PTFE Bellows


PTFE expansion bellows, otherwise known as PTE expansion joints, offer excellent media compatibility and corrosion resistance. Offered in two ranges - standard 'R' and heavy duty 'RHD' - with diameters from 25mm to 600mm. All bellows have Van Stone flanges - any drilling available - and limit rods:

PRODUCT GUIDES

PTFE Bellows

What is a Convoluted PTFE Expansion Bellows?

For excellent corrosion resistance and media compatibility...

  • Materials
    Solid, multi laminated PTFE bellows with coated carbon steel flanges.
  • Application
    Highly corrosive and contamination sensitive media.
  • Rating
    Varies with number of convolutions and strongly with temperature. Electrically conductive.
  • Design
    Minimum porosity and homogeneous wall thickness.

How to select a PTFE bellow


1 Temperature & Pressure2 Compatibility3 Diameter and Length4 Flange Drilling & Restraints5 Movements6 Let us help
PTFE expansion bellowsTemperature is the most critical selection factor as the mechanical strength of PTFE decreases rapidly with increasing pressure. Note that due to the limited strength of PTFE the number of convolutions also strongly influences the rating of the bellows, we provide data for 2-3, 4-6 and 7-10 convolution bellows. The Heavy Duty bellows have a higher pressure rating but a lower range of allowable movements.
PTFE expansion bellows compatibilityPTFE is almost totally chemically inert and highly insoluble in most solvents or chemicals. This makes it an excellent choice in highly corrosive environments or where media contamination is an issue. However where the temperature and mechanical strength of a PTFE bellows is a problem other materials – or a PTFE liner in another type of bellows - may be a better solution, see our Bellows Finder.
PTFE expansion bellows diameters and lengthStandard diameters between DN25 and DN600 in 2-10 convolutions, fixed lengths. For larger diameters and other lengths the Safetech rubber bellows range can be specified with a PTFE liner
PTFE expansion bellows flange drilling & restraintsAny flange drilling can be supplied; if you are uncertain about what you already have installed our Flange Finder will help you identify it. PTFE bellows have Van Stone flanges (see FAQ) with limit rods to prevent over extension. The bellows will exert a pressure force on the pipe (see FAQ) which must be restrained or absorbed at the piping anchors.
PTFE bellows movementsPTFE bellows have a defined movement range, which is shown for each type in the Range tab on this page. The movements listed are non-concurrent (see FAQ).
PTFE expansion bellows helpCall our expert team on +44 (0) 1384 881188 or email us at sales@flexej.co.uk or use Live Chat on this web site - we are here to help, please get in touch.

Can't see what you want? Need help?

Call us. Or use Live Chat.

For instant advice. We can custom-design and engineer almost any expansion joint you need for delivery in the UK or worldwide. Call our expert team on +44 (0) 1384 881188. Or email us sales@flexej.co.uk

FlexEJ's PTFE Expansion Bellows


FlexEJ has the following two ranges of PTFE joints available:

Standard duty, 2-3, 4-6 and 7-10 Convolutions
DN25 to DN600

 
Standard duty PTFE bellows

STANDARD DUTY, 2-3, 4-6 and 7-10 CONVOLUTIONS
Inert, highly compatible

Solid PTFE multilayer convolutions assure minimum permeability and good mechanical performance. Rated from 10 Barg at 50°C, the pressure rating reduces with both increasing temperature and number of convolutions, please see the range charts. Supplied with flanges which can be specified to any drilling pattern in coated carbon steel or stainless steel. Flanges are Van Stone which guarantees that the media is only ever in contact with PTFE. Limit rods are provided to prevent over extension.

Heavy duty, 2-3, 4-6 and 7-10 Convolutions
DN25 to DN600

 
Heavy duty PTFE bellows

HEAVY DUTY, 2-3, 4-6 and 7-10 CONVOLUTIONS
Inert, highly compatible

Solid PTFE multilayer convolutions assure minimum permeability and good mechanical performance. Rated from 16 Barg at 50°C, the pressure rating reduces with both increasing temperature and number of convolutions, please see the range charts. Supplied with flanges which can be specified to any drilling pattern in coated carbon steel or stainless steel. Flanges are Van Stone which guarantees that the media is only ever in contact with PTFE. Limit rods are provided to prevent over extension.

Not sure what flange spec you need?

Use the FlexEJ Flange Finder to find out

FlexEJ stock a full range of specs and types for our bellows. Or call our expert team on +44 (0) 1384 881188.

 

Who can you talk to?


Try our sales and customer service team on 01384 881188

They don't bite. And they know what they're talking about. Call the team any time from 9am to 4pm weekdays or use LIVE CHAT if you would prefer a quick text answer. For more complex queries, send us any pro-forma documentation using the get a quote form below or email us sales@flexej.co.uk.

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Can't quite find the right bellow?

Try the FlexEJ Bellows Finder

Or call our expert team on +44 (0) 1384 881188

Frequently Asked Questions


Q. What is spring rate?
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 contact us or use our Live Chat facility.
Q. What does bellows ply mean?
A. This is a metal bellows term : ply refers to the number of sheets of 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
Q. What is the difference between a bellows and an expansion joint?
A. In this field, the terminology can be confusing, often with no universally accepted meaning. We tend to 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 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 our Live Chat facility.

Q. What are tie rods or a tied metal or rubber bellows?
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 our Live Chat facility.
Q. What is pressure thrust or force?
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. For instance types, tie rod, hinge or gimbal.

For technical assistance please contact us or use our Live Chat facility.

Q. What information do I need to design or select a rubber bellows or metal expansion joint?
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 our Live Chat facility.
Q. What is EJMA?
A. The 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 CHAT link on this page.

Please visit our full FAQ page to see all our frequently asked questions.

Need a detailed quote?

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We will provide full technical details together with, pricing and shipping timescales. For more complex engineered quotes, preliminary sketches and calculations will be available.

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Industry experience

FLEXEJ Ltd was formed in 2002 by two professional engineers who brought together an already highly respected design capability with business and commercial skills gained in large multinational companies.

  • Our focus has always been on application and design – helping our customers find the best value solution.
  • We have a strong engineering and manufacturing team with experience in petrochemicals, refining, nuclear, desalination though to HVAC.
  • The team is also very familiar with meeting complex requirements for documentation, in process NDT and test on projects. We have supplied many large end-users such as EDF, Exxon, Shell, Reliance & QatarGas working with major contractors such as JGC, Foster Wheeler & Technip.
FlexEJ Industry Experience