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Question:

Soldering aluminum cylinder, strength?

I need to make an aluminum cylinder out of 1/8 6061 plate and tube. I don't have a TIG setup and was considering using Bernzomatic aluminum soldering rods. The cylinder will be pressurized from 20-60 psi. Assuming a clean job, is this pressure ok? How much pressure can the joint take? Also, although the solder does not need flux, should i use it anyway?

Answer:

to your setup i might merely persist with the iron. It would not sound like the burden mark downs is going to be properly actually worth the greater suitable probability for a on a regular basis motive force. forged iron is merely greater rugged and can take greater abuse than aluminum. Aluminum has its place yet its no longer in a on a regular basis motive force like it variety of feels you're development.
Whether that weld will be OK depends on the diameter of the cylinder. The force on the weld will be equal to the operating pressure time the radius of the cylinder, with the wall opposite the weld have an equal force. Divide that force by the thickness of the weld to figure the stress. You want to have a safety factor of about 3. As the Bernzomatic has either a brass or aluminum head, which would melt at the temperatures which are required for true welding (melting metals so that they flow together), you will be performing brazing with a Bernzomatic. I cannot comment on the strength of the brazing bond. The thickness of the brazing metal deposit depends on the strength of the brazing alloy, which I also cannot comment on. 6061 will melt at 1206°, which you will not approach with the Bernzo kit. A blowout of a metal cylinder at 60 psi could be pretty ugly. I suggest that you befriend someone who has a TIG welder and get their help. A properly welded 1/8 thick cylinder could handle about 660 psi with no problem. If you create a lap joint, using an outer strip of aluminum, and then band your cylinder with stainless steel hose clamps, you will be relying upon the brazing only to provide a gas seal. The strength would come from the hose clamps. You still need to do some calculation on forces involved. A 1/2 wide stainless hose clamp will probably hold back about 240 lb. of force with a comfortable margin of safety.

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