All about compression fittings tube

[cicididi]

The prior art discloses various designs of compression fittings both of the so-called two-piece type, wherein the sleeve is separate from the driving screw, and of the so-called one-piece frangible tye, wherein the sleeve is initially integral with the driving screw and is broken away from the screw during attachment of the tubing.
While both type of compression fittings tube, when properly manufactured and installed, are capable of effecting satisfactory seals, an objectionable feature of the one-piece fitting, when compared with the two-piece fitting, is the torque characteristic of the one-piece fitting. Specifically, a relatively large torque, approximately 25 to 50 inch-pounds, must be applied to the one-piece fitting to cause the sleeve portion to break away from the driving portion. The torque then drops essentially to zero, after which the proper torque must then be applied to compress the sleeve. The relatively large torque to effect separation of the screw and sleeve can be misinterpreted by the installer as being the torque for compressing the sleeve. The result of such a misinterpretation is a leaking connection.