wire welds itself to the contact tip

[MoonRise]

As to the burn back, that usually indicates too little wire feed. I will get that on my original MIG, just too small for what I was trying to make it do, so I would slow the wire to get more heat into the metal by welding longer to get the same build up. So predictably I would cross the line and weld the wrong parts together [tip to filler]. The gas issue, these valves are typically "dual seat" valves that means the closed position is similar/same as an old fashioned bathroom tap, easy but these have a seat and washer for fully open this means that there is no pressure on the stem/packing to reduce/prevent leakage out the stem. So open the valve FULLY to insure no leakage from before the regulator. This applies to any high pressure bottles Inert, Oxy, Acet, and Propane. Harry

Harry, two things to correct in your quoted text above.

#1, the wire feed speed IS the 'heat' on a wire feed welder. The WFS (wire feed speed) is effectively the amperage adjustment during welding, and that parameter has to balance with the voltage setting to let you weld with a specific wire (type and diameter and shielding gas being used).

There is -some- adjustment available in the settings (voltage and WFS) to control the overall 'heat' (the energy) that you are using during the welding process. (technical note: the actual weld energy is the product of the arc amperage X the arc voltage.)

Slowing down the WFS means less amperage in the arc and thus less energy in the arc.

more tech discussion from some folks in England who do some welding 'stuff'

What is the difference between heat input and arc energy?

These defined for arc and energy beam processes.

www.twi-global.com

#2, although you do indeed want to open an oxygen or inert gas or propane cylinder valve fully (for the reason you mentioned, so that the valve fully 'seats' in the open position),

you DO NOT fully open an acetylene cylinder valve!!!!!!

You only open the acetylene cylinder valve about 1 full turn +/- maybe 1/2 turn. That's all.

Why? So that in a SHTF situation you can QUICKLY turn off the acetylene flow. Same reason that if the small acetylene cylinder (an MC or a B cylinder) uses a wrench to open and close the cylinder valve you MUST leave the wrench ON the valve during use so that you can quickly turn off the acetylene in an emergency and not have to look for or fumble with putting the wrench on the valve.

Fuel your safety knowledge

The subject of oxyfuel safety is vast and would take volumes to cover completely. In fact, most large companies involved in oxyfuel cutting and welding publish their own procedural guidelines for employees to follow.

www.thefabricator.com

Not fully opening an acetylene cylinder valve is even an OSHA regulation.

https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.253#:~:text=The%20cylinder%20valve%20shall%20always%20be%20opened%20slowly.&text=An%20acetylene%20cylinder%20valve%20shall,three%2Dfourths%20of%20a%20turn.

 

[Jack Ryan]

#2, although you do indeed want to open an oxygen or inert gas or propane cylinder valve fully (for the reason you mentioned, so that the valve fully 'seats' in the open position),

Once upon a time, that was true. As I posted already, the instruction from all of the gas (oxygen/argon etc) suppliers I use is:

An opened valve should never be left against the backstop (i.e. fully opened until resistance is encountered)

Jack

 

[Monza Harry]

Well my older "small" welder was off of setting 4 [highest] once in the twenty six years I've owned it. I tried many ways to get it to do what it didn't want/shouldn't do, slower feed gave me my best results, just my experience. I don't claim to know everything, but I do know what I learned and what I was taught. Things are learned along the way and I don't read as much as I did when I learned 40 years ago so I have missed many updates I'm sure. Sorry if my experience is irrelevant. Oh and if Acetylene was meant to be shut off quickly they would have 1 standard shut off, and it would be a handle, not those f...ing things they do have! Harry
Edit:Mine is a "B" bottle

 

[Opa]

As to the burn back, that usually indicates too little wire feed. I will get that on my original MIG, just too small for what I was trying to make it do, so I would slow the wire to get more heat into the metal by welding longer to get the same build up. So predictably I would cross the line and weld the wrong parts together [tip to filler]. The gas issue, these valves are typically "dual seat" valves that means the closed position is similar/same as an old fashioned bathroom tap, easy but these have a seat and washer for fully open this means that there is no pressure on the stem/packing to reduce/prevent leakage out the stem. So open the valve FULLY to insure no leakage from before the regulator. This applies to any high pressure bottles Inert, Oxy, Acet, and Propane. Harry

it is my belief that acetylene is not a high pressure bottle; safety requires to NOT open acetylene bottle valve all the way. let me know if my understanding is incorrect.

 

[welder4956]

it is my belief that acetylene is not a high pressure bottle; safety requires to NOT open acetylene bottle valve all the way. let me know if my understanding is incorrect.

Yes, this is correct. Typical acetylene cylinder pressure is around 250 psi. You need to be able to shut off the fuel gas quickly in the event of a leak or fire. Open at least 1/4 turn to 1 full turn of the valve.

OSHA:
1910.253(b)(5)(iii)(K)
An acetylene cylinder valve shall not be opened more than one and one-half turns of the spindle, and preferably no more than three-fourths of a turn.