PipeMedic™ pre-cured laminates are manufactured as flat sheets that are typically packaged in rolls 4-ft wide x 150 feet long. The thickness of the laminates varies from about 0.010 inch to 0.025 inches. The laminates can be cut easily to any width or length in the field. The thin PipeMedic™ laminates allow them to be coiled for ease of transportation and storage. One of the unique features of this product is that its elastic memory wants the laminate to become flat. Thus, when the laminates are coiled, it is best to use strings to hold the roll in its coiled configuration.
Once inside the pipe, the string can be removed and the elastic memory of the laminate pushes the laminate against the pipe surface -- much like a loaded spring! An epoxy paste is supplied to bond the laminate to the inside of the pipe and to bond the overlapping portions of the PipeMedic™ laminate to itself.
The laminates can be installed in rings or in a continuous spiral manner. When the PipeMedic™ laminates are installed in individual 4-ft wide rings, each ring must be long enough to cover the complete circumference of the pipe plus the required overlap length in the hoop direction to provide structural continuity of the laminate. The next 4-ft wide band of laminate will overlap the first band by the necessary overlap length; this means that the installation of each 4-ft wide band will advance the crew a length of l=48 inches - overlap length along the axis of the pipe. The overlapping of the laminates along the length of the pipe must be done in the direction of the flow to ensure that water will not be able to get under and between the installed laminates.
In spiral installations, a long length of the laminate is cut and it is installed in a continuous spiral with predetermined angle of pitch and overlap length. The spiral installation lends itself to use of robots which can easily maintain and repeat the geometrical parameters necessary to construct a cylindrical tube inside the pipe. We are currently developing a robot that would allow installation of PipeMedic™ laminates in both spiral and individual ring arrangements in existing pipes.
Another method of installation of PipeMedic™ is to use a bladder or packer. These devices are commonly used in the pipe repair industry and consist of a flexible reinforced rubber bladder with wheels at the ends to ensure that the assembly remains centered in the pipe. PipeMedic™ laminate can be coated with epoxy and wrapped around a semi-deflated packer; then the assembly is pulled into position and the bladder is inflated, allowing the coil of PipeMedic™ to unwind and bond to the pipe surface. The bladder can remain in position until the epoxy cures at which time the bladder is deflated and removed.
Is Full Bonding Required?:
One of the questions often asked is whether in installation of PipeMedic™ full 100% bonding of the laminate to the host pipe is necessary. The answer is simply NO!
Unlike the conventional carbon wet lay-up repair of pipes, these laminates are structural members that can create a pipe without the need to be supported on the host pipe. This behavior has been extensively tested and documented by the Gas Technology Institute where PipeMedic™ laminates were used to bridge a 24-inch gap between two steel pipes. Under that severe condition, these tests proved that PipeMedic™ can resist pressures of 250 psi and higher. It is clear that those tests simulated extreme events that are highly unlikely to be encountered in most PipeMedic™ installations; that is to say, while we may have small portions of the pipe where the laminate is not in full contact with the pipe, one would hardly expect that there will be a 2-ft length of the pipe where the laminate will have zero contact with the host pipe. Even under such an extreme condition, PipeMedic™ has tested successfully and received the endorsement of the gas industry for bridging the gap in natural gas pipelines.