metal expansion joints may have a pressure test certificate issued if requested with order. Engineered metal expansion joints are provided with very extensive certification depending on customer requirements, PED if applicable and industry specifications such as ANSI B31.3. The certification required and applicable specifications must be agreed prior to order placement. For technical assistance please contact us or use the Live Help link on this page.

A: You can use the product configurator to find the most suitable product and our FAQ here gives the information you will need for a full selection. For technical assistance please contact us or use the Live Help link on this page.

A: You can use the product configurator to find the most suitable product and our FAQ here gives the information we will need for a full selection. For technical assistance please contact us or use the Live Help link on this page.

A: Elaflex rubber bellows are stocked in a number of standard lengths from 130mm to 300mm, a summary of lengths, diameters and types is here. We also offer fully engineered rubber bellows which are available in custom lengths to suit the application. You can use the product configurator to find the most suitable product. For technical assistance please contact us or use the Live Help link on this page.

A: FlexEJ metal expansion joints for HVAC are stocked in up to 3 standard lengths for each type. Engineered metal expansion joints can be manufactured to any desired length greater than the minimum length required for the design movements. You can use the product configurator to find the most suitable product. For technical assistance please contact us or use the Live Help link on this page.

A: FlexEJ metal expansion joints for HVAC are rated: flanged -16 Barg, copper ended MRCA and union ended MRUA - 6 Barg. The pressure rating depends on the material, diameter and design temperature of the bellows; for engineered metal expansion joints we can normally meet any requirement. For technical assistance please contact us or use the Live Help link on this page.

A: Elaflex rubber bellows are typically rated 16 Barg at 50 DegC up to DN400 decreasing to 6 Barg at 100 DegC for DN1000; please refer to the individual product rating information for each type which can be found here for Elaflex rubber bellows. The pressure rating depends on the material, diameter and design temperature of the bellows; for engineered rubber expansion joints we can normally meet any reasonable requirement. For technical assistance please contact us or use the Live Help link on this page.

A: FlexEJ metal expansion joints for HVAC are rated for between 90 to 300 DegC depending on type. Engineered metal expansion joints can be designed for flowing media temperatures up to 800 DegC and above, the bellows metal temperature is controlled to not normally exceed 400 Deg C by the internal liner and insulation design. For technical assistance please contact us or use the Live Help link on this page.

A: The temperature rating depends on the expansion joint material and the expected lifetime of the bellows. Elaflex rubber bellows are typically rated up to 100 DegC and 130 DegC for the DIN4809 Rotex type. Engineered rubber expansion joints can be rated up to 180 DegC. For technical assistance please contact us or use the Live Help link on this page.

A: Yes, some rubber materials can be used directly with abrasive material, the Elaflex ERV-GSHNBR bellows being the most abrasion resistant. For any Elaflex rubber bellows or engineered rubber expansion joints a stainless steel internal liner can be supplied which prevents the abrasive flow from directly impacting the rubber. For technical assistance please contact us or use the Live Help link on this page.

A: Yes, typically for Elaflex rubber bellows above DN50 a vacuum support ring or spiral is required for FV, the partial vacuum performance varies by type and diameter, please refer to the product data sheets. Support rings or spirals are an option for all standard rubber bellows and may be specified for integration into all engineered rubber expansion joints. For technical assistance please contact us or use the Live Help link on this page.

A: The Elaflex ERV-GS and ERV-GSHNBR rubber bellows are fire resistant for 30 minutes at 800 DegC. Flame protection covers are available to fit to all the Elaflex rubber bellows. For technical assistance please contact us or use the Live Help link on this page.

A: An engineered metal expansion joints bellows can be manufactured from any high ductility metal. The material selection is normally based on either high temperature strength or corrosion resistance, the most frequently used materials are stainless steel 304 / 321 / 316 , high nickel alloys 625 / 825, titanium and duplex. The pipe ends for the expansion joint are often manufactured from a less costly material than the bellows - carbon steel or CrMo for example - but frequently stainless steel is specified. For technical assistance please contact us or use the Live Help link on this page.

A: Yes, if you have the details we can normally offer an equivalent, our FAQ here gives the information we will need for a full selection. For technical assistance please contact us or use the Live Help link on this page.

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: There are three types of allowable movements:

> Axial movement is the movement of the bellows or expansion joint parallel to the centre line of the expansion joint - compression and extension

> Lateral movement is the movement of the bellows or expansion joint in a plane perpendicular to the centre line of the expansion joint

> Angular movement is the movement of the bellows or expansion joint causing the centre line of the expansion joint to follow an arc

Rotation, end to end, is not an allowable movement and will cause the bellows or expansion joint to fail

For technical assistance please contact us or use the Live Help link on this page.

A: As a rough guide rubber expansion joints allow around +/-25mm axial, +/- 25mm lateral, +/-5 Deg angular of non-concurrent movement per arch.

There is no easy guide for metal expansion joints, please contact us with you requirements.

Note that large axial movements are often best accommodated by placing a lateral expansion joint at 90 Deg to the main run of pipe.

See our FAQ for a definition of expansion joint and bellows movements and concurrent vs non-concurrent.

For technical assistance please contact us or use the Live Help link on this page.

A: Concurrent movements are treated in simultaneous combination. For example, if an expansion joint or bellows is specified with concurrent movements of +/- 25mm axial and +/- 25mm lateral both movements can occur simultaneously and, for a metal expansion joint, the fatigue life will be stated for that case.

If movements are stated as being non-concurrent the expansion joint or bellows is capable of achieving the individual movements but either not simultaneously or not within the stated fatigue life for a metal expansion joint.

For technical assistance please contact us or use the Live Help link on this page.

A: Yes, if correctly guided and anchored our rubber bellows can be joined together using a mating flange to seal upon. For technical assistance please contact us or use the Live Help link on this page.

A: No, it is not recommended to join metal expansion joints together. For technical assistance please contact us or use the Live Help link on this page.

A: Yes, you may pre-set the expansion joint within its existing movement capability but care must be taken to ensure the resulting movement cycle is acceptable. For technical assistance please contact us or use the Live Help link on this page.

A: Very roughly above 6 Barg / 130 DegC or above 16 Barg at any temperature a metal expansion joint will be required. For technical assistance please contact us or use the Live Help link on this page.

A: There are three broad applications which may exist in any combination:

> to reduce vibration or noise being transmitted through the piping
> to allow for installation misalignment in the piping
> to allow piping to move in operation, normally due to thermal growth, so to avoid high pipe stress and loads on equipment.

If significant thermal movement is expected a pipe stress analysis should be carried out on a system and that analysis will identify the ideal location for any expansion joints required to achieve acceptable pipe stress and loads. For technical assistance please contact us or use the Live Help link on this page.

A: All expansion joints exert a force pushing the pipe ends apart - pressure thrust - which is proportional to the operating pressure and diameter of the bellows. If the expansion joint is unrestrained the piping system must withstand the force, or, alternatively, the expansion joint may have restraints built in to constrain the pressure thrust force, tie rod, hinge or gimbal.

For technical assistance please contact us or use the Live Help link on this page.

A: A tie rod is a simple pressure thrust restraint. It will allow reasonable lateral movement but not axial extension; it can allow axial compression if the pressure thrust is overcome by the piping movement. See the movements and pressure thrust FAQs for definitions. For technical assistance please contact us or use the Live Help link on this page.

A: A hinge is a pressure thrust restraint which allows angular movement only in one plane and no axial movement. Hinges are often used in pairs to create restrained expansion joints for large single plane lateral movements. See the movements and pressure thrust FAQs for definitions. For technical assistance please contact us or use the Live Help link on this page.

A: A gimbal is a pressure thrust restraint which allows angular movement in two planes and no axial movement. Gimbals are often used in pairs to create restrained expansion joints for large two plane lateral movements. See the movements and pressure thrust FAQs for definitions. For technical assistance please contact us or use the Live Help link on this page.

A: A pressure balanced design uses an additional bellows to provide an equal and opposite reaction force to the pressure thrust; typically used to allows axial movement but not subject the piping system to the pressure thrust force. See the movements and pressure thrust FAQs for definitions. For technical assistance please contact us or use the Live Help link on this page

A: The terminology can be confusing and often words have no universally accepted meaning. We use the following definitions but the terms “bellows” and “expansion joint” are typically considered as interchangeable:

> Expansion Joint - an expansion joint is a complete unit with metal bellows or rubber bellows and end fittings, plus, optionally, liner, cover and external hardware. Other terms used - compensator, flexible connector

> Rubber Bellows - the flexible element within a rubber expansion joint

> Metal Bellows - the flexible element within a metal expansion joint

> Liner - The liner fits within the expansion joint under the metal bellows or rubber bellows to prevent the flowing media directly impinging on the bellows, this reduces flow disturbance and allows the temperature of the bellows to be controlled in the design.

For technical assistance please contact us or use the Live Help link on this page.

A: Please refer to our guidelines for installation, anchoring & guides: rubber expansion joint installation and metal expansion joints installation. For technical assistance please contact us or use the Live Help link on this page.

A: This is a metal expansion joint bellows term; ply refers to the number of sheets metal used in the forming of the bellows, so a 2 ply bellows is made from two sheets of material. A multi ply bellows is generally more flexible that an equivalent single ply bellows. For technical assistance please contact us or use the Live Help link on this page.

A: EJMA is the Expansion Joints Manufacturers Association. Their bellows calculation method is most frequently used for metal bellows expansion joint design. EJMA does not cover rubber bellows or metal hose design. For technical assistance please contact us or use the Live Help link on this page.

A: B31.3 is the ANSI process piping specification frequently applied to industrial, petrochemical and refinery piping systems. Appendix X contains a version of the EJMA metal bellows calculation which uses a different fatigue curve to EJMA. For technical assistance please contact us or use the Live Help link on this page.

A: EN14917 is a recent EN harmonised standard for metal bellows calculation which is based EJMA. For technical assistance please contact us or use the Live Help link on this page.

A: Spring rate is the reaction force of the bellows when it is moved. It is a different force to pressure thrust – both forces act together on the piping. For technical assistance please contact us or use the Live Help link on this page.

A: The liner deflects the flow away from the arch or convolution. This results in smoother flow, less abrasion of the bellows and can provide a reduction in bellows operating temperature used in conjunction with insulation.

Technical - Metal Hose, Technical - Bellows & Expansion, Technical - Pressure Vessels

A: Our Flange Finder contains details for many common flanges. Typically you need to know the bore size or outside diameter and number of bolts to be able to make the identification. For technical assistance please contact us or use the Live Help link on this page.

A: All industry standard flanges are available or any bespoke flange design you require can be supplied. Our Flange Finder contains details for many common flanges. For technical assistance please contact us or use the Live Help link on this page.

A: PED is the Pressure Equipment Directive which applies to any pressurised equipment used in the EU. FlexEJ is accredited to ISO9001:2008 and complies with the requirements of module(s) D,D1, E1 & H of Annexe III of the Pressure Equipment Directive 97/23/EC and Schedule 4 of the UK Pressure Equipment Regulations 1999 (SI 2001). For technical assistance please contact us or use the Live Help link on this page.

Commercial

A: For stock items next day delivery can be arranged; standard items not in stock typically 7-14 working days, engineered or special items will be individually quoted. For sales assistance please contact us or use the Live Help link on this page.

A: Yes. FlexEJ hold a stock of popular size of Elaflex rubber bellows and
metal expansion joints for HVAC, we can also manufacture to order. For sales assistance please contact us or use the Live Help link on this page.

A: Yes, you can either please look at our gallery for examples of what we offer or use the product finder. For sales assistance please contact us or use the Live Help link on this page.

A: Yes, FlexEJ is accredited to ISO9001:2008. For sales assistance please contact us or use the Live Help link on this page.

A: No, we only manufacture to order. For sales assistance please contact us or use the Live Help link on this page.

A: No, we only manufacture to order but lead times can be very short. For sales assistance please contact us or use the Live Help link on this page.

A: Yes, please call us with your details. For sales assistance please contact us or use the Live Help link on this page.

A: Yes, subject to the normal checks, please download our application form. For sales assistance please contact us or use the Live Help link on this page.

A: Bank details for payments in GBP, Euro and USD can be found here. For sales assistance please contact us or use the Live Help link on this page.

Technical - Metal Hose

A: Please refer to our guidelines for metal hose installation. For technical assistance please contact us or use the Live Help link on this page.

A: ISO 10380 is the standard to which our metal hose is typically manufactured; it defines the physical properties of the hose, deration with temperature and movement cycles. For technical assistance please contact us or use the Live Help link on this page.

A: Metal hose is manufactured in continuous lengths from metal strip which is welded and then formed. We offer U form convoluted metal hose which is mechanically or hydraulically formed, with standard or close pitch. Typically the hose conforms to ISO ISO10380. For technical assistance please contact us or use the Live Help link on this page.

A: Metal hose is available in Stainless Steel 304, 321, 316, Alloy 625, Monel and Hastelloy. It may be possible to meet requirements for other specific grades and materials but this will depend on volume and the suitability of the material to be formed. For technical assistance please contact us or use the Live Help link on this page.

A: Hose braid is a woven wire mesh which encases the metal hose. It adds greatly to the pressure retaining capability of the hose and for very high pressure applications we use a double braid. The braid stops the hose growing in length under pressure and also helps prevent mechanical damage to the convoluted core. For technical assistance please contact us or use the Live Help link on this page.

A: Metal hose braid is available in Stainless Steel 304, 316, Alloy 625, Monel and Hastelloy. For technical assistance please contact us or use the Live Help link on this page.

A: Metal hose assemblies can operate from full vacuum to over 200 Barg. The actual rating depends on the temperature, material, diameter and braid – we can quickly advise what is possible for your application. For technical assistance please contact us or use the Live Help link on this page.

A: Metal hose assemblies can operate with media temperatures from cryogenic to over 550 deg C. For technical assistance please contact us or use the Live Help link on this page.

A: The bend radius depends on the hose diameter and the type of motion. The static bend radius is the minimum radius the hose can bend to for a few movement cycles without fatigue failure. The dynamic bend radius the minimum radius the hose can bend to for many movement cycles without fatigue failure. ISO10380 defines these parameters. For technical assistance please contact us or use the Live Help link on this page.

A: Two movements must be avoided in the installation, torsion and axial movement. Torsion can result from many apparently acceptable hose installations and will reduce the life of the hose considerably. Axial extension for a braided hose assembly is impossible as the braid prevents the hose getting longer; axial compression is also to be avoided wherever possible. Generally lateral and loop installations are the most advantageous. Please refer to our metal hose installation for guidelines. For technical assistance please contact us or use the Live Help link on this page.

A: As materials get hotter their mechanical properties – strength – tend to decrease. This has to be taken into account when stating a pressure rating for a metal hose, the pressure rating decreases with increasing temperature. For technical assistance please contact us or use the Live Help link on this page.

A: Any standard or custom flange pattern for fixed flange or lap flange. Pipe ends and threaded ends allow virtually any end fitting to be supplied either welded or screwed. Generally it is preferred to have one end that allows rotation at installation to avoid the hose being under torsion. For technical assistance please contact us or use the Live Help link on this page.

A: A jacketed hose has a second outer hose over the inner which allows typically a cooling or heating medium to be introduced. An example is shown in the gallery. For technical assistance please contact us or use the Live Help link on this page.

A: DN6 to DN200mm, larger possible. For technical assistance please contact us or use the Live Help link on this page.

A: Yes, a strip wound hose can be used as a liner within a convoluted metal hose assembly. Flexibility is reduced to some extent. For technical assistance please contact us or use the Live Help link on this page.

A: Full material traceability / PMI, DP examination of all welds (including hose long seam), hydrotest are all typical for engineered metal hose assemblies. The certification required and applicable specifications must be agreed prior to order placement. For technical assistance please contact us or use the Live Help link on this page.

Technical - Pressure Vessels

A: PD5500, formerly BS5500, Specification for unfired, fusion welded pressure vessels, is a UK standard FlexEJ use to design pressure vessels. For technical assistance please contact us or use the Live Help link on this page.

A: EN13445, Unfired Pressure Vessels, is a standard FlexEJ use to design pressure vessels. It is harmonised under the
PED. For technical assistance please contact us or use the Live Help link on this page.

A: ASME BPVC Section VIII - Rules for Construction of Pressure Vessels, is a standard FlexEJ use to design pressure vessels. For technical assistance please contact us or use the Live Help link on this page.

A: No, at present FlexEJ is not U Stamp accredited. For technical assistance please contact us or use the Live Help link on this page.

A: We can work with most weldable high strength metals - typically Carbon Steel, CrMo, Stainless Steel, Titanium, Duplex Stainless Steel. For technical assistance please contact us or use the Live Help link on this page.

A: Yes, FlexEJ design and manufacture engineered pressure vessels to ASME 8, EN13445 and PD5500, PED as required plus customer specifications. We can also manufacture to your design and drawing. For technical assistance please contact us or use the Live Help link on this page.

A: To design a pressure vessel we need to know the design pressure, temperature, working fluid, volume (or length & diameter) and what material is required. The number and size of connections to the vessel has a big impact on both the design and cost so this is also useful early design information. For technical assistance please contact us or use the Live Help link on this page.

A: Typically up to 3m diameter, 10m long, 15t weight. Please let us know your requirements and we can quickly advise if it is within our capability. There are some examples shown in our gallery. For technical assistance please contact us or use the Live Help link on this page.

A: No, we only manufacture to order. For technical assistance please contact us or use the Live Help link on this page.

A: Yes, we can package the vessel with associated piping, valves, instrumentation and equipment, skid mounted or free standing. There are some examples shown in our gallery. For technical assistance please contact us or use the Live Help link on this page.

A: The pressure vessel design code will stipulate the minimum certification and test requirements which may be augmented by customer specifications – typically we can meet all these requirements. The certification required and applicable specifications must be agreed prior to order placement. For technical assistance please contact us or use the Live Help link on this page.