PIPELINE QRA SEMINAR

PIPELINE RISK ASSESSMENTSOFTWARE/TOOLS FOR RISK ASSESSMENT

• Different software/tools for QRA

• Tools (hand calculations) versus software

• Tools (hand calculations) – actually manual development

of simplified software (typically Excel)

• There are software/tools also for qualitative risk

assessment (e.g. linked to different methods –

HAZID/HAZOP)

• Focus on software/tools for QRA

SOFTWARE/TOOLS FOR RISK ASSESSMENT

Advantages of tools (hand calculations)

• Simple (understanding and execution)

• Flexibility

Disadvantages of tools (hand calculations)

• Standardization (i.e. do we always calculate in the same way?)

• Size and presentation (i.e. number of documents/sheets)

SOFTWARE/TOOLS FOR QRA

Advantages of software

• More advanced (often)

• Accepted (e.g. could be recommended from authorities)

Disadvantages of software

• Black-box (often)

• Non-flexible (e.g. change of parameters)

SOFTWARE/TOOLS FOR QRA

Software:

SAFETI from DNVGL

QRA Open from Taylor Associates ApS

Shepherd from Shell

Riskcurves from TNO

• Software/tools established by consultant companies,

authorities, companies (e.g. oil and gas industry and

process industry) and software companies

• Method depending on the situation (e.g. complexity,

stage of project and time)

• Economical and technological aspects (e.g. costs for

license and knowledge of the software)

• No single best software/tool to solve all problems

SOFTWARE FOR QRA

• “Same, same. But different!”

• Similarities in presentation

• Differences in way of calculations/models (exact

differences hard to establish, since often “black-box”)

SOFTWARE FOR QRA

• Software from DNVGL

• Specialized for onshore process facilities and

petrochemical facilities

• Used frequently in the oil- and gas industry (e.g. BP,

Total, Maersk and Shell)

• Connected to the PHAST software

SOFTWARE: SAFETI

• How does it work?

- Accident scenarios (e.g. PHAST and frequencies)

- Population

- Weather conditions

- Ignition sources

- Quantification of the risk (i.e. individual risk and group

risk)

• Compare with presented methodology for quantitative

risk assessment

SOFTWARE: SAFETI

Advantages of PHAST

• Easy to get some quick results from (compared to

others)

• Interface (i.e. easy to understand and present)

Disadvantages of PHAST

• Black-box (i.e. what happens in the model and change of

parameters)

SOFTWARE: SAFETI

Guidelines/standards:

Pipeline systems - Steel pipelines on land - Guide to the application of pipeline risk assessment to proposed developments in the vicinity of major accident hazard pipelines containing flammables (BS PD 8010-3:2009) (part of framework BS PD 8010-1:2004) from British Standards

Assessing the risks from high pressure natural gas pipelines (IGEM/TD/2)from Institution of Gas Engineers and managers

• Tools (and guidelines/standards) established by consultant

companies, organizations, authorities and companies (e.g.

oil and gas industry and process industry)

• General difference - two categories of tools:

- Scoring systems (i.e. simple ranking of pipeline segments)

- Traditional QRA (i.e. general methodology)

• Standalone versus included in larger risk management

framework

TOOLS FOR QRA

• Detailed difference - three categories of tools:

- Generic values for leakages

- Possibility to modify values for leakage to account for

special properties and situation (e.g. corrosion)

- Possibility to modify values for leakage to account for

special properties and situation (e.g. corrosion) as well as

including of external hazards (e.g. 3rd party interference and

similar)

• What is best? Depending on the situation (e.g.

complexity). Most important to be aware of what is

included and what is not included.

TOOLS FOR QRA

How is a QRA carried out?

TOOLS FOR QRA

EXAMPLE OF QRA

Ringsted, Denmark

- 30’’ gas pipeline

- 80 bar

- 12 mm

- exposed

- no construction work or agricultural work allowed within 50

meters from the pipeline

- shopping centre (opening hours 08.00-20.00) at 100 meters

- parking lot between shopping centre and pipeline

EXAMPLE OF QRA

• What could go wrong?

- Internal corrosion (expected problems with impurities)

- External corrosion (noted damages to protection from

installation)

• As detailed as want (e.g. is the restriction on

construction work followed and possible natural hazards)

EXAMPLE OF QRA

• What is the frequency for the different scenarios?

• Where could we find information?

- Riser & pipeline release frequencies from International

Association of Oil- and Gas Producers (OGP)

EXAMPLE OF QRA

• Riser & pipeline release frequencies from International

Association of Oil- and Gas Producers (OGP)

- 8.1 x 10-5 per km-year (12 mm wall thickness)

- 18% are medium holes (75 mm hole)

• Frequency for specified scenario:

- 1.5 x 10-5 per km-year

• Just one of several scenarios!

EXAMPLE OF QRA

Click icon to add picture

• What is the consequence from the different scenarios?

• Choice: human safety – fatalities

• What do we need to consider?

- Gas cloud - flash fire (extent and radiation from)

- Jet fire (radiation from)

- Pin hole

- Rupture

- Large hole

EXAMPLE OF QRA

• As detailed as want (e.g. are there some of the

combinations we can exclude?)

• What do we need to consider?

- Gas cloud - flash fire (extent and radiation from)

- Jet fire (radiation from) (excluded)

- Pin hole (excluded)

- Rupture

- Large hole

• Remember – all scenarios quantified (increasing effort)!

EXAMPLE OF QRA

• What scenario?

- Gas cloud - flash fire (extent)

- Large hole (75 mm)

- LFL and ½ LFL

- All inside a cloud would be fatalities (>37.5 kW/m2)

• Just one of several scenarios!

EXAMPLE OF QRA

• Combine the frequency for the scenario and the

consequence for the scenario to get the actual risk

• What do we know?

- With the frequency 1.5 x 10-5 per year there will be a

release of gas from the pipeline and the cloud will enclose

the parking lot

EXAMPLE OF QRA

• What do we not know?

- Exposure (e.g. how often are there people in the parking

lot and how many people are there in the paring lot)

- Ignition (i.e. what is the probability of ignition of the gas)

- Weather conditions (e.g. how often wind towards the

parking lot)

EXAMPLE OF QRA

• What do we not know?

- Exposure – in average 50 persons in the parking lot from

08.00 to 20.00 every day and a parking guard there 5 days

a week between 07.30 and 20.30

- Ignition – 50% probability of ignite the gas due to the cars

at the parking lot and the electrical signs on the shopping

centre

- Weather conditions – 10% probability of wind towards the

parking lot (defined as south) due to prevailing wind east

EXAMPLE OF QRA

• Combine the frequency for the scenario and the

consequence for the scenario to get the actual risk

(considerations for the parking guard)

- Frequency x ignition x wind x exposure (individual)

- 1.5 x 10-5 x 0.5 x 0.1 x 0.39 per year

- 2.9 x 10-7 per year

EXAMPLE OF QRA

• What does this mean?

- With the frequency 2.9 x 10-7 per year there will be a

release of gas from the pipeline, the cloud will enclose the

parking lot, the cloud will ignite and the parking guard will

be present (fatality)

- The individual risk (for the parking guard) from this

scenarios is 2.9 x 10-7 per year

• Just one of several scenarios!

• Just one of several scenarios!

EXAMPLE OF QRA

• What about the group risk?

- With the frequency 2.9 x 10-7 per year there will be a

release of gas from the pipeline, the cloud will enclose the

parking lot, the cloud will ignite and in average 50 persons

will be present (fatalities)

EXAMPLE OF QRA

• Is the risk (from this scenario) acceptable?

• Risk acceptance criteria for individual risk

- 1.0 x 10-6 (Danish legislation) – YES!

• Risk acceptance criteria for group risk

- (see figure) (Danish legislation) – MAYBE!

- Separate presentation on ALARP

- Most likely not given contribution from other scenarios

EXAMPLE OF QRA

• QRA is a tool to evaluate and support what in the end

are political decisions whether to proceed with

construction/design (or similar) within questionable,

high-risk and/or consequence areas

• Could have a high consequence and a high frequency,

but anyway an acceptable risk

EXAMPLE OF QRA

• Even the smallest QRA has large complexity

• What has been simplified in this QRA?

- Wind directions (e.g. 4 or 16?)

- Wind speed (i.e. consequences different)

- Ignition probabilities (e.g. models or ignition sources)

- Frequency (i.e. just considered one scenario)

- Consequence (i.e. just considered one scenario)

- Simplified population (e.g. cars on the road and residents)

- Release frequency given per kilometre (e.g. not all releases within

kilometres would give consequences within 1 kilometre)

EXAMPLE OF QRA

How is a QRA carried out?

EXAMPLE OF QRA

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• What is the challenges of quantitative risk assessment?

- Uncertainty (i.e. the risk could be something that has

never happened before)

- Statistic (i.e. availability)

- Assumptions – big effect (e.g. sensitivity analysis)

- Complexity (i.e. how much could/should be included?)

- Ideal model (e.g. would people move from a release?)

EXAMPLE OF QRA

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QUESTIONS?