The process of welding gas or diesel tanks can be extremely dangerous and there is the possibility of igniting fuel vapors. If the welder is using the welding process of MIG or TIG inside a fuel storage tank, they are in danger of suffocating from fumes if argon gas is used. This not only poses a threat to the welder but to anyone who tries to rescue the welder from the interior of the fuel tank. We’ve listed some tips below will help keep you safe if you are required to perform any welds in a fuel tank.
- Before beginning to work on the fuel tank you should first insure that the battery has been disconnected and that the ignition is in the off position. By making sure that all of the power sources are off, you are reducing the chance that a spark might set off any fuel in the tank. Once you have done this you can then proceed to drain the fuel tank of fuel that may still be inside.
- The next step would be to completely drain the fuel tank in an approved gas container designed for use with flammable liquids. It is highly recommended that the draining of gasoline tanks not be performed over or near inspection pits.
- Once you have completely removed all of the gas from the tank you can now remove it from the vehicle. It is important that you use the proper ventilation equipment when working with gas tanks due to the high amount of fumes that may be present.
- After you have safely removed the gas tank from the vehicle you should thoroughly rinse the tank several times with warm, soapy water. The water should be placed in an approved flammable container. Do not dispose of the water in the street or in drains — it can cause a very dangerous situation.
- Your next step will be to evacuate the fuel fumes from the tank using an air hose for a minimum of one hour or until you can no longer detect any fuel fumes. You can conduct chemical tests to determine whether all of the fuel fumes have been thoroughly removed and whether the tank is safe to weld.
- Any welds performed on the tank should be done according to contract specifications and follow all safety standards. When you are finished with the welding, the tank should be allowed to cool to within five or ten degrees of 70 degrees Fahrenheit.
- Once the tank has reached the desired temperature and you feel it is cool enough you can now test the integrity of the weld and look for any leaks by placing a small amount of fuel in the tank. If the tank is leak free, you can now reattach the tank following the manufacturer’s specifications.
Welding aluminium presents some unique challenges compared to welding steel or other common materials, particularly in terms of the chemistry and crack sensitivity. In many cases, welding aluminium requires following some special procedures. Important factors when welding the material include: selecting the right filler metal; proper storage and thorough cleaning of the base material; and proper welding techniques.
Here are some common challenges when welding aluminium and key best practices for addressing them.
Characteristics of Aluminium
A perfect weld is all about chemistry, reduction of hydrocarbons, and proper welding technique. The characteristics of aluminium differ from steel in several ways. The melting point of aluminium is much lower than that of steel and aluminium also has an oxide layer that melts at approximately 3,700 degrees. This oxide layer is much harder than the aluminium and helps the material resist corrosion and abrasion. However, it also acts as an insulator that can create issues during welding.
Because the strength of aluminium tends to increase as service temperature decreases — unlike steel, which becomes more brittle as service temperatures decrease — aluminium is commonly used in cold temperature applications, such as cryogenics and liquid natural gas transportation.
Best Practices for welding aluminium
- Don’t weave – While a weave technique commonly is used to weld steel, it should not be used with aluminium. Instead, use a stringer bead, which helps ensure proper penetration and fusion. For aluminium GMAW, be sure to use higher heat inputs and a fast travel speed to stay in front of the puddle.
- Clean the metal – Thoroughly clean the base material before welding to remove oil, dirt, residue, and moisture. This helps ensure the best results and reduces chances of porosity. An acetone or aluminium cleaner works well for removing hydrocarbons that may be on the material surface. When prepping the weld joints, don’t blow them off with compressed air, as this can introduce contamination from moisture and oils if shop tools are used.
- Remove the oxide layer- After cleaning, use a stainless-steel brush — one that is new or has been used only on aluminium — to remove the aluminium oxide layer before welding. As mentioned previously, aluminium oxide has a much higher melting point than aluminium. It acts as an insulator that can cause arc start problems and very high heat is required to weld through the oxide layer. This can cause burn-through on the base material and porosity, since the oxide layer tends to hold moisture.
- Store it properly – Storage for base materials and filler metals also play a role in preventing porosity. Store sheets of aluminium inside when possible. If they must be stored outdoors, stand the sheets vertically rather than on top of each other to prevent trapping water, which will contribute to the formation of a thicker hydrated
- Monitor the temperatures – Consult an aluminium filler metal guide or code to determine the appropriate preheating temperature ranges. Preheating can be used to reduce the thermal effects of section size when welding thick base metals or dissimilar thicknesses, but keep preheating to a minimum for aluminium applications.
These tips can be used to ensure the safety of the welder as well as those around them! However, you could just bring your fuel tank to the preferred specialists here at Silverton Radiators Pinetown! Give us a call for all your fuel tank repair needs! We also supply refurbished fuel tanks that are ready to be installed.