Selection of Rotary Joint Threads
In the selection and installation of rotary joint, the threaded connection constitutes a fundamental and critical element. The use of appropriate threads not only ensures the leak-tightness and reliability of the rotary joint connection but also prevents installation-related damage, thereby facilitating the stable operation of the entire fluid transmission system. Sun hong presents here the key factors regarding threaded connections.
Rotary Joint Thread Types and Standards
Metric Threads
Designated by the letter M (e.g., M20, M24 × 1.5), these threads feature a thread profile angle of 60°. This type is widely utilized in the majority of equipment across Europe and Asia, serving as the standard choice for most metric threading applications.
British Standard Threads
These can be divided into Whitworth threads and American Standard threads. Whitworth threads have a tooth angle of 55°, while American Standard threads have a tooth angle of 60° and are often distinguished by UNC and UNF. If the equipment or its piping originates from North America or the United Kingdom, then imperial threads must be selected accordingly.
Pipe Threads
Primarily used for sealing pipe connections, these are broadly classified into two categories: sealing and non-sealing. American Standard tapered pipe threads achieve a seal through the taper of the threads themselves and are typically used in conjunction with PTFE tape or thread sealant. Imperial parallel pipe threads require the use of sealing gaskets to achieve a seal. When selecting pipe threads, it is essential to clearly identify whether the piping system utilizes tapered or parallel threads; these two types must not be intermixed.
Considerations for Selecting Threads for Rotary Joints
Meticulousness and standardization are always the most stable and efficient approaches. When selecting a rotary joint, considerations should be made from the perspective of the entire system. Essentially, it is a matching process that requires comprehensive consideration of the equipment interface standards, system operating parameters, and installation environment to ensure that the rotary joint can perform its design functions and achieve long-term stable operation.
Interface standards between equipment and pipelines
As a decisive factor, the thread specifications of the port where the rotary joint connects to the equipment or the existing joint should be confirmed, and the thread type and pitch should be checked to ensure that they are correct. Any mismatch will result in installation failure or a compromised seal.
Working medium and pressure
Different thread types of rotary joints will have different sealing performance and pressure bearing capacity. Under high pressure environment, tapered pipe threads such as NPT will exhibit different characteristics due to their tooth profile structure. Ensure that the selected thread sealing method is compatible with the system pressure, temperature and medium characteristics.
Rotary Joint Sealing Methods and Requirements
The threaded connection itself does not constitute the sole sealing point; it is essential to clarify whether the seal relies on the threads themselves or on a face seal utilizing a gasket. This determination dictates whether the threads selected for the rotary joint installation require additional sealing materials and how the tightening torque must be controlled.
Spatial Configuration and Convenience
In installation environments with limited space, both the thread type and dimensions influence the available operating clearance. While fine-pitch threads may offer a greater number of engaged turns for a given engagement length, their structural strength requires careful evaluation in applications involving frequent disassembly.
What Should be Considered When Selecting the Thread for a Rotary Joint?
Do not rely on visual inspection or subjective judgment based on experience, as this is highly prone to error. Instead, utilize specialized measuring tools—such as thread gauges—to perform precise measurements and accurately distinguish between metric and imperial threads, as well as coarse and fine pitches.
It is crucial to understand whether the sealing function occurs at the threaded connection or at the face of the rotary joint; a misconception regarding this point can lead to installation errors, thereby resulting in leaks.
Avoid forceful installation. If you encounter excessive resistance during installation, stop immediately and re-verify the thread specifications. Forcing the component into place will damage the threads, potentially rendering the rotary joint unusable or damaging the equipment interface, thereby resulting in greater losses.
If you are unsure about the rotary joint thread type or have questions about the sealing method, please feel free to contact us. Sun Hong will provide you with detailed solutions and selection guidance for the joint, and can match the appropriate model for you based on your parameters and operating conditions.
