CSST Testing, Can Energized Branch Circuits Cause Perforation?


We get to work with some really cool guys and from time to time, we do some really cool things; “things that make you go hmmm,” (as Arsenio Hall used to say).

Recently, we worked on CSST testing at Warren. Briefly, CSST (corrugated stainless steel tubing) is flexible metal tubing used to plumb a fuel gas burning appliance like a furnace. It is, in some ways, easier to install than straight black pipe and, some say, less expensive. However, CSST has also been the subject of controversy – which can be researched with a quick Google search.

At issue in this test is whether or not electrical arcs can perforate or pop a hole in CSST. One hypothesis in this vein is that, under fire conditions, typical household voltage (110-120V) is sufficient to do so. This potential has a been a point of discussion in some CSST fires. During the writing of this article, we were trying to not not steal John’s thunder by going into too much detail about the testing because was to be presenting his findings at the 2014 ISFI Conference, but we will say that after some of the tests we ran, it is definitely possible.

Fire energized conductors, one CSST with flowing gas, and an open flame.

Fire energized conductors, one CSST with flowing gas, and an open flame.

In a nutshell, we ran 3 and 4 wire conductors from individual breakers perpendicularly across a length of CSST tubing, attached a fuel gas source, energized the conductors, opened the valve on the gas lines, set a fire under the CSST tubing, and watched it all burn. When it was all “said and done”, we harvested the remains of the conductors and CSST and analyzed them.

Some of the effects could be seen with the “naked eye” while others required more sophisticated equipment. We were able to get a closer look at our heavily burned specimens under the microscope, and with the aid of a scanning electron microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) were able to get compositional analysis of interesting “splatters” on some of the CSST.

Image of a hole in CSST taken with SEM.

Image of a hole in CSST taken with SEM.

Like we mentioned above, some really cool stuff. To find out more from our forensic engineering analysis, check out his publication titled “The Potential for Perforation of Corrugated Stainless Steel Tube (CSST) by Energized Branch Circuits in Fire Conditions.”

Founded in 1997, The Warren Group, forensic engineers and consultants provides technical investigations and analysis of personal injury and property claims as well as expert testimony for insurance adjusters and attorneys. Extremely well versed in the disciplines of mechanical, electrical, chemical, structural, accident reconstruction and fire and explosion investigation, our engineers and consultants are known for delivering the truth — origin, cause, responsibility and cost of an event or claim — with unmistakable clarity.

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