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Network Innovation Allowance
GD - Mains Replacement
Gas Distribution Networks
A conceptual design for a casing spacer (in the form of a wheeled clamp) has been provided by FT Pipeline Systems (FTPS). It is intended that such spacers will be clamped around the PE pipe at an axial spacing of 2 m, during the insertion process.
The spacers will enable the PE pipe to be ‘rolled’ over the Weko seal brackets during insertion, thus eliminating the need to remove the Weko seals; and the associated requirement for man entry to the cast iron pipe. Potential risks for operatives working inside the buried pipes include ground failure and water flooding from adjacent water mains.
The project will involve the following elements/stages:
1. Design review and loading calculations report
ROSEN will perform an assessment of the proposed spacer design, to ensure that the loads on the PE pipe and spacers themselves are acceptable during the installation and operational life of the PE pipe.
2. Development of G23 documentation
ROSEN will lead the development of the G23 field trial procedure and RAMS for installation, with input where required from Cadent and FTPS. The G23 document will contain the installation procedure required for the use of the spacers for PE pipe insertion.
3. Field Trial report
ROSEN will attend two field trials (pipe pushes) for the insertion of PE mains using the spacers, one with Weko seals to navigate, and one without. It is assumed that these field trials will be maximum 300 m long insertions, with spacers installed at 2 m intervals. 300 pipeline spacers will be provided for this project, which will enable the insertion of 630 mm diameter PE pipe into a 36-inch dimeter cast iron main. A Report detailing the outcomes of the field trials, and feedback of operatives following use of the wheeled clamps will be produced following the end of the Field Trials.
The objective of this project is to eliminate the removal of Weko seals by using Pipeline Spacers. The spacers will enable the PE pipe to be ‘rolled’ over the Weko seal brackets during insertion.