Projects: Projects for Investigator
Reference Number NIA_SGN0026
Title Customer Self Isolation and Restoration (Stage 2)
Status Completed
Energy Categories Fossil Fuels: Oil Gas and Coal(Oil and Gas, Other oil and gas) 50%;
Fossil Fuels: Oil Gas and Coal(Oil and Gas, Refining, transport and storage of oil and gas) 50%;
Research Types Applied Research and Development 100%
Science and Technology Fields ENGINEERING AND TECHNOLOGY (Mechanical, Aeronautical and Manufacturing Engineering) 100%
UKERC Cross Cutting Characterisation Not Cross-cutting 100%
Principal Investigator Project Contact
No email address given
Cadent Gas
Award Type Network Innovation Allowance
Funding Source Ofgem
Start Date 01 October 2013
End Date 01 February 2014
Duration 4 months
Total Grant Value £19,331
Industrial Sectors Technical Consultancy
Region London
Programme Network Innovation Allowance
Investigators Principal Investigator Project Contact , Cadent Gas (99.997%)
  Other Investigator Project Contact , Wales and West Utilities (0.001%)
Project Contact , Northern Gas Networks (0.001%)
Project Contact , SGN (0.001%)
Web Site
Objectives The objectives of this Project are to: To safeguard life and property during major off gas incidents. Establish a safety management system to reduce risk of explosion or exposing vulnerable customer to poorly heated environments with risk of hypothermia. Restore customer supplies rapidly and safely. Through-out the Project there will be frequent meetings held between GL Noble Denton and the Network Licensees to update on project progress. Each stage will have its own deliverables and targets which the Project will measure itself against. If there are any unforeseen issues throughout the Project recovery plans will be adopted to ensure minimal impact on time scales, and avoid additional costs. The Project seeks to deliver: Demonstrate the models in the working environment of each Network Licensees. Assess the models effectiveness. Integration of the model into the business, which has been recognised by the HSE. Delivery of a robust safety management procedure that will allow customer self isolation and restoration during major off gas incidents.
Abstract When a gas supply failure occurs it is necessary to isolate every consumer at the meter before the network can be re-commissioned. This is to prevent unburnt gas from entering buildings. Currently Network Licensees have to use competent resources to carry out this isolation and to then purge and relight consumers’ appliances once the network is re-commissioned. In a large supply failure this becomes a long and protracted process that could result in consumers being without gas for several weeks. This creates a risk of casualties (deaths, hospitalisations) caused by insufficient heating if the weather is cold and the incident protracted. Studies have been carried out to investigate whether consummers could carry out their own isolation and restoration in a protracted supply failure in order to reduce the duration of the incident. It has been concluded that this approach would be beneficial under certain circumstances, and the HSE, DECC and other stakeholders are broadly supportive of this approach. However, they require comprehensive risk assessments to be carried out as part of the decision making process. In 2011 work was carried out through the Innovation Funding Incentive to build a model that would provide Network Licensees with 2 graphs; one predicting the number of fatalities caused by gas incidents and the other which predicted the number of fatalities caused by the effects of weather during a gas supply outage. These graphs are used as a Decision Support (Risk Assessment) Tool for determining whether to use competent persons or consumers to isolate and reinstate supplies at the meter during a supply failure incident. Following on from this work the Health and Safety Executive (HSE) and Health and Safety Laboratories (HSL) reviewed the models and methodology. Their conclusion was that appropriate modelling techniques were utilised for both graphs. They did however have a number of recommendations regarding improvements to the model and regarding a number of inputs. As a result, the Network Licensees have made a collective decision to implement these recommendations through an additional project stage i. e. Stage 2. This project is innovative in that historically only competent resources have been used for this work, and the development of a risk assessment model as a decision support tool provides a mechanism for determining where it is acceptable to use consumers to carry out these tasks whilst minimising the overall health and safety risk. This Project will address all of the recommendations provided by the HSE/HSL and modify the model as necessary. As part of the proposed programme of work, GL Noble Denton will refine the existing research and development work they previously carried out and look to address the following: Self Isolation and Restoration Model: Extend the model to consider the risk of a fatality occurring during the isolation procedureThe value chosen for the risk of a fatality from a fall in the home has a significant effect on the predicted number of fatalities. Identify if additional literature can be found and revise estimate if appropriate. Otherwise highlight within the model that the value chosen for this input is a cautious estimate with a large associated uncertainty. The error in the methodology used to calculate the risk of fatality in sections ‘Instructions C1’, ‘Instructions C2’ and ‘Instructions E’ should be corrected. The output of the self-isolation and restoration model is a graph on which the number of fatalities is plotted as a function of the number of properties where a gas supply failure has occurred. HSL recommends that the graph be modified to show the number of fatalities per 1000 affected properties as a function of the duration of the supply loss. The following recommendations relate to the sections of the model that consider the likelihood of a gas explosion occurring following reinstatement of the gas supply. The number of fatalities that are predicted to occur as a result of gas explosions is negligible in comparison to the predicted number of fatalities from flashback. Therefore, whilst it is important that the necessary corrections to the model are made, GL Noble Denton will assess whether the implementation of these recommendations will affect the number of fatalities predicted by the model. In addition, they will: Review the values assumed for the probability of a built in hob being left on and the probability of a freestanding hob being left on. If different values are chosen for these inputs, the reasoning for this should be provided. Combine the results of four separate calculations to determine the risk of fatality associated with a gas release from a hob, using OR logic, not the simple summation that is currently used in the model. Check and make the necessary corrections to a possible error that the HSL has identified with regards to the methodology used to calculate the probability that a gas release will be detected by smell. Modify the ‘Instructions E’ section of the model to include a calculation of the risk of a fatality in the event of an engineer performing the restoration procedure having not shut down all the gas appliances. The development of a collaborative Project allows all Network Licensees to offer their input to what the GB gas industry requiresNote : Project Documents may be available via the ENA Smarter Networks Portal using the Website link above
Publications (none)
Final Report (none)
Added to Database 09/08/18