The non-thrust rotary compensator (also known as the maintenance-free rotary compensator) operates on a principle similar to the hinge-type bellows expansion joint, requiring the combination of two or more compensators to accommodate displacement through changes in angular displacement. The main difference between the two is that the hinge-type bellows expansion joint relies on the deformation of the bellows to create angular displacement, whereas the non-thrust rotary compensator uses the rotation of the tube to achieve angular displacement, which necessitates a force (generated by pipe thermal expansion) and a lever arm to form a torque that drives the rotation. Therefore, it cannot align with the pipe centerline but should be perpendicular to it, allowing for the connection of two non-thrust rotary compensators through a lever arm. When one end of the pipe expands due to thermal expansion, it exerts a torque on one non-thrust rotary compensator, while the connected rotating bellows compensator generates an opposing torque, creating a force couple with equal and opposite torques for force balance. The greater the angular displacement and the longer the lever arm, the greater the compensation. For a single non-thrust rotary compensator, the rotation angle can be arbitrary; however, when two such compensators, along with the lever arm and pipe, form a linkage mechanism, the potential for collision or jamming must be considered. The rotation angle should be less than 90 degrees during thermal expansion to allow for return to the original position during cold contraction. Additionally, friction must be overcome during rotation, and sufficient allowance should be made, typically 20 to 45 degrees, depending on the arrangement and pipe diameter; a larger value is chosen for smaller diameters. Furthermore, a longer lever arm can cause significant lateral displacement, potentially leading to pipe bending and failure, which must be carefully considered. To increase the compensation, a pre-displacement method is used during pipe installation, which is half the required rotation angle in the opposite direction. Since the non-thrust rotary compensator does not have the fatigue life issue of bellows expansion joints, the allowable rotation angle can be doubled, thereby reducing friction and enhancing pipe stability. The advantages of the non-thrust rotary compensator include the absence of internal pressure thrust, no requirement for bellows stiffness, and the ability to use thicker walls, making it particularly suitable for high-pressure and high-compensation applications.

2. The non-thrust rotating compensator has evolved into its second generation, with the first being the non-thrust rotating compensator and the second being the maintenance-free non-thrust rotating compensator. The manufacturing of the non-thrust rotating compensator is advancing towards longer product life and easier maintenance. The second generation non-thrust rotating compensator outperforms other similar compensators in terms of usage.

3. No-Force, No-Maintenance Rotational Compensator: Comprised of a reducer pipe, inner sleeve, sealing seat jacket, flexible graphite packing, a set of nuts, bolts, springs, packing cover, and a spring-tight flange. The packing is equipped with a spring between it and the clamping upper flange, and the longitudinal cross-section of the clamping flange is an U-shaped groove ring. Within the U-shaped groove ring and between two fixed rings at the right end face of the inner conduit, there are roller-type rolling rings that move in coordination with the reducer pipe.

4. Non-thrust rotating compensator: Composed of a reducing elbow, inner sleeve, outer seal seat, flexible graphite filling, nut, bolt spring assembly, and filling cover, complete with corresponding ball bearings.