Thread: Flaring a SS tube

Because SS can work harden it may be worthwhile annealing a few times while you are forming it.

Michael

Originally Posted by Michael G

Because SS can work harden it may be worthwhile annealing a few times while you are forming it.

Michael

Good point - it looks like my forge may be participating in its own construction.

I just read up about annealing SS and can't find a consistent answer.
The suggestions ranges from, ~800ºC for one hour, 1100ºC and then quenching in cold water, and 1000ºC "for a short period"- whatever that means.

BobL, I am thinking gas blacksmith forge right, you should not need a flare end when burner is in the forge because there is back pressure from the enclosure. However I made one for use as a torch by heating to red and inserting my anvil horn inside the tube and tapping tube with a hammer while rotating it, not as pretty finish as a die could give but works fine. I also remember my tech teacher telling us "a quick jerk is better than a long pull" may be the problem with you winding that die down slowly.

Originally Posted by BobL

Any other suggestions?

Weld it on. Make the flare first on a piece of tube until you've got it right then make a couple and weld them to a 3/4" BSP pipe toe.

You wouldn't believe the number of 316 fittings I've welded together while building this boat.

PDW

Originally Posted by calala

BobL, I am thinking gas blacksmith forge right,

correct

you should not need a flare end when burner is in the forge because there is back pressure from the enclosure.

I don't think I need one either. The burners use natural gas and all the talk about burner flares seems to be for LPG torches?

However I made one for use as a torch by heating to red and inserting my anvil horn inside the tube and tapping tube with a hammer while rotating it, not as pretty finish as a die could give but works fine. I also remember my tech teacher telling us "a quick jerk is better than a long pull" may be the problem with you winding that die down slowly.

I'll give it a crack when my forge is running

Originally Posted by PDW

Weld it on. Make the flare first on a piece of tube until you've got it right then make a couple and weld them to a 3/4" BSP pipe toe.

The usual method is to fix the flared tips in place with some grub screws as they do need eventually to be replaced.

Anyway it looks like I don't need to worry about it.

Hi Bob,

Calala is right you don't need a flare when it's in the furnace, the idea of the flare in free air is to reduce the gas velocity to less than the flame velocity, without a flare it simply blows itself out, but inside the furnace that's generally not an issue.

I've built a number of LPG reil style burners, the latest one is a forced air version, and I've given up on steel tubing for burners, I lashed out and got some titanium tubing from ebay, some guy in Latvia of all places, wasn't all that expensive either, and doesn't burn out

I'm curious to see how you will get on with low pressure natural gas, first impression is that the pressure might be too low.. watching with interest..

Regards
Ray

Originally Posted by RayG

Hi Bob,

Calala is right you don't need a flare when it's in the furnace, the idea of the flare in free air is to reduce the gas velocity to less than the flame velocity, without a flare it simply blows itself out, but inside the furnace that's generally not an issue.

I've built a number of LPG reil style burners, the latest one is a forced air version, and I've given up on steel tubing for burners, I lashed out and got some titanium tubing from ebay, some guy in Latvia of all places, wasn't all that expensive either, and doesn't burn out

I'm curious to see how you will get on with low pressure natural gas, first impression is that the pressure might be too low.. watching with interest..

Regards
Ray

Cheers Ray.

I've had one of the burners (no flare) making a nice fat blue LPNG flame outside the forge without it blowing out but I must admit twas a delicate balance of forced air and any breeze sent the flame sideways pretty easily but I guess that won't be a problem inside the forge.

Thanks for the tip on the Ti - I have nearly 3 m of 304L SS to play with so if it proves no good I will check out the Ti.

I made a 1/2" water pipe LPG torch for my aluminium furnace. My flair is a 1/2" gal socket which I tapered internally, works just fine.

Originally Posted by bob ward

I made a 1/2" water pipe LPG torch for my aluminium furnace. My flair is a 1/2" gal socket which I tapered internally, works just fine.

I'd thought about doing a similar thing but an ally furnace doesn't need to get anywhere as hot as a regular furnace which will eventually burn out regular steel and even stainless steel burner ends.