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

Paper Number: 175192

175192 - The Mechanical Characteristics and Sealing Performance of Bolted Pipe Flange Connections With Modified Metallic Flat Gaskets Shapes Under Internal Pressure 

Abstract: 

Various types of gaskets have been widely used in petrochemical, nuclear power plant, semiconductor, aerospace, and so on, for preventing the leakage from bolted flanged connections and pressure equipment such as heat exchangers, valves, etc. The sealing performance of these connections depends on several factors, including gasket type, bolt preload, number of bolts, and operating conditions such as temperature, pressure, and external loads. While extensive research has been conducted on compressed sheet gaskets (CSGs) and spiral wound gaskets (SWGs), recently the demand for extremely low leak rates on the order of 10⁻¹⁰ Pa·m³/s has highlighted the need to investigate the behavior of bolted flanged connections with metallic gaskets under internal pressure. Previous studies suggest that the leak rates decrease when the contact gasket stress exceeds the yield stress of the metal; however, no research has yet demonstrated how to achieve the 10⁻¹⁰ Pa·m³/s leak rate for the connections. The objectives of this paper are to clarify the relationship between contact gasket stress and the leak rate for metallic flat gaskets and to establish a method for achieving ultra-low leak rates in the bolted flanged connections. Platen tests are conducted using three gasket materials (mild steel, aluminum, and copper) and three cross-sectional shapes (rectangular, hexagonal, and oval). The effects of gasket stiffness, contact width, and surface roughness on the leak rate are examined. The leak rates are measured using a soap film flowmeter, and extremely small leak rates are verified with a helium leak detector. As a result, it is found that the leak rate of 10⁻¹⁰ Pa·m³/s can be achieved when copper gaskets with a 1.5 mm contact width and rectangular cross-section are used. Finite element method (FEM) analyses are performed to evaluate contact stress distribution and plastic deformation at the contact gasket surfaces under an internal pressure of 5 MPa. The relationship between the contact gasket stress and the leak rate obtained from the platen tests is applied to predict the leak rate in the bolted flanged connections (Nominal diameter 4B). A good agreement is shown between the prediction results and the experimental results, confirming that plastic deformation at gasket surfaces significantly reduces the leak rate. In conclusion: (1) Ultra-low leak rates of 10⁻¹⁰ Pa·m³/s are achievable with copper gaskets of 1.5 mm width and rectangular cross-section; (2) The leak rates decrease substantially as yielding initiates at gasket contact surfaces; and (3) The established contact gasket stress– the leak rate relationship provides a reliable method for predicting the leak rates in the bolted flanged connections.

Presenting Author: Maksud Uddin Khan Valqua, Ltd.

Presenting Author Biography: Full name : MAKSUD UDDIN KHAN
Date of birth : 10-Apr-1971
Address : 3-12-6-204 Kamiyugi, Hachioji-City, Tokyo-Prefecture, Japan
Email : u-khanmaksud@valqua.com
Place of birth : Dhaka, Bangladesh
Nationality : Bangladeshi

Education & Professional Career:
In March 1995 Bachelor's degree, graduated from Bangladesh University of Engineering & Technology (Bangladesh)
In March 2000 Master's degree, graduated from Saitama University (Japan)
In March 2003 Doctor's degree, graduated from Saitama University (Japan)
In April 2003- March 2006 Post-Doc Researcher, Toyama University (Japan)
In August 2006~ Valqua, Ltd. (Japan)
Chief Engineer
Corporate R & D Institute

Authors:

Maksud Uddin Khan Valqua, Ltd.
Akira Muramatsu Valqua, Ltd.
Toshiyuki Sawa Hiroshima University