Ambient Temperature and Humidity effects

Date 07-02-2002 16:34

I don't know about atmospheric supplied oxygen for the outer cone. I thought all the oxygen was supplied by the torch except for incidental admixture. Shop ambient temperatures and humidity should have no practical affect on the flame since the fuel gas and oxygen are supplied to the torch from a pressurized source and mix together in the torch before they leave the tip thru the torch tip. For that matter I have kept a torch flame lit submerged in a bucket of water just to see if would work. Never tried to cut anything that way because anything more than gradual motion snuffed out the flame. I would also think a torch would stay lit in the vacuum of space if adjusted for it, but I don't think that is high on NASA's proposed experiment list.
If you hear otherwise, I'd appreciate the info.
CHGuilford

By MKaushagen Date 07-02-2002 18:57

A torch in the vacuum of space would also be a source of propulsion in the zero gravity, NASA could get double duty out of it! Hard to do any cutting when you're getting pushed away from the workpiece though.

By CHGuilford (****)

Date 07-03-2002 13:16

Hmm. that sounds like a story line for a "B" movie. Just imagine a space station being saved from a fiery reentry when a space welder lights his oxy-acetylene torch, pulls the cutting lever, pushes the station back into a safe orbit, thus saving the day! (Somehow i don't think it would gross as well as Star Wars but what the hey!)
Couldn't resist the impulse on a slow pre-holiday workday.
CHGuilford

By dee

Date 07-04-2002 00:46

CH,
I believe it was AWS' Welding Encyclopedia, in description of Oxy Acetylene welding torches stated optimum combustion ratio was 3parts O2 to 1 part Acetylene, that regulators are typically set to same pressure (read as flow rate) as tip size, and that additional 2 parts O2 from room air combined outside torch to form distinctive inner and outer cones. Sounds logical? The only gas I know about annoys my wife.

re: torch in tub trick: I also tried it with similar results and had no idea what equipment Mike Nelson used in that episode of SeaHunt.
The book did mention another torch design; perhaps that is what it was built for?

Happy4th
D

By dee

Date 07-04-2002 01:05

Scott
unless you are using the flame as a calibration standard for some kind of equipment I wouldnt worry about temp and humidity for any practical purpose I can imagine, but I liked the question.

Actually I am musing over how they might apply.

You know this will bother me all holiday.

Regards.
D

By scmait

Date 07-08-2002 13:07

Actually something is having an affect on my welding and I did a statistical analysis on data from multiple welds. Temperature & humidity fell out of the analysis as the only two significant variables. My first thought was that the oxygen was the factor, but now I don't believe that there is enough variation in the atmospheric oxygen to cause the variation that is being seen.

By dee

Date 07-08-2002 19:15

I would suspect flame adjustment should compensate for all other variables; more O2 in atmosphere is compensated for by adjusting the valve on the torch? I never thought that hard about the process

I believe a reason for the popularity of electric arc welding is the elimination of a subjective variable; flame adjustment... I may be all wet... but in addition to the size of the flame is it's mixture and characteristic of carbonizing or reducing, which I could only very loosely compare to electrode "stick-out" in GMAW. The flame is of different temperatures according to where the measurement is taken.

How severe were the ambient temperature variations? I would not be surprised if the temperature issue related to the temp of the steel being welded, not the air. As its temp lowers, its tendency to draw heat away from the weld increases, as do other issues in the HeatAffectedZone and indeed the entire weldment. Fortunately, with a torch you can adjust the temperature of steel quite conveniently. I find it much more troublesome to weld in winter cold.

What is your fuel gas?

Does absolute pressure in a tank vary with the barometer? If so how would that relate to [components of] the fuel gas' critical pressure?

Is this an anylitical exercise? Curiosity is valid, but there probably is a reason few (if any) welders concern themselves with these kinds of details. If the issue of primary concern is the weld it's probably OK to ignore the data you collected so far and focus on the nature of the difficulties/deficiencies in your welds... what's going on wrong?

Regards,
D

By scmait

Date 07-08-2002 19:49

These are not of the "melt weld" variety but of the solid state variety. The gases are controlled with a mass flow meter by a PLC. The environment is a production oriented manufacturing floor and there are restrictions to adjustments based on customer specifications.

The variation has occurred within one day during the summer months therefore I don't believe it is part temperature related.

The variation that is seen can cause issues with the customer restrictions, however there has been no degredation in weld integrity seen. I would like to program into the PLC the information needed to adjust for the parameter not accounted for (e.g., humidity or whatever else). This is why I asked the question to begin with. I just wanted to determine if others had experienced this before. Thanks for the information it has helped.

SCMait

By Niekie3 (***)

Date 07-08-2002 20:03

Jislaaik (a word of exclamation and amazement typically used in South Africa) this sounds very interesting. What kind of solid state welding are you performing with oxy-acetylene torches?

Regards
Niekie