Corrugated Stainless Steel Tubing Issue

[Terry Beck]

This topic could go under either the Heating or Electrical forums (or both). Has anyone seen Mike Holt's latest newsletter, "Corrugated Stainless Steel Tubing Issue" (Mike Holt - Corrugated Stainless Steel Tubing Issue (http://www.mikeholt.com/newsletters.php?action=display&letterID=1240))


... there is a lot of controversy in our area regarding the use of Corrugated Stainless Steel Tubing used for distribution of natural gas and propane gas in residential and other structures.


The article starts off talking about vulnerability to lightening strikes, but leaks and explosions are possible under any condition where the CSST gas line comes into contact with an electrical current.

Be sure to also look at readers' comments as followup. Mike Holt - Corrugated Stainless Steel Tubing Issue (http://www.mikeholt.com/newsletters.php?action=display&letterID=1240&email=#comments) Suspect the discussion will continue.

Has anyone seen or heard about problems like this in their inspections?
Do you inspect for bonding, or call out installations where the CSST gas line does not have separate dedicated bonding?
It seems that in most situations the bonding is considered adequate where grounding conductor from the electrical service connects to the furnace. But there are a lot of other installations (i.e. gas stove in kitchen, gas fireplaces/stoves, etc. )

[John Arnold]

Interesting.
One of the posters says that not all CSST manufacturers require additional bonding. Anyone know if this is true, and if so, which manufacturers he's referring to?

[Jim Luttrall]

The article starts off talking about vulnerability to lightening strikes, but leaks and explosions are possible under any condition where the CSST gas line comes into contact with an electrical current.



The litigation was specific to lightening strikes, even limited recovery for bonding based on the areas propensity for lightening.

All standard CSST is required to be bonded per the manufacturer's instructions which is over and above the allowed bonding through the equipment grounding of the appliances allowed for other types of gas piping.

[Jerry Peck]

Interesting.
One of the posters says that not all CSST manufacturers require additional bonding. Anyone know if this is true, and if so, which manufacturers he's referring to?


The litigation was specific to lightening strikes, even limited recovery for bonding based on the areas propensity for lightening.

All standard CSST is required to be bonded per the manufacturer's instructions which is over and above the allowed bonding through the equipment grounding of the appliances allowed for other types of gas piping.

Each manufacturer, by now, probably has their own separate branding CSST which has an outer covering that makes the additional bonding no longer required aas the outer covering is designed to help dissipate the lightning flash energy along its outer covering to prevent burn throughs, which is what caused the holes which allowed the gas out which is what lead to the explosions and fires from lightning strikes to the standard CSST.

Thus, not all CSST requires additional bonding ... all standard CSST does require the additional bonding (all that I am aware of have changed their requirements since that class action lawsuit) - and they developed the newer 'CounterStrike', 'FlashShield', etc., types which do not require the additional bonding.

[David Bell]

Trac-Pipe has been updating it's product line offering Counter Strike which when installed correctly is more resistant than black iron pipe. Bonding is an issue with all metallic piping not just CSST.

[John Arnold]

Trac-Pipe has been updating it's product line offering Counter Strike which when installed correctly is more resistant than black iron pipe. Bonding is an issue with all metallic piping not just CSST.

"More resistant" in what sense? I'm not disagreeing, I just don't understand what you mean. Surely not more resistant to arcing damage?

[Nick Ostrowski]

I advise my clients that proponents of CSST consider bonding to be an acceptable install but opponents of CSST feel it is not sufficient......but both sides agree it helps.

[Lon Henderson]

Guys, can one of you can explain to me why bonding CSST makes such a difference in the event of a proximity lightning strike. The bonding is usually done at the meter. The meter has metal pipe in the ground. Isn't the system grounded just by the fact that it has extensive piping in the ground?

I have read quite a bit on this but have never seen an explanation for why bonding protects the system. I rarely see a system that appears to be properly bonded.

Incidentally, for anyone wondering, a flexible gas line for connecting an appliance to the rigid piping is not considered the type of CSST requiring bonding (at least around here).

[Bruce King]

Guys, can one of you can explain to me why bonding CSST makes such a difference in the event of a proximity lightning strike. The bonding is usually done at the meter. The meter has metal pipe in the ground. Isn't the system grounded just by the fact that it has extensive piping in the ground?

I have read quite a bit on this but have never seen an explanation for why bonding protects the system. I rarely see a system that appears to be properly bonded.

Incidentally, for anyone wondering, a flexible gas line for connecting an appliance to the rigid piping is not considered the type of CSST requiring bonding (at least around here).


The gas service pipe is usually plastic around here with a yellow tracer wire left hanging at the meter even though it often looks metallic.

The basic bonding is achieved at the furnace cabinet at the furnace valve being attached to the equipment ground via the cabinet metal (poor bonding). When no gas furnace is present the chance of having a poor bond or no bond is greatly increased.

The additional bonding that has been done lately is an attempt to achieve equipotential between the gas piping and other metal that is bonded or grounded. Equipotential prevents arcs even when it still has lots of electrical potential. Many lightning surges come in on the ground system and arc from metal parts to the gas piping. If everything is bonded fairly well it does not hurt the pipe even if it has a few thousand volts on it for a few microseconds. Don't think of "ground" as being a perfect thing, its not, its all about equipotential between adjacent metal parts.

[Lon Henderson]

Thanks. I see plastic with the tracer wire here too. I see few furnace installations that would provide adequate bonding for the gas service in the event of a lightning strike.

Around here, yellow CSST is still being used. I run into plumbers who are unaware of this issue and I have gotten several blow backs from recommending having the CSST bonded. I have thick skin, so it is just an annoyance.