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NORSOK M-710 – Qualification of non-metallic sealing materials and manufactures

NORSOK M-710 (Norsk Sokkels Konkuranseposisjon) are standards developed by the Norwegian Technology Centre.

What is NORSOK M-710?

NORSOK M-710 is a globally accepted standard implemented by the Norwegian Petroleum Industry. It defines the qualification demands of polymer (non-metallic) sealing materials and manufactures. It has started with mostly European and Norwegian demands for NORSOK M-710 compliant materials. Throughout the years it has expanded significantly across the world and is now globally recognized.  NORSOK M-710 standard defines the need for equipment to accomplish high levels of quality and conformity in offshore functioning.

The Standard demands that each sub-element of offshore equipment is required to be compliant with established conditions. Particularly, all sealing materials are strictly tested and certified on the basis of various measures including sour gas ageing, sweet gas ageing, material property tests, Rapid Gas Decompression (RGD) and Compression Set tests.

Tests are performed to guarantee suitable value. This adds cost-effectiveness and safety for current and forthcoming crude oil industry evolutions. The NORSOK M-710 standard specifies the demands for extreme polymer (non-metallic) sealing. This includes seat and back up elements for lasting use in subsea, including control structures, ‘trees’, valves, wellheads, and well completion. The specification also concerns topside valves in extreme gas structures. Therefore, the principal difference from prior standards is that every single element among installation components is required to conform to and be accepted by NORSOK specifications, instead of just the final assembly.

There are two important sections in the standard

Annex A – Test media, conditions and procedures for the ageing of elastomeric materials

Annex B – Resistance to Rapid Gas Decompression (RGD)

Rapid Gas Decompression (RGD) Testing

Under pressure, gas or gas blends can be absorbed by touching rubber surfaces. The gas can then be in a compressed condition. Therefore, when foreign stress is decreased (either suddenly or throughout a moderately short interval of time), the compressed gas quickly widens within the rubber. It can cause cracking inside the elastomer, which then expands within the rubber. That leads to cracks or voids to emerge on the elastomer surface. This considerably lessens seal durability and performance.

Throughout examinations, 3 variants are being tested, they are:

  • Temperature – can be tested at +100°C, +150°C or +200°C, the article is heated to this temperature gradually and maintained for 10 minutes
  • Pressure – pressures of 2,175psi; 2,900psi; or 4,351psi are implemented, the material must be kept under these circumstances for at least 72 hours. It is then depressurized at a value of 290-580psi a minute. After this, the cooling down process is allowed. In total, 10 cycles of pressurization and depressurization are performed on the material, keeping stress for 23-24 hours per cycle.
  • Medium – 3 media choices are selected; media preference is being relevant on suggested circumstances

Subsequently, after these tests, the material is then examined by microscopy and raring is given, recapitulating the perceived impairment to the tested material with regards to an amount and extent of internal cracks apparent when the elastomer is split into quarters.

Sour and Sweet Gas Ageing

Test circumstances are simulated to be characteristic of the seal installation surroundings in both sour and sweet service circumstances. Afterward, 3 temperatures are chosen to advance outcomes for prediction, they are all greater than real service circumstances.

Following heating the gas to a certain temperature, the pressure of 1,450psi is implemented. The material is then exposed to these circumstances for the length of time it requires to achieve saturation and is adequate to permit dependable prediction of outcomes.

At least 30 seal samples are examined throughout the whole process. Measurements are acquired for seal proportions, weight and volume before the exposure. Following examinations, seal weight and volume measures are taken once again, tensile qualities are tested and the seal is optically examined for breakage.

M Barnwell Services’ NORSOK M-710 approved rubber materials can be formed into endless profiles and shapes to fit any installation, they include Lip seals, Wiper seals, Spring seals, T seals, O rings, X rings, and bespoke seals. If you require any additional information about our range and/or services, download our catalogue or contact a member of the team.

E & OE. Data provided by manufacturing supply partners.