Improved integration of LOPA with HAZOP analyses

Abstract

Integrating Layer of Protection Analysis (LOPA) with Hazard and Operability Analysis (HAZOP) has many advantages over performing these studies separately. The merits include: fewer actions from the combined effort compared to performing only a HAZOP; team continuity resulting from the combined effort as opposed to two separate teams having possibly differing points of view; and, ultimately, a time and cost savings realized by the combination. This integration defines the risk associated with a given scenario, enabling better decisions that impact business assurance. By using the Center for Chemical Process Safety guidelines to define the independent protection layers upfront, the gray areas can often be reduced or eliminated; thereby enabling a more thorough LOPA. Examples include taking credit if a unit has two independent operators (outside and inside) responding to critical alarms, or taking credit for centralized control rooms that may allow immediate operator interaction and response. This article shows how the guidelines have been used successfully in joint HAZOP/LOPA studies, and describes an initial preparation protocol that can ensure high‐quality results. © 2009 American Institute of Chemical Engineers Process Saf Prog, 2009

Sand casting safety assessment for foundry enterprises: fault tree analysis, Heinrich accident triangle, HAZOP–LOPA, bow tie model

“…The sand casting explosion accident frequency can then be determined based on the Heinrich accident triangle [ 25 – 27 ]. Next, the risk level of a sand casting explosion accident can be reduced by HAZOP–LOPA [ 20 – 22 ] and bow tie analysis [ 28 – 30 ]. Corresponding safety measures can be adopted based on this information to safeguard the foundry enterprise production process.…”

“…HAZOP–LOPA reveals any deviations in system process parameters which may result in an accident; it allows the user to define causes, risk levels and consequences to prevent accidents via independent protective layers [ 20 – 22 ].…”

“…Low venting quality can lead to cavity exhaust blockage. Therefore, we ran a HAZOP -LOPA [20][21][22] on venting quality in an effort to reduce the risk of explosions as shown in table 5.…”

“…Other methods must be introduced to conduct an in-depth analysis of the causes of an explosion and eliminate any hidden dangers in operations. To determine which safety measures most effectively control critical safety hazards, hazard and operability–layer of protection analysis (HAZOP–LOPA) can be used to determine process parameters in the system that are most closely related to accidents; HAZOP–LOPA can also be used to define the causes, risk levels and consequences of accidents as identified by independent protective layers [ 20 – 22 ]. HAZOP–LOPA has been applied for safety assessment in various systems [ 23 , 24 ].…”

Using the ISA 84/HAZOP/LOPA procedure to design a safety instrumented system for a fumed silica burner

“…Although there are many steps to assure the mechanical integrity life cycle of an SIS [5–8], the steps focused on in this article include performing a HAZOP with software that automatically generates LOPA spreadsheets, populating the LOPA spreadsheets for each risk scenario, comparing these results to the corporate risk matrix, and then designing an SIS/SIL (Safety Integrity Level) system to bridge any risk‐related gaps. Recent articles note that combining (“integrating”) a LOPA with the HAZOP Team effort helps save time and ensures decision‐making objectivity [9–11]. The Team for this project overcame a “roadblock” when they identified the need for and subsequently located a Certified Functional Safety Expert (C.F.S.E.)…”