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CSST Installation As a Contributing Factor in a Fire

This NFIRSGram explains how to identify Corrugated Stainless Steel Tubing (CSST) installation as a contributing factor to a fire using the National Fire Incident Reporting System (NFIRS).

In the United States, approximately 500,000 new homes per year have CSST installed in them — approximately half of the number of new homes built each year that use gas for heating and cooking. As of 2012, an estimated seven million homes in the U.S. had CSST installed. Since 1989, approximately one billion feet has been installed in residential, commercial and industrial structures. Source:

Several jurisdictions have contacted the NFIRS Support Center questioning how they could identify yellow CSST as the possible cause of a house fire. As with all approved gas-piping systems, CSST is safe when properly installed. When improperly bonded or grounded, a power surge from a lightning strike near a home with CSST gas lines can puncture the membrane of the CSST. The escaping gas can then be ignited either by the electrical discharge of the lightning or another heat source in the immediate vicinity.

The NFIRS does not specifically list CSST as equipment, and since the issue with CSST is an installation issue, the U.S. Fire Administration recommends the following when identifying CSST installation as a contributing factor in a fire.

  • Code “Item First Ignited” as “64” — flammable liquid/gas in or escaping from container or pipe.
  • Code the “Equipment Involved in Ignition” as “373” — gas regulator. As this code includes propane, butane, liquefied petroleum (LP), or natural gas regulators and flexible hose connectors to gas appliances.
  • Code the “Type of Material First Ignited” as “11” — natural gas for structures being supplied by natural gas or, “12” — LP gas, for structures being supplied by LP gas.
  • Code the “Factors Contributing to Ignition” as “43” — installation deficiency.
  • In the narrative section of the report, note that CSST was a contributing factor in the ignition of the fire.

Need more help identifying CSST installation as a contributing factor in a fire?

Please contact the NFIRS Support Center: Monday – Friday between 8 a.m. – 4:30 p.m. ET, at 888-382-3827 or by email at