Corrugated Stainless Steel Tubing (CSST)
1st generation Gastite yellow jacketed CSST
CSST is used as piping in the supply of gas (natural or liquefied petroleum - LP) to gas burning appliances (not to be confused with the smaller corrugated connector that runs from the main service to the appliance). It was first introduced in Japan since its flexibility made it less susceptible to breakage & leaks caused by earthquakes & tremors. It’s also easier to work with than traditional black pipe for obvious reasons. CSST has been in use in the United States since approx. 1990 mostly for its cost effectiveness in installation compared to traditional methods.
The problems arose in the ensuing years when homes were going up in flames after lightning strikes. It was discovered after further investigations that CSST piping in close proximity to electrical branch wiring or other metal pathways that was bonded poorly or not at all, created a potential for arcing thus puncturing CSST causing leaks and/or fire & even death. Long story short after studies were conducted in the mid to late 2000’s, it was recommended that direct bonding of the CSST to home’s grounding system greatly reduced this potential (although not entirely). Improvements & upgrading of the product has taken place by some manufacturers (particularly Gastite) while most makers of CSST as well as local municipalities require this bonding. Still, it is estimated that there are some 6 - 8 million homes in the US that were equipped with CSST before the installation requirements changed.
It appears that this product is not going to go away any time soon as builders continue to find cheaper ways to get homes built. I’m finding that the majority of new home construction (especially the entry level sector) inspections I perform, CSST is present. That seems to jive with national trending statistics where it is estimated that 500,000 new homes every year are built with CSST installed.
I just did an inspection in the last month on a home in the upscale Steiner Ranch community in Austin and found un-bonded CSST in a home built in the early 90s. I also recently did an inspection on an apartment complex out in Spicewood that was originally built as a three-plex & renovated into a four-plex. Energy for heating was supplied by LP gas & when they installed the HVAC for the new unit, they routed the supply via CSST. It was not bonded. So not only is it being installed at original construction, but also in renovation projects.
And that brings up another potential problem; remodel and renovations. Because the tubing is flexible, it’s not going to have the robust characteristics of traditional steel piping and will be more susceptible to punctures and other kinds of hazards during the process; especially if the presence of CSST is unknown in the building.
Personally in my opinion, I think there are too many potential problems with the product and would have reservations living in a house with CSST. It’s always best to have a qualified professional check out your home or potential home.
More on the subject can be had at these links: