Rib Loc Pipe Renovation keeps Sydney's Traffic Flowing

While the Rib Loc's award winning Ribsteel large diameter sewer relining system featured prominently at the recent International Society for Trenchless Technology No Dig '98 Conference at Lausanne in Switzerland and below, the Company is better known in its home country, Australia, for rehabilitation systems for smaller pipes.

Over the past 3 years more Rib Loc Expanda Pipe has been installed in Australia than either cured-in-place or fold-and-form relining systems in these sizes. While installation is extremely cost competitive, Interflow has gained a reputation for being able to complete relining projects which were unlikely to be possible with other systems.

A recent example is a relining project carried out under Australia's best known section of roadway - the Sydney Harbour Bridge.

With over 85,000 vehicles per day using the Sydney Harbour Bridge, avoiding traffic delays is a high priority for the New South Wales Roads and Traffic Authority. Preventative maintenance is vital - which in this case included relining of 60 year old stormwater pipes.

Although still structurally sound, it was decided to reline the stormwater pipelines on the southern approaches to the Sydney Harbour Bridge before deterioration led to the risk of pipe collapse and possible traffic disruption.

Due to the volume of traffic, lane closures to allow relining work were only permitted at night, between 11.30 p.m. and 4.00 a.m.

These restrictions meant that each section of the work had to be fully completed on the night it was commenced. No extension of nightly working hours was possible, even in the event of difficulties being encountered. It was essential that the road was available for re-opening at 4.00am each morning.

Interflow considered that this project could be accomplished using the Rib Loc Expanda Pipe system. With no need for heating or curing, installation was regarded as being possible within the allowable time frame. Another advantage is that the relining system can be installed without the necessity of bypass pumping.

The Rib Loc system involves spirally winding a strip of plastic into a liner pipe via a small winding machine placed in an access chamber. The specially extruded plastic profile has a T-ribbed outer surface with edges which interlock to form a pipe during winding. The liner pipe is then radially expanded by a patented mechanical process until contact is made with the inner walls of the deteriorating pipe. Once it is installed the pipeline can be put straight back into service and reconnection of laterals, if required, can commence immediately.

An important feature of the system is that heating is not used in any part of the installation process. The pipe is expanded by winding rather than using pressure and heat, and no curing is needed to form a strong structural liner. This means installation can be faster, and, as the winding machine does not block the pipe, the process can be carried out with some flow in the line.

The Interflow crew needed to work to a precise time schedule on the Harbour Bridge project. While traffic diversions and safety signs were the responsibility of the Roads and Traffic Authority, setting up and dismantling of the relining equipment occupied at least one hour at each end of the working period. This meant that just over 3 hours was available to complete the installation process in pipelines ranging up to 54 metres in length.

The installation process involved CCTV inspection, cleaning, proving the pipe diameter, installing the Expanda Pipe liner, and final survey - a busy 3 hours!

Rain fell regularly in the days between the relining sessions, washing debris into the line, necessitating extra cleaning. Night time installation was complicated by 3 heavy rainstorms occurring while relining was under way. With no bypass pumping being possible, the Interflow crew was required to complete relining each time with substantial flow through the pipeline. It was a comprehensive demonstration of the advantages of the Rib Loc Expanda Pipe system when installed by an experienced contractor.             

Article from Rib Loc