The route of an ageing 36 in (915 mm) diameter steel pipeline under a busy road confronted a renowned Canadian oil producer with unanswered questions. Closing the road to replace the pipes in open cut was difficult or only possible in sections; as was a longer-term interruption of the pipeline.
During the project planning phase, the operator therefore decided to rehabilitate the existing pipeline with the trenchless Primus Line® technology, which ensures the continued use of the existing pipeline infrastructure with a service life of up to 50 years. This not only reduced the investment and operating costs, but also resulted in health and safety benefits due to the minimal excavation work required.
This meant that oil production operations could be maintained without interruption during the work. The excavation work was limited to minimal floor openings at the beginning and the end of the rehabilitated section. The liners were pre-folded and delivered by truck and ready-for-installation on transport reels. All that was needed for pulling in was a cable winch. The rehabilitation period was placed between two emptying cycles, so that an initially planned temporary bridging with a bypass was no longer necessary.
INSERTION WITHIN ONE DAY
In order to be able to transport the necessary volume of water that flows through the pipe during the regular emptying of a wastewater or production water basin, two 12 in (300 mm) diameter liners (maximum operating pressure 16 bar) were pulled into the existing pipe, which is operated at a pressure of approximately 10 bar. This provided a feasible and cost-efficient solution.
To connect the liners to the old pipe, Primus Line developed a certified solution in the form of a special flange adapter plate, which was approved with the PTP stamp of a local engineering office. These reducing flanges, from 36 in (915 mm) diameter to twice 12 in (300 mm) diameter allowed the patented Primus Line end connectors to be installed.
In this way, 420 m of pipeline were renewed within one day with the simultaneous pulling-in of both liners in one section. Several bends of up to 45o were also traversed in the process. The entire job, from mobilising personnel and equipment, to cleaning the old pipe, to the final pressure test, took two weeks.
Primus Line supported the measure not only with the production and delivery of the material and equipment, but also with supporting engineering services and the monitoring of the execution phase by a supervisor on site.