Fatigue strength of socket welded pipe joint
- Ishikawajima-Harima Heavy Industries, Yokohama (Japan). Research Inst.
- Hitachi Ltd. (Japan). Mechanical Research Inst.
- Mitsubishi Heavy Industries Ltd., Takasago (Japan). Takasago Research Inst.
- Shibaura Inst. of Technology, Tokyo (Japan). Dept. of Mechanical Engineering
- Japan Power Engineering and Inspection Corp., Tokyo (Japan). Welding Engineering Dept.
Fully reversed four point bending fatigue tests were carried out on small diameter socket welded joints made of carbon steels. Experimental parameters were pipe diameter, thicknesses of pipe and socket wall, throat depth and shape of fillet welds, slip-on and diametral gaps in the socket welding, lack of penetration at the root of fillet welds, and peening of fillet welds. In most cases a fatigue crack started from the root of the fillet, but in the case of higher stress amplitude, it tended to start from the toe of fillet. The standard socket welded joint for a pipe with a 50 mm nominal diameter showed a relatively low fatigue strength of 46 MPa in stress amplitude at the 10{sup 7} cycles failure life. This value corresponds to about 1/5 of that for the smoothed base metal specimens in axial fatigue. The fatigue strength decreased with increasing pipe diameter, and increased with increasing thickness of the pipe and socket wall. The effects of throat depth and shape of fillet welds on fatigue strength were not significant. Contrary to expectation, the fatigue strength of a socket welded joint without slip-on gap is Higher than that of the joint with a normal gap. A lack of penetration at the root deleteriously reduced fatigue strength, showing 14 MPa in stress amplitude at the 10{sup 7} cycles failure life for the 50 mm diameter socket joint.
- OSTI ID:
- 136770
- Report Number(s):
- CONF-950740--; ISBN 0-7918-1344-4
- Country of Publication:
- United States
- Language:
- English
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