Why is it needed?

Pipe rerounding is normally performed on structurally weak pipes. Older pipe networks laid between around the 1950’s to 1970’s, are most likely to be made of pitch fibre. It is a cheap material, that’s easy to handle due to it’s lightness. Pitch fibre pipes are made from wood cellulose impregnated with refined inert coal tar pitch under high pressure. The main issue with pitch fibre pipework being its uncertain lifespan. As a result, pitch fibre pipes are prone to;

  • Weakening and deterioration with age.
  • Chemical erosion (not suitable for carrying hot water or waste that includes oils, fats or petroleum).
  • Blistering that causes obstructions.
  • Leakages that attract roots.
  • Leakages that cause erosion and subsidence.
  • Further damage due to normal forms of maintenance.

What is it?

Pipe rerounding is part of the process of rehabilitating networks composed of pitch fibre pipes. This is due to their tendency to blister or collapse from weakness. A rerounder is a piece of specialist equipment that is pulled through damaged pipes to restore their diameter to the original size. This then allows for the insertion of a new rigid lining that gives it a new 50 years plus, life.

Our Service 

  • A head, or ‘pig’, of the same diameter as the original pipe, is winched through the offending section.
  • When the original shape has been restored after one or more passes, any debris arising from areas that were previously blistered or delaminated is removed.
  • A CIPP or slip liner is then installed to create a new structurally sound pipe.

Our Process

  • A Survey of the host pipe is carried out to assess the condition, original shape and connections to the section to be re-rounded.
  • Initial cleaning removes any silt from the run.
  • A line is sent through the run from the winching end to the upstream manhole.
  • The pig or head of the same diameter of the original pipe is attached .
  • The pig should be winched through the run, not exceeding the predetermined maximum pressure.
  • If necessary, pigs of progressively increasing diameters can be used.
  • Once the pipe has been temporarily restored to its original state (when a pig will run through easily), debris should be cleared.
  • A CIPP or slip liner will then be installed.
  • Any connections covered should be reinstated.
  • A post-work CCTV survey should be carried out.

Requirements

  • Pipes from 100mm to 450mm diameter
  • Flow stopped or diverted

When to use pipe rerounding

  • When a low strength pipe is partially crushed, blistered or delaminating. Depending on the re-rounding method, care should be taken if there is a risk of voids around the pipe.
  • The major benefits are the low disruption for the asset owner/users. The costs are relatively low in relation to excavation depending on the depth and route of the pipe. The environmental benefits of re-using the existing infrastructure are considerable.

How we can help

Our crews have years of experience under their belts. With successful rehabilitation projects throughout GB, NI, and Ireland, we can be relied upon to do the best job, with detailed assessment to ensure risks are accounted for.

 
 
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