Titanium Pipe Welding Tips and Tricks
Titanium piping has become more popular as more of its favorable attributes are being discovered. Titanium is stronger than aluminum and steel. It is also lighter than steel. It is extremely resistant to corrosion, has a long-use life and low maintenance and operation costs.
If you’ve made the investment of purchasing titanium for you piping project, there are some things to know before you begin to work on it. After all, you don’t want to ruin the titanium that you just spent money on buying. You also want strong pipes that will last many years. Why compromise the effectiveness, strength and durability of your titanium pipes by incorrect welding techniques?
The first thing to be aware of is that titanium is highly reactive metal. It reacts to oxygen making it susceptible and vulnerable to oxidization and contamination. Natural body oils, oils from the forming and drawing process, dust and debris from the shop, cutting fluids and lubricants can easily lead to embrittlement of the titanium and possible welding failure. Having the proper equipment and maintaining a clean work area are important in keeping possible contamination and weakened pipe integrity at bay.
Look for Colors
Titanium absorbs oxygen and nitrogen, creating an oxidation reaction that greatly affects the integrity of the pipe. The level of air contamination can be seen in the resulting colors of the weld. The greatest chance for air contamination occurs over 800 degrees, so measures need to be taken to shield out air when the titanium is heated over 800 degrees.
Discoloration in a weld is an indication that something is wrong. Some discoloration is accepted however. Ideally, a bright silver is the best weld color. Silver, light straw, dark straw, bronze and brown discoloration are all acceptable discoloration. Violet, dark blue, light blue, green, gray and white are discolorations that are not acceptable and indicate that the integrity of the weld is compromised.
If any of the unacceptable colors appear, they must be removed before additional welding is commenced.
Consider the Filler Metal
If the thickness of the pipe that you’re welding is less than .010 inches, then you’ll need a filler metal to make the wall of the piping able to be welded. It is recommended to use a metal that matches the yield strength of the grade of titanium that is in the piping. If the filler metal is not an exact match, the integrity of the pipe will be compromised. For these reasons, it is highly recommended that a titanium rod be used as the filler metal.
It is important to keep the filler rod just as clean as the tubing. Using a lint-free cloth and acetone or methyl ethyl ketone cleanser to clean the filler rod just prior to welding. To prevent the body’s natural oils from contaminating the filler rod or base metal, always wear nitrite gloves when handling titanium.
When beginning to weld, clip off the end of the filler rod before every use. This will help prevent contamination of the weld pool via the filler rod.
Clean the outside of the titanium tubing by using a stainless-steel brush and when welding, it is recommended to use the dab technique to help bolster the mass of the pipe.
Be Sure to Properly Shield Gas
When heated, titanium becomes highly reactive and readily combines with oxygen, nitrogen, hydrogen and carbon to form oxides. Oxidized wields can result in a useless part that needs to be scrapped. To reduce the risk of oxidation, the heated area of the piping needs to be shielded from air until the temperature drops below 800 degrees.
Also, check the purity of the gas. Argon gas is the most commonly used gas with titanium should be no less than 99.995 percent pure and with no more than 5 to 20 parts per millimeter free oxygen. It also must have a dew point greater than -50 to -75 degrees.
A post-flow shielding gas timer is also great to have. Its output should be at least 250 amps.
Other Tips and Things to Watch Out For
- If the titanium sheet or pipe lining density is thin enough to be penetrated from the other side or if it gets red hot, then both sides of the weld need to be air-shielded.
- Using a standard sized #7 nozzle will not effectively shield the heated area from air contamination. A larger one is recommended.
At Titanium Processing Center, you’ll find a variety of titanium products including tubing, pipes, rods and sheets. We also have all grades of titanium so you can be sure to get the best one specifically for your project.