Process Plant and Pipeline Risk Analysis

Risk Analysis

Risk Analysis involves hazard identification, hazard evaluation, the development of potential risk reducing measures, and the communication of risk information to decision makers.

Risk analysis typically involves the following key steps:

• Hazard identification (HAZID)
• Frequency analysis
• Consequence analysis
• Quantification of risks using output from frequency and consequence analysis
• Investigation of potential risk reducing measures
• Development of recommendations

In a complex project, the analysis cycle from HAZID through to recommendations is performed repeatedly, until it is demonstrated that all hazards have been identified and all associated risks reduced to a level which is as low as is reasonably practicable.

In design projects, it is preferable that risk analysis proceeds in conjunction with design activities. At the feasibility or concept selection stage, the risk analysis should be high-level. Risk analysis at this early stage can assist in the selection of the optimum design concept. In the later design phases, the risk analysis should be developed in line with design progression to provide ongoing feedback to the designers, so that every aspect can be optimized.

In construction, risk analysis can be used to quantify the risks associated with hazardous procedures and to develop recommendations.

Risk analysis techniques are applied not only to risks to people and the environment but also to business risks. Risk analysis is particularly helpful when there is a balance to be struck between conflicting objectives, i.e. when the right solution is not immediately obvious. As well as assisting the decision-making process, risk analysis can also help demonstrate to third parties that correct decisions have been made.

Risk Analysis Tools

EPCONSULT's risk analysis tools include a comprehensive suite of in-house models for calculating event frequencies and consequences for all hazards normally encountered in the oil and gas and petrochemical industries. These hazards include material and construction defects, environmental loading effects (including earthquake, landslide and fault movement), third party interference, operating errors, fire and explosion etc. For hydrocarbon leaks, models are available for the calculation of release rates, dispersion, toxicity and fire and explosion characteristics. The effects of fire and explosion upon structures and the consequences for people can be analyzed. Evacuation processes and systems can also be modeled.

EPCONSULT's risk assessment models have been programmed in-house variously in Mathcad, Mathematica, Delphi and C++. Commercial software is also used when appropriate, for example, commercial computational fluid dynamics (CFD) programs are used for analysis of complex gas dispersion and explosion problems.

General purpose analytical approaches include:

• Failure modes, effects and criticality analysis (FMEA / FMECA)
• Fault tree analysis
• Event tree analysis
• Monte Carlo simulation

Specialized Types of Risk Analysis

Hazard analysis plays a central role in the risk management process for oil and gas industry facilities such as pipelines, platforms, floating production facilities and terminals. While some hazards can be addressed simply, others require specialized investigations as outlined below.

Offshore Platforms and Floating Facilities

Since the Piper Alpha disaster in 1988, a wide range of specialized types of risk analysis has come into use for assessment of the different aspects of the hazards associated with fixed platforms and floaters. These studies include the following:

• Concept safety evaluation, often to compare different design options
• Fire and explosion risk analysis
• Evacuation, escape, rescue analysis
• Vulnerability analysis of emergency systems
• Ship/platform collision studies
• Dropped object studies
• Dispersion, toxicity and smoke ingress analysis
• Explosion overprotection prediction
• Fire loading analysis of structures and determination of optimized fire protection arrangements
• Emergency readiness analysis
• Temporary refuge impairment study
• Quantitative risk analysis (QRA), which is often a summation of all the preceding studies into a determination of the individual and societal risks, considering all sources of risk

EPCONSULT has extensive experience in conducting all of the above-listed studies. Some of our personnel were involved in developing the methodologies for such studies in the years immediately after the Piper Alpha disaster.

Offshore Pipelines, Risers and Subsea Facilities

Risk analysis for offshore pipelines, risers and subsea facilities normally focuses on the operational phase and on the following aspects:

• Geohazards, such as fault movements, slope instabilities, debris flows, turbidity currents, mudflows and volcanic eruptions
• Marine hazards such as sinking ships, objects dropped from ships, ship anchors and ship stranding
• Trawling hazards
• Internal and external corrosion
• Riser hazards such as ship collision, fatigue, splash zone corrosion, loss of support and dropped objects
• Any other applicable hazards such as military activities, dumping and dredging, spanning, crossings and operational error

The analysis normally quantifies the likelihood of occurrence of various categories of damage and makes recommendations for the measures necessary to reduce the associated risks to as low as is reasonably practicable.

Risk analysis may also be applied to the construction, testing and commissioning phases to evaluate particularly complex or hazardous procedures and to develop recommendations for the appropriate risk reducing measures.

EPCONSULT has conducted many studies for offshore pipelines and subsea facilities, including large and deepwater projects, as well as those in highly seismic and unstable terrain.

Onshore Pipelines

EPCONSULT is experienced in risk analysis for onshore pipelines, which normally focuses on:

• Quantification of leak and rupture probabilities considering all applicable hazards including third party interference, corrosion, subsidence and landslide, seismic hazards, road and river crossings
• Estimation of ignition probabilities
• Modeling of dispersion
• Modeling of fire, explosion and/or toxic effects (as applicable) to predict numbers of casualties
• Combining outputs from the frequency and consequence analyzes into individual and societal measures of risk
• Investigation of potential risk reducing measures and development of recommendations

Refineries, Chemical Plants, Terminals and Onshore Oil/Gas Plants

EPCONSULT has strong experience in risk assessment for refineries, chemical plants, terminals and onshore oil/gas plants and well clusters.

For onshore facilities handling highly hazardous chemicals, special legislation may apply such as COMAH in the UK, the "Seveso II" Directive (96/82/EC) across the EC and 29 CFR 1910.119 in the USA. These regulations came into place following the disasters at Flixborough and Seveso. They impose requirements for effective process safety management systems, risk assessments, and internal and external emergency plans. EPCONSULT can help clients to develop the safety systems and emergency plans for regulatory compliance as well as by conducting the required Quantitative Risk Assessments (QRA's).

The QRA activities for onshore facilities typically include:

• Conceptual risk evaluation to compare different design options (for new projects)
• Hazard identification studies
• Definition of plant operational areas, isolatable sections and failure events to be modeled
• Flammable and toxic gas dispersion analysis
• Fire and explosion consequence analysis, including escalations (BLEVE's, blowouts, tank fires etc)
• Frequency analysis
• Combination of frequencies and consequences in event trees
• Calculation of risk measures – for individual risk, societal risk, environmental risk and business risk
• Identification and evaluation of risk reducing measures
• ALARP demonstration

LNG Projects

EPCONSULT has been actively involved in LNG projects. The work has included code compliance checking, consequence modeling and risk assessment. The code compliance checking closely examines the design of the LNG facilities against applicable codes, which may include:

• 49 CFR 193
• NFPA 59A
• EN 1473
• CSA Z276
• AS 3961

NFPA, API, EN and other codes require or recommend the use of consequence modeling to verify the safety of LNG and LPG facilities siting, building locations, and location and height of the flare. Consequence modeling may also be needed to investigate the consequences of a potential incident to achieve optimal design/layout of the facility.

EPCONSULT has a full suite of in-house software to perform consequence modeling:

• Vapor dispersion modeling
• Fire radiation modeling
• Explosion modeling

Risk assessment involves the review of each process and system in the facility to identify all potential hazardous events, assess the likelihood and consequences of these hazardous events, and determine appropriate risk reduction measures.

Please contact us to request further details of our risk analysis services