Successful Process Safety Management Requires a Barrier Risk Assessment Tool

TASA ID: 20277


The expected outcome of Process Safety Management (PSM) is to minimize the likelihood of a major accident occurring and to ensure that the necessary mitigation and emergency preparedness mechanisms are in place in the event that an accident does happen. PSM programs are designed to establish comprehensive, robust and sustainable systems, practices and competencies for managing process safety and to ensure that a focus on process safety (low frequency-high consequence) issues is maintained. This paper describes in detail how a Barrier/BowTie approach to PSM is established within the framework of an established PSM program and provides the missing link in assurance of process safety. The barrier approach not only enhances process safety but ensures that the processes in place are functioning as expected. A case study example is used to illustrate how continuous improvement is achieved and maintained.

1 Introduction

Over the past 15-20 years, the occupational safety trend has been steadily improving. However, insurance loss claims for process safety incidents have not declined and are, in fact, slightly rising. Many companies focus on impressive occupational safety records as a sign of a good if not great safety performance and overlook low-frequency process vulnerabilities.

1.1 Case Study: Occupational Safety Focus, Process Safety Problem

Misplaced safety focus was evidenced in 1989, when the chemical plant of an unnamed major international Oil company exploded killing 23 and injuring over 100. In response, the plant manager stated that he couldn’t understand how this disaster happened and cited a record number of years of operation without a lost time accident. 

OSHA's investigation found several major contributors:

• lack of process hazard analysis
• inadequate standard operating procedures (SOPs)
• use of non-fail-safe block valve
• inadequate maintenance permitting system
• inadequate lockout/tagout procedures
• lack of combustible gas detection and alarm system
• presence of ignition sources
• inadequate ventilation systems for nearby buildings
• failure to maintain fire protection system in an adequate state of readiness
• proximity of high-occupancy structures (control rooms) to hazardous operations;
• inadequate separation between buildings; crowded process equipment;
• insufficient separation between the reactors and the control room for emergency shutdown procedures

1.2 Shifting Safety Focus

Is there a direct linkage with these failures and a good occupational safety program? Innovations in the past few decades have attempted to shift focus from narrowly defined occupational safety statistics to more systemic causes and have resulted in many enhancements to occupational safety and, to a lesser extent, process safety. Starting in the late 1980’s Safety Management Systems (SMS) were introduced to the oil/gas majors who, in turn, mandated widespread industry use. In the early 1990’s with the advent of tools such as QRAs, HAZOPs, and HAZIDs, risk management techniques began being applied. During the mid-1990’s companies started experimenting with behavioral-based safety programs to influence “Safety Culture”.

Still, recent studies have shown that while occupational health incidents have declined steadily, in many cases by as much as 80%, process safety incidents have not declined. Many of the investigation findings from incidents in 1989 are addressed directly by OSHA PSM regulations and requirements, but process safety management (PSM) measures have noticeable impacts on a company’s facilities only when fully developed programs ensure that PSM controls/barriers are robust and healthy. OSHA PSM regulations do allow alternative suitable methods for PHAs. During the design stage, it is appropriate to use a line by line approach, e.g., HAZOP or What-If etc. During later operational phases, a risk-based approach like BowTie is a more powerful tool. The Barrier/BowTie approach is designed to ensure the health of controls/barriers in a way that is simply and clearly communicated.

To read the full paper, download below. 

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Tasa ID20277

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