What makes STT exceptional in open pipe root pass
Surface Tension Transfer is referred to as STT technology. STT is the advanced mode of Metal Inert Gas process with controlled waveform that runs outstanding root pass within less time, in open pipes. STT offers innumerable advantages over traditional arc processes. Different modes and arc processes can be activated on a single equipment. Here is the explanation of some benefits that make STT technology unequalled in root pass and fill ups. See the usefulness of Surface Tension Transfer.
Ease of learning
Very easy and simple to learn and welders can gain command of its usage so quickly. Less training time, eliminating the complexities that were faced in learning of traditional TIG, Stick, MIG, and FCAW processes.
High quality weld
STT provides outstanding and exquisite welds in those jobs which require one hundred percent weld quality assurance and inspection. Easily accessible for fill ups and gaps, up to 5mm (3/16 inch). Prominent weld profile and definition, with minimum concentration of defects is achieved.
High output
It’s usual practice to apply TIG welding for open pipe root pass in order to achieve defects free, uniform and consistent weld. But TIG is a slower process and does not provide high yields. STT offers more production with almost four times faster travel speed as compared to TIG process.
Thicker weld
It deposits thicker welds as compared to other arc systems. Root and hot passes with Stick welding don’t meet the required thickness. As a result thinner welds are subjected to weld defects, incomplete fusion and not proper size welds. On the other hand weld passes with STT technique are almost two times thicker than the Stick welds.
Low hydrogen weld
It produces crack resisting low hydrogen welds that are highly suitable for high strength steels. Root pass with Stick cellulosic electrodes, have highly diffusible hydrogen that leads to cracking in high strength steels. Surface tension transfer technique runs one thicker pass almost equivalent to two passes of Stick welding. This eliminates many defects and good fusion, excellent bead shape and size is obtained. It provides the means of lower pre-heat temperature welding and thus alleviating problem of cracking in high strength steels.
Also See How to prevent Hydrogen Induced Cracking in weld?
Controlled arc and amperage
With waveform control, arc energy is precisely regulated and adjusted during each cycle. This technique is easy to use as the controlled waveform does all the work. In this technique the current is reduced at certain interval to minimize the spatter and fumes while at certain intervals, current value is increased to give quality weld with excellent fusion. Unlike MIG welding, short arc is kept stable, eliminating fumes and spatter.
Back bead control
During root pass, STT runs a consistent weld control back bead at the inner side of the pipe. High peak current is accessible to the inner side through joint gap, ensures good fusion to the gap sides.
Easy to use
Operating the equipment is as easy as pressing the button and your job is done. Welders can change, easily configure and change the modes by simply turning the knobs.
Sensor
For the monitoring and changing of arc voltage, sensor is used in STT technology. Normally a sensing lead is used for this purpose which is connected near to the joint with the help of magnetic source. This sensing device controls the arc voltage and waveform and consequently helps in continuous feeding with no spatter and fumes.
Modes switchable
This one is the unique feature in STT technology equipment. After the root pass with STT mode, welders can switch to the MIG mode, to run next passes. Aside from root passes the equipment is also applied for high quality fill up passes with minimum downtime. Activation of MIG mode by simply pressing the gun trigger. Moreover if you want to apply gas-shielded Flux cored arc welding, switch to the other gun which is readily installed on the same equipment. For large diameter pipe welding, submerged arc welding process can also be activated on the same equipment.
