type of material used for welding (welding rod, wire fed spoll) if a rod is used you'll end up with weak spots from stoping and going with new rods. A wire fed system (mig welders) will give you an even weld. Also there are different types of grades 60/11, 70/18 rods etc. heat setting, too cold= not enough penetration. Too hot and you'll weaken the steel, usually a good welder uses a heat torch to get the material ready so it doesn't brittle the steel, specially in cold areas. In areas where quality is critical, a weld is ultrasound tested for penetration. A good 1"X1/8" weld could pull up to 1000lbs. If the piece breaks between the weld and the pipe it could be that the pipe used is too weak or too much heat was used. If it breaks at the center of the weld then the welder sucks. My $0.02
