surface yellow gas flex piping?

I am assuming that running flex gas piping on the exterior of a finished wall, or inside a finished wall, is not code, but I cannot find the code justification for it - can someone please help me with this one? It is yellow flex piping as shown in the attached photo. It connects two ends of a rigid steel gas pipe which eventually feeds a gas range. Thanks in advance for any help on this

JoanneSutro 015.jpg

From what I’ve read, it depends on the local jurisdiction. All of the major codes allow it per manufacturers instructions. If it is adequately sized, the correct fittings are used, it’s supported and it is not subject to physical damage it should be ok. I’m sure that someone here is more experienced with CSST than me and hopefully can look at your pic and see if there is a problem. Here is a link to a Design and Installation Guide of a major manufacturer of CSST.

Current construction standards as a guide (“code” is a dirty word for an HI) usually require installation in accordance with manufacturer’s instructions, which usually require protection if “subject to physical damage”. That last part is usually a judgment call.


Don’t forget about the lawsuit regarding CSST piping.

I don’t believe the flex gas lines and the CSST are the same animal. Flex has been around since Col Sanders was a corporal. CSST is a relatively newer product.

If not on a wall or in a wall, then where would it be allowed??? If CSST, it has to be protected from potential damage as someone already stated. CSST can be run anywhere other types of gas lines are installed. If a gas appliance connector, it cannot be run through walls or floors.

Cant tell from the pic, but it depends on the brand stamped onto the line.

Just in case someone needs this:

CSST consists of a continuous, flexible, stainless steel pipe, and typically is covered with a yellow exterior plastic coating. In the case of one of the products manufactured by OmegaFlex, called “COUNTERSTRIKE,” the product is covered with a black exterior coating with yellow lettering. CSST typically is routed beneath, through and alongside floor joists, inside interior wall cavities and on top of ceiling joists in attic space from a gas source to an appliance.

Titeflex’s CSST product is known as “GASTITE,”
Ward’s CSST product is known as “WARDFLEX,”
OmegaFlex’s CSST is known as “TRACPIPE” or “COUNTERSTRIKE,”
Parker Hannifin’s CSST product is known as “PARFLEX.”

Typically, these products may be visible along floor joists, above basements, in attic spaces, or connected to exposed appliances such as water heaters. The piping should be stamped with a manufacturer’s mark.

In my mind CSST is a type of flexible gas piping. Flexible tubing and appliance connectors are also types of flexible gas piping. I just assumed it was CSST (has a plastic outer yellow jacket) from the photos, since it didn’t look like flexible tubing (just painted yellow).

Here are some pics of the various basic flexible gas piping types (the first one is CSST, the second flexible tubing, and the last an appliance connector). But the bottom line is any flexible gas piping needs protection when “subject to damage” … even appliance connectors.

[P.S. There is also a newer type of flex gas piping similar to CSST with an additional thick outer protective jacket which I understand is rated for direct burrial, but I didn’t have a pic of that]


CSST Gas Pipe.jpg

CSST Gas Pipe.jpg

CSST Gas Pipe.jpg


Gas Flex Tubing.jpg

P.S.S. Note the second pic with the painted yellow flex gas tubing is a good example of how flex gas piping should be connected to a furnace/boiler. Note that the flex pipe does not pass through the equipment knockout, but is instead connected to rigid pipe that projects out.

Running flex gas piping through an equipment knockout is a classic no-no that should get written up every time.


that 90 degree bend is problamatic.

Anatol…I thought so too until I read Table 4-1 on pg 49 of the Gastite Installation Guide shown in post #2, now I’m not so sure.

I realize it’s off topic but does the lack of a dust/drip leg in photo 2 bother anyone?

Not me.

now it’s trapped

Although a larger radius sweep is desirable, with Pic #2 as a prime example, very tight bends for that type of flex piping are allowed (note it’s not typical CSST, but painted flexible tubing).

That is a pic of a short run of flexible tubing between the main lines and the equipment connection at the top I believe. But if there was no dirt/drop leg at a low point I would agree that is a concern.


I think he was referring to the CSST bend in the original photo, I know I was. :smiley:

I assumed he was referring to Pic#2 I posted. But even with the piping in the original photo (which I assume is typical CSST like TracPipe) you are right that very tight bends are also allowed … but larger sweeps are better practice.


Being a licenced gasfitter, this installation looks perfectly fine aslong as it was sized correctly. It’s definatly not the most attractive install I’ve seen, but I see nothing wrong with it. Personally I’m almost sceptical of the CSST lawsuit at this time… to me it’s almost like filing a lawsuit against Panasonic because my TV is a fire hazard because it will spark if hit by lightning.