Weldotherm VAI 80 Induction Heat Treatment Unit

Name: Weldotherm VAI 80 Induction Heat Treatment Unit | Seven Star LLC
Brand: Weldotherm
SKU: VAI 80

Medium-frequency induction for fast preheating and PWHT

The Weldotherm VAI 80 is an induction heat treatment unit for preheating, post-heating and stress relieving of welded pipes and components. Instead of resistance mats in contact with the steel, a flexible inductor laid around the joint carries medium-frequency current and the magnetic field generates heat inside the workpiece itself. Weldotherm states that welds can be brought to preheat temperature within seconds and that set-up time falls because heating mats are no longer fitted and removed.

The integrated program controller follows the programmed temperature profile and shows process values and error messages in plain text. Inductors are adapted to the load and application, and several VAI units can be linked for large components.

Technical specifications

Parameter	Specification
Manufacturer / model	Weldotherm / VAI 80
Power at 100% duty cycle	80 kVA
Induction loops / control zones	1
Primary supply	400/460 V AC, 125 A, 50–60 Hz (500 V AC option)
Primary cable	NSSHÖU 5 m, 4 x 25 mm², CEE 125 plug
Secondary output	1,000 V AC / 650 A, 4–10 kHz
Cooling	air or water
Weight	239 kg (air); 279 kg (water)
Dimensions (H x W x D)	1,500 x 560 x 750 mm (air); 1,690 x 560 x 750 mm (water)
Program controller	TC1000 VAI
Temperature inputs	4 x type K (NiCr-Ni), standard compensating jacks
Control range	0–1,200 °C
Protection class / ambient	IP21 / -20 to +40 °C, 90% RH non-condensing
Order number	102601 (air cooled); 102701 (water cooled)

VAI series sizes

Weldotherm builds the VAI in three power ratings. All share the TC1000 VAI controller, one induction loop and four type K inputs:

Model	Power	Primary	Secondary	Cooling and order no.
VAI 40	40 kVA	400/460 V, 63 A, CEE 63	700 V / 600 A, 4–10 kHz	air 102600; water 102700
VAI 80	80 kVA	400/460 V, 125 A, CEE 125	1,000 V / 650 A, 4–10 kHz	air 102601; water 102701
VAI 160	160 kVA	400/460 V, 250 A, fixed connection	1,000 V / 900 A, 4–8 kHz	air 102602

Why induction instead of resistance mats

In general, induction heating puts energy directly into the steel under the coil, so the surface does not have to be heated through a contact element and the heating rate is limited mainly by the material and the power available. Insulation can stay in place under the inductor, and coils do not wear out the way ceramic elements do on repeated cycles. Resistance heating, on the other hand, needs less capital outlay and is easier to split into many independent zones; many contractors use both methods depending on the job.

Power is chosen from the heated mass, target temperature and heating rate, and the inductor is laid out to suit pipe diameter and wall. A standard set of 7.5 m power cables and a printed manual are included; options are a paper chart or screen recorder, wired or LAN remote control, a 500 V primary supply and cables up to 15 m. For resistance heating with mats, see the Weldotherm WR 10,5 inverter unit.

Documents and quotation

The Weldotherm VAI series datasheet is attached to this page; more equipment is listed under Induction Heating & Preheating.

For a quotation, give pipe sizes and materials, required preheat or PWHT cycle, supply voltage, preferred cooling and recorder option.

WELDOTHERM Gesellschaft für Wärmetechnik mbH, based in Essen, Germany, manufactures equipment for the controlled heat treatment of welds and has worked in this field for more than 40 years. Its range covers resistance and induction heat treatment units, heating elements and inductors, thermocouples, and measuring and control technology for site and workshop use. Seven Star LLC is an independent supplier in Muscat that lists the WR 10,5 inverter unit and sources Weldotherm equipment for preheating and post-weld heat treatment.

Weldotherm heat treatment units

The resistance range runs from the single-channel WR 10,5 inverter, which weighs about 18 kg, to the multi-channel STANDARD EUROPA and VAS series with 2 to 12 control zones for 30 V and 60 V heating elements. The VAI series uses induction, generating heat in the material itself. All units are used with Weldotherm heating mats, cables and Type K thermocouples.

Ordering Weldotherm equipment: what we need

State the unit type, the number of control channels, the site mains voltage and the voltage class of the heating elements you already use. For heating elements, give the type, voltage and dimensions. We check the configuration against Weldotherm datasheets and provide them on request.

Frequently Asked Questions