There are many factors that can cause RGD damage. It mainly includes the following aspects:

Type of gas

All types of gases can cause RGD damage, but H2S and CO2 have high permeation rates, so the effects of RGD can be particularly problematic. Due to aggressive carbon dioxide and hydrogen sulfide gas, rapid gas decompression (RGD) leads to degradation and collapse of polymer components, while putting expensive machinery and assets at risk. Careful selection of elastomers and design of sealing systems is recommended when acid gases or carbon dioxide gas are present in the system medium.

Elastomer Selection

Elastomer materials are tested and scored based on their level of RGD resistance. A perfect rating is 0000 meaning the elastomer suffered no damage when exposed to the arduous test conditions. The result of any testing should always be reviewed before selecting an elastomer seal for use where RGD is a risk.

Elevated temperatures

The risk of RGD damage increases substantially with temperature since all elastomers lose strength at elevated temperatures.

Effect of pressure

The risk of RGD damage becomes substantial above 50 bar and increases with pressure. Higher pressures result in greater pressure differential between the gas trapped in the elastomer and the surrounding environment.

Groove fill and interference

Experience has shown that through effective design of the housing geometry, the risk of RGD damage occurring can be reduced. This is done by optimising the levels of groove fill and interference applied to the seal. Specialist sealing engineers can advise on the options available.

Repeated decompressions

Repeatedly pressurising and then rapidly depressurising a system has the potential to amplify the effects of RGD. As system pressure fluctuates, for example as a valve is opened or closed, RGD events have the opportunity to compound their effects; with each cycle, causing an increasing amount of damage to the elastomer and eventually leading to failure.

Using materials that are certified and proven to work in oil & gas environment is one of the simpler and faster ways to reduce RGD risk. HNBR, FKM, FFKM and Aflas compounds can be optimized for RGD resistance. The application engineer of JST Seals can evaluate your situation, help you select the right compound, and reduce the damage related to RGD.