Comparison of Pressure Bearing Capacity between Threaded & Welded Steel Pipes

The pressure bearing capacity of steel pipes is an important indicator for evaluating their ability to withstand pressure in industrial and construction applications. This capacity directly affects the safety and reliability of pipeline systems, making it crucial in engineering design and practical applications. Factors affecting the pressure bearing capacity of steel pipes include pipe materials, wall thickness, diameter, connections, and internal pressure.
 
Common types of pipe connections include welding, threaded connections, and flange connections. Different connections significantly impact the pressure bearing capacity of pipelines. Threaded connections and welded connections are two common pipeline connections, each of which has unique characteristics and applicable scenarios. This article discusses the comparison and analysis of threaded and welded connections regarding the pressure bearing capacity of steel pipes.
 

A threaded connection is a mechanical method that achieves sealing through friction and tight engagement between external and internal threads. Threaded connections do not require special welding equipment or technology, making them easy to install and disassemble. Threaded connections are easily replaced and adjusted, and are suitable for occasions where frequent disassembly is required. Compared to welding, threaded connections have relatively low equipment and labor costs. However, threaded connections also have some limitations. The sealing depends on the quality of the thread. The processing accuracy and surface flatness of the thread directly impacts the sealing effect. Due to the strength and connection method of threads, threaded connections have a relatively low pressure bearing capacity, making them suitable for small and medium diameters and low-pressure pipelines.
 

Welding is the process of heating metal to a molten state and forming a permanent connection upon cooling. The main characteristics of welding include high strength, good sealing capability, and a strong pressure bearing capacity. The connection point after welding is usually stronger than the pipe itself. Due to its continuous combination of metal materials, welding provides good sealing. It is suitable for high-pressure and large-diameter pipeline systems and can withstand greater internal pressure. However, welding also has some limitations. Professional welding processes and operating skills are required, and the cost and equipment requirements are high. Once welding is completed, changes are difficult and may require cutting and re-welding.
 

When choosing a pipeline connection method, it is necessary to make a comprehensive consideration based on the specific engineering needs and conditions: for small diameter and low-pressure environments, a threaded connection is usually a more suitable choice because of its advantages of easy installation and convenient maintenance. For large-diameter and high-pressure environments, welding connections can better meet the safety and reliability requirements of the system due to their high strength and good sealing performance. Welded connections have good continuity and sealing properties and can provide more uniform force distribution, thus performing better in high-pressure environments. Although threaded connections are easy to install, they are prone to leakage or breakage under high pressure because the contact area between the threads is relatively small and cannot effectively disperse the pressure. Therefore, when designing steel pipe structures, welded connections are usually a more reliable choice considering the pressure-bearing capacity. Although welded connections perform better in terms of pressure-bearing, their installation and maintenance are relatively complicated and the cost is higher. Although threaded connections may be risky in some high-pressure application scenarios, their ease of installation and disassembly makes them a practical and economical choice in some medium- and low-pressure application scenarios.
 

Threaded connections and welding connections each have their unique advantages and specific applications. Selecting an appropriate connection method necessitates considering factors such as the operating environment, pressure requirements, and pipeline installation and maintenance. In practical projects, choosing a sensible connection method can enhance system safety and stability, as well as effectively manage project costs and maintenance schedules, thereby better meeting the long-term operational needs of the project.