Portable Post Weld Heating Treatment System with Induction
Portable Induction Preheating System for Welding – MYD-10KW and MYD-20KW
The HLQ Portable Induction Preheating System is a compact industrial induction heater designed for localized weld preheating, pipe joint heating, controlled postheating and selected metal heat-treatment applications.
Available in MYD-10KW and MYD-20KW configurations, the equipment combines high-frequency induction power conversion, a portable generator, flexible heating cables and built-in temperature monitoring.
The MYD-10KW has a published output power range of 1–10 kW, while the MYD-20KW has a published output range of 1–20 kW. Both models operate within a listed frequency range of 5–30 kHz.
The system is intended for industrial workshops, pipeline maintenance, welding operations, pipe fabrication and suitable on-site metal-heating applications.
Engineering clarification: The published power ratings describe the equipment’s nominal output ranges. Actual useful heating power, processing time and allowable operating duty depend on the workpiece, heating coil, temperature requirements and electrical operating conditions.
Quick Answer
What is a portable induction preheating system?
A portable induction preheating system is an industrial heating machine that uses electromagnetic induction to produce localized heat inside electrically conductive metal components.
The HLQ MYD portable series includes the MYD-10KW and MYD-20KW models, with nominal output ratings of 10 kW and 20 kW respectively. The published output frequency range is 5–30 kHz, and the standard input supply is three-phase 380 V, 50/60 Hz.
Main applications: Weld preheating, pipe joint heating, localized postheating, selected metal heat treatment, industrial pipe maintenance and thermal preparation of suitable steel components.
Portable design: The published machine weights are 26 kg for MYD-10KW and 32 kg for MYD-20KW.
Important: For pipe heating, temperature sensors should contact the metal directly beneath the thermal insulation blanket. The flexible induction heating cable is then installed outside the insulation layer and secured using suitable non-metallic, high-temperature insulating straps.
Whether the equipment can complete a specified post-weld heat-treatment cycle must be determined from the applicable material standard, thermal procedure, monitoring requirements and verified heating performance.
Table of Contents
- What is a Portable Induction Preheating System?
- Key Applications
- Suitable Materials
- Working Principle
- Technical Specifications
- Recommended Model Selection
- Process Workflow
- Common Problems and Solutions
- Engineering Selection Guide
- Advantages and Limitations
- Why Choose HLQ?
- 10 Core FAQs
What is a Portable Induction Preheating System?
A portable induction preheating system is a compact induction heating machine designed to heat selected areas of conductive metal components without using an open flame as the primary heat source.
The induction generator converts three-phase electrical power into high-frequency alternating current.
When this current passes through an induction heating coil, an alternating magnetic field is produced around the workpiece.
The magnetic field induces electrical currents inside the conductive metal, generating heat through electrical resistance.
The resulting thermal energy spreads through the metal by conduction.
The portable MYD series is designed for industrial applications where a relatively small heating generator must be moved between different workstations or suitable field locations.
Main Components of the Portable Induction Heating System
| Component | Main Function | Engineering Consideration |
|---|---|---|
| Induction Power Generator | Converts industrial AC input into high-frequency induction power. | Output power, frequency, electrical input and operating duty. |
| Digital Control Panel | Provides operator control of heating functions. | Available power settings and temperature-control functions. |
| Flexible Induction Heating Cable | Generates a magnetic field around the metal workpiece. | Cable length, insulation, turns and electrical matching. |
| Output Connectors | Connect the induction heating circuit to the generator. | Electrical connection and permissible load. |
| K-Type Thermocouple | Measures workpiece temperature. | Direct contact, correct positioning and calibration. |
| Temperature Control System | Monitors or regulates selected heating parameters. | Actual control functions depend on equipment configuration. |
| Thermal Insulation Blanket | Reduces heat loss from the treatment area. | Temperature rating, thickness and installation method. |
| Non-Metallic Insulating Straps | Secure the insulation and heating cable. | High-temperature resistance and electrical insulation. |
| Air Cooling Arrangement | Removes heat from designated generator components. | Airflow, ambient temperature and operating duty. |
What Makes the MYD Portable Series Different?
Compared with larger stationary industrial induction heating systems, the MYD-10KW and MYD-20KW are designed around smaller equipment dimensions and lower machine weights.
They may be considered for localized heating tasks where a larger induction generator would be unnecessary or difficult to move.
The published weights of 26 kg and 32 kg make these models more manageable for relocation between suitable workstations.
However, portability does not eliminate the need for an adequate electrical supply, safe cable routing, appropriate cooling and correct workpiece temperature monitoring.
Key Applications
1. Induction Welding Preheating
Weld preheating raises the temperature of the base metal before welding begins.
For suitable steels, preheating can reduce the weld cooling rate and help control conditions associated with hydrogen-assisted cracking.
The specified preheat temperature depends on the steel grade, material thickness, welding process, hydrogen control and qualified welding procedure specification (WPS).
Portable induction heating can be useful for smaller pipe sections, localized weld repairs and suitable fabricated components.
For related field applications, see the HLQ portable welding preheating equipment technical guide.
2. Localized Post-Weld Heating
Some welding procedures require controlled heating or temperature holding after welding.
This may help manage cooling conditions or support a specified hydrogen-release treatment.
The required temperature and holding period must be established from the applicable procedure.
Localized postheating should not automatically be described as formal post-weld heat treatment.
3. Pipe Joint Heating
Pipe joints often require localized heating before welding, joining or repair.
Flexible induction cables can be arranged around suitable pipe sections to generate heat in the selected treatment area.
Heating performance depends on the pipe diameter, wall thickness, material grade, coil geometry and required temperature rise.
4. Industrial Pipe Maintenance
Portable induction heating equipment can be considered for approved maintenance tasks involving accessible metal piping.
Possible applications include weld preparation, localized postheating and selected repair operations.
Before applying heat to an installed pipeline, evaluate internal contents, pressure, combustible residues, coatings and any restrictions associated with the operating system.
5. Steel Structure Weld Preheating
Some structural-steel fabrication and repair processes require controlled preheating near welded connections.
Portable induction equipment may be suitable when the heating area and thermal load are compatible with the selected generator.
Material-specific temperature limits must be observed, particularly for high-strength and heat-treated steels.
6. Selected Post-Weld Heat Treatment Applications
Post-weld heat treatment involves applying a defined thermal cycle after welding.
A complete PWHT procedure may include controlled heating rates, a specified holding temperature, an approved holding time and controlled cooling.
Formal PWHT may also require multiple thermocouples and traceable temperature records.
The portable MYD series should only be selected for such applications after confirming the generator’s thermal capability, monitoring arrangements and operating duty.
For larger or code-controlled applications, compare dedicated induction post-weld heat treatment equipment.
Industrial Application Comparison
| Application | Heating Objective | Key Requirement |
|---|---|---|
| Weld Preheating | Reach the specified temperature before welding. | Approved WPS and measured preheat temperature. |
| Interpass Temperature Management | Control temperature between weld passes. | Minimum and maximum permitted temperatures. |
| Localized Postheating | Maintain a specified temperature after welding. | Approved temperature and holding time. |
| Pipe Joint Heating | Heat a selected cylindrical workpiece region. | Pipe diameter, wall thickness and coil configuration. |
| Industrial Weld Repair | Provide localized heating for an approved repair. | Repair procedure and worksite safety. |
| Small-Scale PWHT | Follow a controlled post-weld thermal cycle. | Verified heating capability and complete process compliance. |
Suitable Materials
Induction heating is applicable to electrically conductive materials.
Its performance depends on electrical resistivity, magnetic permeability, thermal conductivity, heat capacity and the workpiece geometry.
Carbon steel is commonly heated by induction because its electromagnetic properties can provide favorable coupling.
Material Compatibility Table
| Material | General Suitability | Engineering Consideration |
|---|---|---|
| Low-Carbon Steel | Generally Suitable | Common for localized welding preheat. |
| Structural Carbon Steel | Generally Suitable | Check material grade and welding requirements. |
| Low-Alloy Steel | Application-Dependent | Requires grade-specific temperature limits. |
| Cr-Mo Alloy Steel | Conditional | May require detailed preheat and PWHT procedures. |
| High-Strength Steel | Restricted / Conditional | Excessive heating may change mechanical properties. |
| Austenitic Stainless Steel | Requires Evaluation | Electromagnetic coupling differs from carbon steel. |
| Ferritic Stainless Steel | Requires Evaluation | Magnetic properties depend on composition and temperature. |
| Cast Iron | Conditional | Thermal gradients may create cracking risks. |
| Aluminum | Specialized Application | Requires appropriate coil and power-system matching. |
| Copper | Specialized Application | High thermal conductivity affects heating performance. |
| Plastic or Ceramic Alone | Not Directly Suitable | Conventional induction heating requires a conductive target. |
Material Properties Affecting Heating Performance
| Material Property | Effect on Heating |
|---|---|
| Electrical Resistivity | Influences electrical resistance heating. |
| Magnetic Permeability | Affects magnetic coupling and current penetration. |
| Thermal Conductivity | Determines heat distribution through the workpiece. |
| Specific Heat Capacity | Determines the energy needed for a temperature increase. |
| Wall Thickness | Influences heated mass and through-wall temperature distribution. |
| Heat Treatment History | Determines how additional heating may affect material properties. |
Working Principle
How Does Portable Induction Preheating Work?
The portable induction heater receives three-phase AC electrical power and converts it into high-frequency electrical energy.
This energy is delivered to a flexible induction heating cable positioned around the metal workpiece.
The cable produces an alternating magnetic field, inducing electrical currents inside the metal.
Electrical resistance converts this energy into heat within the conductive material.
Heat then spreads through the workpiece by thermal conduction.
Temperature measurement allows the operator or control system to monitor the heating process.
Induction Heating Process
| Stage | Process | Result |
|---|---|---|
| 1 | Three-Phase AC Input | Electrical energy is supplied to the generator. |
| 2 | High-Frequency Power Conversion | The generator produces a controlled high-frequency output. |
| 3 | Induction Cable Energization | An alternating magnetic field is produced. |
| 4 | Eddy Current Generation | Electrical currents are induced inside the metal. |
| 5 | Resistance Heating | Heat is generated within the conductive workpiece. |
| 6 | Thermal Conduction | Heat spreads through the pipe wall and adjacent material. |
| 7 | Temperature Monitoring | Thermocouples measure selected workpiece temperatures. |
| 8 | Process Control | Heating is adjusted according to the required process. |
Correct Installation of Temperature Sensors, Insulation and Heating Cable
For a typical insulated steel-pipe heating installation, the correct layer arrangement is essential for safe and reliable temperature measurement.
Correct installation sequence:
- Prepare and clean the steel pipe surface.
- Attach K-type thermocouples directly to the steel pipe at the specified measurement positions.
- Wrap the pipe and temperature sensors tightly with suitable thermal insulation blankets.
- Secure the insulation using approved non-metallic, high-temperature insulating straps.
- Wind the flexible induction heating cable around the outside of the insulation blankets.
- Secure the heating cable using suitable non-metallic insulating straps or approved fixtures.
- Connect the induction cable and thermocouple leads to their designated equipment connections.
- Check the electrical supply, insulation, cooling conditions and temperature-monitoring system before heating.
Correct Cross-Section Structure
| Layer | Component | Function |
|---|---|---|
| 1 – Inner Layer | Steel Pipe | Conductive workpiece heated by electromagnetic induction. |
| 2 – Direct Contact | K-Type Temperature Sensors | Measure the pipe temperature directly. |
| 3 – Middle Layer | Thermal Insulation Blanket | Covers the sensors and pipe while reducing heat loss. |
| 4 – Outer Layer | Flexible Induction Heating Cable | Generates the magnetic field around the insulated pipe. |
| 5 – Fixing Material | Non-Metallic Insulating Straps | Secure insulation and cable without introducing unapproved conductive fixing materials. |
Important safety requirement: Do not use metallic fixing bands, metal wire or steel straps to secure the thermal insulation blanket within the active induction-heating zone unless specifically covered by a qualified design.
Suitable fixing materials may include appropriately rated fiberglass or ceramic-fiber insulating tapes and straps.
The thermocouple junction must maintain reliable contact with the metal surface. Sensor leads should be routed and protected according to the approved installation procedure.
For different workpiece geometries and heating arrangements, see flexible induction heating cables and related coil configurations.
Factors Affecting Induction Heating Performance
| Factor | Effect on Heating | Recommended Action |
|---|---|---|
| Operating Frequency | Influences electromagnetic current distribution. | Use a suitable generator and coil configuration. |
| Coil Geometry | Determines the magnetic-field distribution. | Match the cable arrangement to the workpiece. |
| Workpiece Thickness | Affects thermal mass and temperature distribution. | Calculate the expected heating load. |
| Coil-to-Metal Distance | Influences electromagnetic coupling. | Use an approved insulation thickness and cable layout. |
| Thermal Insulation | Reduces heat loss. | Cover the required heating zone correctly. |
| Heating Time | Controls accumulated thermal energy. | Use the required heating cycle. |
| Ambient Temperature | Affects external heat loss and equipment cooling. | Confirm the operating environment. |
| Temperature Sensor Placement | Determines the measured temperature locations. | Use approved positions and direct metal contact. |
Technical Specifications
The following technical data are based on the original published information for the MYD-10KW and MYD-20KW portable induction heating systems.
Some specifications require additional verification because the original page does not fully define their measurement conditions or operating limitations.
MYD-10KW vs. MYD-20KW Technical Comparison
| Technical Parameter | MYD-10KW | MYD-20KW |
|---|---|---|
| Nominal Output Power Range | 1–10 kW | 1–20 kW |
| Input Voltage | 3 × 380 V | 3 × 380 V |
| Input Frequency | 50/60 Hz | 50/60 Hz |
| Input Connection | 4 Wires | 4 Wires |
| Published Input Current | 1–15 A | 1–30 A |
| Published Output Current | 0–200 A | 0–300 A |
| Output Frequency | 5–30 kHz | 5–30 kHz |
| Published Maximum Heating Temperature | 500°C | 800°C |
| Thermocouple Type | K-Type | K-Type |
| Temperature Monitoring | Built-In System | Built-In System |
| Cabinet Dimensions | 650 × 310 × 410 mm | 700 × 330 × 410 mm |
| Published Machine Weight | 26 kg | 32 kg |
| Published Coil Length | 10–20 m | 10–20 m |
| Published Coil Diameter | 15 mm | 15 mm |
| Published Ambient Range | -30°C to +45°C | -30°C to +45°C |
| Published Pipe OD Range | 50–500 mm | 50–500 mm |
Important Technical Clarifications
- The published MYD-10KW specification includes an additional claim of 15 kW maximum power at 150% duty cycle. The permitted duration and operating conditions are not defined.
- The nominal output ratings and published input-current figures require reconciliation with verified electrical input data.
- The published maximum temperatures are equipment-related reference values and do not establish the allowable temperature for every material.
- The 50–500 mm pipe outside-diameter range does not guarantee a particular heating rate or PWHT capacity.
- The 15 mm induction cable diameter requires clarification of whether it refers to the actual cable outside diameter.
- The published ambient temperature range should be confirmed against the latest factory specifications.
- Continuous full-power operation has not been independently verified.
Electrical Installation Considerations
The published input supply is three-phase 380 V, 50/60 Hz.
For a balanced three-phase system, the apparent input power is calculated using:
S = √3 × V × I / 1000
Where:
- S = three-phase apparent power, kVA.
- V = line-to-line voltage, V.
- I = line current, A.
Using the maximum published input-current figures:
| Model | Listed Input Current | Calculated Apparent Input Power |
|---|---|---|
| MYD-10KW | 15 A | Approximately 9.87 kVA |
| MYD-20KW | 30 A | Approximately 19.75 kVA |
These calculated apparent-power values are lower than the respective 10 kW and 20 kW nominal output ratings.
Since actual electrical input power cannot exceed apparent power, and electrical conversion involves losses, the published values require technical clarification.
Do not select electrical breakers, conductors or transformer capacity solely from the historical input-current figures.
Typical Equipment and Accessories
| Item | Function | Configuration Consideration |
|---|---|---|
| Portable Induction Generator | High-frequency induction power supply. | MYD-10KW or MYD-20KW. |
| Flexible Heating Cable | Electromagnetic heating of suitable metal workpieces. | Length, diameter, insulation and matching. |
| K-Type Thermocouple | Temperature measurement. | Number, installation and calibration. |
| Thermal Insulation Blanket | Reduces heat losses. | Maximum temperature rating and thickness. |
| Non-Metallic Fixing Straps | Secure insulation and heating cable. | High-temperature electrical insulation. |
| Thermocouple Extension Cable | Connects sensors to the controller. | Correct cable type and length. |
| Temperature Recorder | Documents the heating cycle when included. | Recording accuracy and available channels. |
| Connection Accessories | Support generator and cable connections. | Electrical compatibility and safe installation. |
The exact scope of supply must be confirmed for the selected model. Not every accessory shown in related HLQ product photographs is necessarily included in the standard equipment package.
Recommended Model Selection
The appropriate portable induction preheating system depends on the heating application, workpiece dimensions, operating temperature and required heating time.
Choosing a machine solely by nominal output power does not establish its suitability for a particular welding or thermal treatment procedure.
MYD-10KW vs. MYD-20KW Selection Guide
| Selection Factor | MYD-10KW | MYD-20KW |
|---|---|---|
| Nominal Maximum Output | 10 kW | 20 kW |
| Published Maximum Heating Temperature | 500°C | 800°C |
| Equipment Weight | 26 kg | 32 kg |
| Portability | Smaller and lighter. | Higher nominal heating power. |
| Preliminary Application Focus | Localized preheating and relatively small thermal loads. | More demanding localized heating tasks. |
| Temperature Monitoring | Built-in system. | Built-in system. |
| Formal PWHT | Requires process qualification. | Requires process qualification. |
| Continuous-Duty Capability | Factory confirmation required. | Factory confirmation required. |
Selection by Application
| Application | Preliminary Selection | Engineering Requirement |
|---|---|---|
| Small Steel Pipe Weld Preheating | MYD-10KW | Verify wall thickness, heating time and insulation. |
| Localized Steel Plate Heating | MYD-10KW / MYD-20KW | Calculate heated mass and coupling conditions. |
| Industrial Pipe Joint Heating | MYD-20KW | Review pipe geometry and useful thermal power. |
| On-Site Welding Preheating | Application-Dependent | Confirm electrical supply and approved heating procedure. |
| Localized Postheating | Application-Dependent | Verify holding temperature and operating duration. |
| Code-Controlled PWHT | Special Engineering Assessment | Confirm heating, soaking, cooling and recording capability. |
| Large Pipeline Heating | Consider Higher-Power Equipment | Evaluate wall thickness, heating-zone width and thermal losses. |
For larger pipe diameters, thicker walls or higher thermal loads, compare the specifications of a dedicated induction pipeline preheating machine.
Process Workflow
The installation process must maintain correct sensor contact with the workpiece and prevent unwanted heating of conductive fixing materials.
Step 1: Inspect and Prepare the Workpiece
Confirm the material grade, dimensions, welding procedure and required heating temperature.
Clean the locations where temperature sensors will contact the steel.
Step 2: Install Temperature Sensors Directly on the Metal
Position K-type thermocouples directly against the metal at the specified measurement points.
Use a suitable approved attachment method to maintain reliable thermal contact.
Route the sensor leads to avoid mechanical damage and inappropriate contact with the induction cable.
Step 3: Wrap the Thermal Insulation Blanket
Cover the temperature sensors and metal workpiece with thermal insulation blankets.
Make sure the insulation covers the required heating region without unwanted gaps.
Step 4: Secure the Insulation with Non-Metallic Straps
Use suitable high-temperature, electrically insulating fixing materials.
Do not use unapproved metal bands, steel wire or metallic fixing straps around the active induction heating region.
Step 5: Wind the Induction Heating Cable Outside the Insulation
Wrap the flexible induction heating cable around the outer surface of the insulation blanket.
Maintain the required spacing and arrangement specified for the heating system.
Secure the cable using approved non-metallic insulating straps or fixtures.
Step 6: Connect the Equipment
Connect the induction heating cable to the generator.
Connect the thermocouple leads to the designated temperature-monitoring inputs.
Step 7: Check Operating Conditions
Verify the power supply, grounding, cable insulation, generator ventilation and applicable cooling requirements.
Check that the temperature sensors provide reliable readings.
Step 8: Set Heating Parameters
Configure the target temperature and available heating controls according to the approved process.
Do not exceed the temperature limits established for the workpiece material.
Step 9: Perform Controlled Heating
Start induction heating and monitor the temperature response.
Maintain the required preheat or postheat temperature for the specified duration.
Step 10: Complete Cooling and Inspection
Follow the approved cooling procedure and inspect the workpiece.
Where required, review or record the temperature history and process results.
Process Workflow Summary
| Step | Operation | Critical Requirement |
|---|---|---|
| 1 | Workpiece Preparation | Confirm material and clean sensor locations. |
| 2 | Temperature Sensor Installation | Thermocouples directly contact the metal. |
| 3 | Thermal Insulation | Cover the sensors and workpiece completely. |
| 4 | Insulation Fixing | Use non-metallic high-temperature insulating straps. |
| 5 | Induction Cable Installation | Wind the cable outside the insulation. |
| 6 | System Connection | Connect electrical output and temperature sensors. |
| 7 | Safety Inspection | Check electrical, cooling and operating conditions. |
| 8 | Parameter Setting | Use approved heating temperatures and controls. |
| 9 | Controlled Heating | Monitor temperature and maintain the specified range. |
| 10 | Cooling and Inspection | Follow the procedure and verify the workpiece condition. |
Common Problems and Solutions
The heating performance of a portable induction heater can be affected by coil matching, workpiece dimensions, insulation, sensor installation and electrical conditions.
Troubleshooting Guide
| Problem | Possible Cause | Recommended Solution |
|---|---|---|
| Slow Heating | Insufficient useful power, large thermal mass or poor coupling. | Review coil arrangement, power and heating-zone requirements. |
| Uneven Temperature | Nonuniform cable placement or variable heat loss. | Check cable spacing, insulation and sensor locations. |
| Incorrect Temperature Reading | Thermocouple not contacting the metal correctly. | Reinstall the sensor directly against the workpiece. |
| Temperature Overshoot | Excessive heating power or control delay. | Review approved settings and sensor response. |
| Heating Cable Overheating | Incorrect cable arrangement or operating load. | Stop heating and inspect the approved cable installation. |
| Abnormal Heating of Fixing Materials | Metallic fasteners or conductive objects near the active coil. | Stop operation and remove unapproved conductive fixing materials. |
| Generator Overheating | Insufficient ventilation or excessive operating duty. | Verify cooling conditions and equipment load. |
| Insufficient Pipe Temperature | Heat loss to adjacent steel or inadequate heating power. | Reassess thermal load, insulation and equipment sizing. |
| Unstable Heating | Changing coil coupling or electrical mismatch. | Inspect cable positioning and approved electrical matching. |
| Unacceptable PWHT Temperature Cycle | Equipment or process unable to maintain the required cycle. | Review the qualified heat-treatment procedure and system capability. |
Preventive Maintenance Checklist
| Inspection Item | Recommended Check | Purpose |
|---|---|---|
| Cooling System | Inspect applicable ventilation and cooling components. | Prevent generator overheating. |
| Induction Cable | Inspect insulation and mechanical condition. | Maintain safe heating performance. |
| Output Connections | Check according to qualified electrical procedures. | Reduce connection-related faults. |
| Temperature Sensors | Check condition, attachment and calibration. | Maintain reliable temperature measurement. |
| Insulation Blankets | Inspect for damage, contamination and degradation. | Maintain suitable thermal insulation. |
| Non-Metallic Fixing Straps | Check mechanical strength and temperature suitability. | Maintain secure, insulated installation. |
| Control System | Review operating functions and fault indications. | Identify abnormal operating conditions. |
Engineering Selection Guide
Correct induction heater selection begins with the thermal energy required by the workpiece and the available heating time.
The nominal generator rating alone cannot determine the actual heating time or processing capability.
1. Calculate the Heated Metal Mass
For a cylindrical steel pipe with a selected axial heating band:
m = π × (D − t) × t × L × ρ
Where:
- m = heated steel mass, kg.
- D = outside pipe diameter, m.
- t = pipe wall thickness, m.
- L = selected heated axial length, m.
- ρ = steel density, kg/m³.
2. Calculate the Required Thermal Energy
The approximate sensible heat requirement is:
Q = m × Cp × ΔT
Where:
- Q = sensible heat, kJ.
- m = heated metal mass, kg.
- Cp = average specific heat capacity, kJ/(kg·K).
- ΔT = required temperature increase, K.
The equations provide an initial engineering estimate for the selected metal volume.
They do not account for all heat losses or temperature gradients during the actual heating process.
3. Engineering Example: Heating a 168.3 mm Steel Pipe
Consider a hypothetical carbon-steel pipe preheating application.
| Calculation Parameter | Value | Unit |
|---|---|---|
| Pipe Outside Diameter | 168.3 | mm |
| Pipe Wall Thickness | 7.11 | mm |
| Selected Axial Heating Length | 250 | mm |
| Initial Temperature | 25 | °C |
| Target Temperature | 150 | °C |
| Temperature Increase | 125 | K |
| Assumed Steel Density | 7,850 | kg/m³ |
| Assumed Mean Specific Heat | 0.49 | kJ/(kg·K) |
Step A: Calculate the heated steel mass.
m = π × (0.1683 − 0.00711) × 0.00711 × 0.250 × 7850
m ≈ 7.07 kg
Step B: Calculate the sensible heat.
Q = 7.07 × 0.49 × 125
Q ≈ 433 kJ
Converting into kilowatt-hours:
Q = 433 / 3600
Q ≈ 0.120 kWh
This represents the approximate sensible heat required by the selected pipe-wall volume under the stated assumptions.
It does not represent the electrical consumption of the portable induction generator.
4. Estimate the Heating Time
If average useful thermal power absorbed by the selected workpiece region is known:
Heating Time = Required Thermal Energy / Average Useful Thermal Power
The table below compares hypothetical useful thermal power levels.
| Assumed Useful Thermal Power | Calculated Idealized Heating Time |
|---|---|
| 1.5 kW | Approximately 289 seconds |
| 3.0 kW | Approximately 144 seconds |
| 5.0 kW | Approximately 87 seconds |
| 6.0 kW | Approximately 72 seconds |
Engineering clarification: These useful thermal power values are hypothetical assumptions, not measured output values for MYD-10KW or MYD-20KW.
Actual heating time may be longer because of heat conduction into adjacent steel, thermal radiation, convection, coil coupling, temperature uniformity requirements and operating limitations.
5. Important Power Selection Factors
| Selection Factor | Engineering Requirement |
|---|---|
| Steel Grade | Determines electromagnetic properties and permissible heating temperature. |
| Pipe Diameter | Determines coil circumference and cable requirements. |
| Wall Thickness | Determines thermal mass and heat distribution. |
| Heating Band Width | Determines the approximate heated volume. |
| Target Temperature | Determines the required temperature rise. |
| Heating Time | Determines the required average useful thermal power. |
| Thermal Insulation | Affects heat losses. |
| Ambient Conditions | Affect equipment cooling and external heat loss. |
| Operating Duty | Determines sustained heating requirements. |
| Temperature Monitoring | Determines measurement and control requirements. |
6. Preheating vs. Postheating vs. PWHT
| Process | Main Purpose | Key Control Requirement |
|---|---|---|
| Preheating | Establish the specified temperature before welding. | Required minimum preheat temperature. |
| Interpass Temperature Control | Manage temperature between welding passes. | Permitted temperature range. |
| Postheating | Maintain or increase temperature after welding when required. | Specified temperature and holding period. |
| PWHT | Apply an approved post-weld thermal treatment. | Heating rate, holding temperature, soaking time, cooling rate and records. |
For pressure-retaining equipment and other critical welded structures, see the engineering considerations for induction heating for pressure vessels.
Advantages and Limitations
Advantages of Portable Induction Preheating
1. Compact Equipment Design
The published MYD-10KW and MYD-20KW models have machine weights of 26 kg and 32 kg respectively, supporting relocation between suitable workstations.
2. Localized Metal Heating
Induction heating generates heat inside conductive materials, making it suitable for selected local heating operations.
3. Flexible Heating Cable
Flexible induction cables can be arranged around suitable cylindrical and irregularly shaped workpieces.
4. Temperature Monitoring
Built-in temperature monitoring provides a means of checking selected workpiece temperatures during operation.
5. Reduced Dependence on Open Flames
Induction heating does not require a gas flame as the primary heat source.
However, hot surfaces, electrical energy and nearby combustible materials still require appropriate safety controls.
6. Suitable for Localized Maintenance
Compact induction equipment may be useful for approved maintenance and welding applications involving relatively small thermal loads.
Limitations and Important Precautions
| Limitation | Engineering Explanation | Recommended Action |
|---|---|---|
| Limited Nominal Power | Large workpieces may require higher useful thermal power. | Calculate the thermal load before selection. |
| Material Compatibility | Different metals have different electromagnetic properties. | Verify the specific material and coil arrangement. |
| Temperature Limits | Equipment temperature capability does not establish material safety. | Follow material-specific temperature requirements. |
| Continuous Operating Duty | The source does not establish complete full-load duty conditions. | Confirm the latest factory specifications. |
| Electrical Supply | The published input-current figures require verification. | Use confirmed installation electrical data. |
| PWHT Compliance | A portable heater alone does not guarantee compliant PWHT. | Use a qualified procedure and monitoring system. |
| Coil Installation | Incorrect cable placement can affect heating and safety. | Follow the approved installation procedure. |
| Metallic Fixing Materials | Conductive fixtures may experience unwanted induction heating. | Use approved non-metallic insulating straps. |
| High Ambient Temperature | Generator cooling performance may be reduced. | Confirm environmental operating limits. |
Portable Induction Heating vs. Flame Heating vs. Resistance Heating
| Comparison | Portable Induction Heating | Flame Heating | Resistance Heating |
|---|---|---|---|
| Heating Method | Electromagnetic induction. | Combustion heat transfer. | Electrical resistance heating. |
| Heat Generated in Metal | Yes, through induced electrical currents. | Heat transferred from an external flame. | Usually transferred from external heating elements. |
| Open Flame Required | No. | Yes. | No. |
| Localized Heating | Depends on coil geometry. | Depends on burner arrangement. | Depends on heater placement. |
| Temperature Monitoring | Can use thermocouple-based monitoring. | Requires a suitable external measurement system. | Can use thermocouple-based monitoring. |
| Primary Limitation | Electrical matching and material coupling. | Combustion hazards and heat distribution. | Element placement and thermal transfer. |
| Energy Efficiency | Application-dependent. | Application-dependent. | Application-dependent. |
Energy savings and productivity improvements should be established through measurements under equivalent operating conditions rather than assumed from generic marketing claims.
Why Choose HLQ?
HLQ Induction Equipment Co., Ltd. supplies industrial induction heating equipment for welding preparation, metal heat treatment, localized heating and related manufacturing applications.
Portable MYD Heating Configurations
The MYD-10KW and MYD-20KW models provide compact alternatives for suitable localized heating applications.
Flexible Heating Arrangements
Flexible induction heating cables can be configured for different pipe and metal-component geometries when properly matched to the power generator.
Built-In Temperature Monitoring
The published portable series includes K-type thermocouple temperature-monitoring functionality.
Industrial Application Coverage
HLQ induction heating products cover welding preheating, localized postheating, pipeline heating and selected thermal treatment applications.
Application-Specific Engineering Selection
Appropriate equipment selection considers material grade, heated mass, target temperature, required heating time, induction cable arrangement and operating duty.
Final operating limits and process capability should be verified against confirmed technical specifications and representative application testing.
10 Core FAQs
1. What is a portable induction preheating system?
A portable induction preheating system is a compact electrical heating machine that generates heat inside conductive metal through electromagnetic induction. It is used for suitable welding preheating, localized postheating, pipe joint heating and industrial maintenance applications.
2. What is the difference between MYD-10KW and MYD-20KW?
MYD-10KW has a published output range of 1–10 kW and weighs 26 kg. MYD-20KW has a published output range of 1–20 kW and weighs 32 kg. Their published maximum heating temperatures are 500°C and 800°C respectively, subject to verification.
3. What is the operating frequency of the portable MYD heater?
The published output frequency range for MYD-10KW and MYD-20KW is 5–30 kHz. The actual operating point depends on the generator configuration, induction cable and workpiece load.
4. Can the MYD portable heater preheat steel pipes before welding?
Yes, provided that the equipment and induction cable are suitable for the pipe geometry and required heating cycle. The correct preheat temperature must be determined from the applicable welding procedure and material requirements.
5. Can MYD-10KW or MYD-20KW perform PWHT?
They may be evaluated for selected small-scale thermal treatment applications. However, formal PWHT requires a qualified thermal cycle, suitable temperature monitoring, adequate heating uniformity and compliance with the applicable standard. The published nominal power alone does not establish PWHT capability.
6. Where should the temperature sensors be installed?
K-type thermocouples should be installed directly against the steel pipe at the specified measurement positions. The thermal insulation blanket should then cover both the sensors and the pipe. The induction heating cable is installed outside the insulation layer.
7. Can metal straps be used to fix the insulation blanket?
Unapproved metallic straps, wire or fixing bands should not be used in the active induction-heating region. Suitable non-metallic, high-temperature insulating straps should be used according to the approved equipment installation procedure.
8. What pipe diameters can the portable induction heater accommodate?
The original product page lists pipe outside diameters of 50–500 mm. This is a published application range rather than a guaranteed heating capacity. Actual suitability depends on wall thickness, heating-zone width, insulation, target temperature and required processing time.
9. Can the MYD-10KW continuously deliver 15 kW?
The original page includes an unverified statement describing a maximum of 15 kW at 150% duty cycle. Because the overload duration and cooling conditions are not defined, this statement should not be interpreted as guaranteed continuous 15 kW operation.
10. How do I select the correct portable induction preheating machine?
Identify the workpiece material, dimensions, initial temperature, target temperature, required heating time, holding requirements, electrical supply and worksite conditions. Estimate the required thermal energy and select the generator based on verified output capability, heating-coil compatibility and operating duty.
