Tanks mechanical integrity

The catalyst storage tank failed earlier than expected if the fireproofing insulation was in good condition and the relief valve was adequate for the fire case. Witnesses indicate that several sections of the insulation had either fallen off or heen removed from the tank 2-3 months ago. The insulation had not heen repaired. (Mechanical integrity)... 

Covers mechanical integrity programs for piping, pressure vessels, storage tanks, and process piping, including corrosion under insulation problems... 

Mechanical Integrity Programs for Piping, Pressure Vessels, Storage Tanks, and Process Piping... 

The mechanical integrity focus of this section covers stationary existing chemical processing plant equipment and piping. Equipment includes storage tanks, pressure vessels, dryers, heat exchangers, reactors, incinerators, columns, filters, knock-out pots, and so forth. As previously stated, this section assumes the equipment is designed and fabricated to... 

The intent of the mechanical integrity section of the OSHA Process Safety Law is to prevent or reduce catastrophic releases. [1] An equipment classification system is a requirement of the law. Earlier in the chapter, a simple system involving three classes was previously defined. Here are the highlights of that section specifically for pressure vessels and storage tanks. 

In 1984, one of the most notable process incidents occurred in Bhopal, India, at a plant owned by Union Carbide. On December 3, 1984, methyl isocyanate (MIC) was vented to the atmosphere from a vent gas scrubber after a run away reaction overwhelmed the scrubber. It is reported that more than 2500 people died and 20,000 people were injured as a result of exposure to MIC. The subsequent investigation showed that the run away reaction occurred in the MIC tanks after water was reportedly intentionally added to the tank. The safety systems, a pressure relief valve, a vent gas scrubber, and a flare were reportedly poorly maintained. The relief valve worked to vent the pressure, but the scrubber was overwhelmed, and the flare was down for maintenance. This incident highlighted several loss prevention areas that needed improvement. The first was mechanical integrity. No strong preventive maintenance effort appeared to be in place. The second was emergency preparedness and response. It appears that while the plant was built 1.5 miles away from the community, zoning problems allowed the community to expand to the plant limits. It does not appear that much effort was made to work with the community on commimication/notification or evacuation needs. ... 

Motiva did not have an adequate mechanical integrity management system to prevent and address safely and environmental hazards from the deterioration of H2SO4 storage tanks. 

Figure 12.14 A collapsed service company vacuum truck tank signals an inadequate mechanical integrity program.

For an historical view of mechanical integrity on tank btrilding and testing as well as poor facility siting, check out the websites reporting on the Boston Molasses Disaster of 1919. This legendary tragedy is steeped in folklore. 

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