How to Seal Propane Tank Fittings

propane tanks connected to exterior gas system

Propane tanks need various hoses and attachments in order to work properly and deliver the needed gas to a propane-powered grill or another appliance. But if you don't know how to seal propane tank fittings, you're going to end up with dangerous and potentially very harmful gas leaks and you could end up with appliances that don't work properly, too.

Knowing how to seal propane tank fittings is one of those things you should know how to do if you have a propane tank that is connected to anything, such as a grill. Because propane is a gas and it is dangerous, it's important that you know exactly what to do and how to do it safely.

What Are Propane Tank Fittings?

Fittings are little items that connect hoses or pipes to each other or to a tank or appliance. Propane tank fittings connect the tank, through hoses or pipes, to whatever needs gas in order to receive power and do what it's intended to do.

You can’t just take a hose or a pipe, stick it into a hole and started using propane. Dangerous gas fumes will leak out around the cracks and the gas itself could leak, too.

Fittings are necessary because this creates a tight seal between the tank and the device that’s carrying gas to the appliance that’s using gas. You can’t skip the fittings for any reason, so you need to know how they work and how to make sure they’re working.

When you are applying propane tank fittings to your tank, you need to exercise a great deal of care. Propane is very volatile and explosive, and poor seals can allow the gas to leak out into the surrounding atmosphere.

You need to properly seal all propane tank fittings because simply attaching them is not enough. To make sure those fittings are truly sealed, you’ll have to take some extra steps.

Seal Propane Tank Fittings

Propane tank fittings must be properly sealed to prevent gas fumes or gas from leaking out and causing problems. You won’t need a lot of tools or DIY knowledge to make this happen.

Anyone can learn how to seal propane tank fittings and basically, all you need is tape and a wrench.

Compression Fitting

One of the main fittings you can expect to see with a propane tank is the compression fitting. If you have a new propane tank, you will probably have a compression fitting that came with the tank.

If you don’t already have a compression tank fitting for the tank, you can easily purchase compression propane tank fittings from a hardware store.

The size of the fitting matters. If you’re using the wrong size, you may as well not seal fittings at all because you’re going to have the same danger.

Try measuring the opening for the fitting and pick up a couple or a few different-sized fittings so you can find one that fits well. The ones you don't use can always be returned.

Push the compression fitting firmly onto the tank. This should take some force because after all, the goal is to have a very tight seal where even fumes can't leak out.

Tightening the fitting down by hand isn’t enough. You’ll need to use a wrench to further tighten the fitting and get a good seal.

In some types of propane tanks, such as those used in boats, it is necessary to attach an adaptor to complete the seal. This can be in the form of an O-ring or similar connecting device.

If the compression fitting or the tank you have requires this adapter, the adapter will come with the fitting.

Tighten the O-ring first, and then attach the propane tank fitting over the top. Again, twist everything in place by hand and then use a wrench to truly tighten the seal and make it leakproof.

Compression fittings are self-sealing. That means as long as you tighten them enough, they will create a tight seal that will prevent gas and fume leakage.

You won’t need to do more than this for compression fittings. However, this is only true for compression fittings.

Remember that over-tightening fittings is also not ideal, as this can cause fittings to crack or break and will cause even more leaks.

Connect the Hose

Once the compression fitting is tightly in place, you can then take your gas line and connect it to the fitting. Push the hose completely into the fitting, and then hold it in place by turning the fitting seal with your fingers.

If you are adding several lines at once, attach the hoses and hand-twist them in place before you truly seal the connection using a wrench to get the tightest fit possible.

Check the fittings at both ends of the hose, because leaks could happen at either end of the pipe or hose. It may take extra time to double check everything and do a little more work but in this case, safe really actually is a lot better than sorry.

Other Types of Fittings

Compression fittings are self-sealing, but threaded propane fittings are not. If you want to create a tight seal with threaded fittings, you need PTFE gas-rated thread tape.

This is also known as Teflon tape. Do not attempt to substitute another type of tape for this task, such as duct tape.

It might seem that all tape is created equal and you probably have some perfectly good tape already. However, using any other type of tape for this task isn’t just inadvisable, it’s actually dangerous.

Only gas-rated tape is safe enough for this job. Other tapes might melt nd they won’t create the seal you need.

Install the propane tank fittings by wrapping the Teflon tape around the threads of the fitting. The tape will allow you to get a good seal on your fitting after you tighten it down and use the wrench to secure it.

PTFE tape is color-coded. White and pink are used for water lines, green for oxygen lines, and yellow for gas lines. This code actually makes things very easy.

Make sure you have the yellow tape that is treated and designed to be heat-resistant and anti-flammable so it can be used with gas. Do not use green, pink, or white Teflon tape on fittings because it is not designed for nor rated for use with gas.

Protect the Propane Tank Fittings

As propane tank fittings are designed to prevent gas from leaking, it is vital that you treat them with due care. One of the most important things to avoid is the use of sealants on the surface of the fitting itself, though it may seem like a great solution and an extra layer of protection.

You can use sealing tape, but any kind of caulking, metal seal, or similar chemical material is not advisable. This is due to the chance that the sealant may corrode the propane tank fittings.

In addition, you should try to avoid placing the fittings near a very hot surface. This can sometimes cause the compression to loosen. Keep the tank and the fittings as far from any potential sources of heat as possible to keep them high-functioning for as long as possible.

How to Check for Leaks

Find out if you have a leak around any of your fittings by filling a spray bottle with some soapy water. Turn the tank's shut-off valve to the on, or open, position.

Spray the soapy water around the fittings. If you see bubbles form, there is a leak.

Use this trick after replacing fittings to check your work and make sure you have a secure connection between all seals.

Check for leaks frequently, because propane leaks can be hard to detect and you don’t want to find out you have a leak after you’re already in danger.

Propane Tank Fittings

Propane is a highly flammable gas that can be used to create heat and cook food, among other things. It can be life-saving but it can also be highly dangerous if the fumes or the gas are leaking out of poorly-sealed fittings.

You should frequently check all openings and seals around the propane tank and on everything connected to the propane tank. Even a small leak can be incredibly dangerous and can keep your propane-powered appliances from functioning.

Propane Tank Fittings FAQ

What is the best way to seal propane fittings?

When propane fittings are self-sealing, the best way to seal them is to make sure they are tightened down completely. Use a wrench to get more torque and tighten fittings more than you can tighten them using just your hand.

When you're working with threaded fittings, use yellow Teflon tape and only yellow Teflon tape. Wrap it around the threads first, then securely attach the fitting with a wrench to get a nice, tight connection.

Check the seal with a spray bottle of slightly soapy water. This will bubble up when there is a leak, so this is a good way to check that your fittings are indeed tightly sealed.

Do I need sealant on propane fittings?

Other than Teflon tape, propane fittings do not need additional sealant. Caulk, liquid pipe sealant, and other materials should not be used with propane tank fittings because these materials are not rated for use with flammable, explosive gas, which is what propane is.

Don’t assume that extra sealant is better. Adding caulk and other sealants can actually create a fire hazard.

Remember to respect propane gas as a highly flammable liquid and treat it as such at all times. This will help you stay safer.

How do you fix a leaking propane fitting?

If you find a leak on a propane fitting, replace the fitting. Over time, fittings can break down and wear down and this can prevent them from sealing properly.

Improperly sealed fittings will leak and fittings are not expensive, so it's worth it to replace the fitting entirely when you find a leak.

Put the new fitting on, tighten it well, and check for leaks to see if the problem is now fixed.

What do you use to seal gas fittings?

Gas fittings should be sealed with tape that is rated for use with gas, which means yellow Teflon tape. This tape is used for propane tank fittings and for all gas fittings because it is made to handle the heat and potential dangers of gas.

You don’t need anything more than this tape to seal fittings. And in the case of compression fittings, you don’t even need the tape.

How do you stop a propane valve from leaking?

When you have a propane valve leaking, the first order of business is to turn off the valve. Tighten the screws around the valve to see if this creates a better seal that stops the leak.

Otherwise, stop using the tank until you can determine the source of the leak and fix it, or until you get a new propane tank that does not have a leaky valve.

There is no such thing s a small propane tank leak. Any gas leak is always a big deal and should be treated that way.

What size are propane tank fittings?

There is no standard size for propane tank fittings, and there is no standard size for propane tanks. These fittings come in all different sizes and if you need to replace a fitting, it may not always be easy to tell what size you need.

If you know the manufacturer of the propane tank, try looking u the model name and number online. You may be able to find out exactly what size fittings you need for your specific tank this way.

Further Reading

4 Important Propane Tank Safety Tips

How to Build a Propane Fire Pit

How to Convert a Gas BBQ to Propane

How to Convert Natural Gas To Propane

How to Determine Pipe Thread Size for Plumbing Fitting

How to Fix a Propane Hose Leak

How to Measure Copper Pipe Fittings

Propane Barbecue Tank Pressure Explained