Process safety incidents occur in operations of all sizes and across the chemical process industries. One thing many process incidents have in common is that they involve a loss of primary containment (LOPC) event. Three past Process Safety Beacon columns demonstrate the ramifications of LOPC:
The January 2014 Beacon showed how corrosion can be a hidden cause of LOPC. In this case, extensive corrosion caused a 4-in. pipe containing liquid ammonia to leak. The quality of the pipe insulation was poor, allowing water to soak into the insulation. The piping system had been partially inspected during the previous turnaround, but this particular section of pipe was not examined. The insulation hid and promoted corrosion, which led to the LOPC incident.
The October 2021 Beacon analyzed an incident where poor isolation fatally injured two people. In this case, the hydrogen sulfide (H2S) alarm system and warning light at a waterflood station on an oil field failed to activate. An employee, who was performing maintenance on a pump at the waterflood station, isolated the pump by closing its discharge valve and partially closing its suction valve, but did not perform lockout/tagout. The pump automatically started, releasing water known to contain toxic H2S gas.
The release of hazardous material can also be caused by mixing incompatible materials. The May 2023 Beacon highlighted an incident where a truck driver connected the delivery hose from a sulfuric acid tank to a connection for a tank of sodium hypochlorite (bleach). The resulting chemical cloud contained chlorine and other compounds, impacting workers onsite and in the surrounding community. Poor labeling (Figure 1), a weak system to communicate the correct connection point, failure of the operator to verify the correct connection, and errors and inconsistencies in the unloading procedure all contributed to the incident.
▲Figure 1. Loss of primary containment (LOPC) is a common theme among process safety incidents in the chemical process industries, with many such incidents having been featured in past Process Safety Beacons. One example, highlighted in the May 2023 column, occurred when a delivery truck driver accidentally connected a tank of sulfuric acid to a tank of sodium hypochlorite, which created a chemical cloud that injured operators and nearby residents. Poor labeling, insufficient communication, weak understanding of process hazards, and inconsistent procedures all led to the LOPC.
Did You Know?
- LOPC is an unplanned or uncontrolled release of material from primary containment.
- LOPC events often have warning signs, such as severe corrosion or terminal valves in hazardous service that are uncapped or unplugged.
- LOPC can be caused by many factors, such as vehicle strikes, mechanical damage, vibration, incorrect operation, incompatible materials of construction, and temperature or pressure changes, among others.
- Damaged insulation allows water into the insulation and can cause corrosion to pipes and vessels.
What Can You Do?
- While making rounds, watch for leaks and promptly report them.
- Place barricades around leaks until the leaking material is identified and the leak is stopped.
- Report missing or damaged insulation.
- Point out leaks that occur in the same place or with the same material. They may indicate a weak point in the system or a bigger problem.
- Share LOPC events during process hazard analyses (PHAs).
Prevent LOPC — keep hazardous materials in the right place.
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