Termination for Sheathed Tubing with Leak Containment and Detection Provisions

Abstract

A fitting for an end of a length of corrugated tubing with an outer sheath includes an engagement ring for gripping the tubing adjacent to an endmost corrugation of the tubing to preclude axial displacement of the retainer on the tubing. The fitting also includes an end plug having at least one threaded surface and a hollow cylindrical part sized to admit and engage with the engagement ring. The end fitting also includes a nut having a threaded portion complementary with the threaded surface of the end plug and an inner surface that defines an inner cavity. An annular groove extends from the inner surface. A vent extends through the sidewall and is disposed between the threaded surface and the groove. A gasket is disposed in the annular groove and a portion of the gasket extends into the inner cavity and is configured to sealingly engage the sheath.

What is claimed is: 
     
         1 . A method of terminating a length of corrugated tubing with an outer sheath, the method comprising the steps of:
 cutting the tubing, thereby forming an endmost corrugation;   cutting the sheath, thereby exposing a portion of the tubing;   inserting the tubing into an engagement ring having a ridge placed axially adjacent to the endmost corrugation of the tubing; and   engaging a threaded portion of a nut with a threaded surface of an end plug to cause the ridge to securely grip the tubing, wherein the nut has a sidewall with an inner surface defining an inner cavity and an annular groove extending from the inner surface and a vent extending through the sidewall and disposed between the threaded surface and the annular groove and wherein a gasket is disposed in the annular groove such that a portion of the gasket extends into the inner cavity and sealingly engages the sheath.   
     
     
         2 . The method of  claim 1 , wherein the gasket comprises an elastomeric material. 
     
     
         3 . The method of  claim 1 , wherein the nut is an integral structure. 
     
     
         4 . The method of  claim 1 , wherein the nut further includes an annular ring adjacent an end of the engagement ring. 
     
     
         5 . The method of  claim 4 , wherein the annular ring divides a first portion of the nut from a second portion, and wherein the threaded portion is on the first portion and the annular groove is on the second portion. 
     
     
         6 . The method of  claim 1 , wherein the end plug and the engagement ring sealingly engage the corrugated tubing to form a sealed annular volume whereby a potential leakage path between the corrugated tubing and the sheath is confined to emit at the vent.