Bolt Electric Heating Rod
A bolt electric heating rod is an electric heater specifically designed for heating, tightening, or disassembling large bolts. It is widely used in the maintenance of industrial equipment such as steam turbines, boilers, and pressure vessels. The following is core information about it:
Working Principle
The bolt electric heating rod generates heat by passing current through internal high-resistance electric heating alloy wires. The heating rod is inserted into the central hole of the bolt and powered on to heat, causing the bolt to expand and elongate due to heat. In the expanded state, the nut is tightened, and after power is cut off and cooling, the bolt contracts, thereby producing precise pre-tightening force and achieving a high-quality flange sealing connection. During disassembly, the same thermal expansion principle is utilized to loosen the bolt for easy removal.
Main Technical Parameters
Executive Standard: ZBK54019-88
Rated Voltage: 220V±20V, DC 100V, or low voltage 50V
Surface Power Density: 811W/cm²
Working Temperature: 400℃
Diameter Specifications: 10mm30mm
Length Range: 100mm4500mm
Insulation Resistance: ≥50MΩ
Withstand Voltage: 1500V/1min without breakdown
Cumulative Service Life: Not less than 50 hours
Structure and Materials
Protective Tube: Made of 1Cr18Ni9Ti heat-resistant stainless steel tube
Heating Element: 0Cr27Al7Mo2 high-resistance electric heating alloy wire
Insulation Filling: High-purity magnesium oxide powder (must be dried)
Cold End Sealing: Requires tight sealing to prevent moisture intrusion from damaging insulation
Product Types
Table
Download as Table
Export as Image
Type Features Applicable Scenarios
Standard Type Heating rod + power control cabinet Routine maintenance of power station boilers and steam turbines
Explosion-proof Type Shell and electrical components meet explosion-proof standards Flammable and explosive places such as petrochemical and natural gas industries
Intelligent Temperature Control Type Equipped with PID temperature control module, can set heating curves Tightening of high-alloy steel bolts sensitive to temperature
Flexible Cable Type Bendable, suitable for confined spaces Occasions lacking sufficient operating space
Usage Precautions
The heating position should be on the bolt shank, avoiding direct heating of the threads and nut part
Ensure that the temperature of the central hole wall does not exceed the maximum service temperature of the bolt to prevent local overheating
The control cabinet shell must be reliably grounded, and the power must be disconnected when installing or removing the heating rod
Strictly prohibit voltage shifting under load
When ordering, geometric dimensions such as bolt outer diameter, total length, and nut length must be provided for customized matching
Typical Application Scenarios
Bolt electric heating rods are most commonly used for disassembly and heating of flange bolts on high/intermediate/low-pressure cylinders of steam turbines, and are also suitable for large bolt tightening operations on other pressure vessels. Compared with traditional flame heating methods, it has advantages such as controllable temperature, uniform heating, no open flame, safety, and reliability.
