In practice, PTFE tape is being used for sealing of a pipe fitting. However, the efficiency, the decrease in work time, and the sealing performance can be improved by using adhesive instead of the tape. When such a pipe fitting is under an internal pressure and external bending moment by an internal fluid and others, however, an influence in the sealing performance is taken by how to use an adhesion. This study deals with the stress analysis and the evaluation of the sealing performance of the pipe fitting with an adhesive under an internal pressure and an external bending moment analyzed by using the 3-dimensional elastic finite element method. Furthermore, the experiment of the leakage test of the pipe fitting with an adhesive was carried out when the above loads were applied to the pipe fitting. From 3-D FEM analysis, the following results were obtained: (1) the stress distribution at the interface between thread and adhesive on the side of the internal pressure is tensile stress, and stress on the opposite side is compressive, (2) the stresses at the area of the clearance between the valley of the screw and the mountain increase as the numbers of turns of the thread in fittings increase, and (3) the compressive stress at the side of the tensile part in the fittings decrease as the external bending moments increase. However, the sealing performance will not change when the bending moment is not so great because the compressive stress at the side of the compressive part in the fitting increases. From the leakage tests, the following results of the sealing performance were obtained: (1) the sealing performance of a fittings with adhesive under an internal pressure and a bending moment didn’t decrease when bending moment was not so great, and (2) when it exceeds fixed pressure, rapid leakage from the fitting with adhesive occurred by the exfoliation of the adhesive. Furthermore, the numerical results are in fairly good agreement with the experimental results.

Volume Subject Area:
Design Engineering
Topics:
Adhesives, Finite element analysis, Pipe fittings, Pressure, Sealing (Process), Stress analysis (Engineering), Fittings, Pipe fitting, Leakage, Stress, Compressive stress, Finite element methods, Thread, Adhesion, Clearances (Engineering), Fluids, Screws, Stress concentration, Tension
1.
Sawa, T, Murakami, T, Furuya, T. and Kagaya, Y., “Stress Analysis of Stainless Steel Elbow and Tee Fittings under Internal Pressure,” Proc. ASME, The 1998 ASME Pressure Vessels and Piping Conference, 1998, no. 375, pp. 69–74.
2.
Shalaby
M. A.
and
Younan
M. Y. A.
, “
Limit Load for PIPE Elbows with Internal Pressure under In-Plane Closing Bending Moments
,”
Trans. ASME, Journal of Pressure Vessel Technology
,
1998
, No.
120
, pp.
35
–
42
.
3.
Cheng
S. M.
,
Swamidas
A. S. J.
,
Wallace
W.
and
Wu
X.
, “
An Experimental Investigation of Tubular T-joints under Cyclic Loads
,”
Trans. ASME, Journal of Offshore Mechanics and Arctic Engineering
,
1999
, No.
121
, pp.
137
–
143
.
4.
Birembaut, Y and Ledauphin, L., “The Use of ISO WD 15848-1 to Qualify Industrial Valves and Different Packing Type Regarding Fugitive Emissions Regulations,” Proc. ASME, The 2001 ASME Pressure Vessels and Piping Conference, 2001, no. 416, pp. 55–61.
This content is only available via PDF.
Copyright © 2005
 by ASME
You do not currently have access to this content.