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Old 11-27-2017, 10:21 AM
crystallographic crystallographic is offline
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Location: Western Sierra Nevadas, Badger Hill, CA
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Quote:
Originally Posted by AllyBill View Post
Not sure how come folk struggle for penetration with the TIG on aluminium. Give it an extra burst of pedal and push some filler through to the back-side. It's easy enough to put twice as much weld on the back as what's on the front. Prettier with a back-purge too if you can get in there.

Repaired an exploded, TIG welded fuel tank from a dragster recently and whoever welded it had started with the material cold, no preheat on 1/8th material. The result was virtually no penetration and a hard weld where the surrounding material had quenched it but further round, as the heat soaked in, the penetration was much better and the weld more compliant. The tank was pressurised to push fuel uphill but the pressurisation went wrong and blew the end of the tank out with a failure beginning at the origin of the weld. Half the battle is understanding the material.

Will
Blower pressure supplies the fuel pressure in some dragsters.
Things go south when the blower sneezes.
However, it is known that the gas welded tanks can expand when this happens, and though they can no longer be removed from inside the chassis (welded tube frame), the cap is replaced and the car continues through the season - because there are no leaks.

Gas welding does its own preheat.

TIG is sure simple and easy - when you have a gas rig around to help it make the grade.

Choose your filler metal wisely: 4043 was designed for welding castings (after WW1), according to the Aluminum Association. Brittle and hard, non-anodizeable 4043 is still a popular filler metal because the welding supply industry has been giving it out as their first choice, for the past 45+ years ..............

(ps, RCD moved in next door to me here, back in 1982, so we get a little overflow of some of the drag guys. )
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Last edited by crystallographic; 11-27-2017 at 10:25 AM.
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