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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.

Coil application on furnace<br />
header tube welds

Coil application on furnace
header tube welds

Induction coil

Induction coil

One-touch-operation coil

One-touch-operation coil


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

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