Today I would like to talk about how cold weld when stick welding and stick welding procedures or rather lack of them contribute to broken welds and consequently weld repair. On my travels to St. Marys and Stratford with my mobile welding service I have noticed that stick welding although relatively medium difficulty technique when used improperly causes many broken welds. Certainly, stick welding is the most popular welding technique on many welding projects and therefore statistically speaking most broken welds are initially done by stick welding. Cold stick welding on large size weld is the most common source of failure. When you weld thick metal and the final weld should be ¾ or 1 inch thick, the first bead is extremely important for the final weld strength. Most welders put this first bead cold. They forget that the whole weld joint is cold and it will take some welding time to worm up the piece. The reverse of the same situation causes the same problem. In this situation welder welds stick very thin metal and uses same amps as he or she would weld medium thickness carbon steel. Lack of backing plate that would absorb the heat cause a poor weld. Reduction of amperage could correct the problem to certain degree but the limitation of stick technique in this case cause substandard weld. Another factor is the assembly of pieces and specifically the gap between assemblies as it refers to the weld size. Real life situation create the need for modifications of welding procedures as they refer to the weld size when a gap is created. We have to remember that we have to increase the weld size by the size of the created gap. Moreover, the first bead on the gap should be done with the penetrating rod that is not specified in particular welding procedure. We should also remember that cleanliness, when removing the slag from the large weld is crucial for the overall weld strength. Remember, using proper wire wheel on the grinder makes the magic. It is worth noticing that stainless steel weld requires stainless steel wire wheel. Generally speaking, I repair broken stick welds with Tig welding. This concludes my few fought about cold weld when welding stick. Cheers from a welding truck my fellow welders. Call 519 872 - 2552 when facing broken weld.
Thursday, 17 May 2012
I've traveled with my mobile welding service all over Ontario fixing broken welds. In my weld repair experience the initial cause of a broken weld was so called "cold weld". I think cold weld can happen to anybody because we, the welders, often do not think before striking an arc. Unfortunately, due to our negligence welders form a weld that lacks sufficient penetration, contains slag impurities or even empty pockets, and then such weld brakes due to lack of strength. Recognition of an imperfect weld I call "reading" the weld. Each welding technique has its own signs of a cold weld.
Friday, 11 May 2012
After a recent job in St. Thomas I came into conclusion that I should start writing more about weld repair. So today I will say a few initial words regarding root causes for a broken weld and consequently the necessary weld repair. In my experience here are the root causes for broken welds:
1. Cold weld
2. Wrong welding technique for joint material used, for thickness of based materials, for specified vibration, for existing heat expansion or heat contraction
3. Lack of welding skills
4. Inadequate weld joint preparation
5. Inadequate cleanliness of based materials
6. Changes of vibration due to mechanical failure
7. Wrong weld design
8. Wrong rod composition for based material used
9. Size of weld too small
10. Lack of preheating
In following blogs I will try to evaluate in a few words each root cause of broken welds and weld repair. I would like to welcome other welders' point of view on this topic.
Monday, 7 May 2012
This blog is about practical welding advices. In that shell, I would like to ask all welders who weld vertically stainless steel about methods that avoid high welds. I think that welding stainless vertically is difficult since it is a "darker" weld and a small amperage difference from ideal cause high weld or "grapes". I personally like to test first and use a smaller rod to have more control. Moreover, I increase horizontal wave a little and I try to keep the rod as close to the piece as possible. However, I still think amperage set up is critical and the tolerance would be about 3-5 amps. So, if you can provide any other advice for welders welding vertically stainless steel, I would highly appreciate it.