optimum root opening

By caweldtech.com Date 05-02-2005 16:10

What is the optimum root opening, for complete penetration weld, in a single pass, one side only for the material and joint described below?
Weld process is GTAW, 3/32 tungsten, 2% thor.

Titanium 6Al 4V, 0.100” thick
Single V butt joint, 60 Deg included angle with 0.025 root face.

Also, please direct me to any formulas that apply for determining root opening.

Thank you,
Dave

By welder5354 (**)

Date 05-02-2005 16:58

Root openings are determined when the joint is qualified on the WPS.
You have indicated that your material is 0.100" thk.. That's not very thick for a V butt joint. Should that be 1.00". If it is 1" thk., then your root opening should be at least 5/32". It also depends what dia. of pipe you will be welding. In any welding process, there is no set rule for root openings. The fitter and welder must take other factors into consideration; for example> overall measurement of the completed job, if it is critical. We have done several courses here on titanium. The root face for a 6" sch. 40 Ti. pipe would be 5/32". To get good penetration on titanium, just leave the filler rod on one bevel (no root face) then use your tungsten to work the filler into the root opening.
For 0.100", a square butt joint should be OK.
Are you using a trailing shield?
welder5354

By caweldtech.com Date 05-02-2005 17:31

Thanks for the Replies.

The material is 6Al 4V Ti, 0.100” (one hundred thousands of an inch ).

I am using an inert atmosphere glove-box that maintains an Argon atmosphere of < 10 ppm Oxygen and < 10 ppm Moisture. The welds always come out nice and shiny, like liquid mercury.
My Ti welding is usually in the thickness range of 0.005” to 0.070”
The 0.100” is giving me a bit of trouble. I will try the method Welder5354 suggested.

Thanks,
Dave