Session: CT-01-01 The James R. Payne Memorial Session on Design and Analysis of Bolted Flange Joints - 1

Paper Number: 174966

174966 - Improvement of the Gasket Creep-Relaxation Management in the European Gasketed Bolted Flange Standard Through Constitutive Modelling 

Abstract: 

Gasket creep/relaxation is recognized as a critical phenomenon in many Bolted Flange Joints (BFJ). In practice, gasket creep/relaxation involves a reduction in gasket contact pressure, which can result in a loss of sealing performance and, in extreme cases to gasket "blow-out." The magnitude of creep depends on the gasket material and can occur even at moderate temperatures, including room temperature. BFJ calculation methods account for this phenomenon in various ways. In Europe, the calculation standard NF EN 1591-1 introduces a supplement to the required initial gasket load to compensate for gasket creep/relaxation through the introduction of a gasket factor called P_QR, measured according to the NF EN 13555 gasket testing standard.

Since the loss in gasket load for a given gasket creep strain depends on the BFJ stiffness, the NF EN 13555 test procedure involves determining the gasket load loss for different simulated stiffnesses. This necessitates an increase in the number of required tests, and in practice, only one stiffness value is often tested. The P_QR value is then used directly in the calculation without any correction, even if the calculated BFJ has a different stiffness from the one used during testing.

This paper proposes an improvement to how gasket creep/relaxation is accounted for in the European standard for BFJ calculations, correcting the P_QR for the stiffness of the calculated BFJ while reducing the number of required tests. This approach utilizes constitutive creep modeling. The work involves first an analysis of the range of stiffness for standard BFJ. Then the variation in P_QR values associated with this stiffness range are experimentally determined for two sheet gasket materials (fiber-based and PTFE-based materials). Finally, the extrapolation of P_QR values for different stiffnesses from a test performed at one stiffness is proposed using a creep constitutive model.

Presenting Author: Hubert Lejeune CETIM

Presenting Author Biography: Mechanical engineer – Sealing Technologies senior expert
Working in the Sealing Technology Lab of Cetim (Technical Center for Mechanical Industry) since 2002 in the field of calculation and testing of gasketed bolted joints and valve packing. In charge of the R&D projects coordination within the Lab since 2010. Co-pilot of the Cetim Hydrogen R&D roadmap.

Member of the ASME special Working Group on BFJ (Bolted Flange Joints)
Member of the ASME PVP Computer Technology and Bolted Joints Committee
Convenor of CENTC74/WG10 concerning bolted flange calculation (EN 1591,..)
Convenor of the RCC-M (French Nuclear Code) working group concerning bolted flange joints

Authors:

Hubert Lejeune CETIM