09 - Loss of Utilities

Since public utility supplies, eg. gas, water, power, can be disrupted after a seismic event its important to design and maintain on-site utilities  to minimize disruption to production and maintain a safe working environment during and after the seismic event.

This is especially critical for industries where safety and integrity of equipment rely on continuous operation, eg. kilns, ovens. High-voltage facilities are particularly susceptible to seismic damage due to the size and nature of the equipment. Damage to pipelines and water tanks are also common problems. 

Hazards

  • Inadequate or missing anchorage of the transformers and tall equipment due their high center of gravity.
  • Insulators and the attached conductors are not designed for seismic forces. The connections of the insulators, which are tall equipment, require special considerations. The conductors attached to the insulators can swing during an earthquake and contact adjacent conductors or equipment causing a short-circuit.
  • Poorly anchored roof-mounted equipment and tanks. Displacement due to seismic motion, which is usually higher at roof level in buildings taller than 5 storeys, can result in damage to the equipment as well as the piping with secondary consequences, eg. water leakage.
  • Poor anchorage of tanks and equipment piping. Tall equipment or liquid containers are especially susceptible to damage if not properly anchored. Piping connected to such equipment, if not provided with flexible joints and suitable bracing, are also susceptible to damage.
  • Unreinforced masonry or concrete block walls are a common feature of industrial buildings. Collapse of these, which can occur even at low seismic force levels, are a hazard not only to the equipment but also to worker safety.

Controls

  • All production critical equipment, including fire-fighting pumps, water tanks, etc. to be properly anchored to the foundations. Anchor bolt configuration and foundation design are to be checked by qualified structural engineer.
  • Avoid connection of critical piping, including fire fighting water, valves and equipment to unreinforced masonry or concrete block walls. Such components are to be supported by engineered frames anchored to the concrete floor slab and load-bearing elements (columns, beams, etc.). Since these components may alter the seismic performance of the load-bearing elements a qualified structural engineer should control the adequacy of the elements.
  • Flexible connections should be provided at connection of piping to equipment, seismic joints and other critical locations.
  • Use seismic gas shut-off valves with caution. These should be designed for the pressures, temperatures, pipe diameters, etc. prevalent at the facility in which they are to be installed. Impact of sudden gas shut-off on operation of facility, handling of gas already inside the facility, etc. are just some of the issues that should be considered during valve selection. Installation and maintenance can only be performed by qualified technicians. In some countries, the components must be approved by regulatory authorities.