Process Safety Fundamentals: DSEAR Risk Assessments and Process Hazard Analysis

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Process safety involves the identification, assessment, and mitigation of risks associated with industrial processes to prevent major accident hazards, injuries, and environmental harm. It focuses on the design, operation, and maintenance of facilities to ensure the safe handling of a potentially dangerous substance or hazardous chemicals in order to eleminate risks and catastrophic incidents in the workplace.

In this short article, we will explore the differences and similarities between the UK’s Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) and another process safety tool, the Process Hazard Analysis (PHA), in order to provide some guidance on how to choose the best consulting solution for your organisation.

What is DSEAR?

DSEAR is the UK’s Dangerous Substances and Explosive Atmospheres Regulations 2002. These regulations apply to any workplace where dangerous substances, such as flammable gases, liquids, combustible dusts, pressurised gases, or corrosive materials, are handled, stored, or processed.

DSEAR Requirements

This set of potentially explosive atmospheres regulations require employers to:

  • find out what dangerous substances are in your workplace, assess the risks of fire & explosions from dangerous substances, and take mitigation measures to eliminate or reduce them.
  • determine the likelihood of an explosive atmosphere forming and the size of the zonal extents to define the Hazardous area classification (HAC). The HAC should have appropriate equipment and protective systems selected to be suitable and free of ignition sources.
  • ensure that employees are properly informed and trained to control or deal with the risks from dangerous substances.
  • create and implement clear emergency plans and procedures to deal with accidents, incidents, and emergencies involving dangerous substances.

It must be remembered that a DSEAR risk assessment must be carried out by a competent person. This is a person with good knowledge of DSEAR regulations as well as explosive substances and atmospheres.

Useful DSEAR & Guidance and Industry Specific Resources:

  • Health and Safety Executive (HSE) website provides guidance on how to comply with the DSEAR regulations, including an Approved Code of Practice and guidance (ACOP), leaflets, case studies, and FAQs.
  • The British Standards Institution 60079 provides guidance on, HAC for flammable vapour and dust in part 10 and Electrostatic hazards in part 32.
  • The Energy Institute’s EI 15 provides guidance on HAC for installations handling flammable liquids.
  • The Institution of Gas Engineers and Managers’ (IGEM) SR/25 provides guidance on HAC of Natural Gas installations.
  • The UKLPG Code of Practice provides guidance on HAC for Bulk Liquid Petroleum Gas (LPG) Storage.

What is a Process Hazard Analysis (PHA)?

Process Hazard Analysis is a systematic method of identifying, evaluating, and controlling the potential causes and consequences of process-related incidents. PHA involves a specialised multidisciplinary team who uses various techniques to identify and evaluate the possible scenarios that could lead to a loss of containment, ignition, or escalation of a hazardous event. 

When to conduct PHA?

  • During the design and construction phase, to ensure that the process is inherently safe and complies with the relevant codes and standards.
  • Before the start-up or commissioning phase, to verify that the process is ready for operation and that the operating procedures and emergency plans are in place.
  • Periodically during the operation phase, to review the performance and effectiveness of the existing safeguards and to account for any changes or modifications that may have occurred.
  • After any major incident or near-miss, to investigate the root causes, lessons learned and to implement the necessary corrective actions.
  • Functional safety systems compliance with IEC 61508 & IEC 61511 standards.

PHA Requirements

Successful PHA requires commitment from leadership to allocate resources to conduct PHAs and support recommendations. Here are typical resources needed:

  • Facilitator to chair the meeting, a scribe to write meeting minutes, and knowledgeable personnel involved in operations, design, and maintenance.
  • Availability and quality of reliable, accurate data and assumptions on, Process Description, Process Flow Diagrams (PFD), Process & Instrumentation Diagrams (P&ID), Site Layout Drawings, Equipment Info, Materials of Construction, Standard Operating Procedures (SOP), Maintenance History, Reliability Data, Incident & Near Misses History, Safety Data Sheets (MSDS) and Industry Standards.

Types of PHA

There are many methods used to conduct hazard analysis and each has their own advantages and disadvantages.

Hazard identification methods include Hazard and Operability Study (HAZOP)Hazard Identification (HAZID), and What-if. HAZOP is the most structured and comprehensive method. HAZID is a high-level qualitative method for screening hazards in early design stages. The What-if method encourages creativity and allows flexibility to generate scenarios.

Semi & Fully Quantitative methods provide further analysis to support decision making.  Failure Modes and Effects Analysis (FMEA) ranks each failure mode within a system. Layers of Protection Analysis (LOPA) evaluates effectiveness of protection layers to control major accident consequences. Quantitative Risk Analysis (QRA) outputs a numerical measure such as the radiation from a fire event.

Post Hazard Identification methods such as Fault Tree Analysis (FTA), Event Tree Analysis (ETA) and Bowtie display analysis on safeguards in diagrams. FTA diagram shows combinations of failures to cause the scenario. ETA diagram shows worst-case paths of events. Bowtie integrates FTA & ETA displaying causes, consequences, and controls in a simple intuitive diagram.

Useful PHA & Guidance and Industry Specific Resources

  • The Institution of Chemical Engineers (IChemE) website provides information and resources on process safety, including publications, events, training, and networks on topics such as Process Hazard Analysis.
  • The United Kingdom Onshore Pipeline Operators’ Association UKOPA provides a guide to pipeline process safety studies and methodologies UKOPA/GPG/35 this includes safety studies details on HAZID, HAZOP, What-if, FMEA, LOPA, QRA, FTA, ETA, Bowties and more.
  • British Standards Institute (BSI) provides guidance on HAZOP (61882), FMEA (60812), FTA (61025),
  • Centre for Chemical Process Safety (CCPS), IGEM and EI also provide risk management techniques and methodologies.

DSEAR & PHA benefits

Hazard identification and evaluation helps an organisation understand the risk to their employees, the public, environment, and their business. Increased understanding of major risks helps organisations factor risk into decisions. This improves business performance and prevents or at least minimises the losses and damages from process safety incidents.

Enhancing the planning and making progress on recommendations from DSEAR and PHA assessments offer numerous benefits, including the potential to minimize or avoid penalties resulting from non-compliance. This is achieved by demonstrating that the risk is actively being managed As Low As Reasonably Practicable (ALARP).

Improving safety in the workplace boosts employee morale, particularly when they participate in a PHA, collaborating with other departments and contributing to the organisation’s efforts to eliminate risks.

DSEAR & PHA differences

DSEAR is a regulatory document where compliance is enforced by the Health and Safety Executive (HSE) or the local authorities, depending on the type of workplace. Failure to comply with DSEAR can result in prosecution, fines, or imprisonment.

PHA is a risk assessment tool that is not a direct UK legal requirement. However, conducting PHA is a form of risk assessment in the workplace to ensure UK legal compliance with Management of Health and Safety at Work Regulations 1999.

DSEAR assessments are carried out by a person with specialist knowledge (competent person) whereas PHA are typically completed by a multi-disciplinary team. The goal of DSEAR is to protect people from dangerous substances, whereas, the goal of a PHA can be set to protect the environment and businesses too.

DSEAR and PHA: effective integration

DSEAR and PHA both aim to protect workers and the public from hazardous releases, but they have different scopes, requirements, and benefits. There are clear overlaps such as identifying hazards, likelihoods, severity, and recommendations i.e., control measures. They can both be integrated effectively to achieve a high level of process safety and regulatory compliance.

Organisations who receive DSEAR assessment reports not only satisfy some legal requirements, but they also provide process information to support the completion of a successful PHA. It is advisable to engage the same process safety consultancy firm for both a PHA and DSEAR assessment. This approach allows the consultant, already acquainted with the site processes, to streamline the learning curve and expedite the process.

At the design phase, requesting a PHA to be completed can help anticipate DSEAR risks and design processes to be DSEAR compliant. A DSEAR assessment during the design phase can determine HAC to ensure appropriate equipment are budgeted and selected. This prevents the costly consequence from over-zoning and making changes post design stages.

PHA might encompass a thorough assessment of risk through rigorous quantification and the evaluation of safeguard effectiveness. This can assist DSEAR assessors in minimizing the zonal extent if the assessed risk safeguards effectively reduce the potential for a flammable atmosphere.

The most effective DSEAR and PHA integration is through Process Safety Management System implementation where resources for audit, gap analysis, improvement plan and communication paths can be shared to avoid completing similar tasks separately.

Sigma-HSE Solutions

DSEAR solutions include Hazardous area classification, providing a basis of safety and HAC drawings following on-site or online Desktop site visits. Sigma-HSE can also provide bespoke QRA for modelling flammable atmosphere zonal extents to support minimising zones so far as reasonably practicable. FRurthermore, Sigma-HSE can also provide consultancy solutions including DSEAR training, policy, procedure, gap analysis and management support.

As for Process Hazard Analysis our most popular solutions are HAZID and HAZOP on-site facilitation. Sigma-HSE can provide bespoke PHA including QRA to complete consequence modelling using Process Safety risk assessment tools such as PHAST for fire, explosion, and toxic dispersion modelling. In addition, we provide other PHA techniques such as FMEA, LOPA, FTA, ETA, and BOWTIE analysis.

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