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Polymer Testing

TWI has the capability to carry out mechanical testing and assessment on welded polymers using a comprehensive range of techniques and equipment.

TWI has years of experience having invested heavily in polymer-testing equipment and expertise, in order to give our Members confidence in the relevance and reliability of the findings of our research.

Objectives of Testing

Tests and analysis in this area can benefit Members and wider industry in a number of ways. Through our work in welded polymer testing we aim to:

  • Develop flaw acceptance criteria and service life prediction for plastic welds
  • Support the development of standards both in the area of plastic pipes and for moulded plastic components
  • Encourage the adoption of Engineering Critical Assessment (ECA) as a concept in the field of welded plastic fabrications and components. This is being done alongside the development of reliable non-destructive testing techniques
  • Support research and development into plastics welding process development and optimisation.


We have experience and facilities to carry out mechanical testing of polymer welds, including pipes up to 415mm in diameter – the testing methods we can conduct include:

  • Bend
  • Tensile
  • Peel
  • Tensile impact
  • Dynamic mechanical
  • Whole component/bespoke
  • Whole pipe creep rupture
  • Accelerated ageing
  • Crush testing

TWI also has experience in NDT inspection of polymers - find out more

Unique Polymer Testing Equipment

These tools include a bespoke, purpose-built high-pressure facility for permeation testing of polymeric materials. This versatile piece of equipment allows materials to be tested with a variety of gas mixtures, at pressures up to 650 bar and temperatures up to 250°C, and then graded in terms of performance.

View our permeation testing rig factsheet (PDF)

We also recently acquired six large-volume autoclaves that allow us to test large components in a constantly maintained test environment; something that was previously difficult. The highly specified autoclaves were specially commissioned to advance our work in exposure testing of polymers and other materials. The largest of these autoclaves has an internal depth of 1000mm making it ideal for conditioning tubular components made from thermoplastics, fibre-reinforced composite or coated metal parts.

View our enhanced HPHT sour testing facility factsheet (PDF)

The controls on the autoclaves also allow the pressure to be reduced under operator control to reproduce a rapid gas decompression (RGD) event. As the pressure is reduced, the released gas can be sampled by TWI’s extensive suite of gas chromatographs, ready for analysis.

The latest addition to TWI’s equipment for environmental testing of polymers is a unique high-pressure flow loop, designed to simulate the conditions in which oil and gas equipment would operate in real-world use. Capable of circulating sour fluids meeting the criteria for ISO 23936-1:2009 at pressures up to 89barg and temperatures up to 130°C, it allows experiments to be conducted that replicate realistic field conditions in terms of flow and mass transport.

Covering the Full Spectrum of Polymer Test Types

In addition to the above, we can also offer the following polymer testing capabilities:

  • Static load: 0.5kN to 1750kN
  • Temperature: -196°C to +400°C
  • Fatigue testing: numerous machines, 0.1kN to 1000kN
  • Whole pipe creep rupture testing (up to 80°C with a maximum pipe diameter of 315mm)
  • Ring pull test (composite pipe)
  • Short beam shear test

As well as our broad range of equipment, our extensive experience of developing custom tests, interpreting results and evaluating products means that you can depend upon the results we provide, no matter what type of polymer testing you require.

With gas-specific permeation measurement, diffusion and permeation characteristics can be measured while testing with gas mixes. Supercritical carbon dioxide testing is also available, and we can report on changes in physical and mechanical properties of polymers using techniques that include differential scanning calorimetry and Fourier transform infrared spectroscopy and dynamic mechanical analysis.

As polymers are increasingly selected for deployment in harsh locations, so rises the importance of testing them in a representative environment.

Where components provide a safety-critical function, we can provide estimates of service life using accelerated exposure testing. We can conduct tests on polymers using various aggressive chemicals, including acids and solvents, and can perform exposure and permeation testing with hydrogen sulphide.

Standards Activities

TWI is represented on the following standards committees:

  • ISO TC138/SC5/WG17 (Plastics Pipes, Fittings and Valves, Alternative Test Methods)
  • CEN TC249/WG16 (Thermoplastics Welding)

Standards published:

  • EN 12814-1:2000 (Bend test)
  • EN 12814-2:2000 (Tensile test)
  • EN 12814-3:2014 (Tensile creep test)
  • EN 12814-4:2001 (Peel test)
  • EN 12814-6:2000 (Low temperature tensile test)
  • EN 12814-7:2002 (Tensile test with waisted test specimens)
  • EN 12814-8:2001 (Requirements)

With our support and the results of our polymer testing, our Members have been able to consider new polymer materials for a wide range of applications in extreme environments, in the process finding cost savings and efficiency improvements.

For more information, please email

For more information please email: