FEMA E-74 Example 6.4.2.3 Compressed Gas Cylinders

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6.4.2.3 Compressed Gas Cylinders

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This category includes single or multiple gas cylinders. These may be attached to piping, anchored to carts for mobility, or stored for future use.

Provisions

Building Code Provisions

Since compressed gas cylinders are generally not permanently attached to the building utilities, they are considered “temporary or moveable equipment” and are exempt from the requirements of Minimum Design Loads for Buildings and Other Structures (ASCE/SEI 7-10).

When gas cylinders are connected to building utilities, ASCE/SEI 7-10 Chapter 13 requires anchorage for cylinders in Seismic Design Categories D, E, and F weighing over 400 pounds. Lighter cylinders may be exempt if the component Importance Factor Ip = 1.0. Cylinders that are exempt from the anchorage requirement are still required to be restrained to prevent damage between the gas cylinder and associated pipes.

Retrofit Standard Provisions

Seismic Rehabilitation of Existing Buildings (ASCE/SEI 41-06) classifies compressed gas cylinders as hazardous materials storage. Anchorage of compressed gas cylinders requirescompliance with the anchorage provisions of the standard when the performance level is Life Safety or higher. Prescriptive (non-engineered) anchorage approaches may be used.

Typical Causes of Damage

  • Unanchored tanks may slide, overturn, and roll; connected piping may be damaged.
  • Contents may be flammable or hazardous; leaking cylinders may be dangerous.
  • Tank installations equipped with chains or straps are still susceptible to damage unless the chains or straps are properly secured around the tanks.

Damage Examples

Photo of fallen unanchored tanks inside fence enclosure.
Figure 6.4.2.3-1 Unanchored tanks inside fenced enclosure in the 1994 magnitude-6.7 Northridge Earthquake (Photo courtesy of OSHPD).

Seismic Mitigation Considerations

  • Wall restraint detail shown at top of Figure 6.4.2.3-8 is a non-engineered detail for tank storage; this detail does not provide sufficient restraint for tanks attached to piping.
  • Engineered details with additional restraints are required for tanks attached to piping; see corral detail at bottom of Figure 6.4.2.3-7 or scheme shown in Figure 6.4.2.3-2 and Figure 6.4.2.3-3.

Mitigation Examples

Photo of seismic mitigation example showing gas cylinder anchorage with attached gas lines undamaged in the 2001 Peru Earthquake.
Figure 6.4.2.3-2 Gas cylinder anchorage with attached gas lines undamaged in the 2001 magnitude-8.4 Peru Earthquake (Photo courtesy of Eduardo Fierro, BFP Engineers).

Photo of seismic mitigation example showing detail of undamaged gas cylinder installation showing restraints for cylinders.
Figure 6.4.2.3-3 Detail of undamaged gas cylinder installation (Photo courtesy of Eduardo Fierro, BFP Engineers).

Photo of seismic mitigation example showing wall-mounted cylinder restraints.
Figure 6.4.2.3-4 Wall-mounted cylinder restraints upgraded with stiffener plates following the 2001 Peru Earthquake(Photo courtesy of Eduardo Fierro, BFP Engineers).

Photo of seismic mitigation example showing steel tube supports for mobile gas cylinder carts.
Figure 6.4.2.3-5 Steel tube supports for mobile gas cylinder carts (Photo courtesy of Eduardo Fierro, BFP Engineers).

Photo of seismic mitigation example showing detail of steel tube supports and chains.
Figure 6.4.2.3-6 Detail of steel tube supports and chains (Photo courtesy of Eduardo Fierro, BFP Engineers).

Photo of seismic mitigation example showing enclosures for airgas tanks with quick release hooks.
Figure 6.4.2.3-7 Detail of enclosures for airgas tanks in a hospital; chains attached with quick release hooks (Photo courtesy of Maryann Phipps, Estructure).

Mitigation Details

Seismic mitigation detail for gas cylinders, for which engineering is required. Restraints for gas cylinders which are located against wall or freestanding are shown. Consult an engineering professional for implementation. For assistance reading this diagram, please contact us by email at fema-nehrp@fema.dhs.gov.
Figure 6.4.2.3-8 Compressed gas cylinders (ER).

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Last Updated: 
05/14/2013 - 13:22
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