Dec 2016
Gas Distribution
Practical Solution for Overbuilds
Dec 2016
Dec 2017
Northern Gas Networks
Neil Travers
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Network Innovation Allowance
Gas Distribution Networks
This project is to work in partnership between SVI and Northern Gas Networks to design, develop and demonstrate a suitable method for sealing the annular space between the inserted PE gas pipe and the old metallic gas main.

The purpose of the project is to remove the risk to ‘overbuilt’ properties by designing and developing a system and all associated technology to enable a Steve Vick International (SVI) Contracting Team to fully fill the annular space between the two pipes beneath the entire width/length of the building residing above the metallic gas main.

The developed system will require G23 status and enter a period of field trials whereupon a set number of installations will be carried out on a range of pipe diameters and lengths.

The project team will monitor progress throughout this period and undertake feedback from all interested parties.

Once the system is installed, the abandoned annular space will be monitored by NGN for gas build up via a standpipe and valve assembly or other suitable means, attached to the injection point of the sealant. The valve will terminate at an accessible location of NGN’s choosing.

Design & Development (In-house) - SVI Design Engineers and Technical teams to design, develop and in-house test the following prototypes:

Annulus entry systems – More than one method for gaining entry and injecting annular sealant into the metallic main will be designed to allow for several work scenarios.

Sealant injection system – A small, non-disruptive sealant injection machine will be designed and developed to allow operators to transport the system through a customer’s property if required. The injection method should not require fuel powered hydraulic or pneumatic plant to operate.

Field Trials – Field trials will be carried out in collaboration with the NGN Project Team and their field technicians. Information from the trials will be fed back to SVI design and development staff and acted upon accordingly until a successful, cost effective and safe system is developed. Field trials will be monitored by an SVI Project Manager and NGN Project Team representative.

Project completion – The project will be deemed complete once the field trial stage has been completed successfully and all of the project criteria have been met. Upon field trial completion, an SVI Project Manager will produce the project completion report for review by the NGN and SVI Project Teams. Upon successful review, the Final Project Report will be published and presented to NGN.

The project will be deemed successful if the following criteria are met:

  • The system is transportable through a customer’s property.

  • The system fully fills the annular space beneath a property and by at least 2m outside of the building line

  • Injection of sealant can be accomplished through varying connections to the annular space.

  • It realises an increased ability to plan ‘Live Mains Insertion’ projects with built over properties in the vicinity.

  • Enables the total decommissioning/abandonment of annular spaces beneath customer properties.

  • Be deployable from remote, less sensitive areas within the customer’s private boundary as and when required.

  • Reduce disruption to members of the public by abandoning annular spaces without the need to fully excavate them or carry out expensive and disruptive diversion work.

  • Improve safety to members of the public.

  • Cost benefits due savings made against main laying operations.

  • Cost benefits due to the ability to abandon the annular space without the need of multiple excavations to allow main laying techniques such as diversions.

  • Greatly improved customer relationship.

  • Zero or very minimal waste is produced that will be removed by SVI Technicians.