The Internal Live Service Insertion (ILSI) project seeks to extend the completion date of the project following complications during initial field trials.
Currently, service renewals to properties are carried out using several techniques, one of which is the ‘Live Service Insertion’ (LSI) method. The standard LSI technique requires a small excavation in the customers private land or garden. The relining of the service is carried out from this excavation towards the parent main and back towards the customers property to the existing meter position.
Internal LSI has been designed for use from within a customer’s property, permanently abandoning the annular space between the existing metallic service and the new PE liner, allowing the undertaking of excavations within the customer’s land boundaries to be avoided.
Reason for extending the project
Following the first project extension in September 2019, in which the project was extended on the basis that further field trials were required:
“Field trials were undertaken to assess the newly designed ILSI system against the project success criteria. Field trials are the last phase of the ILSI project and carried out under G23 documentation.
Selected field trial sites were found to be unsuitable. The services selected had a substantial amount of Dupont service pipe connecting the existing service to the parent main. This prevented the passage of the Nosecone system. CCTV inspection revealed that all the remaining field trial sites were of the same design and therefore not suitable for ILSI”
Since then, the project has identified a further issue with identifying trial sites. The identification of suitable network services applicable for use with the ILSI technique is somewhat reliant on local knowledge, making it extremely difficult to identify the necessary volume of field trials and impractical for everyday deployment. The issue subsequently requires addressing, before the technique can be implemented into business as usual.
To resolve the outstanding issue, the project will carry out an additional work activity, identifying all suitable services for the use of the ILSI technique across the network. Once identified, the remaining field trials will be undertaken.
To continue with the project, the project timeline requires extending. There will be no impact to the project cost.
Recommendation
The projects original drivers and anticipated forecasted benefits remain current. Although delays to the original project timeline have occurred, it will not attract any additional Capex costs. However, internal overhead cost will be impacted, but are expected to be minimal.
Continuing with the project is deemed a credible option, therefore It is recommended the project completion date is extended to 30th July 2020.
Objectives
The agreed sealing length will have an impact upon the final design for the Nosecone used in the system as well as all other tooling including sealant injection and pipe pushing systems. SVI will use their extensive knowledge of sealants and injection techniques to help determine the best possible solution.
Sealant Application
The standard sealant application systems will not be suitable for use inside a customer’s property. They are inherently bulky and are not clean enough to be transferred from an external scenario to an interior one. A new applicator system will be able to inject sealant via the service head adapter port with a steady flow. SVI will aim to incorporate a self-mixing system into the applicator gun, this will remove the potential risk of spillages inside a customer’s property when mixing a two-part sealant by hand in buckets or within a sealed sachet. Powering the applicator will require discussion between NGN and SVI to establish an acceptable power source. It is thought that the agreed power source may also be used to power the PE pipe pushing system.
Alternative Mixing - Options
In order for a clean and simple injection of LC14 sealant to be carried out, it will be necessary to investigate and produce a system with the capabilities to mix the LC14 sealant as it is injected. This will reduce the risk of spillage within a customer’s property.
Nosecone
A redesigned nosecone will be required in order for the new system to negotiate an increased number of bends and increased length of service. It will be necessary to carry out gas flow testing on the new Nosecone to assess its performance when compared to the original Nosecone design. A redesigned Nosecone should outperform the original Nosecone design in all aspects with minimum pressure loss once installed. It may be decided that the Nosecone design will incorporate a ‘lead in’ or extended nose portion to allow the easy insertion of PE into the metallic service. Design consideration will be made to allow the easy reconnection to the new PE parent main.
PE Insertion Device
It is expected that the increase in service length and the increased number of bends will have a detrimental effect on the ability to insert a Nosecone and PE pipe. There is also the distinct possibility that the area in which a skilled service layer is required to work in will be dramatically reduced. It is therefore necessary to investigate a new method/machine that will enable the insertion of the new service from a confined space within a customer’s property and be able to overcome the requirement for additional force to be applied during insertion.
Learnings
Outcomes
Due to overall unsuccessful G23 Network Field Trials the Internal Live Service Insertion technique will not be fully implemented for use within Northern Gas Networks. This decision is based upon inconsistent field trial results, with a number of trials resulting in the need for field operatives to excavate and replace existing service pipework by traditional means, to limit disruption to consumers.
Furthermore, the potential workload for ILSI forecasted during project scoping was based upon work that is currently applicable for replacement by the existing LSI technique (Approximately 750 uses per annum). However, due to the variations in service pipe construction across NGNs footprint, the actual workload (assuming successful field trials) was expected to significantly lower, resulting in an overall reduction in cost benefit for both NGN and its customers.
Some of the newly developed technology associated with ILSI that was trialled throughout, specifically the new pipe pusher & sealant applicator is showing promising signs of being able to reliably and consistently improve the methodology & efficiency of the existing LSI technique. It is Northern Gas Networks intention to continue working with Steve Vick International to carry out further field trials of this equipment combined with the already approved LSI technique to assess if any further efficiencies can be achieved.
Lessons Learnt
· Throughout the project, during regular reviews, it was identified that a key assumption used to produce the project business case were not able to be validated when it came to carrying out field trials. The volume of annual workload identified during project scoping was significantly lower than first evaluated, this resulted in challenges with identifying initial field trial sites and additionally would have culminated with lower cost benefits than initially planned, if the solution was to be fully implemented.
· Ensure that workshop testing carried out by vendors and suppliers is more accurately modelled on “real world” conditions. Although the workshop testing by SVI was reliable and reported with a high confidence level, ultimately the workshop trials did not mirror the conditions encountered day to day on the network; specifically, with regards to condition of metallic services, level of internal debris, various fittings and pipe configurations found across the district.
· Identifying and planning in field trial sites was a key challenge encountered during this project, due to the limited scenarios in which ILSI & LSI can be utilised. This aspect was also impacted by COVID-19.
· For the full ILSI solution to achieve G23 Network Approval and subsequent implementation, further development work is required to ensure that the solution can deliver reliable and consistent results of replacing 1” metallic service configurations that are found across the UK GDNs. This will require further development of the new nosecone design and consideration for how existing service pipework can be prepared to a standard that would enable the longer length of service pipework (when compared to LSI) to be replaced without issues with obstruction or restriction.
· Although the project was not 100% successful, the newly developed technology associated with ILSI that was trialled throughout, specifically the new pipe pusher & sealant applicator is showing promising signs of being able to reliably and consistently improve the methodology and efficiency of the existing LSI technique.
