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Gate valves serve a wide range of industrial applications; their main purpose is the regulation of flow for different mediums that pass through pipelines. This post will elaborate on the main steps involved in gate valve maintenance.
Gate valves usually in pipelines of more than 100 mm in diameter. Its main purpose is to start or stop the flow of media, raising or lowering a gate/wedge inside the valve. It has advantages, including low flow resistance and ease of operation. Its disadvantage is that the valve sealing surfaces are easily worn out, and it is never used for flow regulation.
Gate valves consist of several key components:
Body and Bonnet: Typically made of carbon steel or alloy steel, depending on operating temperature and pressure.
Stem and Gate: Responsible for the opening and closing of the valve.
Packing Seals: prevent media leakage along the stem.
Remove the Bonnet:
Loosen the bolts on the valve bonnet.Turn the stem counterclockwise to disengage the frame from the body and then remove the bonnet with the aid of lifting equipment.
Extract the Gate and Stem Assembly:
Utilize appropriate tools to compress the packing and introduce a clearance to remove packing rings.
Carefully lift out the gate and stem assembly, ensuring the sealing surfaces remain undamaged.
Inspect the Body Interior:
Clean the valve's internal surfaces and check the seat for wear or damage.
Disassemble the Stem:
Release the packing gland and rotate the stem out for inspection.
Remove the gate assembly, taking note of shim thickness and alignment.
Valve Seats:
Use grinding tools with progressively finer abrasives to achieve a polished surface. Repair deep scratches or grooves using machining processes.
Gate Surface:
Polish manually or with a grinder. For significant damage, consider re-machining or replacing the gate.
Stem and Packing Area:
Check for rust, bends, or excessive wear. Straighten or replace as needed.
Check trapezoidal threads and lubricate with graphite grease.
Fasteners and Bearings:
Clean all bolts and nuts. Replace corroded or damaged fasteners.
Check bearings for smooth operation and lubricate them thoroughly.
Packing Seals:
Replace worn packing material with high-quality alternatives, ensuring proper dimensions and density.
Mount the gate to the stem, taking care for proper alignment to the sealing surfaces. Adjust shims for uniform contact.
Put the bonnet on the valve body with appropriate packing to ensure a tight seal.
Evenly tighten bolts to avoid leakage or misalignment.
Manual opening and closing tests to be conducted to see that the valve operates with ease.
Pressure tests to be conducted to ensure there are no leaks.
Ensure that all parts are aligned and tightened accordingly.
The valve should move freely without hang-ups.
Record maintenance activities and results for future reference.
Free from defects such as cracks, sand holes, or erosion.·
Inside clean and free-flowing without restrictions.·
No bends or excessive wear.·
Thread wear not more than one-third of the depth of the original thread.
Polished to a surface roughness less than 0.1 µm.
Full contact between the gate and seat when closed.
Correctly selected materials by temperature and pressure application.
Compressed correctly to eliminate leaks and provide for smooth operation of the stem.
Periodic Inspections: Routine checks reveal and help address potential issues before they could get worse.
Lubrication: Lubrication reduces friction in moving parts, thus decreasing wear and tear.
Pressure and Temperature Monitoring: Operating valves inside limits specified to prevent material fatigue.
Qingdao Fluido Industrial Co. Ltd. is a world-leading manufacturer of high-quality industrial valves. Founded in 1994, FLUIDO has over 20 years of experience in the manufacture and export of steel valves, fittings, and flanges to over 35 countries and regions.
FLUIDO offers an extensive product range with over 150 series, such as cast iron gate valves, cast steel valves, ductile iron pipe fittings, and many more. Committed to quality, we hold ISO9001 and European CE certifications. Choose FLUIDO for incomparable quality and professionalism.
For industrial valves and accessories of the highest rank, contact Qingdao Fluido Industrial Co. Ltd.:
Email: info@FLUIDOvalve.com
Phone: +86 13210153062
