CAST-IN TUNNEL SEGMENT GASKETS

Cast-in gaskets (also known as anchored gaskets or cast in situ gaskets) are integrated with the segment during the casting process.

This is opposed to being glued into a pre-made groove once the concrete segments have been cast.

Cast-in Gasket in Concrete Segment

Cast-in seals ‘anchor’ themselves to the segment as the concrete surrounds the legs at the base of the seal.

This process ensures a consistent positioning of the gasket around the segment.

The design of the legs ensures that the seal is secure in the segment and will not move during or after the segment is cast.

This is especially important during installation of the tunnel segments.

 

Benefits of Cast-in Gaskets

    • No need to apply adhesive
    • Cleaner to work with
    • Provide cost savings due to the removal of adhesive and the gluing process.
    • A more secure fit in the segment leading to reduced movement of the seal during installation and increased performance

 

UNIQUE CORNER JOINTING SYSTEM

No Solid Corners

No Solid Corners

Cracked or damaged segments caused by corner point loading has traditionally been a problem faced by tunnelling engineers and designers.

VIP’s Cast-in gaskets are designed specifically to eliminate this due to the unique patented (GB2541978 – international patent pending) corner jointing system.

This has allowed us to dramatically reduce the volume of rubber at the corners, thus ensuring the gasket can collapse into the groove and the load on the corners is equal to the rest of the gasket.

MINIMISING RUBBER VOLUME AT THE CORNER JOINT

VIP’s unique jointing process results in the profile of the gasket being maintained up to the corner edge. This ensures that the compression performance of the gasket is equal along the entire face of the gasket.

This differs to a traditional shot-joint corner which can result in excess rubber travelling along the gasket voids during the moulding process.

This results in making the gasket unable to compress at the corners due to the voids being full of rubber, creating a ‘solid’ corner.

Minimising Rubber Volume

The energy exerted at these points during closure of the segments can lead to cracks and spalling as it dissipates through the segment, finding the path of least resistance.

CORNER ANGLES THAT PERFECTLY MATCH THE SEGMENT

VIP can manufacture corners for cast-in gaskets to obtuse, acute and 90° angles, therefore matching the profile of the segment design perfectly.

90° Angles
90° Angle
Acute Angles
Acute Angles
Obtuse Angles
Obtuse Angles
Z Axis AnglesZ Axis Angles

Segment design can differ with each project. Recognising this and the importance of the gasket matching the exact shape of the segment.

VIP can also vary the profile orientation along the Z axis.

The following profiles comprise VIP’s cast-in core range.

28mm Cast-in Tunnel Segment Gasket
35mm Cast-in Tunnel Segment Gasket

Further profiles are available or can be developed on request to meet specific design requirements.

GLUED-IN TUNNEL SEGMENT GASKETS

Traditionally the industry has used elastomeric gaskets that are glued into pre-formed grooves in the concrete segments.

VIP manufactures a range of profiles which are compatible with many pre-existing segment mould groove designs.

The following profiles comprise VIP’s glued-in core range. Further profiles are available or can be developed on request to meet specific design requirements.

Glued-in VIP024 Tunnel Segment Gasket
Glued-in VIP028 Tunnel Segment Gasket
Glued-in VIP028H Tunnel Segment Gasket
Glued-in VIP028LHT Tunnel Segment Gasket
Glued-in VIP035 Tunnel Segment Gasket

 

 

 

 

 

 

CORNER ANGLES THAT PERFECTLY MATCH THE SEGMENT

VIP’s glued-in profiles have corner joints that can be manufactured to match the angles of the segment design including 90°, acute and obtuse angles.

The corners are formed using an injection process in moulds that match the profile of the extruded gasket.

This ensures that when the segments are joined together, the gasket can collapse into the groove and the load on the corners is equal to the rest of the gasket.

HYDROPHILIC TUNNEL SEGMENT GASKETS

VIP also manufacture hydrophilic gaskets for both our Cast-In and Glued-In profiles.

Hydrophilic compounds are designed to swell when they come into contact with water which can close the gap between the gasket faces.

VIP Hydrophilic Gasket Types

VIP supply hydrophilic gaskets in 2 main formats:

Hydrophilic cord inserted into a slot in a TSG prior to installation Hydrophilic Chord
Hydrophilic strip co-extruded onto an elastomeric TSG Co-extruded Hydrophilic Strip

TSG RUBBER COMPOUNDING AND MANUFACTURE

VIP’s tunnel segment gaskets are manufactured in our Cambridgeshire headquarters in the UK, which is certified by The British Standards Institute to ISO 9001, using the latest manufacturing equipment and processes.

RUBBER COMPOUND

VIP compounds its own rubber at our on-site mixing facility to proven formulations developed by VIP’s rubber technologists. The compounds used meet WRAS and other internationally recognised standards where required.

VIP Rubber Compounding

Predominantly EPDM is the rubber of choice for tunnel segment gaskets as it provides the sealing and material qualities required. However in instances where resistance to more aggressive chemicals is required, VIP can compound and manufacture using NBR (Nitrile).

LIFE EXPECTANCY

A study carried out by Loughborough University in the UK on behalf of VIP concludes that one of the major elements affecting the gaskets’ long term sealing ability is ‘Stress-Relaxation’. This is the measurement of the force that a compressed gasket exerts over time which is crucial to the sealing performance.

 

EPDM Long Term Stress Relaxation Chart

The research also revealed that with correctly formulated and processed rubber, as supplied by VIP, the life expectancy of our gaskets is in excess of 120 years.

EXTRUSION

To begin the manufacturing process, VIP’s gasket profiles are extruded through one of the most modern microwave curing lines. This manufacturing technique creates the profile length by forcing the rubber through a die prior to curing. This is then cut to lengths determined by the segment requirements.

TSG Profile Extrusion

CORNER JOINTS

All VIP’s corner joints can be manufactured in obtuse, acute and 90° angles to perfectly fit with the corresponding segments.

Using the latest laser guided cutting technology enables virtually any joint angle to be achieved and their design ensures that the sealing properties and closure forces match the extruded gasket section.

QUALITY INSPECTIONS

In order to ensure the final product meets the high standards set by VIP, physical checks are made by our quality team both during the manufacture process and on final completed gaskets against:

  • Profile Size – to ensure a consistent profile shape during the extrusion process
  • Joint Integrity – to check the strength of moulded joints
  • Geometric Requirements – to check the shape of the finished gasket meets the segment design requirements

IN-HOUSE LABORATORY AND TSG TESTING

VIP’s laboratory and quality team undertake various tests and inspections throughout the manufacturing process of our TSGs.

These tests provide assurance that our products are produced to the highest standard and perform as expected.

Tests are undertaken on both the uncured rubber compound prior to manufacture with further tests on the final extruded product which check for:

  • Rheometry
  • Hardness
  • Tensile strength
  • Elongation
  • Compression set
  • Dimensional checks
  • Stress relaxation

Completed gaskets are finally checked on specially designed jigs to ensure they are the correct dimensions for the corresponding segment shape.

Tunnel Segment Gasket Product Testing

Tests Designed to Replicate Real World Applications

Gaskets are also tested at our UK headquarters in specially designed test rigs, which replicate the build of a segment ring in order to measure their performance.

VIP undertake a range of tests using T & X rig testing in order to replicate closure forces and pressures experienced both during the tunnel build and throughout the service life of a tunnel.

Pressure testing is undertaken at maximum and minimum gaps, and zero-to-maximum offset / deflection.

This replicates the gaps and displacements that occur between segments either as a result of building tolerances, changes in direction of the tunnel or due to the effects of ground movement.

Tunnel Segment Gasket Pressure Test with No Offset
Pressure test With No Offset
Tunnel Segment Gasket Pressure Test with Offset
Pressure test With Offset

 

 

Typical Pressure Curve

Diagram showing typical pressure curve

Typical Load Deflection Curve

Diagram showing typical load deflection curve

ACCESSORIES AND SERVICE

ADHESIVE

VIP can recommend a number of approved adhesive suppliers for the application of glued-in gaskets onto the segment. If required, we can also arrange the supply of the adhesive.

tunnel segment gasket adhesive

LUBRICANTS

VIP recommends applying lubricant to the surface of the gasket during segment installation to assist the segments sliding into place.

This process reduces the friction between gaskets, ensuring corner positioning and reducing the risk of gaskets moving or pinching during installation which can potentially affect their performance. We can recommend and supply an appropriate WRC-approved lubricant.

tunnel segment gasket lubricant

STORAGE

TSGs should be stored in the same conditions as for most elastomeric products and ideally in accordance with ISO 2230:2002 (rubber products guidelines for storage). VIP can supply details upon request.

tunnel segment gasket storage

QUALITY

VIP operates a quality system, which is approved to ISO 9001 standard and certified by BSi. We are renowned in the seal and gasket industry for the high quality of all of our products, and our approach to quality extends to TSGs.

tunnel segment gasket quality

PIPE REPAIR CLAMPS & FITTINGS

 

VIP14

VIP-Polymers have for a number of years developed and manufactured a range of sealing gaskets for pipe fittings and repair clamps used on a variety of applications:

 

  • End load restraint systems
  • Repair couplings
  • Repair clamps
    (using “waffle pattern” repair mats)
  • Stepped couplings
  • Flange adaptors
  • Dismantling joints
  • Shoulder couplings
  • Gripper couplings

With an advanced rubber to metal bonding facility available in-house, we can also offer reinforced repair mats incorporating components made from stainless steel, lead, aluminium, copper and iron. Large compression and injection moulding presses enable us to offer components up to 2.4 metres wide whilst our extrusion facility enables us to produce profiles of up to 300mm width.

VIP43   NS2

Approvals

Many of the compounds we use to manufacture repair clamp gaskets hold multi region potable water approvals. This means our customers enjoy the benefits of reduced inventory as stocks of gaskets for different global regions are no longer necessary.

STANDARDS

BS6920. Suitability of non-metallic products for use in contact with water intended for human consumption with regard to their effect on the quality of the water.

ISO 3302-1:2014. Specifies classes of dimensional tolerances and their values for moulded, extruded, and calendared solid rubber products.

BS EN 681-1. Elastomeric seals. Material requirements for pipe joint seals in water and drainage applications.

ISO 2230:2002. Rubber products. Guidelines for storage.

BS EN 598:2007+A1:2009. Ductile iron pipes, fittings, accessories and their joints for sewerage applications. Requirements and test methods.

BS EN 545:2010. Ductile iron pipes, fittings, accessories and their joints for water pipelines. Requirements and test methods.

TYTON® GASKETS

Tyton® Seals

  • Dual Hardness and available for ductile iron pipes up to 2200mm diameter
  • Physical properties in accordance with EN681-1 WA/WC
  • Designed to fit DIN28603 sockets and suitable for pipe manufactured in accordance with DN545 & EN598
  • Materials fully WRAS approved and BS6920 compliant – up to 60º
  • Approved for use in Germany, France, Middle East, as well as a number of other countries globally

VIP06

VIP-Polymers – The world’s largest manufacturer of Tyton® Gaskets

VIP-Polymers can mould dual hardness Tyton® gaskets for Ductile Iron pipe in sizes from DN80 to DN2200. With over 40 years’ experience of manufacturing these seals, today our Tyton® gaskets are selected by a number of the leading Ductile Iron Pipe manufacturers worldwide as original equipment.

The Tyton® joint is a standard push-fit, flexible joint for water pipelines offering a high performance joint with a number of benefits;

  • Quick and easy to install.
  • Capable of angular deflection without loss of performance

 

Table of Maximum Working Pressures

 Nominal Diameter mm  Angular Deflection  Maximum Working Pressure
DN80 60 bar
DN100 60 bar
DN150 60 bar
DN200 60 bar
DN250 53 bar
DN300 47 bar
DN350 43 bar
DN400 40 bar
DN450 38 bar
DN500 36 bar
DN600 33 bar
DN700 31 bar
DN800 29 bar
DN900 28 bar
DN1000 27 bar
DN1100 26 bar
DN1200 25 bar
DN1400 25 bar
DN1800 25 bar
DN2000 20 bar
DN2200* 20 bar

 

n.b. Maximum angle of deflection can vary depending on the pipe manufacturer.

VIP-Polymers offer dual hardness Tyton® gaskets in both EPDM to BS EN681-1 WA/WC for and in Nitrile material meeting the physical requirements of BS EN682. In addition to physical properties, our Tyton® gaskets are approved for use by potable water authorities across the globe. Details of these approvals can be supplied upon request.

Please note when ordering that above DN600, not all Tyton® socket dimensions are in accordance with DIN 28603 so please consult our technical department to ensure the correct gasket is selected.

STANDARDS

BS6920. Suitability of non-metallic products for use in contact with water intended for human consumption with regard to their effect on the quality of the water.

ISO 3302-1:2014. Specifies classes of dimensional tolerances and their values for moulded, extruded, and calendared solid rubber products.

BS EN 681-1. Elastomeric seals. Material requirements for pipe joint seals in water and drainage applications.

ISO 2230:2002. Rubber products. Guidelines for storage.

BS EN 598:2007+A1:2009. Ductile iron pipes, fittings, accessories and their joints for sewerage applications. Requirements and test methods.

BS EN 545:2010. Ductile iron pipes, fittings, accessories and their joints for water pipelines. Requirements and test methods.

MOULD & DIE SOLUTIONS

VIP-Polymers utilise a combination of practical engineering experience and the very latest computer aided design software to develop mould and die solutions.

Continuous investment in the latest design and manufacturing technologies with integrated CAD/CAM systems enable full three dimensional machining of complex forms to be undertaken.

Tooling is at the core of VIP-Polymers manufacturing technology with the ability to develop both low cost prototype and high volume precision tools for every aspect of the production process including:

  • Extrusion Dies
  • Multi-Cavity Injection Moulds
  • Multi-Cavity Compression Moulds
  • Transfer Moulds

RUBBER EXTRUSIONS

VIP-Polymers are long established manufacturers of precision rubber extrusions.

We produce even the most complex profile shapes in a comprehensive range of compounds ranging from EPDM, Natural, Silicone and SBR-based extrusions up to 90 IRHD for a variety of industries:

  • Potable and Drainage Water Pipelines
  • Engineering
  • Marine
  • Flame Retardant Seals for the Rail Industry including London Underground
  • Ministry of Defence Approved (MOD Naval) Products

We understand the numerous applications and environments that our rubber extrusions are used in and can provide the optimum solution by applying engineering expertise, sound business economics with a common sense approach. Our experienced team of compound technologists and development engineers are available to design, develop and ensure the smooth production of profiles using bespoke compounds.

VIP55 VIP-102

 

Where extruded sections are required to be joined, we have the very latest computer controlled, fully integrated cutting equipment and a range of joining presses to facilitate this process. Our extrusion facilities also include continuous inkjet equipment enabling product to be coded with customer part numbers, batch numbers and barcodes.