Venture’s Participation in Process Hazards Analyses

Hazard and operability studies (HAZOPs) originated with a critical examination process developed by ICI in the 1960s. The process was refined over time. In 1974, the disaster at the Royal Dutch Shell caprolactam manufacturing operation in Flixborough, England, led to broad acceptance of the HAZOP as a tool to identify hazards and operability problems. The Bhopal disaster in 1984, killing thousands through the release of methyl isocyanate, reinforced the importance of HAZOPing.

Related Regulations
In 1992, OSHA issued the Process Safety Management of Highly Hazardous Chemicals standard (29 CFR 1910.119), which contains requirements for the management of hazards associated with processes using highly hazardous chemicals. In 1996, EPA issued regulations requiring risk management and planning for designated substances. These regulations reinforce the need for HAZOPing, such as when process changes occur, and maintaining current planning documents.

Approach
HAZOPing occurs after the equipment list and the PIDs have been finalized. HAZOPing is typically conducted in a series of meetings, with a multidisciplinary team. Bringing various backgrounds together in a facilitated setting is conducive to creativity and the brainstorming process. The team explores specific points of the design (nodes) searching for deviations from the design intent. Lead by parameter guide words, the team walks through the process searching for deviations from the design intent and the potential for unexpected outcomes. Typically findings include: additional logic needs for the functional specifications, additional monitoring points, compatibility issues related to materials of construction and potential for contamination of feed stocks, intermediates and products.

Traps
It is tempting to find solutions for problems as they are uncovered. Staying focused on the goal of identifying hazards and operability problems is key. It is the facilitator’s responsibility to keep the HAZOP on mission. Issues uncovered by the HAZOP study are delegated and resolved outside of the HAZOP meeting. In some cases, the outcome will be no action required, but others will require further action.

A second important consideration is to minimize interruptions. Cell phones need to be off. Some companies rent facilities off-site to prevent interruptions. For this reason, when Venture facilitates a HAZOP, we recommend that we host the HAZOP in our conference room.

The Flixborough Disaster This incident was the result of a modification related to maintenance.  A temporary bypass line ruptured, releasing an estimated 40 tonnes cyclohexane.  The cloud found an ignition source and exploded. All eighteen people in the control room, plus another ten, died.  Thirty six people were injured on-site, and fifty three injuries were reported off-site.  Casualties would have been higher had the incident not occurred on a weekend, when the main office block was unoccupied.

The Flixborough Disaster
This incident was the result of a modification related to maintenance. A temporary bypass line ruptured, releasing an estimated 40 tonnes cyclohexane. The cloud found an ignition source and exploded. All eighteen people in the control room, plus another ten, died. Thirty six people were injured on-site, and fifty three injuries were reported off-site. Casualties would have been higher had the incident not occurred on a weekend, when the main office block was unoccupied.

The process can also get derailed by not allocating sufficient meeting time to fully evaluate all the deviations, consequences and safeguards pertaining to each identified process node. Rushing through a node without fully considering all deviations can lead to oversight of critical hazard or operability fault(s).

Follow through is also key. Delegation of tasks, tracking of progress, and verifying completion is necessary to realize the benefits of the HAZOP. One person needs to be appointed to this task. This is where the benefits of a HAZOPing software such as Dyadem’s PHA-Pro, become clear.

Conclusions
Today HAZOPing is recognized as a beneficial tool beyond just the industries required to use them. Recently, Venture facilitated or participated in HAZOP studies for three projects:

  • An 18 million gal/year biodiesel plant producing biodiesel from multiple feed stocks including soy oil and animal fat
  • A 1.5 MGD wastewater treatment plant for a steel mill, that included both Physical, chemical, and biological treatment processes
  • A 2.8MM landfill gas to high BTU gas plant

We also participate in Process Safety Reviews, Pre-Startup Safety Reviews, and other functions. As a multi-disciplinary company serving a variety of process industries, Venture stands ready to assistyou in meeting your HAZOPing needs.