Plasma Transferred Arc (PTA) Welding

PTA Hardface Welding

Plasma transferred arc welding, often referred to as PTAW or PTA Welding, is a form of plasma arc welding and hardface welding that uses a tungsten electrode and the workpiece as the anode to create and transfer a plasma arc inside a stream of ionized gas. This reaction creates heat and a plasma state that can melt and apply metallic materials to other metal surfaces at a temperature of 23,000 °F. The heat energy of the constricted arc creates deeper weld penetration in a narrower field. This reduces the heat affected zone, increases the welding speed over TIG and MIG, and creates an incredibly stable arc for precise surface coatings.

PTA Gun Diagram

PTA Welding Surface Solutions

PTA welding has many benefits as a laser cladding alternative for hardfacing applications where a metallurgical bond is necessary. It can handle abrasion better than most thermal spray coating processes and can be built up much thicker. The metallurgical bond also allows it to operate in environments where impact damage is likely to occur.

Common PTA Weld Hardfacing Materials:

  • Nickel based alloys in the Colmonoy® product line
    • Colmonoy® 6
    • Colmonoy® 56
    • Colmonoy® 69
    • Colmonoy® 88
    • Many more
  • Cobalt based alloys in the Stellite™ or Wallex™ product lines
    • Stellite™ 1
    • Stellite™ 6
    • Stellite™ 12
    • Wallex™ 50
    • Many more
  • Tungsten carbides
    • Wallex™ 55
    • Colmonoy® 75
    • Colmonoy® 635
  • Stainless steels 

Common Parts That Benefit from PTA Hardfacing:

  • valve stems and seats
  • auger flights and large screw flights
  • pump components
  • direct impact cutting tools

PTA Hardfacing Properties 

Bond Mechanism


Max Spray Rate

4-26 lbs/hr

Coating Thickness Range


Special Features

Wear and abrasion resistance, corrosion resistance, metallurgical bond, lower HAZ than traditional weld

Wear Resistance


Corrosion Resistance