Use of KLINGER KGS GII Rubber-Steel-Gaskets in existing and future-oriented gas infrastructure

Permanent, technical and costable certainty in planning, design and sustainability with any concentrations of hydrogen in natural gas up to pure hydrogen processes.

Specific features of Rubber-Steel-Gaskets used in hydrogenous processes

Hydrogen is considered a chemically very inert substance under the aforementioned operating, pressure and temperature conditions. From a physical point of view, however, it has a very high diffusion pressure due to its very small kinetic molecular diameter (approx. 2.3 to 2.9 [mA]). This means that there is an intensive interaction between hydrogen and all materials coming into contact with hydrogen.

With regard to acrylonitrile butadiene rubber (NBR), this means that prevention of embrittlement of the elastomer due to a high content of acrylonitrile (ACN) in the rubber compound itself must be assured on an ongoing basis, while ensuring that the rubber-elastic properties are retained. In particular, it is important to keep the glass temperature of NBR as low as possible in order to enable use at low temperatures (as low as -30 °C).
Furthermore, when manufacturing Rubber-Steel-Gaskets, it is important to ensure that no cavities can form in the elastomeric moulded body itself during the manufacturing process. Otherwise, there is a risk of rapid gas decompression.

Likewise, the bond between the elastomer and the steel insert must be particularly strong. Rubber and steel are closed-pore materials that do not form a chemical bond with each other and only bond to each other by interlocking. To significantly improve the adhesion of the elastomer, the steel insert is first subjected to a surface treatment, i.e. primed. This causes the adhesion force of rubber to the primer – adhesion – to be greater than the cohesive force of the rubber itself. Even after heavy moulding of the steel insert in the Rubber-Steel-Gasket, there is no shearing of the elastomeric moulded body or bubble formation between the elastomer and the steel insert. However, the prerequisite for this is that the cohesion of the primer and the adhesion of it to the steel insert are always greater than the cohesion of the elastomer itself.

Thanks to the carefully selected materials and precise production under very high pressures of up to 300 bar, the KLINGER KGS GII is a Rubber-Steel-Gasket with unique features.
After testing and evaluation by TÜV SÜD, the KLINGER KGS GII Rubber-Steel-Gasket was recognised as a particularly high-quality gasket. For NBR quality, when it comes to the chemical and physical resistance of the elastomeric synthetic rubber, unrestricted use for hydrogen applications, compliance with the leakage limits according to TA-Luft (the German Clean Air Act) after ageing for 1,500 hours (VDI 2440: 2000-11, L0.01 DIN EN 13555:2014-07) in the sense of technical tightness, as well as blow-out safety class C (blow-out safety under TRwS [Technical Rules for Substances Hazardous to Water], Qs min: 4 [MPa] at 100 [bar]) are certified. In addition, the balanced high acrylonitrile content (ACN) provides long-term resistance to hydrogen.

Ease of use and safe installation for sustainable use of KLINGER KGS GII Rubber-Steel-Gasket

A gasket must essentially close two potential leak sources:

1. Diffusion through the gasket itself – here it’s very important to close any pores or channels in the sealing material by means of adequate pre-tensioning between two flange blades. Since the elastomer in question – NBR – is a closed-pore sealing material and, once manufactured into a KLINGER KGS GII Rubber-Steel-Gasket, a non-porous sealing material, diffusion is counteracted to the maximum even in the non-pretensioned state.
2. Diffusion between the phase limits of the gasket and the surfaces of the flange sealing strips of a flange connection – in this case an effective and cavity-free tight fit needs to be achieved with adequate pre-tensioning of the gasket.

The defined working range of a gasket begins with the minimum pre-tensioning of a gasket, the point at which a tightness demonstrably occurs with reference to the aforementioned points 1 and 2 and ends with the maximum pre-tensioning of this before the gasket is destroyed.

Ideally, a gasket should have a wide working range, making handling and assembly significantly easier, i.e. a low minimum pre-tensioning is required for sealing and a high maximum pre-tensioning is possible, e.g. when using high-strength screw grades (8.8, 25CrMo4, etc.).

The elastomeric synthetic acrylic-nitrile-butadiene rubber (NBR) KLINGER KGS GII Rubber-Steel-Gasket has a working range of 0.5 MPa to 40 MPa (QSmin(L) to Qsmax),Smax) – unprecedented in Rubber-Steel-Gaskets. Detailed tightening torques can also be provided on request as minimum and maximum data for various screw grades and metric dimensions (DIN EN 1514-1: 1997-08) up to an operating pressure of 40 bar (MOP – Maximum Operating Pressure 40 bar).

A special version – the KLINGER KGS GII HP Rubber-Steel-Gasket – is available for PN 63 and PN 100 (dimensions according to DIN EN 1514-4) with operating pressures of up to 63 bar and 100 bar. Installation conditions can be provided on clarification.

KLINGER KGS GII/NBR Rubber-Steel-Gasket findings:

A variety of tests and test series have demonstrated that the KLINGER KGS GII/NBR Rubber-Steel-Gasket delivers durable and safe technical tightness with easy handling and installation. The sealing coefficients determined in accordance with DIN EN 13555 (Helium, He) can be used to calculate flange connections in hydrogenous and/or hydrogen-containing processes.