Pipe Welding Tips and Techniques

Pipe welding was formally done using three approaches: The Gas tungsten arc welding (GTAW), gas metal arc welding (GMAW) and the shielded metal arc welding. The Gas tungsten welding also called the TIG has low travel speeds, high heat input and high level of skilled operation is required for this method. The gas metal pipe welding is faster than the GTAW though, fusion in this method varies due to the heat input difficulty. On the other hand, shielded metal arc welding popularly called "STICK" is cost effective. One disadvantage in this method of pipe welding, is the frequent starts and stops experienced in the welding process. The open root welds can be completed 3 or 4 times faster than the GTAW when using the surface Tension Transfer process. This process employs very high frequency inverter technology to create a high quality weld with less smoke.

In controlling the spatter and smoke, the STT welding process is used. This process results in a wholesome backbeat without shrinkage from the 12 to six 0'clock positions. Again, as current control does not depend on the wire feed speed, it brings more flexibility in any condition. The STT is a Lincoln electronic process that uses wave form control technology to rapidly control current during the welding process. It does not use the constant voltage (CV) or the current voltage (CC). Rather, there is an automatic power adjustment to the heat requirements of the arc.

This pipe welding process reduces spatter and smoke. When spatter is reduced, it minimizes the final weld preparation and gives the welder more time before the gun nozzle would finally be cleaned up of accumulated spatter. There is a reduction in cost as Sparta is reduced due to the electrode being applied to the weld joint. Though the GMAW process does not directly control the current, it does control the average voltage. This might increase the fluidity which will result to a flat or shrinking of the internal body. This is called "suck back". Again, when the conventional short arc is in use, the welder must make sure that there is good penetration and fusion by concentrating the arc on the leading puddle edge. There wont' be proper penetration if the arc is not close to the puddle. But when it is too far ahead, it causes the electrode to shoot through the gap and brings whiskers that form inside the pipe.

Because STT independently controls the welding current, it becomes easier to control the temperature which will ensure proper fusion and penetration. This is why it is used commonly in open root pipe welding processes. In the 5G positions, the welder only has to stay in the puddle. This is why experienced operators prefer this process both in comfort and ease of welding, particularly the improvements made in the reduction in spatter when welding in the 6 0'clock position. This process of pipe welding is gradually gaining recognition along with other applications that require proper control of heat input. Because of the direct control of the heat, the internal backbeat profile is even controlled.

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