20 Ton Steel Plant Maintenance Crane

We designed a 20 ton steel plant maintenance overhead crane system for heavy equipment repair and maintenance.

The project required two double girder EOT cranes with open winches.

The cranes operate in a demanding steelmaking environment with:

Ambient temperature up to 65°C
Fine iron dust
Relative humidity up to 95%
Frequent crane starts
36 m hook stroke
55 m travelling course
To match these conditions, the reference design uses A5 crane structure classification, M5 hoist and trolley mechanisms, IP65 Class H motors, IC411 cooling, PTC temperature protection, 40% ED and up to 100 starts/hour.

Project Data

Customer Requirement: A Crane for Steel Plant Maintenance

This crane is used for maintenance work inside a steelmaking plant.

The lifting requirement is different from a normal fabrication workshop.

The maintenance team may need to remove a motor from its foundation, lift a gearbox, replace a pump or move a heavy mechanical assembly during a shutdown.

Typical maintenance loads include:

Electric motors

Gearboxes

Pumps

Valves

Mechanical assemblies

Replacement components

Maintenance tools

Lifting fixtures

The project required:

2 × 20 ton double girder EOT cranes

The rated capacity is 20 ton. For a similar project, the buyer should also confirm the actual weight of the heaviest component, including lifting beams, spreaders or other attachments where applicable.

The Site Conditions Changed the Crane Design

The most important part of this project was not the 20 ton capacity.

It was the working environment.

The reference conditions included:

65°C maximum specified ambient temperature

Fine iron dust

95% relative humidity

Frequent starts and stops

Long lifting stroke

Regular maintenance requirements

These conditions directly affect the selection of motors, electrical equipment, cooling, insulation, protection devices and maintenance access.

A crane designed for a normal indoor workshop should not automatically be transferred into a steelmaking area without reviewing these conditions.

Four Engineering Issues Had to Solve

High Temperature - Up to 65°C
At 65°C, motor thermal performance becomes an important design input.

Our engineering review needs to consider:

Motor insulation
Motor temperature rise
Cooling capacity
Brake performance
Electrical components
Cable insulation
Lubrication requirements
Control cabinet operating conditions
The reference design uses Class H motor insulation and IC411 cooling.

The motor selection still needs to be checked against the actual load and duty cycle.

Fine Iron Dust

Fine metallic dust can increase contamination and maintenance requirements.

The reference crane uses IP65 motors.

For the complete crane, engineers should also review:

Electrical enclosures

Cable entries

Limit switches

Sensors

Control components

Motor cooling surfaces

Inspection points

IP65 on the motor does not mean every electrical component on the crane automatically has the same protection level. Each component should be specified according to its location and function.

Frequent Starts and Stops

Maintenance work is usually intermittent.

The crane may repeatedly:

lift → travel → stop → position → lower → release → lift again.

The reference project specifies:

40% ED

Up to 100 starts/hour

M5 hoist mechanism

M5 trolley mechanism

A5 crane structure classification

This gives the engineering team a basis for checking motor heating, brake operation, gearbox loading and mechanism selection.

36 m Hook Stroke

A 36 m hook stroke is another major design input.

It affects:

Wire rope length

Rope drum capacity

Rope reeving

Sheave arrangement

Hook block

Brake selection

Upper/lower limit protection

Additional hoisting-path protection

The project also specifies rotary and counterweight limit devices for additional hoisting protection.

Solution

20 Ton Double Girder EOT Crane + Open Winch

The configuration provides a suitable bridge arrangement for the required lifting capacity, long hook stroke, duty and maintenance access.

Engineering Configuration

This is the key part of the our company approach:

Site conditions are converted into engineering requirements before the final crane configuration is fixed.

Motor Protection: Why These Specifications Matter

IP65 Motor Protection

The reference design uses IP65 motors.

This provides protection against dust ingress and water jets.

It is relevant to steel plant areas where fine dust is present.

The complete electrical system still needs to be reviewed according to the actual installation location.

Class H Motor Insulation

The motors use Class H insulation.

This provides a higher thermal insulation class for the motor winding system.

For a specified ambient temperature of up to 65°C, motor thermal conditions need to be reviewed carefully.

The insulation class should be considered together with:

Motor temperature rise

Duty cycle

Load

Starting frequency

Cooling method

Ambient temperature

IC411 Cooling

The reference motor uses IC411 cooling.

This is a totally enclosed, fan-cooled motor arrangement.

For high-temperature applications, the cooling system must be checked against the motor's actual operating load and ambient temperature.

PTC Temperature Protection

PTC thermistors monitor motor winding temperature.

This gives the control system an additional way to detect excessive motor temperature.

It is particularly useful when the crane has:

High ambient temperature

Frequent starts

Repeated lifting cycles

Duty Class: A5 and M5 Are Not Just Numbers

The project specifies:

A5 crane structure classification

M5 hoist mechanism

M5 trolley mechanism

40% ED

Up to 100 starts/hour

These parameters describe how the crane is expected to work.

For buyers, the important question is not simply:

"Is M5 a heavy-duty crane?"

The better question is:

"Does M5 match my actual operating cycle?"

When requesting a quotation, provide:

Working hours per day

Working days per year

Average load

Maximum load

Lifting frequency

Travel frequency

Starts per hour

Expected service life

If the duty classification is unknown, the actual work cycle can be provided to the crane manufacturer for engineering review.

Maintenance Access Was Designed Into the Maintanance Overhead Crane

A steel plant maintenance crane has a special requirement:

The crane itself must be easy to inspect and service.

The reference design includes provisions for:

Full-length walkway

Anti-slip flooring

Handrails

Maintenance platforms

Access ladders

Stairs

Inspection covers

Motor access

Gearbox access

Brake inspection

Rope inspection

Wheel inspection and replacement

Maintenance lifting points

The buyer should check access to every component that may require service.

This includes the:

motor, gearbox, brake, rope drum, wire rope, sheaves, wheels, bearings, limit devices and electrical equipment.

A good crane layout should answer a simple question:

When a component needs to be inspected or replaced, can the maintenance technician reach it safely?

10. Safety and Protection Features

The reference design includes several layers of protection.

Overload Protection

A dedicated microprocessor-based overload protection system is specified.

The overload setting is limited to a maximum of 10% above rated load.

When overload is detected, the system is designed to:

Stop upward hoisting

Allow lowering where required

Prevent continued lifting under overload

The final protection logic should follow the approved electrical control design.

Hoisting Limit Protection

The crane uses additional hoisting-path protection with:

Rotary limit device

Counterweight limit device

These devices help control the hook within the permitted lifting range.

Travel Protection

For the 55 m travelling course, travel limit and control arrangements should be incorporated into the final crane design according to the site layout.

What the Buyer Gets From This Engineering Approach

For the customer, the value is straightforward.

The crane is matched to the actual site.

Not just to the 20 ton rated load.

The electrical system is selected around the environment.

65°C, dust and humidity become engineering inputs.

The hoisting system is selected around the lifting height.

The 36 m hook stroke affects the rope and drum arrangement.

The duty is based on the work cycle.

40% ED and 100 starts/hour are evaluated against actual crane operation.

Maintenance is considered before fabrication.

Walkways, platforms and component access are incorporated into the crane layout.

This reduces the risk of discovering access problems after installation.

Buyer Checklist: What to Include in Your RFQ

If you are sourcing a steel plant maintenance overhead crane, send these details to the crane manufacturer.

Lifting Data

Rated capacity

Maximum load

Heaviest maintenance component

Lifting fixtures or spreader weight

Hook stroke / lifting height

Crane Geometry

Crane span

Runway length

Travelling distance

Available headroom

Existing runway rail information

Duty

Working hours/day

Working days/year

Average load

Load spectrum

Lifting frequency

Starts/hour

Required service life

Environment

Maximum temperature

Minimum temperature

Dust type

Humidity

Indoor/outdoor installation

Corrosive atmosphere, if applicable

Electrical and Control

Voltage

Frequency

Phase

Control method

Radio remote requirement

Existing power supply arrangement

Engineering

Required standards

Building drawings

Crane runway drawings

Maintenance access requirements

Inspection requirements

Required documentation

The more complete this information is, the more useful the quotation becomes.

A request saying "20 ton EOT crane for steel plant" gives the manufacturer the capacity.

It does not give enough information to engineer the crane correctly.

FAQ for Steel Plant Maintenance Crane Buyers

What type of overhead crane is suitable for steel plant maintenance?

For heavy maintenance applications, a double girder EOT crane with an open winch can be suitable when the required capacity, lifting height, duty and site conditions support this configuration.

The final selection should be based on the complete operating requirements.

Can a 20 ton crane operate at 65°C?

A 20 ton crane can be engineered for a specified high-temperature environment, but the complete system must be reviewed.

Motor insulation, cooling, brakes, electrical components, cables and lubrication all need to be checked against the actual ambient temperature.

Why use an open winch?

An open winch provides separate motor, gearbox, brake, coupling and rope drum components.

It is useful for cranes requiring long lifting strokes, demanding duty and practical access for maintenance.

Why are IP65 motors specified?

IP65 provides protection against dust ingress and water jets.

It is relevant where fine iron dust is present.

The protection level of other electrical components should be selected according to their actual installation conditions.

What does 40% ED mean?

40% ED refers to the specified motor duty cycle.

It should be evaluated together with load spectrum, operating hours and starts per hour.

Is 100 starts/hour important?

Yes.

Frequent starting increases motor heating and affects the selection of motors, brakes, contactors or drives and the overall duty assessment.

What maintenance access should be included?

The crane should provide safe access to components requiring inspection and service.

Typical provisions include walkways, handrails, platforms, ladders and access to motors, gearboxes, brakes, rope drums, wheels and electrical equipment.