In the January 1994 earthquake in Northridge, California, it was reported that there were at least 50 gas-related fires in structures above ground, where rigid pipe had been the predominant gas piping material for decades. In the 1995 Kobe earthquake in Japan, where flexible gas piping had been in general use for more than 25 years, there were a negligible number of gas leaks reported in CSST piping systems compared to those reported in threaded rigid pipe. In the larger cities in Japan, CSST is now mandatory for house gas piping.
In the U.S., Factory Mutual Research (Approval Guide May 2001 Section 7-7) approved CSST gas piping systems based upon demonstrated ability in the laboratory to withstand the stresses imposed by shifting or tipping appliances and/or by damage to structural framing caused by earthquakes, without fracture or leakage. Factory Mutual approval is based upon testing side-by-side with black iron piping components by a nationally recognized seismic laboratory.
It is now documented that conventional rigid piping systems with threaded joints are more prone to breakage under seismic loading than flexible systems. This testing demonstrates that CSST has the ability to withstand the same motions that cause threaded rigid pipe to leak.
This was demonstrated in a recent fire in Pennsylvania. A lightning strike to the house at the electrical meter caused extensive damage and fire to the house. The home was originally built in the 1950s, but a master bedroom suite and garage were added in the late 1990s, and CSST was used in the addition because of its ease of installation. As a result of the fire, the addition was completely destroyed, and the roof and walls caved into the master bedroom and garage area below.
Upon examination, it showed that the CSST installed in the addition withstood the falling roof and walls, and that the CSST line was still intact after the fire. The loads placed on the CSST lines were so severe, that it stretched the corrugations out of the CSST until the pipe was almost smooth. There is no question that if rigid steel pipe were installed in that addition, it would have cracked and leaked natural gas in the fire, causing much more damage. Thanks to CSST, that danger was averted.