Anti-extrusion sealing system for the outlet of a plastic-lined compressed gas cylinder

A method for sealing an outlet of a fibre-wrapped, plastic-lined cylinder, the plastic-lined cylinder comprising a plastic liner and a boss, the boss having a bore for accessing the cylinder, the method comprising:

• axially extending a liner outlet of the plastic liner into the bore of the boss to form a profiled bore;
• engaging an annular distal end of the liner outlet against a stop in the boss for maintaining an axial position of the annular distal end in the profiled bore;
• and
• engaging an insert having a profiled surface with the profiled bore for forming an annular, primary seal and an annular tapered interface with the liner outlet by:
• engaging an annular seal element on the insert with a cylindrical, sealing bore portion of the profiled bore to form the primary seal,
• engaging a tapered compression surface on the insert with a tapered bore portion of the profiled bore to form the tapered interface for compressing the liner outlet around the seal element, and
• axially engaging a bore-securing surface on the insert with a insert-securing bore portion of the profiled bore for securing the insert to the boss.

A method for servicing a sealing system of an outlet of a plastic-lined compressed gas cylinder, the cylinder comprising a plastic liner and a boss, the boss having a bore for accessing the cylinder which is normally sealed with an insert, the method comprising:

• disengaging the insert from the outlet of the cylinder for exposing a profiled bore of a liner outlet extending axially into the bore of the boss;
• replacing an annular seal element located about the insert, the seal element normally sealably engaging the profiled bore;
• and
• refurbishing at least one sealing surface located on the profiled bore.