If you have corrugated stainless steel tubing (CSST) installed in your home for gas distribution you are strongly urged to read the following information. I have long been against the idea of installing CSST for gas piping. As with many other building materials that have been developed to decrease costs to the home building industry, the manufacturers of this product seem to have cut too many corners. In the process they have increased the need for precise installation of the product and decreased the safety of homeowners saddled with these, apparently unsafe, installations.
I have monitored the CSST installations over time for performance and have made many changes accordingly to the wording in my inspections reports. However, my low opinion of the product has not changed. In fact, it is now my position that I would not have this product in my own home under any circumstances. I also strongly urge any of my clients with CSST piping in their homes to consider the following information and exercise due diligence regarding this product.
This is the current report verbiage I use. It is subject to change as more information comes to me.
The CSST gas lines do not appear to be properly bonded as required by NEC 250.104(B):
(B) Other Metal Piping. Where installed in or attached to a building or structure, a metal piping system(s), including gas piping, that is likely to become energized shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with 250.122, using the rating of the circuit that is likely to energize the piping system(s). The equipment grounding conductor for the circuit that is likely to energize the piping shall be permitted to serve as the bonding means. The points of attachment of the bonding jumper(s) shall be accessible.
The CSST gas lines do not appear to be properly bonded as required by IRC G2411.1.1 (310.1.1) CSST. Corrugated stainless steel tubing (CSST) gas piping systems shall be bonded to the electrical service grounding electrode system. The bonding jumper shall connect to a metallic pipe or fitting between the point of delivery and the first downstream CSST fitting. The bonding jumper shall be not smaller than 6 AWG copper wire or equivalent. Gas piping systems that contain one or more segments of CSST shall be bonded in accordance with this section.
The CSST gas lines do not appear to be properly bonded as required by the National Fuel Gas Code (NFPA 54) 7.13.1 Pipe and Tubing Other than CSST. Each aboveground portion of a gas piping system other than CSST that is likely to become energized shall be electrically continuous and bonded to an effective ground-fault current path. Gas piping, other than CSST, shall be considered to be bonded when it is connected to appliances that are connected to the appliance grounding conductor of the circuit supplying that appliance. AND 7.13.2 CSST. CSST gas piping systems shall be bonded to the electrical service grounding electrode system at the point where the gas service enters the building. The bonding jumper shall not be smaller than 6 AWG copper wire or equivalent.
Additionally, the CSST gas lines do not appear to be bonded as per the manufacturer’s installation instructions. Gastite (and others) recommends that all continuous metallic systems be bonded and grounded. The owner should confirm with a licensed master electrician or electrical engineer that each continuous metallic system in a structure has been bonded and grounded by an electrical professional in accordance with local building codes. This should include, but is not limited to metallic chimney liners, metallic appliance vents, metallic ducting and piping, electrical cables, and structural steel. This is a fire and explosion hazard which must be immediately addressed.
Your are strongly urged to have this system inspected and properly bonded by a licensed master electrician or electrical engineer prior to the end of any time periods associated with the purchase of this home.
The CSST gas piping is subject to damage from nail strikes, electrical wiring shorts, lightning strikes, et al. both during and after construction. The entire system is not accessible for a visual inspection and the presence or absence of damage to this piping cannot be ascertained without destructive forensic examination of the house which is beyond the scope of this inspection.
Even when the flow of leaking gas does not cause a fire or explosion, the possibility of gas poisoning is very real.
Concealed hazards may exist. You are strongly urged to have this system leak tested and thoroughly inspected for condition and proper installation by a licensed master plumber with experience both CSST installation and in gas leak detection, as well as the CSST manufacturer, prior to the end of any time periods associated with the sale or purchase of this home.
Research suggests that, at a minimum, and in addition to proper installation and bonding, the installation of lightning protection systems as per NFPA 780 and gas excessive flow valves (EFVs) may be essential in the presence of CSST, though not the end of due diligence. Finally, replacement of the CSST with threaded steel gas piping may be the only method certain of avoiding the risks involved with this product.
CSST was deemed by a jury to be a defective product. See:
ATTENTION: FIRE AND EXPOSION HAZARD!
Based upon the evidence currently available, it is this inspector’s opinion that the CSST gas piping may be unsafe even if installed as per the manufacturer’s installation instructions.
You are strongly urged to consider having this system completely replaced with threaded steel gas piping prior to the end of any time periods associated with the purchase of this home and, more importantly, prior to occupying this home. Additionally, the owner of this home should be advised to immediately vacate the home and have the system either made safe (if possible) or replaced with threaded steel piping prior to moving back in.