Consequence and risk analysis of releases of hazardous materials from buried pipelines made easy

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Releases of hazardous materials from buried pipelines can have disastrous consequences.

A rupture and ignition of flammable gas from a buried pipeline in British Columbia, Canada initiated a forest fire which resulted in 1.6 hectares of land being burnt (see Figure 1). Fortuitously, no fatalities were recorded or evacuation needed as the incident happened in a remote area. The rupture also led to the formation of a large crater (17m long, 7.6m wide and 1.1. m deep, see Figure 2).

Plant - Consequence and Risk Analysis of releases of hazardous materials from buried pipelines made easy - aerial-view

Figure 1: Aerial view of the accident site showing burnt forest area (source here)

Plant - Consequence and Risk Analysis of releases of hazardous materials from buried pipelines made easy - crater

Figure 2: Picture showing crater formed (source here)

The statements below represent a selection of questions we (i.e. DNV GL Software) have received relating to the modelling of the consequences (using Phast) and risk (Quantitative Risk Analysis (QRA), with Safeti) associated with releases of hazardous material from buried pipelines.

  • “My pipeline is buried – how do I undertake a QRA for this using Safeti?”
  • “Can Phast be used to model buried pipelines?”
  • “How do I assess the consequences related to a buried pipeline?”

Let us take a moment to explore how Phast and Safeti can be used to address the questions above.

Phast, Safeti and Pipelines – what is possible now?

Phast includes a dedicated “Long Pipeline Model” to assess the specific consequences related to discharges from pipelines (above ground). Equally, Safeti has the capability to utilise those consequence results for a pipeline QRA.

Safeti 7.2 (released in September 2016) featured a bespoke “Pipeline Risk Model” – a dedicated model for pipeline QRA that leverages the existing “Long Pipeline Model” and enables more speedy and efficient risk analysis. It also brought significant updates to the existing capabilities. Read more here.

Despite the extensive modelling features and updates afforded by Safeti 7.2, one gap existed – modelling “buried pipelines”. Naturally, there were workarounds to this problem (see “International Association of Oil and Gas Producers Report 434-07 Risk assessment data directory – Consequence modelling” for an example of how to approach this) – but these involve manual tweaking of input data and the need for engineering judgement – a huge task for all but the most experienced analysts.

Looking to the future

All this is about to change with the next version of Phast/Safeti (version 8) which takes things one step further and adds dedicated support for buried pipelines within the existing “Long Pipeline Model”.

Users will be able to specify:

  • What sections of their pipeline are buried?
  • The burial material – clay, sand etc.
  • The height below ground
  • The size of the release hole – pinhole, full bore rupture etc.

Figure 3 outlines a conceptual schematic of the model; whilst Figure 4 shows the input screen in Phast/Safeti 8.

Plant - Consequence and Risk Analysis of releases of hazardous materials from buried pipelines made easy - conceptual-schematic

Figure 3: Conceptual schematic of the buried pipeline model

Plant - Consequence and Risk Analysis of releases of hazardous materials from buried pipelines made easy - phastsafeti-input-screen

Figure 4: Buried pipeline model input screen in Phast/Safeti 8

With this input information, Phast will calculate the release discharge characteristics (crater size, dimensions etc.) which will be used for further consequence calculations (e.g. dispersion, explosion etc.). The consequence calculations can also be leveraged within Safeti as part of a QRA for a buried pipeline.

The theoretical underpinning of the model is based on work done by Phil Cleaver et al[1] drawing on experiments conducted at DNV’s Large scale research facility in Spadeadam. Full details of the model (e.g. theoretical basis, validation, verification etc.) will be provided in documentation that will accompany the product once released.

The benefits are clear. Phast and Safeti will offer the ability to rigorously and robustly assess the hazards/risks associated with buried pipelines. Equally important is that this will done in an efficient manner eliminating the need for manual tweaks.

More broadly, version 8 of Phast/Safeti will bring a wide-ranging array of new modelling capabilities – including a new gas dispersion model discussed here.

Seeing is believing

We will be showcasing the new version at our 2017 user conferences around the world (currently planned for: Malaysia, France, China, South Korea, USA, Mexico and UAE) over the next few months (see our events page for details of when/where and how to register).

We will also have dedicated Phast/Safeti 8 workshops at the conferences where users will have the opportunity to test drive all the new functionality. If this is of interest to you – please register to attend one of our conferences. We look forward to seeing you and getting your feedback.

Pipeline risk management solutions from DNV – the broader view/big picture

Phast and Safeti represent a subset of the broad array of tools from DNV for managing the design, operations and risk management of pipelines. We are working to bring these tools together into a seamless, integrated and cloud based analytical platform that will “transform and optimise engineering and operational work processes” and “reduce costs” by:

  • breaking silos across work functions
  • streamlining data transfer
  • enabling lifecycle asset data management, and
  • offering cutting edge analytical tools (physics and data based)

We call this our “Pipeline Ecosystem”. For all pipeline owners, designers, operators – it’s a “one-stop solution” for anything and everything to do pipelines – from design to operation to optimization.

We are well advanced in integrating all our pipeline solutions into a single platform. One solution demonstrating the benefits of this integration work is our real time predictive pipeline risk assessment offering called “Synergi Pipeline Ticket Risk Assessment”. The solution provides damage prevention personnel a complete view of:

  • security of supply,
  • excavation risk,
  • facility risk including excavation complexity, operational impact including human impact (using models from Phast) and customer impact.

This powerful solution seamlessly combines analytics from within Synergi Gas, Phast and Synergi Pipeline. It enables utility companies to be more proactive, addressing the threats by scheduling field personnel to oversee the location and excavation. Read more about “Synergi Pipeline Ticket Risk Assessment” here. The advances in modelling consequences from buried pipelines in the latest version of Phast will provide a valuable improvement to the effectiveness of this solution.

The level of convenience, performance and efficiency gains offered by such an integrated offering will be far in excess of anything that currently exists. A classic case of the whole being greater than the sum of the parts. This in a nutshell is the power of the pipeline ecosystem from DNV. We are yet to find something similar on offer. To put it simply – most would describe this as “stuff of dreams”. Not anymore. At DNV, we make dreams into reality.

[1] Cleaver, P., Halford, A., Warhurst, K., and Barnett, J., “Crater size and its influence on releases of carbon dioxide from buried pipelines”, 4th International Forum on the Transportation of CO2 by pipeline, Newcastle, June 2013

Authors: Kenny Shaba and Colin Hickey

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