cold weather welding

so I was in the shop tonight working on assembly of my front end and realizing that my space isn't particularly well heated. it got me thinking.

Does welding in cold weather (on cold steel) make the welds or surrounding steel brittle?

should one pre-heat the sections to be welded? or am I making a mountain out of a molehill.

if it is an issue what temp should one be concerned? my shop was probably about 40 when I went out and fired up the sad little heater--probably didn't get above 55.

thanks in advance for your thoughts

 

your good, i only wish my shop was 55

 

I cant remember the exact "critical temperature" but in production welding for any company I worked for we did not allow welding on steel that was below "room temp" say 60 degreees. You can definately run into brittle weld issues from too rapid cooling. Then again I've been involved in construction sites were they were welding on steel at near zero temps without apparant issues. Myself I would try to get the material to the 50 degree range if possible, especially on steering components. For any alloy steels you need pre-heats into the 300 degree range depending on the material. Most welding books say not to weld at temps below "room temperatures".

 

LOL. This shop's like the one I had in iowa (only smaller). I got spoiled by SC temps that rarely dipped below 40 in the winter for the last few years--however I'd rather have to invest in a heater than deal with those summers

 

Well gents I don't have any answers but the next time I see one of the welders on the Alaskan pipeline that I know I'll ask him if he brings the pipe up to room temp before welding it. Or I'll ask my son who tig welds stainless daily in a lot less than desirable conditions. Around here 55 is tshirt weather for some guys I know so I don't think that would be considered the least bit cold for welding anything.

 

.....Hi......My son is a welder for a major pipeline company.....He said out side temp affects your body more than the steel............he does stick welding....maybe wire feed welding needs warmer temps.......I know I've welded in my cold shop with no problems........

 

I use a self ignite propane torch to make a light pass over the seam when cold. It helps for the first strike and drys the moisture out of the seam.

 

Inatimate objects do not "feel" the cold and windchill like humans. Breeze is bad when welding, regardles of the temp

 

I don't think I'd worry about it in a shop condition even in the 40s. unless these are very heavy sections or critical weldments.You could always keep some postheat on it by wrapping in welding blankets. I did some sub freezing welding on a ski lift with a forest service inspector taking pics the whole time. Couldn't get a straight answer on "their" procedure so we used a preheat to kill the chill and insulated afterwards. We tried one full pen joint on 5/8" plate about 2'long as a test,no special pre or post ,lost that one on the root,sounded like a rifle shot. So we used preheat and wrapped as we went . This was 35 years ago and the lift is still running to my knowledge.

 

Holy crap I wish my garage got up to 50's today, it was lower 30's all day in there today.

 

Apparently not or all of those boiler room pipes that we welded in sub freezing weather would have blown up by now. Those iron workers were always up on those decks with us in the winter time. To my knowledge they are still standing. I never met a wimp up on those decks.

No it makes no difference.

 

40 is'nt cold so I would'nt worry about it.

 

Never had an issue with it other than hands being to cold to function with full dexterity . I prefer welding in cooler tempts casue I'm not so hot with all the gear on

 

I dunno, bridges are built in the winter so are buildings.

I try not to weld when it is in the lower 20s out but its because I don't like the cold. I have welded on structures when it was down in the teens. They are still standing although I'm sure it was not my exceptional welding skills that caused it.

You should be alright. You can certainly preheat and it won't hurt a thing. If your metal is real cold it is going to take more to get it up to the proper temp for good penetration. Usually if I am welding on a forged piece or a piece of cast aluminum I preheat anyway, I don't really know how necessary it is but that was the way I learned to do it.

 

CSA W59 Standard outlining requirements for structural steel welding Clause 5.1.2
"Welding shall not be done when the ambient temperature is lower than
-18C (0 F) except with the express consent of the Contractors Engineer".

All other codes and standards for boilers and pressure piping and vessels have similar requirements for welding at lower temperatures.

Another thing to remember is that all welding work done on critical components like structural steel or boilers and pressure vessels-pressure piping is done to codes and standards and is subject to welding procedures and strict quality control inspection.

The welding procedures specify material types and filler metals as well as plenty of other requirements such as pre-heat,post -heat etc.

So to blatantly say that piping and structural steel etc. etc. have no requirements is wrong.

If you are working on cold steel in the cold, at the very least I would use a torch to warm the metal to the point where it forms a "sweat" that is moisture appears on the surface from condensation as it is heated, then dries as it evaporates.

That would be adequate warming-pre heat.

 

You will notice that there is an optimum temperature for a good bead flow and penetration, to preheat any metal is going to give you a better result, they do preheat the piping on the Alaska pipe line, they have a hoop that they fit over it with about 20 propane nozzles on it so they can get a nice spec weld that will pass the inspection. The guys with the most beautiful welds are plying that heat right in a 20 degree range out of 500 degrees, they can tell by that puddle flow exactly what that temp is. If you really want to do the very best welding you can every time you do it, yes it is important.

 

welding isn't painting.

 

I'm a welder by trade,boilermaker actually, and my .02 cents is that temp doesn't matter. They have codes for high pressure tubing but they are very strict procedures and don't pertain to shop welding

 

i had some probs with my 75-25 argon mix..my welds started looking like ass.i was told to unhook the bottle lay it on the ground and roll it back and forth..he said the oxgen and argon can seperate..it helped....

 

Never seen anybody killed cause their paint job failed.
Go ahead and preheat. hings just go better with warmer metal.

 

I would be more worried about damage to the welder. Some Mig and Tig machines do not like welding in cold weather. Coil and resisters have been known to blow at start up, if the machine was not allowed to warm up before you start welding.

 

Great question falconsprint63. I have a ton of repect for career welders, and I believe we've got a few answers here with a consensus: it don't really matter that much, especially here in the S.E.

I work in a facility with a boiler and a lot of 4" & 6" stainless pipe, much of it tig welded in cold weather. But it is a great question.

 

I understand the concern. Here's my take on it:
I once tried to press a piece of tubing into a hub for a project, and there was less than a .050-inch difference between the tube and the hub. I stuck the tubing in the freezer over night, then the next day put the hub in the oven and brought it up to 450 degrees. The hole in the hub didn't expand enough, and the tubing didn't contract enough, to allow them to be press-fitted together, even with over a 400 degree difference in temperature.

I don't think the contraction of steel at 30 degrees is significantly more than 50-degree or 70-degree steel, and I don't think a simple 20, 30 or 40 degree difference in material temp is going to affect a weld.

-Brad

 

I work for oklahoma natural gas and im around pipe welders all day....we have to pre heat the pipe to 350ish before welding(stick using 6010 and 7010)
weld on cold steel and then pre heat the metal and see how much nicer the weld is and the penatration at first is alot better

 

And this post proves you have no idea what you are talking about. The temperature of the metal regarding contraction or expansion is not a factor in the quality of a weld.

The effect of the metal temperature however can have a metallurgical effect on the weld in regard to heat input and cooling rates and will affect the physical and mechanical properties of both the weld and the parent metal in the heat affected zone.

 

I understand that--but the original poster is talking about a difference of twenty or thirty degrees. There's really a difference in welding steel that's 40 degrees versus 70 degrees?

-Brad

 

For it to become brittle, it may need some additional carbon, however mild stuff (low carbon) can be cold worked to a point where it will fail. Or as mentioned in post #29.

 

Probably not a huge difference there depending on the welding process used. A Mig weld freezes faster and is by nature a harder less ductile weld that the same weld done with a different process.

In that regard, the chill effect of the cooler metal may have a small effect on the weld.

With a different process like Tig which is slower and allows more heat input because of that, a little extra amperage to offset the cold steel would probably overcome the problem.

And would result in a better weld of course.

 

Don't be too sure of that, even with lower carbon steel, rapid cooling will cause a metallurgical effect called martensite which is hard and brittle.

 

Years ago when I had a TV They did a show on the first Alaskan pipeline build.

They showed a large ring that went around the pipe joint with many heating torches, before the guys welded. I don't recall them saying much about the technical reasons.

I kind of recall later on that some welds were failing because the preheating was overlooked in some locations along the line?