Many homes built between 1990 and 2010 have yellow flexible gas lines installed known as CSST. Corrugated Stainless Steel Tubing was a new product that often replaced the threaded black pipe gas lines in new construction.
The flexibility of CSST made it easier and more efficient to install and run through the different places in the house. It also involves the use of significantly fewer fittings, reducing areas for leaks to develop. This was a definite advantage as homes began to have gas fireplaces and gas stoves installed in multiple locations – often quite a ways away from the gas line entrance in the house.
However, the biggest disadvantage to CSST Gas lines is the safety hazard they pose if not properly bonded.
As new building materials are developed, our awareness of potential issues sometimes lags behind. Over time we learn of the disadvantages of certain products, sometimes with disastrous consequences. This was the case with CSST gas lines.
CSST gas lines are prone to potential damage if there is a nearby lightning strike. The lightning can cause arcing which can lead to pinhole leaks in the flexible gas line. A leaking gas line is obviously a very serious concern.
The solution to preventing these leaks and reducing potential damage is to have the gas line bonded. Bonding of the gas line typically involves an electrical grounding/bonding clamp installed on the rigid portion of the gas line. This clamp is then connected with a bonding wire to the electrical grounding system in the house. This bonding greatly reduces the risks associated with lightning strikes.
The majority of houses we inspect with CSST gas lines installed have yet to be bonded. The gas lines were often installed before our knowledge of their need to be bonded. Consequently, the lack of bonding of CSST gas lines is a common issue that will show up as a safety hazard on a home inspection report and should be taken seriously.
Generally, the bonding process is fairly straightforward (depending on the location of the gas line and electrical ground system in the house). We recommend contacting a licensed electrician to perform this work. Having a gas line bonded typically costs between $100-$300.
In addition to the yellow CSST gas line originally available, a newer black CSST gas line includes an arc shield in its construction to eliminate the need for bonding. However, many municipalities are now requiring that this black gas line also be bonded. We recommend checking with your local municipality about their codes and regulations regarding gas line bonding.