Valve maintenance, maintenance of the most complete professional knowledge

Valve maintenance knowledge

How to maintain the valve Description:

First, seal the leakage at the filler

Analysis of production reasons:

Stuffing aging

2. excessive force when operating too much;

3. Packing gland bolts loose;

Fault elimination method:

1. Should be timely replacement of aging, damage to the sealed packing, according to the circle placed, the connector was 30 ° ~ 45 °;

2. should be normal operation evenly, not allowed to apply casing or other ways to lengthen the arm;

3. Uniformly tighten the packing bolts with packing glands;

Second, the sealing surface leakage

Production reasons:

1. Valve installation direction and media flow does not meet;

2. valve is not in place;

3. long closed the valve in the sealing surface fouling;

4. Sealing surface slightly rubbing;

5. Seal surface damage is serious;

Fault elimination method:

1. Note the valve installation check;

2. Re-adjust the high-speed screw on the actuator, in strict condition;

3. Open the valve to a seam, so that high-speed liquid washed away fouling;

4. high-speed gasket to compensate;

5. re-grinding, high-speed gasket compensation;

Third, the flange connection outside the leak

Production reasons:

1. stud tightening force uneven;

2. Gasket aging damage;

3. The choice of gasket material and working conditions do not match the media requirements;

Fault elimination method:

1. Re-tighten the bolts;

Replace the gasket;

3. According to the requirements of the correct selection of gasket material and form, if necessary, please contact the manufacturer, request help selection, selection, order to specify the requirements.

Four, handle, hand wheel damage

Production reasons:

1. use is incorrect;

2. Firmware loose;

3. Handle, hand wheel and stem connection damage;

Fault elimination method:

1. prohibit the use of pipe wrench, lengthened lever, impact tools;

2. Repair at any time;

3. repair at any time;

Five, worm gear, worm drive card bite

Production reasons:

1. embedded in the dirt, affecting lubrication;

2. operation is not correct;

Fault elimination method:

1. remove dirt, keep clean, regular refueling;

2. If the operation found the card bite, great torque, can not continue to operate, immediately stop, thoroughly check;

Six, electric valve installation failure

Production reasons:

1. Lubricant bad, the valve has a foreign body stuck, resulting in large damage to the torque side;

2. motor failure;

Fault elimination method:

1. On the refueling, so that tubing is good, packing should be adapted to pressure, should be promptly removed from the valve foreign body, to keep clean;

2. The motor working time does not exceed 15 minutes, the power supply should be normal, to avoid the motor damp.

Valve leakage reasons:

Valve leakage in life, production is very common, ranging from a waste, or to bring danger to life, such as water valve leakage, heavy lead to serious consequences, such as chemical industry toxic, harmful, flammable, explosive and Corrosive properties of the leakage, etc., a serious threat to personal safety, property safety and environmental pollution accidents. An electric butterfly valve relies on external force to drive the opening and closing valves are designed with a sealing device both used in the packing culvert to install a certain number of packing seals, and even to achieve the sealing effect, but the sealing situation? Valve leakage at the filler is the most prone to leakage in the valve part of the first, but the reason there are two reasons.

One, corrosion one reason

Corrosive conditions are:

1. Stem of the natural oxidation of corrosion, electric butterfly valve as the valve stem at the table at the oxidation, the formation of iron oxide (rust) off, resulting in thinner stem, causing leakage;

2. Asbestos - type filler chloride leakage caused by corrosion;

3. Corrosion of Graphite Packing on Stainless Steel;

4. Media on the stem of the corrosion and so on.

Second, the reasons for packing

The filler is now mainly used:

1. Asbestos, asbestos material due to the presence of chloride ions on the stem corrosion, and asbestos containing carcinogenic substances, endangering human health, the state of the product has been taken to disable or less;

2. Synthetic resin and synthetic fiber, tax planning advice Some of these products are limited in the scope of use, such as pure polytetrafluoroethylene use temperature must be ≤ 150 ℃, filled with PTFE ≤ 250 ℃, PTFE particles Packing compensation performance is poor, only applies to low-pressure valves, PTFE fiber, carbon fiber or both mixed packing, and the price is too high, unfavorable promotion;

3. Expanded graphite, there will be serious electrochemical corrosion.

Valve repair procedures:

Valve maintenance of the general procedures:

1, the valve is removed, the steel word on the valve and valve connected to the flange, the maintenance number, and record the valve working medium, working pressure and working temperature, in order to repair the use of the corresponding material.

2, maintenance valve, the requirements in a clean environment. First clean the outer surface of the valve, or use compressed air blowing or kerosene cleaning. But to remember the nameplate and other logo. Check the appearance of damage and record. Then remove the other parts of the valve, with kerosene cleaning (do not use gasoline to clean, so as not to cause a fire), check the other parts of the damage, and for the record.

3, the valve body cover strength test. Such as high-pressure valves, but also for non-destructive testing, such as ultrasonic testing, x-ray detection.

4, the seal can be used red Dan powder test, seat, gate (valve) of the degree of fit. Check the stem for bending, whether it is corroded, and how the threads are worn. Check the degree of wear of the stem nut.

5, to check the problem to deal with. Valve body welding defects. Surfacing or renewing the seal. Straighten or replace stem. Repair all parts that should be repaired; can not be replaced by repair.

6, re-assembled valve. When assembling, the gasket and packing should be replaced.

Common valve faults and handling

LD solenoid valve stuck:

Solenoid valve slide valve sleeve and spool with a small gap (less than 0.008mm), are generally single-piece assembly, when there are mechanical impurities into or less oil, it is easy to stuck. Treatment method can be used to pull the wire from the head hole, so that it bounced back. The fundamental solution is to remove the solenoid valve, remove the spool and spool sleeve, with CCI4 cleaning, making the spool in the valve sleeve action is flexible. Disassembly should pay attention to the assembly of the parts and the external wiring position, so that re-assembly and wiring is correct, but also check the oil mist spray hole is blocked, the oil is sufficient. Steam solenoid valve.

Valve maintenance of the top ten Note:

(1) must first identify the valve, the downstream pipeline has been unloaded pressure, in order to disassemble the decomposition operation.

(2) non-metallic parts should be immediately removed from the cleaning agent, not a long time soaking.

(3) the bolts on the flange must be symmetrical, step by step, evenly tightened.

(4) cleaning agent should be with the valve in the rubber parts, plastic parts, metal parts and working medium (such as gas) are compatible. When the working medium is a gas, the metal parts can be cleaned with gasoline (GB484-89). Non-metallic parts are washed with pure water or alcohol.

(5) the decomposition of a single part can be washed with immersion. Metal parts that are left with undecomposed non-metallic parts can be scrubbed with a clean, fine, dipped silk cloth (to prevent fiber from falling off on the part). Cleaning to remove all adhere to the wall of the grease, dirt, plastic, dust and so on.

(6) decomposition and reassembly must be careful to prevent damage to the sealing surface of parts, especially non-metallic parts, remove the O-ring should use special tools.

(7) after cleaning to be washed wall cleaning agent volatile (can be used without cleaning detergent cloth) for assembly, but not for a long time to shelve, otherwise it will rust, dust pollution.

(8) New parts need to be cleaned before assembly.

(9) Use grease to lubricate. Grease should be compatible with valve metal material, rubber parts, plastic parts and working medium. When the working medium is gas, for example, special gas is used. Apply a thin layer of grease to the surface of the seal mounting groove, apply a thin layer of grease to the rubber seal, apply a thin layer of grease to the sealing surface and friction surface of the valve stem.

Control valve bypass

The following conditions should be set to bypass:

(1) corrosive fluids;

(2) Where the severe parts of the trimmed parts are described in 8.2.3 (2);

(3) other important occasions, such as boiler feed water regulating valve.

The following conditions do not set the bypass:

(1) clean fluid;

(2) Nominal diameter DN> 80mm occasions;

(3) LD control valve failure or maintenance, will not cause the occasion of the accident;

(4) the process is not allowed or can not use the bypass valve operation of the occasion. Such as emergency interlocking vent valves and slurry and easily crystallized fluids.

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