In previous articles we discussed earthquake protection for fire protection systems. We now turn the discussion from maintaining the ability to control a fire to lowering the chances of a fire or explosion occurring after an earthquake.
In general, if equipment having flammable material or is a potential ignition source needs to be braced and/or anchored. The piping that transports flammable material should be provided with proper hanging, bracing, clearance and flexibility; the movement of the flammable material through the piping also needs to be stopped during the earthquake.
The common ignition sources at your site could include electrical equipment; equipment with hot surfaces, open flames or containing molten materials; and process equipment where hazardous chemical interactions could result in potential fire. Anchorage is needed to prevent the release of these sources.
Equipment Holding Fuel
Seismic restraint is needed to ensure the equipment remains stable, even for equipment that is not considered critical to operations; the fuel is the concern here, not the equipment.
Restraint Method for Equipment
The restraint for equipment may need to prevent sliding, uplift, overturning, rotation or swaying. Avoid using friction alone as the method or restraint. The restraint system equipment can be to the floor or to the roof system, but not both; differential movement between floor and roof may cause the release of the ignition or fuel source.
The amount of seismic load to design against should be at least 50% of the weight of equipment and its contents. The local building codes may prescribe a higher percentage
Gas cylinders need to be restrained near their tops and bottoms with little clearance. If restrained inside a cabinet, the cabinet needs to be restrained in the same manner as the equipment.
For flammable liquid cabinets, the cabinet itself should be restrained just as the equipment, keeping in mind that the operations of doors and vents need to be maintained. The cabinets should be kept closed and latched to prevent the contents from escaping.
Dispensing drums should be restrained. If the drum is on a support, saddle or platform, the drum needs to be restrained to the system and the system itself restrained.
A shutoff valve, automatically actuated, should be provided to shut off fuel gas sources for each building. The valve should be outside, downstream of the regulator and accessible. Package valve systems normally have their own sensing equipment and are limited to about 60-psi system pressure. Higher-pressure systems should use safety shutoff valves actuated by seismic switches or seismically actuated pneumatic valves.
Emergency shutoff valves are needed and should be provided on the supply side of flammable liquid piping systems, where the liquid has a flash point below 100°F or where the liquid is heated to its flash point for process purposes or by ambient conditions. Seismic switches should actuate these valves.
Welding piping should be used in place of fittings and couplings. The ends of the pipe should have vertical restraint. Maintain at least 1 ft. clearance from unrestrained pipe and equipment, or restrain the exposing pipe/equipment. Piping resting on structural members or trapeze hangers need to be restrained. Avoid using hangers using C-clamps, or provide retaining straps for the clamps.
Sway bracing, clearance and flexibility are needed on the piping. The guidelines for their location and strength are fairly similar to the guidelines used for sprinkler piping, though the pipe diameter comes more into play.
Test, inspect, repair and replace the restraint and shutoff systems at about a five-year frequency to ensure you are prepared for fire after an earthquake.
Instill procedures to incorporate the above items for new equipment and processes, and when existing equipment and/or processes change.
Do post-earthquake inspections on equipment, storage and piping to check for safe operation when. This includes clean up of spills, repair of any leaks, inspection of ignition sources, and ensuring that all fire protection systems are operational.
All inspections and recommendations are purely advisory and intended for the use to assist our clients in loss prevention and property conservation procedures. Comments and recommendations are the result of conditions and practices observed and information made available to us at the time of our visit or review. We do not purport to refer to or guarantee full compliance with local, state or federal regulations, which may be applicable to such practices and conditions. Also inspections, reports and recommendations do not signify or imply that other hazards or deficiencies do not exist. No responsibility for your implementation, management and operation of loss prevention and property conservation procedures is assumed. No liability shall be assumed by virtue of any inspection, report or recommendation review letter.