- Author
- Maupin, A. R. | Swanger, W. H.
- Title
- Strength of Soft-Soldered Joints in Copper Tubing.
- Coporate
- National Bureau of Standards, Washington, DC
- Report
- BMS 58, September 20, 1940, 27 p.
- Keywords
- copper | tests | pipes
- Abstract
- An extended investigation was made of the strength, under tensile loading, of sleeve joints in copper tubing, with wrought-copper and cast-brass couplings, soldered with (50-50) tin-lead and (95-5) tin-antimony alloys. In short-time tests (speed of movable head 0.06 inch per minute) the strength of the joints was substantially equal to that of the tubing or fittings. The strength varied directly with the depth of insertion of the tubing into the fitting, and was greater at diametral clearances of 0.004 to 0.010 inch between tubing and fitting than at greater clearances. The strengths were higher at 0 deg F than at 85 deg F and decreased rapidly as the temperature was further increased. In long-time tests (10,000 hours or more) under constant tensile loads, the strength of joints soldered with tin-lead was about one-eighteenth of that obtained in short-time tests, from 85 deg to 250 deg F; joints soldered with tin-antimony had from one-fifth to one-seventh of the short-time strength, depending upon the temperature. At 250 deg F and upwardc, diffusion of copper from the tubing into the solder films, in joints made with tin or tin-alloy solders, may weaken or destroy the metallic bond between the solder and tubing. Results of pulsating tensile-load tests, limited to the joints soldered with (50-50) tin-lead, indicated that the strength under repeated loading was not less than under steady loading.