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Comparison of Twinwire HotTIG v other proceses for Corrosion Resistance Alloy (CRA) weld cladding
Parameters:

CRA material: Inconel 625
Dilution requirement: <5%
Processes: Hotwire TIG, Pulsed MIG
Weld length: 3000mm
CRA height: 4mm
Pipe Orientation: horizontal
welding position: 1G
welding times in hours
Number of layers : 1 or 2

spoolbodye.g TwinWire HotTIG is used for CRA cladding of pipes and spool bodies


The Table below compares the actual welding times of pipes of different bore diameters
using the TwinWire HotTIG and Pulsed MIG processes

welding process Bore size 6 12 24 30
SingleWire Hot TIG
2
19.4 38.3 77.69 97.1
SingleWire Hot TIG + oscillation
1
17.4 34.9 69.9 87.4
TwinWire Hot TIG + oscillation
1
  21.8 43.7 54.6
Single Arc Pulsed MIG
1
11.6 23.3 46.6 58.2
 
No of layers
welding time (hr)

Comment : Single arc Pulsed MIG is comparable to TwinWire HOT TIG with oscillation.
Both processes are capable of achieving 5% dilution in a single layer weld


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TwinWire™ HotTIG weld cladding

The TwinWire™ Hot TIG process is a PEC process used extensively for weld cladding pipes, spool bodies, tubing hangers etc with the component bore in the horizontal position.
Welding in this position offers a number of productivity, metallurgical and weld finish benefits.
•  High qulaity weld overlay using the HotWire TIG process
•  Weld thickness and iron dilution requirements met in a single layer deposit
•  High productivity (3kg/hr)
•  Controllable weld thickness eliminates material waste, reduces machining & welding time, optimises consumable usage
•  Control of metallurgical properties of the weld bead by using two, carefully selected, different consumables

TwinWire™ HotTig welding Process
Two filler wires are fed into a single arc from the same side of the tungsten electrode. The component is held in the horizontal position. Each wire has to be pre-heated (hotwire) prior to melting in order to achieve high metal deposit rates. The large amount of metal melted requires that the torch is oscillated (weave) to spread the weldpool which produces a weld deposit of between 10-20mm width. The speed of oscillation and that of rotation (welding speed) are critical to achieving the required weldment height, iron dilution, surface finish and fusion depth.
The weld current pulsing rate also needs to be synchronised to the rotational speed.
This synchronisation of parameters is done automatically by our SynerTIG™ welding control system software. If the operator changes any of the synchronised parameters, an appropriate correction is made automatically to other related parameters to ensure the weld inetgrity is maintained.

TwinWire Torch
TwinWire HotTIG welding

weve weld
TwinWire HotTIG weld