Should you use Teflon tape and pipe dope on gas lines?

When installing gas lines, using the proper materials is crucial for safety and avoiding leaks. Two common products used are Teflon tape and pipe dope. But should you use both on gas line joints or is just one sufficient? Here is a look at whether using Teflon tape and pipe dope together provides any added benefit for gas line installations.

What is Teflon Tape?

Teflon tape, also known as PTFE tape, is a thin, white tape made from Polytetrafluoroethylene (PTFE). This tape is non-stick, flexible, and resistant to high temperatures. It is commonly used in plumbing applications to seal threaded pipe connections. When wrapped around the male threads of a pipe fitting, Teflon tape helps fill in any small gaps or imperfections in the threads. This improves the seal and helps prevent leaks. Key properties and uses of Teflon tape include:

• Non-stick surface allows for smooth tightening of fittings
• Can be stretched to conform to threads
• PTFE material is stable up to 500°F
• Chemically inert and resistant to corrosion
• Prevents leaks by improving thread seal
• Commonly used on water, gas, fuel, and refrigeration lines

Teflon tape is an important tool for any plumbing job. It is inexpensive, easy to use, and reliable at sealing threaded pipe connections from leaks. The non-stick nature also prevents connections from binding up.

What is Pipe Dope?

Pipe dope, also referred to as pipe thread sealant, is a compound used to seal threaded fittings and increase friction when tightening them. Typical pipe dopes are pastes or gels that get applied to the threads before assembling fittings. Pipe dope is often used in combination with Teflon tape to enhance the seal and lubrication. Common ingredients in pipe dope include:

• Petroleum oils to lubricate threads
• Fine metal powders (zinc, copper) to fill gaps
• PTFE resins to improve lubricity
• Bentonite clay to increase viscosity
• Dyes and fragrances

The oils and PTFE help ensure smooth tightening while the metal particles and clay fill voids in the threads to prevent leaks. Pipe dope is useful for sealing all types of threaded fittings including galvanized steel, black iron, brass, copper, PVC, and CPVC. It can be used at low and high pressures and temperatures from -50°F to 500°F depending on the formulation.

Using Teflon Tape and Pipe Dope on Gas Lines

When installing gas lines such as for natural gas or propane, using both Teflon tape and pipe dope can provide enhanced safety and leak prevention. Here are some key benefits of using both products:

• Teflon tape seals the threads while pipe dope lubricates – The non-stick tape seals leaks while the dope allows tightening to proper torque specs.
• Dope fills voids missed by tape – The metals and clay in pipe dope fill any small gaps left between the threads.
• Additional insurance against leaks – Using both products provides redundancy if one material fails.
• Complete seal at high pressures – Gas lines see pressures up to 1/2 psi for residential lines and over 100 psi for commercial lines requiring robust seals.
• Prevents galling or friction damage – The lubricants protect threads from damage during tightening.

The combination of Teflon tape and pipe dope compounds each other’s strengths. Tape forms a tight seal in the threads while dope fills any voids and smoothes tightening. This provides complete leak protection. Neither product alone can fill gaps, lubricate, and seal as effectively.

Proper Application Procedure

To properly install gas lines using Teflon tape and pipe dope, follow this procedure:

1. Clean pipe threads with emery cloth to remove dirt, grease, and burrs
2. Wrap pipe threads with 1-2 layers of Teflon tape, going clockwise to follow the threads
3. Smooth any ridges or bumps in the tape so it conforms to threads
4. Apply a thin layer of pipe dope over the Teflon tape
5. Assemble and hand-tighten joint as far as possible
6. Use wrench to tighten fitting per torque recommendations
7. Wipe away any excess dope

Applying too much dope or tape can cause pipes to crack under pressure. Follow manufacturer specs for proper number of wraps and thickness of pipe dope. Also be sure to use products rated for gas service – pipe dopes and tapes are made with different materials depending on the application.

Pipe Thread Sealants for Gas

For gas service, be sure to use Teflon tape and pipe dopes rated for natural gas or propane. These products will be clearly labeled for gas use and contain the proper materials to withstand gas line temperatures and pressures. Some examples of pipe thread sealants for gas lines include:

Product	Details
Oatey Gasoila Tape	Yellow Teflon tape infused with pipe dope, NSF approved for gas
RectorSeal No. 5	White non-hardening, petrolatum-based pipe dope for up to 2,000 psi
Blue Monster PTFE Gas Tape	PTFE tape with silicone lubricant, rated for natural gas and propane
La-Co Slic-Tite Paste with Teflon	Sealing paste with PTFE, meets BS standards for gas lines

Avoid pipe dopes and tapes designed for only water or threaded fittings like hex bolts. Be sure any products used are certified for gas service on the label.

Reasons to Avoid Using Only Pipe Dope

While pipe dope alone can seal some gas fittings, there are a few reasons why sole use is not recommended:

• Can be messy – Thick consistency makes dope hard to apply without dripping and glopping
• Difficult to fully tighten – Friction and resistance from dope alone can prevent proper tightening
• Can “pump off” threads – Seal can be forced away from threads under high pressure
• Less stable at temperature extremes – More prone to drying out or becoming brittle
• Not as good filling fine thread grooves – Tape can get into micro voids

The viscosities required for pipe dopes to seal large gaps lead to application difficulties. Pairing with Teflon tape helps offset these downsides for a more robust seal.

Reasons to Avoid Using Only Teflon Tape

Relying solely on Teflon tape also has some drawbacks including:

• Prevents proper tightening – Can cause over-compression and damage
• Can loosen over time – Seal may deteriorate with vibrations
• Not formulated to handle gas – Most tapes designed for water only
• Minimal gap-filling – Cannot seal voids between threads
• Prone to installation errors – Must be applied carefully

Teflon tape alone is easily botched and does not adequately fill larger void spaces in the threads. Combining with pipe dope enhances the seal performance.

Safety Tips

When working on gas lines, keep these safety tips in mind:

• Turn off gas supply and depressurize lines before working
• Ventilate work areas to avoid gas buildup
• Perform leak checks with approved devices after assembly
• Do not use sealants rated for water or steam on gas lines
• Adjust torque settings to manufacturer specs
• Use caution when handling compressed gases

Gas can leak and accumulate undetected in enclosed spaces. Take precautions to avoid health risks and potential fire or explosion hazards.

Signs of Leaks

Watch for these signs of possible gas leaks:

• Rotten egg odor – Added mercaptan creates distinctive smell
• Hissing sound near pipes
• Bubbling paint or rust around joints
• Visible vapor clouds near fittings
• Dead vegetation in otherwise wet areas
• Flames coming from ground or blowouts
• Dirt blowing from a hole in the ground
• Elevated reading on gas detector

If a leak is suspected, evacuate occupants immediately and call the gas company or emergency services. Do not operate any switches or electronics that could create a spark.

When to Call a Professional

While small DIY gas line jobs are permitted, it’s recommended to call a professional for:

• Major new gas line installations
• Connections to main gas supply lines
• Repairs required in crowded spaces
• Buried, concealed, or roof-mounted lines
• High-pressure commercial or industrial lines

Improper gas work can result in deadly leaks. Licensed pros have the tools and experience to safely route, fit, and seal specialized gas line systems.

Conclusion

Using both Teflon tape and pipe dope to seal threaded gas line fittings provides superior leak protection compared to either product alone. The tape wraps the threads to seal leaks while the dope fills voids and enables tightening to proper torque values. This combination provides a reliable gauge and void fill to handle the demands of gas line pressures. Follow proper application procedures and use only products designed for gas service. With the right materials and techniques, gas lines can be sealed safely and effectively.