Research Papers: Other (Seals, Manufacturing)

Experimental Study of the Performance of Static Seals Based on Measurements of Real Contact Area Using Thin Polycarbonate Films

[+] Author and Article Information
Isami Nitta

Mechanical and Production Engineering, Faculty of Engineering, Niigata University, Igarashi 2-nocho 8050, Nishi-ku, Niigata,950-2181, Japannitta@eng.niigata-u.ac.jp

Yoshio Matsuzaki

Mechanical Engineering, Ishikawa National College of Technology, Japan, Kitachujo, Tsubata-machi, Kahoku-gun, Ishikawa, 929-0392, Japanmatsu@ishikawa-nct.ac.jp

J. Tribol 132(2), 022202 (Apr 06, 2010) (7 pages) doi:10.1115/1.4000838 History: Received May 12, 2009; Revised December 06, 2009; Published April 06, 2010; Online April 06, 2010

To clarify the sealing characteristics of metal gasket seals, leakage rates of gas and the real contact area of the seal surfaces were measured under several closing loads. The static seal consisted of a ring-shaped copper gasket and the two steel flanges that held the gasket in place. Gasket widths in the radial direction were 2 mm, 3 mm, and 5 mm. The contact surfaces of the flanges were finished by lathe turning. To determine the leakage flow paths between the gasket and the flanges, the real contact situation between them was observed using a thin polymer film 1μm in thickness. The results indicated the leakage flow paths on the gasket surface were the radial direction perpendicular to the lathe-turned groove and the circumferential direction along the groove. As the closing loads increased, the leakage flow in the radial direction ceased and only that in the circumferential direction remained. Therefore, the cross-section of the aperture for the leakage flow in the circumferential direction was evaluated from the measured real contact area, and the leakage rates were estimated by assumption of laminar flow. The results agreed well with the measured leakage rates.

Copyright © 2010 by American Society of Mechanical Engineers
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Figure 1

Shapes and dimensions of the specimens

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Figure 2

Profile curves of the specimens

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Figure 3

Cross-section of the experimental apparatus

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Figure 4

Leakage as a function of contact pressure

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Figure 5

Leakage as a function of inlet pressure

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Figure 6

Real contact area measured with a thin polymer film of 1 μm in thickness (gasket width: 5 mm)

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Figure 7

Real contact area measured with contact marks (gasket width: 5 mm)

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Figure 8

Contact marks on the polycarbonate film and how to measure them

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Figure 9

Ratio of real contact area at each contact mark

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Figure 10

Channel form for leakage calculation

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Figure 11

Abbott bearing area curve of the flange surface: A0 is an integral value of the total Abbot bearing area curve, ΔA1+ΔA2 is an integral value from h0 to h1 of the Abbot bearing area curve, A is a cross-sectional area of the rectangular channel, wp is the pitch of the ridges on the flange surface, w1 is the real contact width on the gasket surface (wp−w, as shown in Fig. 1), w is the width of the hypothetical rectangular channel, noncontact width on the gasket surface, h0 is the maximum height of the flange surface, h1 is the maximum clearance between the gasket surface and a valley of the flange surface, and h is the height of the supposed rectangular channel

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Figure 12

Evaluation of leakage rates



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