Method for installing a substantially rigid thermoplastic pipe in an existing pipeline
AssigneeNuPipe, Inc.
InventorCampbell H. Steketee, Jr.
Life of this patent
Estimating the term…
Abstract
A thin, flexible tubular membrane provides a heat containment tube for inserting into and inflation within an underground conduit to be repaired. Folded rigid thermoplastic pipe is inserted into the tube while hot and flexible. The tubular membrane is pressurized to exclude unwanted fluids from within the existing conduit. Hot stem is injected into the tube to heat the pipe full-length externally and internally until flexible. The pipe is then rounded and expanded against the walls of the conduit with the tube therebetween. The rounding and expanding of the pipe is carried out progressively by moving a plug through the pipe and by injecting hot steam under pressure behind the plug.
Claims20
A method of installing a normally substantially rigid thermoplastic pipe in a length of existing conduit comprising the steps:
- inserting a flexible tubular member which is substantially air and water tight into the length of an existing conduit to be lined such that at least one end of the tubular member is accessible at an end of the length of conduit to be lined,
- inflating the tubular member to at least a partially rounded condition to provide a controlled environment within the tubular member,
- heating a length of the thermoplastic pipe in a collapsed condition wherein the cross-sectional dimensions are less than the conduit to render the thermoplastic pipe deformable, and
- inserting the thermoplastic pipe into the tubular member such that the thermoplastic pipe extends the full length of the length of conduit in which the tubular member is inserted in the conduit,
- with one end of the tubular member at least restricted and with the collapsed thermoplastic pipe inside, forcing a hot fluid into the tubular member and the collapsed thermoplastic pipe from the other accessible end to heat the thermoplastic pipe inside and outside throughout its length and thereby render the normally rigid collapsed thermoplastic pipe deformable, and
- while the thermoplastic pipe is deformable, applying an internal expansion pressure to said pipe to expand the pipe from the collapsed condition to the internal configuration of the conduit with the tubular member retained between the expanded thermoplastic pipe and the conduit.
A process of lining an existing conduit with a substantially rigid thermoplastic pipe, comprising:
- heating a thermoplastic pipe which is in a reduced condition with dimensions less than the dimensions of the existing pipeline and is within a flexible tubular member which is substantially air and water tight with one end of the tubular member restricted to provide a controlled environment within the tubular member to render the thermoplastic pipe deformable;
- and,
- inserting the collapsed thermoplastic pipe within the flexible tubular member into the existing conduit;
- forcing a hot fluid into the tubular member and the collapsed thermoplastic pipe from the accessible end to heat the thermoplastic pipe inside and outside throughout its length and thereby render the normally rigid collapsed thermoplastic pipe deformable,
- applying internal pressure to the deformable thermoplastic pipe to expand the deformable thermoplastic pipe from the reduced condition to a cross-section substantially similar to the cross-sectional dimensions of the existing pipeline with the flexible tubular member between the thermoplastic pipe and the conduit;
- and
- cooling the expanded thermoplastic pipe while maintaining the internal pressure to render it substantially rigid in the expanded condition.
Dependencies are inferred from the claim text.