Maintenance explosion incidents

Centrifugal pumps serve the industries well, but can be involved in accidents even if they are correctly sized and specified, made of the correct materials, and properly installed. Three pump incidents follow. This first case history involves an explosive incident that occurred during maintenance to remove a defective pump. Incidents two and three occurred during operations. 

Louisville, Kenmcky, USA, Chemical Manufacturing Plant, Explosion and Fire A large explosion at a chemical plant killed two workers and injured two others, resulted from a failure by the company to investigate similar but smaller explosive incidents over many years while deferring crucial maintenance of the large elearic arc furnace that exploded. 

A similar incident occurred on a solids drier. Before maintenance started, the end cover was removed, and the inlet line was disconnected. When maintenance was complete, the end cover was replaced, and at the same time the inlet pipe was reconnected. The final job was to cut off the guide pins on the cover with a cutting disc. The atmosphere outside (but not inside) the drier was tested, and no flammable gas was detected. While cutting was in progress, an explosion occurred in the drier. Some solvent had leaked into the inlet pipe and then drained into the drier [19]. 

Testing, of course, must be thorough. The following incident is described in the form of a conversation between an inspector investigating a boiler explosion and the maintenance foreman [12]. 

The Chemical Process Industry (CPI) uses various quantitative and qualitative techniques to assess the reliability and risk of process equipment, process systems, and chemical manufacturing operations. These techniques identify the interactions of equipment, systems, and persons that have potentially undesirable consequences. In the case of reliability analyses, the undesirable consequences (e.g., plant shutdown, excessive downtime, or production of off-specification product) are those incidents which reduce system profitability through loss of production and increased maintenance costs. In the case of risk analyses, the primary concerns are human injuries, environmental impacts, and system damage caused by occurrence of fires, explosions, toxic material releases, and related hazards. Quantification of risk in terms of the severity of the consequences and the likelihood of occurrence provides the manager of the system with an important decisionmaking tool. By using the results of a quantitative risk analysis, we are better able to answer such questions as, Which of several candidate systems poses the least risk Are risk reduction modifications necessary and What modifications would be most effective in reducing risk ... 

Two incidents of pump explosions in chemical plants are reported, both occasioned by nitric acid reaching parts of a pump it should not and there corroding metal or contacting electrics. Proper pump selection, installation and maintenance would have avoided these incidents. 

Thirteen of the twenty-seven major refinery incidents reported from 1980 to 1995 in the large property damage report were piping failures. Six of twenty-four major petrochemical plant major incidents were the result of tube or piping failures or improper maintenance procedures involving valves. Recent examples of piping failures which resulted in massive fires or explosions follow. 

The munition route following the unpack area is the Explosive Containment Cubicle (ECC) containing four different demilitarization machines which will be remotely operated. Operation within the ECC will be followed by closed circuit television surveillance. Since there is a chance of an explosive fire incident, the ECC is designed for explosive and agent containment. Each step in demilitarization of munitions is controlled by a computer which also stops the operations within the ECC when a problem develops or equipment maintenance is needed. 

Though there do not seem to be any generally available technical reports, there are genuine stories of explosions and burn accidents caused by the inadvertent formation and subsequent decomposition of hydrates of hydrocarbons in railway tank cars in the cold climate of Canada. Incidents occurred due to the practice of washing empty tank carr following their use for transporting liquid hydrocarbons. In a cold winter climate, it is possible to form hydrates with small amounts of hydrocarbon residues, which later decompose when the tank car warms up, e.g., when exposed to sunshine. For example, the clathrate hydrate of isobutene (2-methyl-propene, b.p. -6.9" C) needs only 1.12 bar at 273 K to be stable. Precautions were not taken around such nominally clean and empty tankers, and exposure to sparks or naked flames led to flash fires and explosions. While the main content of the tankers was butane, other hydrocarbons were present. In another kind of industrial accident, a worker was killed by H2S gas liberated from H2S hydrate residue in a heavy water production plant, during a shutdown for maintenance. 

On April 2, 2010, an explosion and fire at the Tesoro refinery in Anacortes, WA, killed seven workers. The incident occurred when a heat exchanger suddenly ruptured during maintenance, releasing a highly hazardous chemical that subsequently exploded. 

For an existing facility it is necessary to review all corrosion, explosion, fire incident, breakdown, equipment/control failure, and maintenance issues. 

Already from Clause 3.2.5 it is known how major accidents/incidents are defined. It is now wise to consider some commonly used guided words in HAZID Unignited hydrocarbon (HC) released Hydrocarbon (HC) released—fire HC released—explosion Toxic exposure High pressure High/low temperature Corrosion Object dropping Improper access/escape Radiation Maintenance Construction/startup Explosives Electrical Mechanical Stmctural Effluent disposal Biological and others... 

If an incident such as an explosion did occur because of lack of maintenance of gas protection measures in a commercial or similar building, then it is likely that the owner and/or operator would be prosecuted under Health and Safety legislation. A similar scenario would be where the owner of a gas barrier did not maintain it and this caused gas migration to another site and resulted in an incident such as an explosion. 

In 2012, there were 88 fatalities (80 onshore and 8 offshore) that occurred in 52 separate incidents. The activity with the highest fatalities was "maintenance, inspection, and testing," in which 41 fatalities occurred in nine separate incidents. These incidents included a gas leak and explosion following the loss of mechanical integrity of a pipeline in Mexico that resulted in 31 fatalities. The activity "construction, commissioning, and decommissioning" accounted for 14 fatalities. 

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