As a key equipment in the metallurgical industry, the safety and technical performance of electric single-girder bridge cranes for lifting molten metal is directly related to production safety and personnel life protection. Compared with ordinary single-girder bridge cranes, this type of crane has more stringent requirements in terms of structural design, safety configuration and operating specifications. This article will systematically analyze the safety and technical performance characteristics of this type of crane, and discuss it from multiple dimensions such as design standards, key safety technologies, intelligent safety innovation, management and maintenance. In combination with the latest industry standards and technological developments, it puts forward thoughts and suggestions on safety performance optimization, aiming to provide a reference for the design, use and management of related equipment.
The working environment of lifting molten metal has the typical characteristics of high temperature and high risk, which makes electric single-beam bridge cranes face unprecedented safety challenges in this application field. Molten metal usually refers to liquid metals such as molten steel and molten iron with a temperature of hundreds or even thousands of degrees Celsius. Once it leaks or falls during the lifting process, it is very easy to cause catastrophic accidents such as explosions and fires, causing casualties and major property losses. Historically, molten metal overturning accidents caused by crane failures in metallurgical enterprises at home and abroad are common. For example, the particularly serious accident of ladle overturning in Tieling Steel Plant in Liaoning in 2007 was directly caused by the failure of the crane main controller. This kind of painful lesson has prompted my country to formulate extremely strict safety and technical standards for cranes lifting molten metal.
Compared with ordinary LD single-beam cranes, electric single-beam bridge cranes for lifting molten metal have significant differences in safety and technical performance. Ordinary cranes mainly focus on the lifting safety of conventional loads, while molten metal lifting cranes need to additionally consider the impact of high-temperature radiation and heat conduction on metal structures, as well as the dual safety protection mechanism to prevent molten metal leakage. According to TSG Q0002-2008 “Technical Supervision Regulations for Safety of Hoisting Machinery – Bridge Cranes”, this type of crane has special requirements in all aspects from design, manufacturing to inspection and use, especially in terms of structural welding quality, drive configuration, braking system, safety protection devices, etc., which put forward higher standards.
In recent years, with the implementation of the industry standard “Electric Single-beam Crane for Lifting Molten Metal” jointly drafted by 20 units including Henan Dafang Heavy Machinery Co., Ltd. on August 6, 2020, it marks that my country’s safety technical requirements for such equipment have formed a systematic and standardized standard system, replacing the original local standard DB41/T1380-2017, and realizing unified specifications across the country. The standard clearly stipulates the types and basic parameters, technical requirements, test methods, etc. of the crane, providing a technical basis for improving the inherent safety level of the equipment. Based on these standards and the latest technological developments, this article will deeply analyze the safety and technical performance of electric single-beam bridge cranes for lifting molten metal.
The design and manufacture of electric single-beam bridge cranes for lifting molten metal must follow a series of strict technical specifications and standards, which constitute the basic framework of the equipment’s safety performance. my country has established a relatively complete standard system for this type of special equipment, and has stipulated mandatory safety technical requirements at different levels. TSG Q0002-2008 “Regulations on Safety Technical Supervision of Hoisting Machinery-Bridge Cranes” is the earliest document that specifically regulates the safety technical requirements of this type of equipment. It clearly puts forward a series of special regulations for cranes for lifting molten metal, including key contents such as the selection requirements of electric hoists, forward and reverse contactor fault protection functions, and remote control or non-follow-up operation methods. The promulgation and implementation of this regulation is directly derived from the lessons of the Tieling steel ladle overturning accident, marking that my country’s safety management of molten metal lifting equipment has entered a new stage.
The industry standard “Electric Single-beam Crane for Lifting Molten Metal” (implemented in August 2020) further refines the technical requirements and becomes the latest basis for current design and manufacturing. This standard applies to bridge cranes with electric hoists as lifting mechanisms, but does not include equipment used in explosive or corrosive gas environments. The standard makes comprehensive provisions for the type parameters, test methods, inspection rules, etc. of cranes, among which special emphasis is placed on the configuration requirements of the low-speed safety brake of the transmission system: electric hoists with a rated lifting capacity of 5-16 tons must be equipped with a safety brake at the low-speed level of the transmission system; and when the rated lifting capacity is ≤5 tons, specific design conditions must be met. These regulations are intended to ensure that the crane can still safely and reliably withstand the rated load when the working brake or transmission component fails.
From the perspective of design parameters, electric single-beam bridge cranes for lifting molten metal need to meet special requirements in the following aspects: the lifting mechanism should be equipped with two sets of independent drive devices and corresponding brakes to form a double protection mechanism; a second-level lifting height limiter must be installed to prevent overtravel and top impact and be able to disconnect a higher-level power source. At the same time, the standard puts forward higher requirements on the welding quality of metal structural parts, and strict welding process assessment and non-destructive testing standards must be adopted to ensure the integrity of the structure in a high-temperature working environment. In terms of electrical systems, it is required to have forward and reverse contactor fault protection functions to avoid the risk of loss of control due to contactor adhesion.
The regulations on the operation mode also reflect the importance attached to personnel safety. The standard clearly requires the use of remote control or non-follow-up operation methods away from heat sources to reduce the possibility of operators being exposed to high-temperature dangerous areas. This “remote operation” concept has become an important principle in the design of cranes for lifting molten metals, effectively reducing the impact of high-temperature radiation on operators and the potential risk of injury.
It is worth noting that the safety standards for cranes for lifting molten metals are a dynamically developing system. With the advancement of technology and the accumulation of accident lessons, relevant requirements are also constantly being updated and improved. For example, the Henan Provincial Market Supervision Administration abolished the local standard DB41/T1380-2017 of the same name in April 2020, and uniformly implemented the new industry standard, reflecting the trend of standard integration and upgrading. Designers and manufacturers must keep track of these standard changes in a timely manner to ensure that their products meet the latest safety requirements. At the same time, there may be differences in standards between different countries and regions, and exported equipment must also meet the relevant specifications of the destination market, which increases the complexity of design and manufacturing, but also promotes the global coordinated development of safety technology.
The safety technical performance of the electric single-beam bridge crane for lifting molten metal is reflected in multiple key systems, and the synergy of these systems constitutes the basic defense line of the equipment against risks. In-depth analysis of these key technical characteristics will help understand the essential difference between such cranes and ordinary cranes, as well as the safety assurance mechanism under extreme working conditions.
As the core component of the crane, the safety performance of the hoisting mechanism directly determines the reliability of the whole machine. For the electric single-beam bridge crane for lifting molten metal, the safety design of the hoisting mechanism adopts strict standards far exceeding ordinary cranes. The most prominent feature is the configuration of the dual drive device, which requires two sets of independently working drive systems and corresponding brakes to ensure that when one of the systems fails, the other can still maintain a safe load. This redundant design greatly reduces the possibility of accidents caused by a single fault and is an important barrier to prevent molten metal from falling. In practical applications, these two systems usually use electrical and mechanical dual interlocking to ensure their synchronous operation and independent emergency response capabilities.
The brake system is another key to the safety of the hoisting mechanism. New cranes generally adopt a composite braking solution of “electromagnetic braking + mechanical double insurance”, which achieves a quick response within 0.2 seconds, which is a qualitative leap compared to the braking time of more than 1 second of traditional equipment. For equipment with different lifting weights, the standard has differentiated regulations: electric hoists with a rated lifting weight of 5-16 tons must be equipped with a safety brake at the low-speed stage of the transmission system; while hoists with a rated lifting weight of ≤5 tons must meet specific replacement conditions. This classification requirement reflects the scientific and targeted nature of the standard formulation. The role of the safety brake is to reliably support the rated load and prevent the load from falling when the working brake or transmission component fails. A case study shows that after installing a safety brake that meets the standards, the load sliding distance under system failure can be controlled at the millimeter level, which is much lower than the 0.5-1 meter dangerous sliding that may be caused by traditional brakes.
The high temperature working environment places special requirements on crane parts, and material selection becomes an important factor affecting safety performance. When lifting molten metal, parts such as hooks and beams that are in direct contact with or close to high temperature loads must be made of high temperature resistant alloy steel and regularly inspected for possible cracks or structural damage. The selection of wire rope is also critical. Ordinary wire ropes will deteriorate rapidly at high temperatures, so special high temperature resistant wire ropes such as asbestos rope cores or metal strand cores must be selected. These special wire ropes can maintain sufficient mechanical strength in high temperature environments, significantly extend their service life and reduce the risk of sudden breakage.
Thermal insulation protection design is also an effective measure to deal with the effects of high temperature. Some advanced models install heat insulation panels between the electric hoist and the hoisted object, or set up thermal barriers around key electronic components to reduce the impact of thermal radiation on the electrical system. At the same time, the standard requires that the main load-bearing components should have good high temperature creep resistance to avoid the gradual reduction of structural strength caused by long-term heat exposure. Practice has shown that replacing parts that are susceptible to high temperatures (such as brake friction pads) regularly is more secure than waiting for them to be completely worn out before replacing them. This requires the establishment of a preventive maintenance system based on time rather than just visual inspection.
Multi-level safety protection devices are an indispensable technical feature of cranes for lifting molten metal. In addition to conventional overload protection, limit protection and emergency stop functions, such cranes must also be equipped with a secondary lifting height limiter as the last line of defense to prevent top impact. The first-level limiter operates within the normal working range, while the second level is designed to cut off the higher-level power source in extreme cases, providing a deeper level of protection. This hierarchical protection concept runs through the entire safety system design.
Anti-collision devices are particularly important in densely populated operating areas. When multiple cranes share a working track, advanced distance sensing technology and automatic deceleration systems can effectively prevent mutual collisions. In terms of electrical systems, the forward and reverse contactor fault protection function is a mandatory requirement to prevent false operations caused by contactor adhesion. In addition, the crane should also be equipped with electrical safety measures such as voltage fluctuation protection, phase sequence protection and phase loss protection to ensure safe shutdown in the event of power failure.
Operation stability control is also crucial for the safe lifting of molten metal. Sudden starting or braking may cause the load to swing violently, increasing the risk of collision or splashing. The use of variable frequency speed regulation technology can significantly improve operation stability and reduce dynamic loads through a smooth speed curve. Test data shows that variable frequency control can reduce the swing amplitude of a 10-ton load from the traditional 30 cm to less than 5 cm, greatly improving operational safety. This technical advantage is particularly valuable in metallurgical workshops with limited space, creating better conditions for precise positioning and safe production.
Table: Comparison of key safety technical indicators of electric single-beam bridge cranes for lifting molten metal
| Technical safety indicators | General single girder crane | Special crane for lifting molten metal | Safety improvement effect |
| Braking system response time | ≥1 Second | ≤0.2 Second | Increase by more than 80% |
| Load swing range (10 tons) | About 30cm | Within 5cm | Reduce by more than 83% |
| Drive system redundancy | Single drive system | Dual independent drive system | Fault tolerance increased by 100% |
| Limit protection level | Single-stage limit | Secondary limit + power cut off | Protection depth has been greatly increased |
| Wire rope temperature resistance | Ordinary wire rope | High temperature resistant special wire rope | Lifespan extended 3-5 times at high temperatures |
With the rapid development of Industry 4.0 and intelligent manufacturing, electric single-beam bridge cranes for lifting molten metal are undergoing unprecedented technological changes, and intelligent safety innovation has become a key driving force for improving the inherent safety level of equipment. These innovative technologies not only solve the inherent safety problems of traditional cranes, but also set a new safety benchmark for molten metal lifting operations.
Anti-sway control technology is one of the most groundbreaking safety innovations in recent years. It is difficult for traditional cranes to avoid the swing of the load during start-up, braking and operation. Especially in the lifting of molten metal, this swing may cause liquid sloshing, splashing and even overturning, threatening the safety of personnel and equipment. The new crane adopts an intelligent anti-sway system of “variable frequency speed regulation + AI algorithm” to suppress the swing of the hook in real time by automatically adjusting the lifting and running speed. The system monitors the swing state of the load through high-precision sensors, and the AI algorithm predicts the control strategy according to the swing model, dynamically adjusts the motor output, and forms a closed-loop control. Actual measured data shows that this intelligent anti-sway technology can reduce the swing amplitude of a 10-ton load from 30 cm of a traditional crane to within 5 cm, and the control effect reaches more than 83%. Such a significant improvement not only improves safety, but also enhances operational accuracy, allowing molten metal to be lifted to the target location more accurately and reducing pauses and adjustment time during operations.
The intelligent braking system represents another major technological advancement. Traditional braking systems have obvious delay problems, and there is still a sliding distance of 0.5-1 meters during emergency braking, which can have catastrophic consequences in molten metal lifting scenarios. The new intelligent braking system combines the dual mechanisms of electromagnetic braking and mechanical braking. By monitoring the load status and braking performance in real time, it achieves a fast response within 0.2 seconds, which is more than 80% faster than traditional equipment. More advanced designs also introduce predictive braking functions. Based on the analysis of operating modes and operating trends, the braking parameters are pre-adjusted before potential dangers occur to achieve preventive safety intervention. This shift from “passive response” to “active prevention” reflects the core value of intelligent safety technology.
The application of remote monitoring and fault diagnosis system has brought a new mode of crane safety management. Modern electric single-girder bridge cranes can be equipped with a variety of sensors to collect key parameters such as lifting weight, braking status, structural stress, temperature, etc. in real time, and transmit the data to the central monitoring platform through the Internet of Things technology. After intelligent analysis of these data, abnormal trends can be discovered in time and potential faults can be warned, such as excessive brake wear, structural microcrack development, and electrical component performance degradation. A case study shows that the predictive maintenance strategy based on vibration analysis and temperature monitoring can warn of key component failures 20-50 hours in advance, greatly reducing the risk of sudden failures. This condition monitoring technology combined with regular inspections has formed a more complete equipment health management system, which is particularly suitable for molten metal lifting operations in high-risk environments.
Automated operation technology is changing the traditional human-machine interaction mode. Due to the extremely high requirements for operation accuracy and safety in molten metal lifting, manual operation is inevitably subject to uncertain factors such as fatigue and error. The new generation of cranes adopts programmed control technology, which allows common lifting paths to be learned and memorized to achieve semi-automatic operation. The operator only needs to set the starting and ending points, and the system can automatically complete a series of actions such as lifting, walking, and positioning, while maintaining smooth speed and stable load during the process. This approach not only reduces the difficulty of operation, but also reduces the possibility of human error, while allowing the operator to stay away from high-temperature dangerous areas, in line with the provisions of TSG Q0002-2008 on “operating away from heat sources”. A further development is the fully autonomous intelligent lifting system, which realizes the automatic transfer of molten metal without human intervention through 3D environmental perception and path planning algorithms, which represents the future development direction of technology.
Digital twin technology is beginning to emerge in the field of crane safety. By establishing a digital mapping of physical equipment, simulating and predicting the status of cranes under various working conditions in real time, engineers can test extreme situations and safety boundaries in a virtual environment without affecting actual production. Digital twins can also run synchronously with physical equipment, and detect potential problems early by comparing the differences between theoretical behavior and actual performance. This technology is particularly suitable for high-risk operations such as lifting molten metal, because it allows safety assessments and operation training without taking actual risks. With the improvement of computing power and the advancement of modeling technology, digital twins are expected to become a standard tool for safe design and operation and maintenance of cranes.
The integrated application of intelligent safety technology has created the concept of a new generation of “intelligent safety cranes”. This type of equipment not only meets the basic safety regulations, but also achieves a higher level of safety performance through embedded intelligent systems. A byproduct of intelligence is the accumulation of a large amount of operation and safety data, which can be fed back to the update of design standards and safety regulations after mining and analysis, forming a positive cycle of continuous improvement. It can be foreseen that with the development of technologies such as artificial intelligence, 5G communications, and edge computing, the safety technology of cranes for lifting molten metal will move towards a new stage of greater intelligence and autonomy, providing more solid equipment guarantees for safe production in the metallurgical industry.
The excellent safety and technical performance of electric single-beam bridge cranes for lifting molten metal not only depends on advanced design and manufacturing, but also requires strict safety management and systematic maintenance throughout the life cycle as support. A sound safety management system and a scientific maintenance strategy are key factors to ensure the long-term stable operation of the crane and prevent accidents. For this type of high-risk special equipment, my country has established a relatively complete safety management framework, but it still faces various challenges and complex situations in actual implementation.
The establishment and implementation of safety rules and regulations constitute the core of the management system. According to the safety management requirements of lifting machinery and equipment, special safety rules and regulations must be formulated and improved to clarify equipment operating procedures, prohibited behavior codes, and accident emergency plans. For cranes that lift molten metal, the rules and regulations should pay special attention to the special risks of high-temperature working environments, such as the regular replacement cycle of wire ropes, the inspection requirements of thermal insulation protection devices, and the molten metal disposal procedures in emergency situations. The practice of a metallurgical enterprise shows that visualizing the operating procedures and posting them in a prominent position in the operating area can reduce human errors by more than 30%. At the same time, the rules and regulations must be dynamically adjusted with equipment updates and changes in standards to ensure that they always reflect the latest safety requirements. Training is the guarantee for the effective implementation of rules and regulations. Operators, maintenance personnel and relevant management personnel need to receive professional training, which should include equipment principles, safety device functions, emergency handling, etc., and regular retraining and assessment should be carried out.
Equipment signs and warning sign systems are the infrastructure of safety management. Setting obvious signs and warning signs on lifting machinery and equipment can continuously remind operators to pay attention to key safety issues. For cranes for molten metal, important signs include: rated lifting weight warning, high temperature danger zone marking, safety device indication, emergency stop button location, etc. These signs should be made of high temperature resistant materials to ensure long-term legibility in a thermal radiation environment. A more advanced approach is to use LED dynamic signs to automatically change the display content according to the equipment status, such as flashing warnings when overloaded, to improve the warning effect. The design of the sign system should comply with ergonomic principles to ensure that it can be quickly and accurately identified under various lighting conditions and viewing angles.
The establishment of a preventive maintenance system is crucial to ensure long-term safe operation. The working environment of cranes for molten metal is harsh. Factors such as high temperature, dust and metal splash accelerate the aging and wear of parts, and a more frequent and stricter maintenance plan than ordinary cranes must be implemented. Preventive maintenance should be triggered based on time, operating hours or condition monitoring data, rather than relying solely on post-failure repairs. Key maintenance items include: brake performance test, wire rope condition check, structural connection looseness check, electrical system insulation test, etc. In particular, for key components such as safety brakes, maintenance procedures may require a comprehensive inspection and test every 250 working hours. Maintenance records should be detailed, complete and electronically managed to facilitate tracking equipment status trends and analyzing potential problems. Actual cases show that metallurgical enterprises that strictly implement preventive maintenance systems have a crane failure rate that is 40-50% lower than the industry average.
Regular inspections and performance tests are important means of discovering potential hidden dangers. In addition to daily inspections, cranes for molten metal should be subject to statutory regular inspections, including annual inspections and comprehensive inspections, in accordance with the requirements of the special equipment safety technical specifications. The inspection content must cover metal structure crack detection, safety device function verification, electrical system reliability testing, etc. It is particularly important to perform non-destructive testing on key load-bearing components such as hooks and beams to detect internal defects that are invisible to the naked eye.
Contact our crane specialists
Send us a message and we will get back to you as soon as possible.
