QB Explosion-Proof Overhead Cranes

What Are QB Explosion-Proof Overhead Cranes?

QB Explosion-Proof Overhead Cranes are specialized industrial cranes designed for safe operation in hazardous environments where flammable gases, vapors, or combustible dusts may be present. The name combines:

"QB" – A Chinese model designation for overhead bridge cranes

"Explosion-Proof" – The safety certification indicating they won't ignite surrounding explosive atmospheres

 

Core Purpose: Safety in Hazardous Areas

These cranes are engineered to eliminate all potential ignition sources – electrical sparks, hot surfaces, static electricity, or mechanical friction sparks – that could trigger explosions in volatile environments.

 

How They Differ From Standard Overhead Cranes

Feature	Standard Overhead Crane	QB Explosion-Proof Crane
Electrical Components	Standard enclosures	Sealed, reinforced enclosures
Sparks Prevention	Not considered	All components non-sparking
Temperature Control	Normal operation	Strict temperature limits
Certification	General industrial	ATEX/NEPSI/IECEx certified
Materials	Standard steel	Special alloys (copper-based, anti-static)
Cost	Standard	40-100% higher

 

Why Choose a QB Explosion-Proof Crane?

Legal Compliance – Required by safety regulations in classified hazardous areas

Insurance Requirements – Often mandated by insurers for risk reduction

Operational Continuity – Allows work to proceed safely in otherwise restricted areas

Accident Prevention – Eliminates risk of catastrophic explosions

 

Core Components：Bearing, Gearbox, Motor, Pump

Place of Origin：Henan, China

Warranty：1 Year

Weight (KG)：2000 kg

Video outgoing-inspection：Provided

Machinery Test Report：Provided

Design：Double beam

Effectiveness：high efficiency

Operating speed：High speed operation

Stability：Anti-swing function

Color：Optional

Power Source：110V/220V/230V/380V/440V,customized

Span：7.5-31.5m

1. EXPLOSION-PROOF HOISTING SYSTEM

A. Explosion-Proof Hoist Motor

Type: TEFC (Totally Enclosed Fan Cooled) with Ex d or Ex e rating

Features:

Reinforced cast iron or aluminum alloy enclosure

Double-sealed bearings with temperature sensors

Increased insulation class (typically Class H, 180°C)

Non-sparking cooling fan

Embedded RTDs for continuous temperature monitoring

Protection Method: Flameproof (Ex d) or Increased Safety (Ex e)

B. Explosion-Proof Brake System

Disc Brake Assembly:

Stainless steel or copper-alloy friction discs

Explosion-proof brake motor (Ex de)

Manual release mechanism (for emergency lowering)

Adjustable torque settings

Shoe Brake Alternative:

Non-asbestos, spark-resistant lining

Phosphor bronze or aluminum-bronze shoes

C. Gearbox & Drum Assembly

Gearbox:

Helical gears for smoother operation

Sealed housing with magnetic drain plugs

High-temperature synthetic lubricant

Wire Rope Drum:

Machined steel with precision grooves

Conductive coating to prevent static buildup

Anti-friction bearings with Ex-rated seals

D. Wire Rope & Hook Block

Wire Rope:

Non-rotating, galvanized steel construction

Conductive core for static dissipation

Special lubrication (non-reactive)

Hook Block:

Forged steel hook with safety latch

Sheaves with bronze bushings

Grounding strap for static discharge

2. TRAVEL MOTION COMPONENTS

A. Bridge/Trolley Travel Motors

Specifications:

Brake motors with integrated Ex-rated brakes

Dual-speed or variable frequency control

Thermal overload protection with Ex i barriers

Mounting: Direct coupling to gearboxes via flexible couplings

B. Travel Gearboxes & Wheels

Gearboxes:

Horizontal or vertical mounting

Oil-bath lubrication with sight glass

Wheels:

Forged steel with conductive tread

Tapered tread for better tracking

Double-flanged design on bridge wheels

Wheel Bearings: Sealed, pre-lubricated with high-temp grease

3. ELECTRICAL CONTROL SYSTEM

A. Main Power Distribution

B. Control & Safety Devices

Control Pendant (Ex de):

Cast aluminum or stainless steel housing

Membrane-sealed control buttons

Emergency stop with mechanical latch

Strain relief cable glands

Radio Remote Control (Optional):

Certified for Zone 1/21

Intrinsically safe (Ex ia) transmitter

Redundant communication protocols

Limit Switches:

Explosion-proof mechanical or proximity

Dual contacts for redundancy

Corrosion-resistant enclosures (IP67)

 

4. STRUCTURAL COMPONENTS WITH EXPLOSION PROTECTION

A. Bridge Structure

Main Girders:

Box girder design with sealed interiors

Conductive paint system with grounding points

Non-sparking trolley bumpers (polyurethane)

End Trucks:

Welded construction with rounded edges

Conductive wheels with grounding brushes

Adjustable wheel alignment system

B. Trolley Frame

Construction: Welded steel with smooth surfaces

Features:

Spark-resistant rail clamps

Conductive trolley wheels

Grounding strips between trolley and bridge

5. SAFETY & MONITORING SYSTEMS

A. Explosion-Proof Safety Devices

Load Limiting Device:

Ex i certified load cell

Digital display in Ex e enclosure

Two-stage warning system

Anti-Collision System:

Laser or ultrasonic sensors (Ex ia)

Wireless communication between cranes

Temperature Monitoring:

RTDs on all motors and bearings

Display in control cabin

Automatic shutdown at preset temperatures

B. Environmental Protection

Anemometer: Ex-rated wind speed indicator

Gas Detection Interface: Inputs for area gas detectors

Emergency Lighting: Ex e certified LED lights

6. CABLE MANAGEMENT & CONNECTIONS

A. Cable Systems

Power Cables: Mineral insulated (MICC) or armored with Ex-rated glands

Control Cables: Shielded cables with intrinsic safety barriers

Cable Carriers:

Explosion-proof festoon systems

Conductive cable trays with covers

B. Connection Systems

Cable Glands: Double-compression type with "Ex d" marking

Junction Boxes: Cast aluminum with threaded entries

Conduit Systems: Sealed, threaded conduit runs

 

7. AUXILIARY EQUIPMENT

A. Operator Cab (Optional)

Construction: Pressurized (Ex px) or flameproof (Ex d)

Features:

Air conditioning with filtration

Fire suppression system

Emergency escape hatch

Conductive floor mats

B. Lighting System

Work Area Lights: LED fixtures with Ex d or Ex e certification

Warning Lights: Rotating beacons (Ex de)

Indicator Lights: Color-coded for different functions

8. SPECIALIZED MATERIALS USED

Component	Standard Crane Material	QB Explosion-Proof Material
Brake Friction Material	Steel/Asbestos	Copper-Alloy/Ceramic
Electrical Contacts	Silver/Cadmium	Tungsten/Silver-Nickel
Bearing Cages	Steel	Brass/Bronze
Fasteners	Steel	Stainless Steel/Bronze
Paint	Standard industrial	Conductive epoxy

9. CERTIFICATION MARKS & LABELING

Every component bears specific markings:

"Ex" symbol with protection type (d, e, i, p, etc.)

Gas Group (I, IIA, IIB, IIC)

Temperature Class (T1-T6)

Certificate Number and issuing body

IP Rating (minimum IP65 for dust, IP54 for gas)

10. MAINTENANCE-SPECIFIC COMPONENTS

Test Points: Grounding verification points

Drain Plugs: For condensation removal from enclosures

Observation Windows: Tempered glass with flame arrestor mesh

Pressure Indicators: For pressurized enclosures

Seal Replacement Kits: For maintaining enclosure integrity

Sketch

Main technical

 

 

UNIQUE ADVANTAGES OF QB EXPLOSION-POF CRANES

1. Safety-Critical Superiority

Zero-Ignition Guarantee: Engineered to eliminate all potential ignition sources - electrical sparks, hot surfaces, static electricity, and mechanical friction sparks

Multi-Layer Protection: Combines 4+ protection methods (Ex d, Ex e, Ex i, Ex p) for redundant safety

Certified Compliance: Built to international explosion-proof standards (ATEX, IECEx, NEPSI) ensuring regulatory compliance

2. Operational Excellence

Uninterrupted Production: Enables continuous operation in hazardous zones without shutdowns for safety concerns

Precision Control: Advanced VFD control systems provide smooth acceleration/deceleration - critical for handling volatile materials

Environmental Resilience: Rated for extreme conditions including corrosive atmospheres, high humidity, and temperature variations

3. Economic Benefits

Insurance Premium Reduction: Most insurers offer 20-40% premium discounts for certified explosion-proof equipment

Reduced Liability: Minimizes risk of catastrophic losses from explosions (average explosion incident costs exceed $5M in industrial settings)

Lower Downtime Costs: Prevents production stoppages that typically cost $10,000-$50,000 per hour in chemical plants

4. Maintenance & Reliability

Predictive Maintenance: Integrated temperature monitoring and vibration sensors enable condition-based maintenance

Extended Component Life: Special materials and sealed designs provide 2-3x longer service life in corrosive environments

Easier Certification Renewal: Designed with maintenance-friendly features that simplify annual recertification

5. Technological Features

Smart Monitoring: IoT-enabled systems with intrinsically safe data transmission

Adaptive Control: Automatic derating in high-temperature conditions

Remote Diagnostics: Certified technicians can perform diagnostics without entering hazardous areas

 

PRIMARY APPLICATIONS BY INDUSTRY

1. Chemical & Petrochemical

 

Typical Capacity: 5-50 tons

Special Features: Chemical-resistant coatings, vapor-tight enclosures

2. Pharmaceutical & Biotechnology

API Manufacturing: Handling solvents (methanol, acetone, hexane) in production areas

Sterile Areas: Ethylene oxide sterilization rooms

Extraction Facilities: Ethanol and supercritical CO₂ extraction areas

Powder Processing: Combustible dust zones (Zone 22)

3. Oil & Gas

Offshore Platforms: Drilling module service cranes

LNG Facilities: Liquefaction and regasification plants

Pipeline Compressor Stations: Maintenance in classified areas

Fuel Terminals: Gasoline, jet fuel, diesel handling

4. Aerospace & Defense

Paint Hangars: Aircraft painting with flammable paints/thinners

Fuel Cell Maintenance: Hydrogen service areas

Ordnance Facilities: Explosive manufacturing buildings

Rocket Fuel Handling: Hydrazine and other hypergolic fuels

5. Food & Beverage

Ethanol Production: Distillation and handling areas

Flavor Extraction: Solvent-based extraction rooms

Spray Drying Areas: Combustible powder clouds (milk powder, starch)

Brewery/Distillery: Alcohol vapor areas

6. Specialty Manufacturing

Paint & Coatings: Formulation and filling areas

Adhesives Manufacturing: Solvent-based adhesive production

Printing Industry: Ink mixing and storage with flammable solvents

Semiconductor: Wafer fabrication with flammable process gases

 

Phase 1: Design and Engineering

This is the foundational phase before any physical work begins.

Customer Requirements Analysis: Engineers review the specific requirements: capacity (e.g., 32/5 tons), span, lifting height, duty class (e.g., A5, A6), and any special needs (e.g., explosion-proof, high-temperature environment).

Structural Design: Using CAD (Computer-Aided Design) software, engineers design the main girders, end carriages, and trolley frame. Finite Element Analysis (FEA) is often used to simulate stress, deflection, and dynamic loads to optimize the design for strength and weight.

Mechanical and Electrical Design: This includes selecting and designing the drive systems (motors, gearboxes, wheels), the hoisting mechanism, and the complete electrical control system with panels, variable frequency drives (VFDs), and safety devices.

Bill of Materials (BOM) Creation: A detailed list of all raw materials (steel plates, profiles) and purchased components (hoist, motors, brakes, wire rope, wheels) is generated.

 

Phase 2: Raw Material and Component Procurement

Steel Plates and Profiles: High-quality steel plates (typically Q235B or Q345B according to Chinese standards, equivalent to S235JR/S355JR) are procured in required dimensions and thicknesses.

Purchased Components: Critical components are sourced from reputable suppliers. These include:

Hoist unit (may be manufactured in-house or purchased)

Electric motors for bridge and trolley travel

Reducer gearboxes

Wheels and axles

Brakes

Electrical components (controllers, contactors, limit switches, VFDs, cabling)

Bearings

 

Phase 3: Main Steel Fabrication & Machining

This is the core of the manufacturing process.

1. Main Girder Fabrication:

Cutting: Steel plates are cut to the required size and shape using CNC plasma or flame cutting machines for high precision.

Web/Flange Preparation: The vertical web plates and horizontal top/bottom flange plates are prepared. For long spans, the girders are often designed as a tapered "I-beam" profile (wider in the middle) to optimize strength-to-weight ratio.

Assembly and Welding: The girders are assembled on large jigs to ensure straightness and correct camber (a pre-set upward bend to counteract deflection under load). This is a critical step. Submerged Arc Welding (SAW) is commonly used for its deep penetration and high-quality, consistent welds on long seams.

Stress Relieving: After welding, the main girders often undergo stress relieving heat treatment in a large furnace. This process removes internal stresses created during welding, preventing future distortion and ensuring dimensional stability.

Machining: The mating surfaces for the end carriages and trolley rails are machined using a planer or milling machine to ensure a perfectly flat and level surface.

2. End Carriage (End Truck) Fabrication:

The end carriages are fabricated from steel sections and plates.

They house the wheels, drive motors, and gearboxes for the bridge movement.

The wheel bases are drilled and machined to precise tolerances to ensure proper alignment and that all wheels make contact with the runway rails.

 

Phase 4: Mechanical Assembly

1. Bridge Assembly:

The two main girders are positioned parallel to each other and connected to the end carriages using high-strength bolts or by welding, forming the complete bridge structure.

The trolley rails are precisely aligned and bolted onto the top of the main girders.

2. Trolley Frame Assembly:

The trolley frame is assembled, and its wheels, drives, and the main hoisting unit (including the wire rope drum, motor, gearbox, and hook block) are mounted onto it.

3. Drive System Installation:

The travel drive units (motor, gearbox, coupling) are installed on the end carriages (for bridge motion) and on the trolley frame (for trolley motion).

All mechanical components are aligned to prevent binding and premature wear.

 

Phase 5: Electrical System Installation

Cable Reeling System: The main power supply system for the crane (e.g., conductor bars or festoon systems) is installed along the bridge girder.

Control Panel Installation: The main control panel, VFDs, and other electrical components are mounted in a protected enclosure, usually on the bridge girder.

Wiring: All motors, brakes, limit switches, and safety devices are wired according to the electrical schematic.

Operator Control Station: The pendant control station (hung from the crane) or a radio remote control system is connected and tested.

 

Phase 6: Surface Treatment and Painting

Surface Preparation: The entire crane structure is shot-blasted to remove mill scale, rust, and welding slag, creating a clean, rough surface for optimal paint adhesion.

Priming: A rust-inhibitive primer is applied immediately after blasting to prevent oxidation.

Painting: Multiple coats of high-quality industrial enamel paint are applied. Color is often according to customer specification or standard factory practice (e.g., international orange/yellow for visibility). The painting process protects the crane from corrosion in industrial environments.

 

Phase 7: Factory Acceptance Testing (FAT)

Before disassembly for shipment, the fully assembled crane undergoes rigorous testing.

Visual Inspection: Checking dimensions, weld quality, and assembly.

No-Load Test: Running the crane, trolley, and hoist in all directions to verify smooth operation, correct speed, and functionality of all controls and limit switches.

Static Load Test: The hoist is lifted with a test load 25% greater than the rated capacity (as per FEM/ISO standards). The load is held for 10-15 minutes to check for structural deformation, weld integrity, and brake holding capacity.

Dynamic Load Test: The crane is operated with a test load 10% greater than the rated capacity. All motions are tested to ensure performance under dynamic stress.

Electrical Safety Tests: Insulation resistance, grounding continuity, and proper functioning of all emergency stops and safety circuits are verified.

 

Phase 8: Dismantling, Packaging, and Shipping

After passing FAT, the crane is carefully dismantled into transportable sections (main girders, end carriages, trolley, electrical panels).

All components are professionally packaged and protected against damage during transit.

They are shipped to the customer's site, where they will be reassembled and installed by technical crews.

Workshop view:

The company has installed an intelligent equipment management platform, and has installed 310 sets (sets) of handling and welding robots. After the completion of the plan, there will be more than 500 sets (sets), and the equipment networking rate will reach 95%. 32 welding lines have been put into use, 50 are planned to be installed, and the automation rate of the entire product line has reached 85%.