Pneumatic O-ring ball valve structure:
A ball with a middle through hole is installed inside the valve body, and a through hole with a diameter equal to the pipe diameter is opened on the ball. The ball can rotate in the seal seat, and there is a ring elastomer on both sides of the pipe direction to achieve sealing. By rotating the ball 90 °, the direction of the through hole can be changed, thus realizing the opening and closing of the ball valve. The valve core (ball) is spherical. From the structural point of view, the ball valve seat is embedded on the valve body side valve seat when sealing. The relative moving parts are all made of self-lubricating materials with very small friction coefficient, so the operating torque is small. In addition, the long-term sealing of sealing grease makes the operation more flexible. It is generally used for two position regulation, and the flow characteristic is quick opening.

Cause of failure of rotary compensator and optional sleeve compensator
In addition to good compensation ability, high reliability is the main reason why rotary compensator can be widely used in many industries. Its reliability is guaranteed through multiple links such as design, manufacturing, device, operation management, etc. Any link out of control will lead to the reduction of life of the compensator or even failure. After years of statistics, Baochen Pipeline found that the reasons for the failure of rotary compensator were: design accounted for 10%, the manufacturer's jerry building accounted for 50%, the device did not meet the equipment clarification request accounted for 20%, and other reasons were caused by improper operation management.
Failure Types and Causes of Rotary Compensators
1. Failure type
The failure of rotary compensator occurred during pipeline pressure test and operation. There are mainly three types of problems in pipeline pressure test: support damage and failure of rotary compensator due to improper temporary support of pipeline system or unreasonable setting of fixed support of pipeline system; Due to the insufficient pressure or displacement safety margin considered in the rotary compensator design, the rotary compensator will lose its stability and deformation during the pipeline pressure test; The manufacturing quality of the compensator was poor. The manufacturer cut corners and changed the 5 layers of stainless steel to 3 layers or less without permission. The failure of rotary compensator during operation is mainly manifested by corrosion leakage and instability deformation, of which corrosion failure is the most. From the anatomy of the rotary compensator for corrosion failure, it is found that the corrosion failure is usually divided into pitting corrosion perforation and stress corrosion cracking, of which the chloride stress corrosion cracking accounts for about 95% of the total corrosion failure. There are two types of instability of rotary compensator: strength instability and structural instability. Strength instability includes plane instability and circumferential instability of external pressure rotary compensator; Structural instability is the column instability of internal pressure rotary compensator.
2. Relationship between design fatigue life, stability and stress corrosion
The design of the rotary compensator mainly considers the three factors of pressure resistance, stability and fatigue performance. Although the national code and the American EJMA code have clear rules for the calculation and evaluation of these aspects, it is found from years of application theory and rotary compensator failure analysis that the calculation and evaluation methods for stability given in the code are not comprehensive enough, and fatigue life only gives a relatively broad boundary range (uniform fatigue life is applicable in 103~105). Sometimes a product that fully meets the requirements of the specification will also present some problems in practical application. For example, in the pre displacement state of the internal pressure axial compensator, the rotary compensator is prone to plane instability during the pressure test, the rotary compensator is prone to circumferential instability under the full displacement working state of the large diameter external pressure axial compensator, and the column instability is prone to occur under the full displacement working state of the small diameter compound rod type compensator and hinge type compensator. The excessive deformation of the rotary compensator not only affects its stability, but also provides favorable environmental conditions for stress corrosion. As a professional manufacturer of sleeve compensators, today I would like to introduce why we choose sleeve compensators?
Reason for purchasing sleeve compensator: sleeve compensator has a long service life, and its fatigue life is equivalent to that of pipeline. After special treatment, the sliding surface has good corrosion resistance in salt water, salt solution and other environments, more than 50 times higher than austenitic stainless steel. At the same time, if the sealing effect is weakened due to wear many years later, the flange can be tightened again to strengthen the sealing performance, or the bolt can be loosened, the pressure ring can be removed, and then one or two layers of sealing rings can be installed, and the pressure ring can be tightened for further use.
Application and maintenance of sleeve compensator
1. During the pipeline operation, the sliding sleeve of the compensator is strictly subject to the external lateral thrust, and should always be concentric with the pipeline axis, and prevent the normal sliding of the sliding sleeve from being obstructed.
2. During maintenance, check the installation condition of the seal and tighten the bolts in time to ensure that the seal has no leakage.
3. If the outer surface of the sliding sleeve of the compensator is severely corroded and the anti leakage effect is not obvious after the bolt is tightened, the compensator should be replaced.