Recently, the problem of valve handwheel connection fracture has frequently occurred in the industrial field, which has attracted widespread attention. This problem not only affects production efficiency, but also may pose a threat to equipment safety and the personal safety of operators. This article will deeply explore the causes and effects of valve handwheel connection fracture, and introduce the current countermeasures and relevant data statistics in the industry.
Table of contents
1. Overview of handwheel connection fracture
1. Overview of handwheel connection fracture
As a key component for operating valves, the reliability of the connection parts of the valve handwheel is of vital importance. In actual production, the fracture of the handwheel connection part is manifested as cracks or even complete disconnection of the connecting shaft, connectors and other parts between the handwheel and the valve, resulting in the handwheel being unable to transmit the operating force normally and the valve being unable to open or close as expected. During the daily maintenance of butterfly valves, the Chengjiao Mine Drilling Team found that more than 90% of the butterfly valve handwheels were damaged, deformed or broken during the disassembly and transportation process due to inadequate protection and insufficient material strength, making the butterfly valve unable to be repaired and increasing the material cost investment. This data intuitively reflects the severity of the problem of fracture at the handwheel connection part.
●Material problems
1. Insufficient strength: Some handwheel manufacturers use materials with lower strength to reduce costs. For example, in some small valves, the handwheel connection parts are made of ordinary carbon steel, and the appropriate alloy steel is not selected according to the actual working conditions. When the valve is operating under harsh conditions such as high pressure and high torque, the connection parts made of ordinary carbon steel cannot withstand huge stress and are prone to breakage. According to incomplete statistics, cases of handwheel connection parts breaking due to insufficient material strength account for about 30%.
2. Poor corrosion resistance: In industries such as chemical and marine, the environment in which valves are located is often highly corrosive. If the material of the handwheel connection part has poor corrosion resistance and is corroded by corrosive media for a long time, the structure of the material will gradually be destroyed, the strength will be reduced, and eventually cause breakage. For example, in a coastal chemical enterprise, due to the erosion of seawater, the handwheel connection parts that did not use corrosion-resistant materials suffered serious corrosion and fracture after half a year of use. Such fracture cases caused by corrosion resistance problems account for about 25% of the total cases.
● Design defects
1. Unreasonable structure: If the design structure of the handwheel connection is unreasonable, it will lead to serious stress concentration. For example, the transition radius between the connecting shaft and the handwheel is too small, or the shape design of the connecting part does not conform to the principle of mechanics, so that when the handwheel is operated, the local area of the connection part is subjected to excessive stress, far exceeding the allowable stress of the material, thereby causing fracture. Relevant research shows that the fracture problem of the handwheel connection part caused by unreasonable structural design accounts for about 20% of the total problems.
2. Size mismatch: The mismatch of the connection size between the handwheel and the valve body is also an important factor. If the size of the connection part is too large or too small, additional assembly stress or looseness will be generated during installation and use. When the handwheel is subjected to a large operating force, these additional stresses will aggravate the damage of the connection part and eventually lead to fracture. For example, in the process of renovating some old equipment, due to the selection of handwheels with mismatched sizes, the connection parts frequently break. Such fracture cases caused by size mismatch account for about 15%.
● Improper installation and use
1. Non-standard installation process: During the valve installation process, if the installer does not install the handwheel according to the correct installation process, such as the tightening torque of the connector is too large or too small, and the connecting shaft is not correctly aligned, it will have an adverse effect on the performance of the handwheel connection. Excessive tightening torque may cause deformation or even cracks in the connection part, while too small tightening torque may easily loosen the connector, causing shaking and impact when operating the handwheel, accelerating the damage of the connection part. According to statistics, about 10% of the cases of handwheel connection part fracture are caused by non-standard installation process.
2. Operation violation: In daily operation, if the operator uses too much force, operates too frequently, or forcibly operates the handwheel when the valve is stuck, the handwheel connection part will be subjected to excessive torque and impact. Under such harsh operating conditions for a long time, the material of the connection part will gradually fatigue and eventually break. For example, in the production workshop of a factory, because the operator frequently and vigorously operated the handwheel in order to speed up the production progress, the handwheel connection part broke in a short time. Such fracture cases caused by operational violations account for about 20%.
●Fatigue and wear
1. Long-term repeated operation: Valves usually need to be opened and closed frequently in industrial production. The handwheel connection part will be subjected to alternating stress during long-term repeated operation. As time goes by, tiny cracks will gradually appear inside the material. These cracks continue to expand and eventually lead to fracture of the connection part. For example, in some automated production lines, the operation frequency of valves is extremely high, and the fatigue fracture problem of the handwheel connection part is particularly prominent. According to relevant data, cases of fatigue fracture caused by long-term repeated operation account for 35% of the total cases.
2. Wear effect: The handwheel connection part will produce friction with the surrounding parts during rotation. If the lubrication conditions are poor or there are impurity particles, the wear will be aggravated. Wear will not only reduce the size of the connection part and reduce the strength, but also cause pits and scratches on the surface. These defects will become a source of stress concentration and accelerate the fracture of the connection part. In some mining enterprises, due to the harsh working environment, dust and impurities, the handwheel connection part is severely worn and fracture problems occur frequently. Such fracture cases caused by wear account for about 20% of the total cases.
1. Optimize design
Material selection: Major valve manufacturers have begun to pay more attention to the material selection of handwheel connection parts. According to different working conditions, high-strength and corrosion-resistant materials such as stainless steel and alloy steel are selected. At the same time, the quality of materials is strictly controlled to ensure that the performance indicators of the materials meet the design requirements. For example, when a well-known valve company produced valves for the chemical industry, it used special corrosion-resistant alloy steel for the handwheel connection parts. After actual use, it was verified that the probability of fracture accidents was effectively reduced.
Structural improvement: By optimizing the structural design of the handwheel connection parts, stress concentration can be reduced. The strength and stability of the connection parts can be improved by adopting reasonable transition fillets, adding reinforcement ribs, etc. For example, some companies have designed a new handwheel connection structure, changing the traditional single connection axis to a multi-axis linkage structure, dispersing the operating force, reducing the force of a single connection part, and thus improving the overall reliability of the handwheel.
2. Strengthen quality control
Production process detection: In the valve production process, advanced detection equipment and technology are introduced to strictly detect the processing accuracy and material properties of the handwheel connection parts. For example, non-destructive testing technology is used to detect whether there are cracks and other defects in the connection parts, and hardness tests are performed to ensure that the hardness of the materials meets the standards. Only products that have passed strict testing can enter the market for sale.
Quality traceability system: Establish a complete quality traceability system to record the production batch, raw material supplier, production process parameters and other information of each valve and its handwheel in detail. Once a quality problem such as a broken handwheel connection occurs, the root cause of the problem can be quickly traced back and corresponding measures can be taken to improve and recall.
3. Training and standardized operation
Operator training: The company strengthens the training of operators to make them familiar with the correct operation methods and precautions of valves. The training content includes the force control of handwheel operation, the operation frequency requirements, and the correct handling methods when encountering abnormal situations such as valve jamming. Through training, the operating skills and safety awareness of operators are improved, and the problem of handwheel connection parts breaking due to improper operation is reduced.
Formulate operating specifications: Develop detailed valve operating specifications and post them in a conspicuous position at the operation site. The specifications clearly stipulate the operation process, maintenance requirements and other contents of the handwheel, and require operators to operate strictly in accordance with the specifications. At the same time, strengthen the supervision and inspection of the operation site to ensure that the operating specifications are effectively implemented.
4. Regular maintenance and inspection
Daily maintenance: The company arranges special personnel to perform daily maintenance on the handwheel, regularly check whether the handwheel connection parts are loose, worn, etc., and promptly clean up impurities and dust in the connection parts to ensure good lubrication. If problems are found, repair or replace them in time.
Regular inspection: Develop a regular inspection plan and conduct a comprehensive inspection of the handwheel connection parts. Use advanced detection technologies, such as ultrasonic testing and stress testing, to assess the health of the connection parts. Take preventive measures in advance based on the test results to avoid fracture accidents. For example, a large petrochemical company conducts a comprehensive inspection of the handwheel connection parts every quarter. Through long-term inspection and maintenance, the incidence of fracture accidents at the handwheel connection parts has been effectively reduced.
A power plant valve handwheel fracture accident
In the steam pipeline system of a power plant, a Spoke Hand Wheel used to control the steam flow suddenly broke during operation. According to the investigation, the handwheel connection part is made of ordinary carbon steel, and the high temperature and high pressure steam in the steam pipeline has caused serious corrosion to it, resulting in a significant decrease in material strength. At the same time, the operator sometimes uses too much force during operation, which further aggravates the damage to the connection part and eventually causes the fracture. The accident caused the steam flow control to fail, affecting the normal power generation of the power plant and causing certain economic losses. After the accident, the power plant completely replaced the handwheel with high temperature and corrosion resistant alloy steel, and strengthened the training and management of operators.
A chemical company butterfly valve handwheel fracture problem
During the production process of a chemical company, the handwheel connection parts of multiple butterfly valves frequently broke. After analysis, the main reason is that the chemical environment in which the butterfly valve is located is highly corrosive, and the material of the handwheel connection part is not corrosion resistant enough. In addition, during the opening and closing process of the butterfly valve, the handwheel connection part will be subjected to a large torque. The original design structure cannot effectively disperse the torque, resulting in severe stress concentration. In response to this problem, the company cooperated with the valve supplier to redesign and select materials for the butterfly valve handwheel. A special corrosion-resistant alloy material was used, and the structural design of the connection part was optimized, with reinforcement ribs and transition fillets added. After the transformation, the fracture problem of the butterfly valve handwheel connection part was effectively solved.
With the development of industrial technology, the reliability and safety requirements of Solid Valve Handwheel are increasing. In the future, the industry will focus on studying the problem of handwheel connection fracture, and continue to optimize the design, manufacturing process and maintenance management. With the help of new materials and new technologies, such as using new composite materials to create connection parts and using intelligent monitoring technology to warn of risks, it is expected to significantly reduce the incidence of fractures and ensure the safety and stability of industrial production.
The fracture of valve handwheel connection parts is an important challenge in the industrial field. By analyzing the causes, taking countermeasures, and strengthening industry exchanges and cooperation, we are confident that we can gradually overcome the difficulties and promote the steady development of the valve industry.
