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Marston NTG / NRG Conventional Grooved Disc Assemblies

Marston – NTG / NRG Conventional Grooved Rupture Disc / Holder Assemblies

Marston NTG/NRG conventional discs are simple forward acting discs. They are manufactured from thin, precise foils, usually metallic, chosen to satisfy the individual process requirements. These discs incorporate a precise scoring across the dome. When the disc is subjected to excessive pressure the disc bursts and opens along the scored groove lines without fragmentation making it an ideal disc for the upstream protection of safety relief valves.

With no grooves on the process side of the disc, the NTG/NRG disc has a smooth surface, which minimises the likelihood of product deposition and build-up.

When subjected to vacuum conditions, NTG discs will often withstand high levels of vacuum without a support.

These discs are suitable for all relieving phases. Operating ratios are dependent on materials, pressures, and temperatures. The Marston NTG/NRG disc type is generally suitable for operating ratios of up to 80% of minimum bursting pressure. However, it is possible, particularly at higher pressures, that the design may be capable of 90% operating ratios.

Ntg Nrg


Fragmentation: None
Operating Ratio: Up to 80%
Vacuum Duty: Generally Full Vacuum
Pressure Cycling Duties: Good
Leak Tightness (To Vent): <1 x 10-6 mbar.l.sec-1
Leak Tightness (To Atmosphere): <1 x 10-5 mbar.l.sec-1
KR Value: KRGL 0.4


Marston is fully committed to an ongoing Total Quality Improvement programme. This was recognised with Marston audited and approved to design and manufacture bursting discs with its Quality Control procedure registered to the highest standard required by BS EN ISO 9001 Certification.

Quality is an integral part of all processes to provide customer satisfaction and confidence.

NTG/NRG bursting discs are manufactured and tested in accordance with the requirements of the relevant standard, including BS 2915, AD Merkblatt A1, ISPE SL, ASME VIII, ISO 6719, and EN ISO 4126.

All of the Marston standard disc designs have been approved for use in accordance with the requirements of the P.E.D., 97/23/EC.


Standard tolerance on all NTG/NRG bursting discs over 1.0 Bar is ± 5%. Improved tolerances may be available, please contact us for further assistance.

Corrosion Resistance:

NTG/NRG bursting discs can be manufactured from all commonly used disc materials, including Tantalum, Nickel alloys, and Stainless Steel. Fluorocarbon lining provides an excellent protection for corrosive duties.

The Effect of Temperature:

Changes in temperature affect all bursting disc materials. Typically, as the temperature rises, the material strength reduces and the bursting pressure falls.