Explosion pump failure

In a batch reaction plant, an exothermic reaction was cooled by water circulating in a jacket. The circulating pump failed and the reactor went out of control causing a violent explosion. A low flow alarm was present but was inoperable. A critical pump bearing had not been lubricated during maintenance, and the collapse of the bearing had led to the pump failure. 

Beaumont, TX, USA, Chemical Plant, Explosion/Fire Failure of pump expansion joint inlet. 

The explosion was due to a failure to directly measure the property that we wish to know. The temperature point was not measuring the temperature in the reactor but the temperature near the pump. This got hot because the pump was running with a closed suction valve. Similarly, the trip initiator on J2 showed that its motor was energized. It did not prove that there was a flow. 

At 2 20 A M., another explosion occurred, the BLEVE of sphere 407. Its fireball was less intense than the earlier one. The sphere s top section traveled 190 m (620 ft) and caused the destruction of a firewater tank and one of the plant s fire pumps. Other sections further damaged other units. The pressure relief valve of this sphere traveled 500 m (1600 ft). The damage from projectiles was much greater than that caused by the first sphere failure because they traveled farther and in more damaging directions. 

During the experimental large scale continuous polymerisation of acrylic acid in aqueous solution in presence of an initiator and a moderator, failure of one of the feed pumps led to an unusually high concentration of monomer in solution. This led to runaway polymerisation which burst a glass vent line and the escaping contents ignited and led to an explosion and fire. 

In a continuous operation to bleach a fat-derived acid, the latter was stirred and treated at 80°C with a slow stream of 50 wt% hydrogen peroxide. Un-noticed failure of the agitator led to peroxide build-up, layer formation and eventual formation of an explosive mixture. When this passed into a centrifugal pump, it detonated. 

Liquids under pressure (pipeline leaks, pump seal failures, etc.), will be thrown some distance from the point source, while atmospheric leakages will emit at the point of release. The other characteristic of liquid releases is their flash points. High flash point liquids, not operating above their flash point temperatures, are inherently safer than low flash point liquids. Most liquid fires are relatively easy to contain and suppress while gas fires are prone to explosion possibilities if extinguished and source points are not isolated. 

Normally where it is necessary, fireproofing is preferred over water spray for several reasons. The fireproofing is a passive inherent safety feature, while the water spray is a vulnerable active system that requires auxiliary control to be activated. Additionally the water spray relies on supplemental support systems that may be vulnerable to failures, i.e., pumps, distribution network, etc. The integrity of fireproofing systems is generally considered superior to explosion incidents compared to water spray piping systems. The typical application of water sprays in place of fireproofing is for vessel protection. 

Sometimes two other incidents are attributed to LNG The first one - a construction accident on Staten Island in 1973 - was cited as a LNG accident because work was carried out inside an empty LNG tank. The second - an electrical seal failure on a LNG pump that failed in 1979 - caused an explosion because gas (not LNG) entered an enclosed building. This event gave rise to a thorough revision of the code for electrical seals used with all flammable fluids underpressure [10],... 

More Flow Line fracture Pump seal failure Control fault Spillage (possible large explosion) Spillage (possible small explosion) Consider bypass... 

The primary causes for loss of containment of fluids are pipe or flange failure, pump seal failure, explosions, fires, overfilled tanks, over-pressured tanks, and overturned drums or containers. Because loss of containment creates serious situations, the early... 

In the present case, uncertainty about the failure rates of the pumps, block valves, check valves and relief valves is represented using the lognormal probability distributions defined in the probabilistic approach, whereas the possibihly distributions introduced in the possibihstic approach are used to represent the uncertainty about the failure rates for the explosive valves and the tank. 

Small towers sometimes are reinforced PVC, and there is no need for a lining. A potential problem with PVC or other nonconductive material is the accumulation of a static charge. The explosion of a set of three PVC dryers in a mercury-cell plant was attributed to static discharge in the presence of an explosive gas [27]. The root cause of the incident was the failure of the power supply to the mercury pumps, which allowed mercury to drain from the cells and uncover the steel bottoms. This led to the formation of large quantities of hydrogen. The investigators concluded that towers should be constructed of acid-proof conductive material that can be held at ground potential. 

If it can be proved beyond all doubt that effective ignition sources are expected only at rare operation disturbances and equipment failures, an explosion-resistant design and an installation of FA s is not required for these vacuum pumps. 

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