Sep 2017
Gas Distribution
Squeeze free flow stopping on PE mains
Sep 2017
Mar 2021
Northern Gas Networks
Mick Smith
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Network Innovation Allowance
GD - Repair
Gas Distribution Networks

Radius PLUS has commenced a development project of its own to develop live access electrofusion access saddles for deployment of stopper systems to PE mains, specifically the smaller diameter type needed for its RTP stopper deployment. Such systems will be available for mains 63mm to 450mm when fully completed, including imperial 3” to 8” sizes. It is proposed that the NIA project run concurrently with that development to accelerate the development through offline deployment testing, review and definition of engineering standards for medium pressure RTP stoppers, preparation of codes of practice/engineering policy documents that all lead to ability to undertaken field trial deployment safely within the network. Three field trial deployments have been included within the scope of the RSL cost elements, the value can clearly be adjusted if further field trial deployments were preferred for the purpose of statistical or practical confidence of the technique in the network.

  1. Conduct failure mode and effects analysis (FMEA) for the holistic system of flowstopping PE mains using the technique. Identify system issues to be resolved in design and testing to de-risk technique.
  2. Conduct FMEA on access saddles with a gap analysis to GIS/PL2-4 and GIS/PL3 for long term integrity of saddles post flowstopping, document design/test requirements to a suitable addendum
  3. Conduct testing of saddles in accordance with revisions proposed to the GIS/PL2-4 and GIS/PL3 standards to provide specific third party peer reviewed engineering reports on suitability of products
  4. Conduct FMEA on RTP style inflatable stoppers with a gap analysis to GIS/E19 and GIS/E20 and commit to a new draft GIS/E20;part 2 document on tests to be applied to the stopper elements
  5. Validate test methods proposed for GIS/19 and GIS/E20 in respect of both stopper and deployment to PE (particularly concepts of size range rating and friction slippage factors) by simulation/practical test
  6. Undertake off-line trials on representative sizes of PE mains to validate the technique over the size range 90-630mm (proposed 90, 180, 315, 500 & 630mm, 4” & 8”) including lifetime testing of assets
  7. Prepare method statements, supporting evidence and risk assessments suited to the development of engineering policy in relation to the proposed method of flow stopping for MP mains
  8. Subject to sign-off, conduct field trial evaluation on the operational network on a selection of pipe sizes sufficient to confirm confidence in the use of the technique (e.g. small/medium/large pipe size)
  9. Prepare final project report for disclosure of overall findings in relation to enabling standards and underpinning data for engineering policy to assist in national adoption (excludes proprietary designs)
The successful operational deployment of unsupported bag flow stopping systems on medium pressure gas distribution mains 90mm to 450mm PE (with future scope to go down to 63mm) enabling withdrawal of policy approval for use of squeeze off techniques in this size range specifically relating to medium pressure PE mains.