Highly Efficient Post Weld Heat Treatment (PWHT) Technology

Piping installation involves tens of thousands of PWHT points in a large plant, and dozens to hundreds of points even in a small maintenance project-a fact that means the impact of PWHT on a piping construction schedule can be considerable. This highly efficient PWHT technology using induction heating is a time saving technique that enables a far higher heat-up rate (1,000 degrees C/Hr) than conventional PWHT with an electric resistance heating element.

Induction coil One-touch-operation coil Coil application on furnace header tube welds


Rate of Heat-up and Efficiencies
Heat-up Method Rate
(degree C/hr)
Conventional electric resistance heating 200 1 step/night
Induction heating More than 1,000 2 steps/night
  • Wide and uniform heated zone
    Wide enough to cover ASME-specified uniform heated zone at PWHT
  • Highly accurate temperature control
    Inverter-controlled power source enables accurate heat-up/hold/cool-down steps
  • High level of safety
    Differ from annealing with an electric resistance heating element, a non-heat-generating induction coil assures a high level of safety
  • Easy installation
    One-touch-operation coil (a built-in coil sheet to be placed around piping) enables simple fixing and removal as compared with induction coil winding around piping


  • Piping construction in general, furnace tubes


Plant/Piping Materials No. of Joints
Amine Plant Carbon Steel 200
Gas Plant Carbon Steel 800
CCR Plat. 9Cr-1Mo+Incoloy800 250
HDS/CCR Carbon Steel,9Cr-1Mo 800
CCR Plat. 1-1/4Cr-1/2Mo 50
CCR Plat. 9Cr-1Mo 500
Gas Plant Carbon Steel 160
Gas Plant Carbon Steel 850