Method of making welded pipe joints
US4626308A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 9, 1984 |
| Grant date | Dec 2, 1986 |
| Priority date | — |
| Expiry date | Feb 9, 2004 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T156/1082
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
The invention provides a method of forming a welded joint between an end of a thermoplastic pipe or pipe like member and a surrounding pipe fitting including a thermoplastic sleeve, comprising the steps of forming around the internal wall of the sleeve a helical cut, said cut being inclined to the surface of the wall along the line of the cut, and the cutting tool and its angular relationship to the bore of the fitting being chosen such that during incision an internally extending flap of the thermoplastic material produced by the incision is caused to open out and deform transverse to the direction of incision whereby a helical cavity is formed within the sleeve wall; feeding into said cavity an electrically conducting wire; working the internal wall of the sleeve so as to lay, at least partially, the flap against that wall and enclose the wire within the cavity between the flap and the sleeve wall; fitting the sleeve about the end of the pipe or pipe like member; and passing an electrical current through the electrical wire so as to fuse the sleeve to the pipe or pipe like member.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.