Stainless steel sanitary-grade tubing Maintenance precautions! Stainless steel sanitary-grade tubing The maintenance precautions have already been introduced above. Nowadays, many industries are adopting sanitary-grade equipment, and sanitary-grade valves are one of them. So how should we maintain these valves? Is the maintenance process for sanitary-grade valves the same as that for sanitary-grade stainless steel pipes? After reading the article below, you’ll clearly understand the key points to keep in mind when maintaining, servicing, installing, and using sanitary-grade valves.
One) Hygienic-grade valves should be stored in a dry, well-ventilated indoor area, and both ends of the nominal diameter must be sealed to prevent dust ingress.
2) For long-term storage, regular inspections are recommended, and the machined surfaces should be coated with oil to prevent rusting.
3) Before installing sanitary valves, carefully verify that the markings match the specified usage requirements.
4) During installation, the inner cavity and sealing surfaces should be cleaned, the packing should be checked to ensure it is properly compressed, and the connecting bolts should be tightened evenly.
5) Hygienic valves shall be installed in accordance with their permitted operating positions, but attention must be paid to ease of maintenance and operation.
Six) During use, do not partially open the sanitary-grade gate valve to regulate flow, as this may damage the sealing surfaces when the medium flows at a high velocity. It is recommended to either fully open or fully close the valve.
7) When turning the handwheel to open or close, do not use any other auxiliary levers.
8) Transmission components should be regularly lubricated with oil. When using sanitary-grade valves, frequently apply oil to the rotating parts and coat the trapezoidal thread section of the valve stem.
9) After installation, regular inspections should be conducted to remove dirt from the internal cavity, check the sealing surfaces, and examine the wear condition of the valve stem nut.
Ten) There should be a set of scientifically sound and correct installation operation standards. During maintenance, sealing performance tests must be conducted, and detailed records should be kept for future inspection.
11) Other precautions for sanitary-grade stainless steel pipes:
1) Sanitary valves should generally be positioned before pipeline installation. Piping should be installed naturally; do not forcibly bend it if the position is incorrect, as this could leave residual stress.
2) Before positioning, low-temperature sanitary valves should, whenever possible, undergo opening and closing tests in a cold state (e.g., immersed in liquid nitrogen), ensuring that they operate smoothly without any sticking or jamming.
3) The liquid valve should be configured with the valve stem inclined at a 10° angle to the horizontal, so as to prevent liquid from flowing down along the valve stem and increasing cold losses. More importantly, this configuration helps avoid the liquid coming into contact with the packing seal surface, which could cause the packing to become cold-hardened and lose its sealing effectiveness, resulting in leakage.
4) The connection points of sanitary safety valves should be equipped with bends to prevent direct impact on the sanitary valve; additionally, it is essential to ensure that the sanitary safety valve does not frost over, so as to avoid failure during operation.
5) When installing sanitary-grade shut-off valves, the flow direction of the medium should be consistent with the arrow indicated on the valve body. This ensures that when the sanitary-grade valve is closed, the pressure is applied to the cone at the top of the valve, while the packing remains unloaded. However, for sanitary-grade valves that are not frequently opened and closed but must provide a strict leak-proof seal in the closed position (such as heated valves), they may intentionally be installed in the reverse orientation so that the medium pressure helps to keep them tightly closed.
6) Large-size sanitary gate valves and pneumatic sanitary control valves should be installed vertically to prevent the valve core from tilting to one side due to its own weight, which could increase mechanical wear between the valve core and the bushing and lead to leakage.
7) When tightening the compression screw, the sanitary-grade valve should be kept slightly open to prevent damage to the valve seat sealing surface.
8) After all sanitary-grade valves have been installed, they should be operated once more to ensure smooth opening and closing without any sticking or jamming; this indicates that they meet the required standards.
9) After the large air separation tower has undergone bare cooling, perform a preliminary tightening of the flanges connecting the sanitary-grade valves under cold conditions to prevent leakage at low temperatures that might not occur at room temperature.
10) It is strictly prohibited to use the valve stem as a scaffold for climbing during installation.
11) High-temperature sanitary valves operating at temperatures above 200℃, when initially installed at room temperature, experience thermal expansion of the bolts and increased clearances as the temperature rises during normal operation. Therefore, these valves must be re-tightened after installation—this process is known as “hot tightening.” Operators should pay close attention to this procedure; otherwise, leaks are likely to occur.
12) When the weather is cold and the water valve has been shut off for an extended period, any accumulated water behind the valve should be drained. Similarly, after the steam valve is shut down, any condensed water should also be drained. If there’s a screw plug at the bottom of the valve, you can open it to drain the water.
13) Non-metallic sanitary valves—some are hard and brittle, while others have lower strength. When operating these valves, avoid applying excessive opening or closing force, especially avoiding sudden, vigorous movements. Also, take care to prevent the valve from being struck or bumped by other objects. 14) When using a new valve, do not tighten the packing too tightly; just ensure there is no leakage, so as to avoid placing excessive pressure on the valve stem and accelerating wear.