Can CSST Flexible Gas Line Be Used Outside? (Answered) (2023)

Corrugated Stainless Steel Tubing (CSST) is a perfect flexible gas line pipe. It is flexible to use under the joist or pavements. If you look at the build quality of this pipeline, you will get why people love to use the CSST gas line.

It’s a famous gas pipe to transfer natural gas. It will last for decades and will give you the optimum service. Let’s find out if you can use it outside.

Can CSST flexible gas line be used outside?

CSST flexible gas lines can be used outside. The name itself refers to the flexibility that ensures the optimum fittings both inside and outside the home. You will find the CSST gas line in both commercial and industrial areas. If you want, you can use it in your building gas line.

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Can CSST Flexible Gas Line Be Used Outside? (Answered) (1)

The outside gas line must be compatible and must come with the string build. It needs to bear both the pressure and weather for which the typical gas line is not preferred to use outside. You might use the polycarbonate or plastic-made gas line inside your building.

When it comes to using the gas line outside, it’s your job to ensure safety. You cannot use the regular or any typical gas line. Stainless steel-made gas lines should be your priority. Here, the CSST is also a stainless steel gas line.

Therefore, you can safely use it outside the home or buildings.

Yellow csst gas line:

You can use the yellow csst gas line outside since it is also a strong gas line that can bear pressure and lightning strike. Usually, the yellow color gas lines are the safest pipe to transfer the natural gas from one place to another.

They are strong enough to bear the pressure and remain in good shape.

For that reason, you can use the yellow CSST gas line outside and inside your home. You must use this gas line in your house; you can check and confirm this fact. It’s a popular choice, and manufacturers also know it.

Pro flex csst gas line:

You can also use the ProFlex CSST gas line outside the home within a while.

If you want to install the gas line fast and plan to avoid unnecessary effort, the ProFlex CSST gas line would be greatly relieved. It has a strong and flexible build which will allow you to install it sooner than other pipes.

Pro flex CSST gas line is a commercially used pipe to transfer the natural gas through the walls, joists, and other ceilings. It has a solid surface to protect the gas line from external damage. Therefore, you can securely use the ProFlex CSST gas line outside.

Can csst gas line be used underground outside?

The CSST gas line can be used underground outside. It is waterproof and can bear high pressure without being damaged or destroyed. If you have options to choose the best CSST gas line, I’d prefer to go for the ProFlex CSST gas line.

It’s best to use any non-metallic gas line to transfer the natural gas through underground routes. You can rely on the quality and will get the best installation process. Using the ProFlex CSST gas line will save both your time and cost in various ways.

Underground gas lines need to be flexible and must come with non-metallic components. You need to fulfill the requirements to use any gas line underground outside.

If you use the regular gas line, it will be broken, and you can’t bear the pressure. Consequently, your cost will be higher.

3 reasons why you can use csst gas line outside

You can use the CSST gas line outside because of the firm and flexible build, waterproof features, and ease of installation. I will explain these reasons in detail so that you can understand better.

Strong & Flexible Build:

The CSST gas lines have the strongest build and flexibility that allow you to use them outside your buildings. Manufacturers use stainless steel and try to give this gas line a perfect design to use everywhere.

You cannot expect a regular or usual gas line to provide you with the flexibility to use outside.

But the CSST gas line is there to give you everything to use outside your home. Flexibility comes first since you need to install the gas line through walls, ceilings, and underground.


If you want to use any particular gas line outside or underground, it must have the waterproof feature to avoid any damage or leaks. Outside material must have this feature to resist rainwater and moisture.

Here, the CSST gas line is a 100% waterproof gas line.

The stainless steel-made gas line will not allow any water or moisture to come inside and damage the gas quality. It will become the safest gas line that you can use outside or underground to supply natural gas.

Easy to Install:

You can use the CSST gas line outside because it is easy to install. Regular gas lines have some complications in installation. If you use them outside, you need to put in double the effort, which will decrease your productivity.

So, easy to install should be your first consideration while selecting the best gas line.

Luckily, the CSST flexible gas line comes with the easiest installation process. You can install it on the ceiling, underground and pretty much everywhere.

How long can you run csst gas line outside?

CSST gas lines could be run outside up to mainly 3 feet, but it can be 6 feet for two other types. Generally, the connector can run up to 3 feet. When used for clothes dryers and gas ranges, the limit extends slightly, and the CSST gas line can be run up to 6 feet.

One concern is that you cannot join or splice the connector with any nipples. The CSST can be run the same both indoors and outdoors. While running the CSST outside, they must carefully use metallic conduct bigger than the pipe to cover it up.

Any fitting must be avoided when you bury the CSST below your ground level. Be conscious of 3 feet for general and 6 feet for cloth dryer and gas ranges.

How to use csst gas line outside?

Using CSST gas outside requires a careful approach.


The tubing must be supported in an orderly fashion using pipe straps, bands, or hangers proportionate to the tubing’s size and weight.

The tubing must be routed on top of ceiling joists and other structural parts that conform with the horizontal spacing requirements to be properly supported.


Any exposed portions of the stainless steel tubing must have tape or a sleeve wrapped around them to protect them from potential hazards posed by cleaning masonry solutions based on chlorine or acids.

Due to its long-lasting nature, self-bonding silicone tape is the material of choice here.


When installing Gastite via a sheet metal enclosure (such as a fireplace), make sure the tubing is routed or supported so that it does not come into contact with the enclosure itself. Rubber grommets can be utilized if direct contact is unavoidable.

Where can I use CSST gas line?

You can use the CSST gas line everywhere. Let’s see what the best places for using this gas line are.


For underground usage, it must be protected from corrosion by being installed inside a sealed conduit. A protective sleeve sealed against the foundation will be wrapped around any piping that must pass through the foundation wall.

It has to be encased in a non-metallic conduit half an inch larger than the pipe itself. The underground segment must be devoid of any fittings.

Interior Walls:

One of the many advantages CSST comes up with is its flexibility. You can use it anywhere you want. Your interior walls are no exception. It is highly durable, so you should have it in your internal walls without any worries.

Gas piping systems that use CSST have fewer joints, and as a result, they have a lower risk of developing leaks.


Use of CSST in the outer environment is acceptable. UV protection and flame resistance are both included in the jack.

For this, an external pipe installed above ground must have a stable support system and be placed in an area where it will be safe from being damaged by the elements.

Pipes that go through outside walls must have an additional layer of protection against corrosion in the form of a coating or wrapping made of an inert material that is certified for use in such situations.

Final Thoughts

Because of the easy installation, waterproof & durable build quality, you can use the CSST flexible gas line outside. It’s a perfect gas line to use both inside and outside the building. You can use it in commercial and industrial areas since it has the best build quality and durability.


Is CSST approved for outdoor use? ›

A: Hi, Ron - CSST is mostly for indoor use. However, it can be used outdoors if protected by a non-metallic (pvc) conduit that is at least 1/2" larger ID than the OD of the CSST. Further, there should be no fittings (just tubing) inside the PVC.

Does flexible gas line meet code? ›

Homes built with CSST flexible gas Lines before the Building Code required bonding were built correctly to the Building Code at the time they were built. BUT that does not mean they are safe. These homes may, or may not have bonded gas lines.

What is the problem with CSST gas line? ›

– The real problem: CSST is so thin-walled that it creates a significant fire hazard anywhere it is installed. CSST gas line is extremely thin, with walls typically around 0.008" in thickness. Black iron gas pipe is typically 0.12" in thickness.

Can Flex gas line be exposed? ›

A conduit or chase is required for installations in exposed unprotected areas within 6 feet of grade. Conduit shall be supported with proper size pipe hooks, pipe straps, bands, or hangers.

What is the difference between yellow and black CSST gas line? ›

The black conductive jacket of CounterStrike® has been shown to be up to 400 times more resistant to the damaging effects of electrical energy than yellow CSST. It also lays straighter and pulls easier than yellow CSST.

What kind of gas pipe to use outside? ›

PVC gas pipes work well for underground exterior gas lines because they're durable and resistant to corrosion. PVC pipes are an inexpensive solution, but some locations don't allow them as they can break during the installation process.

Can flexible gas line be ran outside? ›

Pro-Flex CSST can supply gas throughout a home or commercial building. Route it through walls, floor or ceiling joists, or outside to a variety of appliances.

Is CSST better than black pipe? ›

The patented CSST innovation was first developed in Japan in the 1980s. It was deemed 'safer' since it was more flexible than black iron pipes. The latter are known to break and start fires during earthquakes, which occur approximately 1,500 times a year in Japan.

What is the yellow flexible gas line called? ›

The gas piping is known as corrugated stainless steel tubing, or “yellow CSST.” “Homes with yellow CSST are at risk of perforation to the gas line caused by lightning strikes which could cause gas leaks or fires,” says Insurance Commissioner Karen Weldin Stewart.

What is the lifespan of CSST? ›

Flexible gas lines (corrugated stainless steel tubing – or CSST) usually last up to 30 years, whereas the traditional black steel pipes can last up to 75 years or more.

How long does CSST gas line last? ›

How Long Does a Flexible Gas Line Last? CCST usually lasts about 30 years.

Do you have to bury CSST gas line? ›

And remember, while the CSST can be buried, Gastite® fittings must always be located in an accessible area and therefore must not be buried.

Can you run CSST through conduit? ›

Yes, however it must be sleeved in a non-metallic conduit ½” larger than the pipe. The underground section must not contain a fitting. Is Home-Flex® CSST pipe certified?

Can you run CSST through joists? ›

Besides providing greater durability, CSST is flexible, allowing it to be routed beneath, through and alongside floor joists in your basement, inside interior wall cavities and on top of ceiling joists in attic spaces or connected to fixed appliances such as water heaters.

Can you run CSST behind drywall? ›

The thread title says “CSST through solid wall.” If this is the question, the answer is “yes,” CSST can pass through a solid wall. CSST can also be directly connected to fixed appliances.

Can you use yellow CSST outside? ›

You can bond CSST inside or outside. Not only does the newest version of the code allow CSST to be bonded anywhere, but CSST manufacturers also allow CSST to be bonded anywhere. For example, Gastite says “The bonding clamp attachment point may be at any location within the gas piping system.”

What is the code for bonding CSST gas line? ›

G2411. 2 (310.2) Gas Pipe Bonding—Systems That Contain CSST

A gas piping system that contains any corrugated stainless steel tubing (CSST) shall be electrically continuous and shall be directly bonded to the electrical service grounding electrode system.

Can you use CSST for natural gas? ›

Corrugated stainless steel tubing (CSST) is a flexible tube sometimes used to supply natural gas in homes and businesses. If your home or business was built after 1987, or if work on your natural gas piping system has been performed since then, CSST may have been installed.

Can you use flexible gas line for garage heater? ›

Connect the flexible gas line to the heater using a variety of gas pipe, fittings, elbows, and nipples. Use pipe dope to secure all the connections. Drill a hole on the other end of the garage and install a vent to ensure there is another air flow to allow exhaust to escape the room.

What is the best pipe for outdoors? ›

Polyethylene Pipe

It is durable and provides long-term resistance to environmental conditions in outdoor and underground uses.

Can you connect CSST to black pipe? ›

CSST can be used in conjunction with black iron pipe, steel pipe fittings and other brands of CSST. The best protection is to install the tubing in areas that do not require protection from mechanical threats.

How long can you run yellow flex gas line? ›

The flexible connector length usually is limited to 3 feet except for gas ranges and clothes dryers. For these appliances, 6 feet generally is allowed. Splicing or joining connectors with nipples often is prohibited.

Can gas lines be in the backyard? ›

Having a natural gas line in your backyard can offer the benefits of convenience and warmth for your outdoor space.

Can CSST gas line go through walls? ›

CSST can be run through walls and floors (but should have protection plates installed), underground (must be protected in conduit), in attics, and outside (but most be physically secured and protected if installed within 6' of grade).

How far can you run a flex gas line? ›

❖ Flexible connectors must bear the label of an approved agency and are limited to a maximum of 6 feet (914 mm) in length.

What is the advantage of CSST? ›

CSST is a continuous, flexible, stainless steel pipe with a plastic covering. It is flexible and lightweight, and requires fewer joints than conventional black iron pipe. CSST requires much less time and labor to install than iron pipe, in part because it is flexible.

What is the pressure rating of CSST gas line? ›

Pipe - CSST tubing shall be 300 series Stainless Steel Strip conforming to ASTM A240 rated for 25 psi and have an elevated pressure rating of 125G for sizes up to 1 ¼” and 25G for 1 ½” and 2”.

Can anyone install CSST? ›

In addition to be licensed in the jurisdiction, FlashShield+ or Gastite corrugated stainless steel tubing (CSST) flexible gas piping material must only be installed by an installer who has been successfully trained through the FlashShield+ and Gastite® training program.

Can you run CSST into a fireplace? ›

Fireplaces. Gastite CSST shall not be directly routed into the metallic enclosure of a gas fireplace utilizing a metallic vent that penetrates a roofline. The CSST connection shall be made outside of the metallic gas enclosure to a section of rigid metallic pipe, stub-out, or termination fitting.

Can I use CSST under my house? ›

CSST is allowed in any location that other gas piping is allowed. If the flex gas line you were referring to was in fact, CSST, there may be no problem with that application. Also, CSST can pass through walls floors etc.

Does all CSST require bonding? ›

All new CSST systems must be bonded regardless of whether the systems include only CSST or include other piping materials (steel pipe or copper pipe/tubing) in combination with CSST. Existing non-CSST piping systems must be bonded when CSST is added to the system regardless of the length of CSST added.

Can you cut CSST with regular pipe cutter? ›

A: Yes. This tubing can be easily cut to length with a standard tubing cutter. You need to use the fittings supplied specifically for the tubing as there are at least two manufacturers of CSST products.

Is yellow CSST safe? ›

This can shock anyone who comes in contact with the CSST or gas appliances that are connected with CSST. And in some cases, such as a lightning strike, the CSST can become damaged and start a fire. However, CSST that is properly bonded and grounded is considered to be generally safe even when struck by lightning.

Is CSST UV resistant? ›

All CSST products are UV resistant. ❖ Protect the tubing along the side of a structure under 6-ft elevation. ❖ Tubing must not be in direct contact with the ground.

Is CSST gas pipe allowed in California? ›

CSST may be used if it is part of a system listed by an approved agency, “ ... except that the local administrative authority may disapprove use of corrugated stainless steel tubing based on health, safety or performance considerations.”

Is CSST rated for direct burial? ›

Can Gastite® CSST be buried? Yes, it can. Gastite® CSST is suitable for both internal and external installation allowing for direct burial. The manufacturer's instructions must be adhered to.

Is CSST gas piping available with an arc resistant jacket? ›

All CSST pipe we carry is arc-resistant type (Flak-Jacket from ProFlex) and is approved for indoor, above-ground installation for natural (NG) and propane (LP) gas distribution in residential and commercial structures.

Does CSST need to be sleeved? ›

Yes, however it must be sleeved in a non-metallic conduit ½” larger than the pipe. The underground section must not contain a fitting. Is Home-Flex® CSST pipe certified?

Can Pro-Flex CSST be used underground? ›

Can Pro-Flex CSST and Flak Jacket Arc-Resistant CSST be buried? Flexible gas piping systems [Pro-Flex CSST and Flak Jacket Arc Resistant CSST] may be used underground when routed in a water-tight, non-metallic conduit – no Pro-Flex fittings are allowed in the conduit.

Can you use flexible gas line underground? ›

The fittings are made of plastic. HOME-FLEX Underground gas pipe and fittings are for use with natural gas and LP (propane) gas. This poly gas pipe must be installed outdoors and underground only. The plastic pipe may never be used above ground, in a building or under a building.

Can you run CSST in a basement? ›

Besides providing greater durability, CSST is flexible, allowing it to be routed beneath, through and alongside floor joists in your basement, inside interior wall cavities and on top of ceiling joists in attic spaces or connected to fixed appliances such as water heaters.

What is the difference between CSST and rigid pipe? ›

Another difference between CSST and rigid pipe is CSST doesn't require turn fittings, or elbows. A rigid pipe install requires careful measurement, cutting and assembly of a series of 90-degree elbow fittings. CSST, however, can be quickly bent and routed where needed.

Where does CSST need to be bonded? ›

The CSST must be permanently bonded directly to the grounding electrode system of the electrical service of the home in which the CSST is installed.


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