NEW UK PIPELINE RISK ASSESSMENT CODES – …

1 NEW UK PIPELINE RISK ASSESSMENT CODES IGEM TD/2 AND PD 8010 PART 3Dr. Jane V. Haswell1, Graham D. Goodfellow2, Neil W. Jackson3and Prof. Rod McConnell4 FIChemE (Speaker)1 PIPELINE Integrity Engineers Ltd., Newcastle upon Tyne, e-mail: Ltd., Newcastle upon Tyne, e-mail: Grid, Warwick, e-mail: Kingdom Onshore PIPELINE Operators Association, Ambergate, Derbyshire, e-mail: United Kingdom Onshore PIPELINE Operators Association, UKOPA was formed in 1997 by UKpipeline operators to provide a forum for representing PIPELINE operators interests in all mattersrelated to the safe management of pipelines. One of the key requirements is ensuring the pipelinedesign and operating CODES represent best practice, and that there is a common view amongstoperators and the regulators in terms of compliance with these hazard cross country pipelines are laid in 3rd partyland with an operational life typically greater than 50years.

2 During this time, the land adjacent to a PIPELINE issubject to change, and developments are likely to occurnear the PIPELINE route. This often means there is an increasein residential or working population near the PIPELINE , and asa result the PIPELINE may become non-compliant with coderequirements which originally routed the PIPELINE safelyaway from populated address this situation, land use planning is appliedso that the safety of, and risk to developments in the vicinityof major hazard pipelines are assessed at the planning Health & Safety Executive (HSE) are the statutory con-sultees in this process, and they set risk-basedconsultation zones around such pipelines, within whichthe risks to people and developments must be assessedand taken into account when planning authorities considernew planning applications.

3 For most cases, standarddecision tables are applied by the planning authority fromthe HSE document PADHI (Planning Advice for Develop-ments near Hazardous Installations), but for borderline ordifficult cases, site specific quantified risk assessments(QRAs) are applied to obtain risk levels, and to assess poss-ible mitigation measures to reduce risk ASSESSMENT (QRA) requires expertise,and the results obtained are dependent upon consequenceand failure models, input data, assumptions and has worked to obtain cross-stakeholder agreementon how QRA is applied to land use planning assessments. Amajor part of the strategy to achieve this was the develop-ment of the new CODES IGEM/TD/2 and PD 8010 Part 3,in order to provide authoritative and accepted guidance onthe risk analysis of site specific PIPELINE details, forexample increased wall thickness, PIPELINE protection(such as slabbing) depth of cover, damage type and failuremode, and the impact of mitigation measures which couldbe applied as part of the development.

4 The availability ofthis codified advice helps to create a standard and consistentapproach, and reduces the potential for disagreementbetween stakeholders with respect to the acceptability ofproposed new CODES are now complete and were publishedin early paper describes the guidance given in the newcodes in relation to prediction of PIPELINE failure frequency,consequence modelling, application of risk criteria andimplementation of risk mitigation, and summarises theassessment examples United Kingdom Onshore PIPELINE OperatorsAssociation (UKOPA) was founded in 1997 to represent theviews and interests of UK PIPELINE operators responsible formajor accident hazard pipelines (MAHPs) regarding safety,legislative compliance and best practice. Its membersinclude:- BP, BPA, Centrica Storage, Eon, ExxonMobil,National Grid, Northern Gas Networks, OPA, SabicEurope, Scotia Gas Networks, Shell, Total, Unipen, andWales & West strategic aim of UKOPA has been to achieve agree-ment with all stakeholders in PIPELINE quantitative riskassessment (QRA) methodologies, and the inputs andassumptions applied in the ASSESSMENT , so that consistencyin decisions on land use planning can be AND OPERATION OFHAZARDOUS PIPELINESP ipelines are designed, built, operated and managed inaccordance with the goal-setting PIPELINE Safety Regu-lations 1996 (PSR 96) [HMSO, SI 825, 1996] which setout duties to ensure that risk levels from pipelines are aslow as reasonably practicable (ALARP).

5 The guidance tothese regulations states that British Standards provide asound basis for the design of pipelines, but other nationalor international standards or CODES are acceptable providedthat they give an equivalent level of the 1960s, before the discovery of North Sea gasand subsequent development of long distance gas trans-mission pipelines, UK PIPELINE CODES [Institution of GasEngineers, 2001, British Standards Institution, 2004] weresimple interpretations of American ASME B31 codesbased on North American they were subsequently updated to accom-modate a higher level of land development and higherSYMPOSIUM SERIES NO. 155 Hazards XXI#2009 IChemE308population densities. This led to changes to these CODES ,including material properties, fracture propagation and theneed for high-level pre-commissioning addition, the concept and use of a building proxi-mity distance (BPD) was adopted for the gas codeIGE/TD/1 [Institution of Gas Engineers, 2001], this beingthe minimum separation distance between occupiedbuildings and the PIPELINE , used when the PIPELINE route isfirst selected.

6 The BPD is calculated from the pressureand diameter of a PIPELINE , and presented as charts in theexisting non-natural gas pipelines, the British StandardBS 8010 was developed in the 1980s, and high hazard sub-stances such as hydrogen, LPG and ethylene (and includingnatural gas) were labelled Category E substances. Thesesubstances have a Minimum Distance to Occupied Build-ings (MDOB) specified based on substance factors givenin the code . BS EN 14161 (based on European CODES ) super-seded BS 8010 which was withdrawn in 2004, and the Pub-lished Document PD 8010 [British Standards Institution,2004] was published by BSI in its are long-life assets located on 3rd partyland and changes in land use adjacent to the PIPELINE arelikely to occur over time which can result in increases inpopulation density and buildings constructed in close proxi-mity to the PIPELINE ( within the BPD).

7 This can result inthe PIPELINE becoming non-compliant with the original CODES therefore require the PIPELINE operator toassess changes along the route to identify situations wherethe PIPELINE no longer complies with the code routing anddesign requirements, and may pose unacceptable risks tothe population. In such cases, QRA is usually applied toassess whether the risk is risk levels are considered to be unacceptable,risk mitigation measures may be applied to avoid down-rating the PIPELINE operating pressure. Mitigation measuresmay involve assessing the protection provided by the localdepth of cover, installing PIPELINE protection (concrete slab-bing with marker tape), relaying the section of PIPELINE inthicker wall and so reducing the BPD, or diversion of thepipeline away from the populated area.

8 QRA is used toassess the effectiveness of mitigation and to select themost appropriate measure in a specific situation. Guidancein the new CODES aims to ensure consistent ASSESSMENT ofrisk mitigation measures in terms of the risk LAND USE PLANNINGLand use planning (LUP) is a multi-disciplinary processwhich is used to order and regulate the use of land in anefficient and ethical way, for the benefit of the wider popu-lation, economy and protection of the environment. Theprocess involves several factors such as selection of physicallayout, scale of the development, aesthetics, landscape,economics, and in particular, public safety and environ-mental Control of Industrial Major Hazard (CIMAH)Regulations 1984 established a Consultation Zone around major hazard sites within which Local PlanningAuthorities were required to seek the advice of the Health &Safety Executive (HSE) concerning new authorities were not obliged to follow thisadvice, but the HSE had the right to call in the planningapplication so that it would be considered by an independentplanning inspector, and a public inquiry.

9 Zones were appliedto fixed sites during the mid-1980s, and this was extended tohazardous pipelines in the late 1980s. The consultation zoneis currently defined in 3 levels:.the inner zone (IZ), which is immediately adjacent to thepipeline, equivalent to an individual risk level of1025per middle zone (MZ), which applies to significantdevelopments, equivalent to an individual risk level of1026per year, outer zone (OZ), also known as the ConsultationDistance (CD), equivalent to an individual risk levelof 3 1027per year, which applies to vulnerable orvery large zones are shown diagrammatically for apipeline in Figure ADVICE FOR DEVELOPMENTS NEARHAZARDOUS INSTALLATIONSO riginally HSE guidance for developments inside the landuse planning zones resulted in many marginal planningdevelopments being referred back to the HSE for detailedassessment.

10 Subsequently HSE produced an improveddecision matrix and guidance document called PlanningAdvice for Developments near Hazardous Installations(PADHI) [Health and Safety Executive, 2004].Figure distance and zonesSYMPOSIUM SERIES NO. 155 Hazards XXI#2009 IChemE309 The planning authority will usually refuse planningpermission for a new development if PADHI indicates thatthe risks posed by the hazardous PIPELINE are too high, andonly in a few cases will the development be referred tothe HSE for a more detailed site-specific PADHI process uses risk-based inner, middle andouter zones combined with the sensitivity level of the devel-opment which is proposed, to assess the acceptability of thedevelopment with respect to the PIPELINE risk. The zones arecalculated by the HSE using PIPELINE details notified by theoperators of major accident hazard pipelines as required byPSR 96.