Gaskets and mechanical seals testing

Seal testing is characterized by 2 main methods of calculating the strength of flange-bolted connections:

Taylor Forge method (used in WUDT-UC-WO/19 and ASME BPVC.VIII.1),
The method described in EN 1591-1

The above algorithms consider the behavior of the entire flange-bolt-gasket system and take into account both the tightness and strength criteria. In order to correctly carry out the strength calculations of flange-bolt connections, it is necessary to determine the coefficients describing the gaskets.

A highly specialized research stand allows to determine the above-mentioned coefficients based on:

1) the algorithm described in the EN 13555:2014 standard, which determines a number of parameters based on the physical properties of the gasket, e.g. minimum and maximum stresses on the gasket, tightness class, etc.

2) the algorithm described in ASTM F3149-15, which defines the following factors:

  • m – coefficient increasing the clamping force of the gasket in its operating conditions, i.e. after applying the internal pressure
  • y –  installation pressure coefficient, determines the gasket clamping force that is necessary in the conditions of gasket installation to ensure tightness

3) based on the obtained coefficients „m” and „y” described by the algorithm in the ASTM F3149-15 standard, we can determine the coefficients for WUDT-UC-WO/19

  • σ m -Minimum forming stresses to be applied to the gasket during assembly to achieve the so-called the formation of the seal, related to the active surface of the seal,
  • σ r – Minimum operating stresses, minimum contact stresses that must remain on the seal during the movement of the device.
  • b – Coefficient taking into account relaxation and creep of the gasket at elevated material temperatures. Increasing the pressure on the gasket during assembly b-times exceeding the minimum operating stresses is to ensure that the contact stresses are maintained during the movement after the connection has been relaxed.

The tests can be carried out at temperatures up to 600 0C, at pressures up to 160 bar. Helium is used as the test gas.