Pipe liner process
US4986951A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 29, 1988 |
| Grant date | Jan 22, 1991 |
| Priority date | — |
| Expiry date | Apr 29, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S138/05
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
Method is provided for lining a pipe wherein a thermoplastic liner is initially formed in a cylindrical shape with a diameter slightly larger than the internal diameter of the pipe. The liner is temporarily deformed at an elevated temperature to a different cross-section, preferably U-shaped, to reduce its overall cross-sectional dimension to facilitate insertion into the pipe to be lined. Once inserted, the pipe liner is reheated to the crystallization temperature of the thermoplastic material to cause the liner to return to its original cylindrical shape. Pressure within the liner is also increased in two stages to cause the liner to conform to the interior surface of the pipe. An expansion pig may also be employed to ensure even more exact conformance. After expansion, ends of the liner which extend beyond the pipe are flared into engagement with the pipe flanges. Service fluid under pressure is introduced into the liner to maintain the liner in its cylindrical shape.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.