Historical SECO SEALS document – Post 9 is a17-page report on “Torque Vs. Load Study Flared Tube Fittings” which was presented at the Society of Automotive Engineers at their 26 April 1960, Spring Meeting in Miami, Florida. An extract from that study follows.
“… It was found that of 160 test samples assembled at standard maximum torques only four wee able to contain helium gas at 3,000psi and most failed below 500. When a material with a low yield point, in this case soft copper, was placed at the sealing interface, the same fittings contained pressures of 3,000 to 4,000 psi with only 9 exceptions – most of which were traced to gross tube defects… Our assumption now is that the minimum torque required to seal helium with a corrosion resistant steel flared assembly is that torque which will develop a stress of 30,000 psi at the sealing interface.”
