Boosting Long Term Efficiency in Iron Mains Replacement

The Challenge

In the UK the Health & Safety Executive have mandated that gas distributors need to replace all their iron mains by 2023. For the UK’s largest distributor Cadent, this is an enormous task that needed to be carefully planned. Cadent have a network of more than 131,000km of iron mains, to hit the target date they will need to renewal approximately 1,700km annually. The sheer scale of the works means that robust optimisation and scheduling of the pipe renewals can help drive major cost efficiencies. Cadent also need to meet their key performance targets, which include ensuring there is no supply interruptions to supply, maintaining health and safety standards and achieving environmental targets.

The sheer scale of Cadent’s asset base, rendered the problem intractable at asset level for more traditional Asset Investment Planning and project portfolio tools. The assets would have needed to be aggregated into cohorts or the problem split into many smaller ones. Using spreadsheets and databases to analysis data and plan work schedules was also too labour intensive. Both these approaches would result in unnecessary and inefficient data processing and suboptimal decisions.

 

“Advanced data analytics can be used to coordinate widescale iron mains replacement, driving efficiencies in the gas sector.”
Dr Tim Watson
Co-founder & chief strategy officer, Probit Consulting

 

The Solution

Probit Consulting Asset Investment Manager (AIM) 4.0 software, was selected in a competitive process for an asset investment planning (AIP) solution that can be deployed at the scale Cadent required. AIM 4.0 has powerful analytical capabilities to interpret dynamic relationships and optimise investment for specific operational requirements and performance targets over a given time horizon.

Examples of the way AIM 4.0 was used:

• To measure the current health of assets and how they would perform over time
• Identify which distribution mains to prioritise for renewal
• Assess the relative benefit of each pipe renewal
• Understand the likely cost
• Coordinate the work so that it can be done in the most economical and timely way

How Probit Consulting delivered the project

Data was collected from a variety of sources and combined to create intelligence that optimised the scheduling of pipe renewals and helped reduce costs. Cadent had a large quantity of good quality detailed data about the age, size, materials, pressure and locations of pipes in the network. AIM 4.0 connected directly with many data sources at asset level, these included business operations, asset management software, database management systems, geographical information systems (GIS) and spreadsheets.

Where data was limited industry accepted models or expert opinion were used and stored in a templated model library in AIM 4.0. A governance strategy was adopted to identify work required to improve the data and related models over time.

 

“The GD2 Distribution Mains Renewal programme is a massive undertaking and the models generated by the AIM 4.0 software are already providing us with a level of detail on pipe condition and costs we haven’t had previously.”
Sam McGauley
RIIO-GD2 mains renewal investment lead, Cadent

 

How AIM 4.0 is contributing to Cadent mains renewal plan

The Cadent’s Distribution Mains Renewal plan is focused on low, medium and intermediate pressure pipes of two to 48 inches (50-1220mm) in local transmission systems and the AIM 4.0 platform is being used for five purposes:

1. To assess the health of each pipe and predict how it will perform over time, including how many failures it will have and how that will change with age, depending on materials and other factors
2. To assess the consequences and cost of failure in terms of repairs, customer service and community impact
3. To assess risk to the environment from release of carbon dioxide into the atmosphere
4. To assess health and safety risk from gas potentially trapped in buildings – gas ignition could cause explosion with risk of fatality and injury
5. To assess risk of interruption of customer supply and potential penalties

The key strength of the model for this application is that it can assess one pipe against another and indicate which should be renewed first. For example, the location of a given pipe might make it more expensive to renew, but if it is failing more often, and its failure has a greater impact on customers, the model can pick this up and show the greatest total benefit.

 

Creating a model to meet regulatory targets

The model is programmed to ensure completion of the iron mains work by 2032, in accordance with the Health & Safety Executive regulatory mandate. In December 2019, Cadent submitted its distribution mains renewal plan for RIIO-GD2, the gas distribution price control review that runs from April 2021 to March 2026.

The programme of works comprised of three elements

1. HSE-mandated renewal of all iron mains of 8-inch (203mm) diameter and below, situated within 30m of a building. These pipes comprise 93% of all renewal work.
2. Other mains that are above the safety threshold and require renewal. This is cohort mainly comprises ageing steel mains.
3. The cost benefit assessment mains (CBAMs), which are not necessarily a safety risk but are failing and are cheaper to renew than maintain.

All three programmes were run simultaneously. Rigorous analysis of the network and the schedule means the whole renewal programme can be delivered at optimal efficiency according to best performance and cost and within the regulatory timeframe.

 

Optimising Cadent’s mains asset renewal plans

The development of a monetised risk-based methodology and framework made it possible for Cadent to make consistent and robust comparisons between potential asset investments. The framework identifies the potential impacts of decisions made on individual assets through assessment of risk, consequence and financial cost of failure. This means risk can be projected forward to determine whole-life cost of ownership. The effect of intervention plans and the associated risk impact can also be assessed, enabling the comparison of current and future risk with and without proactive investment.

The core of AIM 4.0 is a powerful simulation and optimisation engine. Optimisation is performed using the leading commercial mathematical optimiser and has been particularly chosen for Cadent’s large-scale infrastructure. Combinations of drivers can be optimised including budget, resource, risk, serviceability, asset performance, whole-life benefit and whole-life cost.

 

“I’m looking forward to moving on to the tactical plan, where we use the model to identify specific pipes, based on further analysis. By inputting additional data and running models we expect to be able to be able to prioritise renewals.”
Sam McGauley
RIIO-GD2 mains renewal investment lead, Cadent

 

Creating Risk Maps for Cadent

AIM 4.0 produced Risk Maps for Cadent, which are graphical representations that link cause and effect. They can integrate all the components required to make investment decisions and calculate intervention benefits, such as the new failure rate following proactive replacement. The scenario builder within AIM 4.0 enables Cadent to ask questions in an intuitive manner to assess the trade-off between risk, service and cost.

Typical questions Cadent might ask:

• If I do nothing, and just react, what will happen?
• How much will it cost to maintain current performance?
• What is the best level of service and least risk I can achieve with a limited budget?
• If I want to maintain my network in the same condition what will it cost?
• If I replace assets based on the age of pipe what will it cost?

AIM 4.0 has a built-in model equation editor that allows for any mathematical function, such as an estimated deterioration relationship, to be input and stored. This helps Cadent produce statistical models that represent asset performance and serviceability through time and other relationships such as costs and benefits. Equations may be as simple or complex as required and a full audit trail means they can be saved in a model library and evolve over time as new data or expert opinion becomes available. Results can be compared across simulations and optimisation scenarios; exported from within a scenario; produced spatially, at asset level; and extracted from drilldowns into the data itself.

All scenario results can be exported from AIM 4.0 at asset, or any aggregated level, to give short- and long-term programmes of work, identifying cost-beneficial projects. This output can be imported directly into Cadent’s GIS and business intelligence software for sense checking and validation.

 

“Decision analytics software like AIM 4.0 offers asset-intensive organisations like Cadent the capability to make major investment decisions with much more accuracy, gaining more value from the underlying data and driving cost efficiency.”
Dr Tim Watson
Co-founder & chief strategy officer, Probit Consulting