Troubleshooting must be performed by fully trained personnel under the guidance of the welder manufacturer. Most HF Welder manufacturers have a service staff available by phone 24 hours a day, 365 days a year. Operators should never hesitate to contact the manufacturer for help. If a problem cannot be solved over the telephone, the manufacturer will dispatch a field engineer to perform on-site emergency service. Welder faults fall into several categories: problems outside the welder, in the weld area setup, or in the mechanicals. If the heat fluctuates without adjustment of the welder controls, the problem could be either impeder saturation or a breathing or rolling vee. If the impeder is going in and out of saturation, this will be shown as weld current not flowing regularly in the vee and flowing on the inside diameter of the tube. This typically happens if the impeder does not get enough coolant or the coolant lines become blocked during operation. The solution is to verify whether the impeder coolant is flowing properly. If it is, then the strip presentation to the weld point should be examined. The strip must address the weld point in a stable manner (the vee length must remain stable). If it varies, the weld current will vary, causing a noticeable heat fluctuation in the weld. A similar problem is insufficient heat generated into the weld vee, especially on small-diameter tubing. This can happen because no impeder was used, or it was too small or, depending on the tubing size, the vee length is well beyond the norm for that particular tube outside diameter. The rule of thumb for HF induction welding is that the impeder should occupy 75 percent of the outside diameter of the tube and should extend 0.125 inch beyond the apex of the weld rolls, extending upstream through the coil by one coil width. The more impeder an operator can fit inside the tube without any mechanical interference, the more efficient the welding operation will be. The impeder is the most easily overlooked component but perhaps the most important for welder efficiency. The vee length should be kept to a minimum. Typically, its length depends on the mill design, but it should not exceed the tube outside diameter. Another kind of problem is a short circuit in the welding system, usually noticed by a fault registered by the diagnostics. When a fault is registered, first visually inspect the system with power off. Check the oscillator, output station, and power supply to identify anything unusual, such as water leaks, burning, arc marks, or damaged or cracked components. If no obvious problems are found, the system needs to be separated and Tarpaulin Welding Machine troubleshooting should begin.
