The Task
Our clients required assistance undertaking the replacement of a 20” cast-iron strategic water main, which runs through Gateshead.
The section in need of replacing ran from Computer House on Gateshead High Street, through to the new Aldi Store on Sunderland Road.
Of the 300m of pipeline to be replaced, 204m would require slip-lining a welded 450mm HDPE pipeline through the existing cast iron main. DrainsAid were tasked with the completion of this.
Due to the location of the pipe, our client’s arranged lane closures on Sunderland Rd and Lindisfarne Drive, which were in place whilst the works were carried out. A footpath on the north side of the location was also closed.
Our clients were carrying out excavation works when the slip-lining process was started. This was considered in the planning of our work, particularly for the welding of pipe lengths.
Our Approach
We began work at the site by undertaking a CCTV investigation of the existing cast-iron main. This was used to confirm the condition of the pipe, following a previous inspection carried out in 2014.
204m of HDPE pipe in 12m lengths were supplied to us by Westwood Pipelines. We used a McElroy Butt Fusion machine to weld the pipes together, and ensured the jointing area was protected from wind, rain and dust by the use of tenting.
A Debeader was used to remove the beading, which was tested on a BDI machine to give an indication of the strength and integrity of the weld.
The results were recorded and showed each weld was faultless first time.
We added a bespoke insertion trumpet to the original cast iron pipe, which ensured that if the new HDPE pipes met with any protruding ridges, it wouldn’t scar or damage their outer structure.
The front pipe also had a nose cone welded to it, to allow the pipe to safely pass through the existing cast main.
Once the full-length of pipe was in place, we removed the test-ends and inserted a soft foam pig into the line, which was pushed through and out using controlled water.
We then installed Mechanical Aqua Grips, reattached the test-ends to form a seal, and filled the pipe with water to test the pressure of the new pipe.
The Results
Both the BDI results and pressure test results passed their assessment. Our clients were very happy with the services provided throughout the process and the standard of the work completed.
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