Views: 0 Author: J-VALVES Publish Time: 2021-10-28 Origin: Site
I. INTRODUCTION
In the industrial field, BRONZE BUTTERFLY VALVES are widely used, and their leakage rate is one of the key indicators for measuring the performance of valves. Different international standards have their own regulations for the leakage rate testing of butterfly valves. Among them, API 598 AND ISO 5208 are two commonly used standards. Understanding the differences in their pressure curves helps to evaluate the quality and performance of BRONZE BUTTERFLY VALVES more accurately. This article will conduct a comparative analysis on this aspect.
II. PRESSURE CURVE OF LEAKAGE RATE TESTING OF BRONZE BUTTERFLY VALVES UNDER API 598 STANDARD
1. PRESSURE TESTING STAGE
According to the API 598 standard, first, the butterfly valve will be installed on a specialized testing device, and the system pressure will be gradually increased to the specified test pressure value. This pressure increase process usually has a relatively stable rate requirement. For example, the pressure will increase by a certain value per minute (specifically depending on the valves of different specifications and actual requirements) to ensure that the valve can be tested under a stable and comparable pressure environment.
2. PRESSURE STABILIZATION STAGE
After reaching the test pressure, it is necessary to maintain this pressure for a period of time, generally lasting for several minutes. The purpose is to allow the internal structure of the valve to fully adapt to this pressure state. Meanwhile, it is also convenient to observe whether there is any leakage under this stable pressure and record relevant data. During this stage, the pressure curve basically presents as a horizontal straight line.
3. PRESSURE REDUCTION STAGE
After the test is completed, the pressure will be slowly reduced at a specified rate until it returns to the normal pressure state. The pressure reduction process also needs to be operated smoothly to avoid additional impacts on the valve caused by sudden pressure changes. Correspondingly, the pressure curve will decline steadily.
III. PRESSURE CURVE OF LEAKAGE RATE TESTING OF BRONZE BUTTERFLY VALVES UNDER ISO 5208 STANDARD
1. PRESSURE APPLICATION METHOD
When applying pressure according to the ISO 5208 standard, it also gradually increases from the initial pressure. However, it may have more meticulous control over the accuracy and segmentation of the pressure increase. For example, it may increase the pressure in multiple small stages, and each stage has a corresponding pressure holding time for inspection. This makes the pressure curve show some small "step-like" changes during the pressure increase stage, which is different from the relatively smooth pressure increase under API 598.
2. CHARACTERISTICS OF THE PRESSURE STABILIZATION PROCESS
During the pressure stabilization stage, the requirements for the pressure stabilization time and the allowable pressure fluctuation range specified by ISO 5208 are different from those of API 598. It emphasizes more precise pressure maintenance during pressure stabilization. The requirement for the straightness and stability of the pressure curve at this stage is higher, and it is more stringent on relevant conditions such as the stability of the testing environment.
3. DIFFERENCES IN PRESSURE REDUCTION OPERATIONS
During the pressure reduction process, the settings such as the pressure reduction rate and the detection nodes in the ISO 5208 standard also have their own characteristics. The slope of the pressure curve decline and the control of key points in the process are not exactly the same as those of API 598. The overall pressure reduction process pays more attention to capturing subtle changes.
IV. COMPARISON TABLE OF PRESSURE CURVES IN API 598 AND ISO 5208 STANDARDS
Comparison Items | API 598 Standard | ISO 5208 Standard |
Pressure Increase Process | Relatively stable pressure increase, increasing to the test pressure at a certain rate | Pressure increase in stages, paying more attention to the segmentation accuracy and the holding time of each stage, with the curve showing small step-like changes |
Pressure Stabilization Stage | Maintain the specified time, the pressure curve is basically a horizontal straight line, with relatively conventional requirements | Require more precise pressure maintenance, stricter control over the pressure stabilization time and the allowable fluctuation range, and higher requirements for the straightness and stability of the line |
Pressure Reduction Stage | Steadily reduce the pressure at the specified rate, and the pressure curve declines steadily | The pressure reduction rate and detection nodes have characteristics, pay more attention to capturing subtle changes, and the slope of the curve decline and the control of key points are different |
V. CONCLUSION
Through the comparison of the pressure curves in API 598 AND ISO 5208 standards for the leakage rate testing of BRONZE BUTTERFLY VALVES, it can be seen that the two standards have different focuses and requirements in each stage of the testing. In practical applications, users need to choose the appropriate standard for the leakage rate testing of butterfly valves according to specific engineering requirements, industry norms, and the usage environment of the valves, etc. Only in this way can the obtained test results be accurate and reliable, providing a powerful guarantee for the quality control and safe use of bronze butterfly valves.
