Is it Safe to Weld a Fuel Tank? – All You Need To Know


If you are welding, you want to ensure proper safety protocols, no matter what type of item you are working on.

Understanding safety measures when it comes to welding fuel tanks are even more important with the added element of a flammable substance.

Is it safe to weld a fuel tank? Welding a fuel tank can be an extremely dangerous task. Even if the tank is empty, there may still be leftover fuel vapors that can easily ignite, causing fires or explosions. Understanding the different components at play when welding a fuel tank, and taking necessary precautions is the only way to weld a fuel tank safely.

There are many considerations to be made, and you will want to ensure you have done your research first.

But if you are a confident welder with a lot of experience, there are precautions to make to allow you to complete your welding of a fuel tank safely.

Why Welding a Fuel Tank is Dangerous

The main concern with welding a fuel tank lies in the risk of combustion or fire.

The vapors from the gas can easily ignite at any time while you are welding a tank that has housed any type of fuel at any point.

Whether you are working with a large, stand-alone fuel tank or a vehicle fuel tank – many of the concerns remain the same.

Weld a Fuel Tank

The constant flying sparks, while you are welding, is the primary concern for interaction with any residual fuel left in the tank.

Those sparks may seem small and harmless, but they stay surprisingly hot even as they fly through the air.

According to the American Welding Society Safety and Healthy Fact Sheet, flying sparks, molten metal, and spatter are the leading causes of fires and explosions in welding. From the work area, those little particles can travel up to 35 feet.

Not only can they travel a far distance, but they can also get lodged in different areas without you even knowing. For example, they easily get stuck in:

  • Clothing
  • Pipe holes
  • Cracks or crevices
  • Pipe holes

If a spark has lodged itself in any of these areas while gas is present, it can easily cause a fire. Any type of welding in an area that gas of any type is or was present is going to be a fire and safety hazard.

The other main concern over welding a fuel tank is the process being used for the welding itself.

If MIG (Metal Insert Gas) or TIG (Tungsten Insert Gas) are being used, there is even a risk of suffocation while inside the fuel tank if there is a presence of argon gas.

Both MIG and TIG commonly use argon gas or a mixture that includes argon as a shielding gas.

Mixtures of argon containing oxygen and carbon dioxide or helium are not considered dangerous to your health. However, they are considered asphyxiants.

Because of the added asphyxiation risk, welding inside of a larger fuel tank can be hazardous.

While there is still a threat posed for smaller, vehicle fuel tanks and any mixtures of argon gas, it is far more dangerous when working in larger tanks where airflow could be compromised.

Therefore, without proper ventilation, equipment, and precautions, if argon is present inside the fuel tank, it can cause suffocation.

Because argon and other gases used as shielding gas are scentless and cannot be seen, they are a danger that often time will go undetected if proper safety precautions are not put in place.

It is always recommended to have a gas detector that will be able to alert you of the presence of argon or other dangerous elements in the air that are undetectable by scent or sight.

Related reading: Can You MIG Weld Steel With Pure or 100% Argon?

How Do You Clean a Gas Tank Before Welding? 

To clean a gas tank before welding, you should clean out the tank with soap and water several times to ensure there is no fuel or fumes left inside.

To do so, you should first confirm the vehicle has no power, making sure the ignition is off, and taking out the battery to reduce the chances of any unwanted sparks from igniting any fuel within the tank.

You can then, using an approved container meant for flammable liquids, drain and dispose of the fuel inside the tank.

Once it is fully drained you can remove the gas tank and begin washing with warm water and soap.

Do this several times to thoroughly remove the fuel and be sure to dispose of the fuel infused soap water in the same manner as the fuel itself.

As gas fumes pose such a threat, it is also important to evacuate the fuel fumes from the tank by using an air hose for a minimum of an hour prior to welding.    

What Causes a Hole In The Gas Tank? 

There are several reasons that a gas tank can get a hole in it. A hole can appear in your gas tank as a result of hitting a large pothole or rock.

If it doesn’t get a hole from hitting those things directly, it is also possible to break the tank hanger assembly when you hit them, causing it to drag and form a hole in the gas tank that way.

You can also get a hole in your gas tank from a buildup of salt and metal-eating chemicals if the tank has undercoating.

Due to the components that make up undercoating, salt is easily retained along the surface and can cause and speed up rusting.

How Much Does It Cost To Fix a Hole In A Gas Tank? 

How much does it cost to fix a hole in a gas tank? If you bring it to an auto shop or independent welding contractor, this cost could jump up to as little as $200, though it can exceed this depending on where you bring it so be sure to shop around for the best deals.

 A professional size tube of JB Weld for instance is only $19.99.

If you add in the cost of sandpaper, brake cleaner, and the terry cloth towel that are recommended tools for application, you would be looking at as little as $40 to $50.  

How much it costs to fix a hole in a gas tank will depend on the size and method used to repair it.

Needless to say, there will be a considerable difference in the cost between having someone TIG or MIG weld the hole shut compared to the cost of doing it yourself with JB Welding.

Related reading: 9 Different Type Of Welding Processes and Their Advantages

Can You Use JB Weld on The Gas Tank? 

Can you use JB weld on the gas tank? Yes, you can use a JB Weld on a gas tank. JB Weld is both water and gasoline resistant and has a tensile strength of 5020 PSI and can withstand up to 550 degrees Fahrenheit.

Apply the putty firmly over the hole, working the edges of the product flat against the tank to create a seal. Once done, allow it to set for 4-6 hours and cure for up to 24 hours.   

This makes for an easy, alternative fix for your gas tank. The steps for preparation are markedly different from MIG or TIG welding.

Fixing your gas tank with JB Weld requires you to clean and sand the gas tank where the hole is.

This will remove rust, grime, and paint to allow the product to adhere to the tank. Use a brake cleaner and terry cloth towel to clean and wipe the sanded area.

You can then take the amount of SteelStik needed for the repair and knead the colors together.

Can You Use Flex Seal on a Gas Tank? 

Can you use Flex seal on a gas tank? No, you can not use Flex Seal on a gas tank. According to, the use of Flex Seal is not recommended for use on gas tanks or other containers for flammable liquids.

It can neither withstand extreme heat or pressure and is therefore not a viable product for fixing your gas tank.  

If you are looking at Flex Seal as a cheaper option then MIG, TIG, or even JB Welding, try KwikWeld instead. It both sets and cures faster, and has two-thirds of the strength of JB Weld.

It can withstand up to 300 degrees Fahrenheit and is rated at a tensile strength of 3,127 PSI, making it a safe and durable alternative.

Best Practices to Safely Weld a Fuel Tank

While there will also be an element of danger when it comes to welding a fuel tank, there are ways to prepare and ensure that you are as safe as possible.

Following guidelines, making necessary precautions, and doing your due diligence ahead of time will help in limiting the amount of risk.

Developing safety practices by knowing the type of job, what types of elements are at play, and what your equipment needs will be, are all part of the prep you will want to take.

Here are some of the most common practices when preparing for a welding job in a fuel tank:

  • Remove all ignition sources when possible and turn any others odd.
  • Drain the tanks but try to do it in a well-ventilated area whenever possible.
  • Make sure you keep the drained fuel in proper containers that are intended for flammable liquids and keep them stored in a safe area.
  • Only utilize approved siphoning equipment to drain the tanks. Using a hose or any other makeshift tool with flammable substances can be dangerous.
  • If you are working with a vehicle fuel tank or anything with fuel lines, you will want to be sure that all the lines have been fully cleared of gas. This is especially important if you are going to be welding near the line.
  • Ensure the area you are working in has been thoroughly cleaned.
  • If indoors, ensure proper ventilation is in place, and the space you are working in is safe from any other flammable materials.

As an additional safety tip, some will also opt to fill the tank with a little bit of water. You don’t need much, but it can help ensure that any falling sparks will land safely in the water, rather than the bottom surface that could have residue gas on it, causing the spark to ignite.

The other main concern for staying safe while welding fuel tanks has the proper equipment.

Not only do you want to make sure the welding tools are the right type for the job, but you also want to have additional safety equipment such as:

  • Gas Detectors
  • Fire retardant welding helmet
  • Goggles and face shields
  • Leather, or fire-resistant jackets, aprons, and other clothing
  • Respirators
  • Heat-resistant boots

Related Article: Personal Protective Equipment for Welders – PPE | List, and Requirements

Welding On The Gas Tank: Practical Tips

One of the most practical tips for welding on a gas tank is to make sure you have proper ventilation.

If you are using MIG or TIG welding the use of argon gas can result in suffocation so it is important to make sure there is no lingering fuel or fumes within the gas tank.

It is highly recommended you do this by using a chemical test to ensure removal.

For added safety, you can also try filling the gas tank with water several inches within the area that will be welded.

All welding should adhere to safety standards and meet contract specifications. It should then be allowed to cool off to within five to ten degrees of 70 degrees Fahrenheit.

Is It Safe to Weld a Diesel Fuel Tank?

You will want to take many of the same precautions if you work with a diesel fuel tank, as with any other fuel tank.

The main thing to remember is that diesel in liquid form is typically a safe substance, but the vapor form of diesel can pose the same threats as other gases and easily ignite.

Once temperatures reach 100 degrees F, diesel liquid can begin to vaporize. So, if you are working with a tank or in an area that has been exposed to extreme heat, this should be a point of concern.

If you choose to weld a diesel tank, remove the fuel and make sure the area around you is safe, clean, and free of other dangerous gases or elements.

For additional information on regulations, requirements, and safety measures, OSHA (Occupational Safety and Health Administration) provides detailed safety requirements when welding, cutting, or brazing.

Is It Safe to Drill a Hole In A Gas Tank? 

Is it safe to drill a hole in a gas tank? Yes, if taking the proper precautions, drilling in a gas tank can be safe. If you are going to drill into a gas tank, make sure to clean it out completely of any fumes or flammable liquids.  

Follow the directions in question “How Do You Clean a Gas Tank Before Welding?”    of this FAQs page to minimize the risk of igniting any gasoline within the tank.  

Otherwise, drilling into an empty gas tank without properly washing it can have disastrous consequences.

Just emptying it of its liquid contents is not enough, as drilling into an empty gas tank is more of a hazard then drilling into a full one.

So, make sure to rid the tank of gas fumes too. Without doing so the drill is capable of creating a spark that will then ignite the contents inside.

Conclusion: Welding Fuel Tanks

Welding fuel tanks will always pose a certain level of danger.

The risk is in the combination of combustible gases mixed with oxygen and the possibility of sparks igniting.

If you take the proper precautions and follow all regulations, it can be done safely.

But without correct planning and adherence to guidelines, it can become extremely dangerous.

Always follow all rules and requirements if you plan on welding any type of fuel tank.

How to safely prepare a used metal gas tank for welding >> Check out the video below

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David Harper

David is the Co-Founder and Senior Editor at David's an experienced fitter and tuner/welder who's passionate about helping others develop in life through new skills and opportunities.

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