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Bakelite valve installation, operation and maintenance

2016-07-20 13:18:49
After correctly selected bakelite valve, but also properly installed, maintained with the operation, so as to fully play its effectiveness.

Section installation quality bakelite valve mounted directly affect the use, and therefore must be careful attention.

(A) direction with the position of the valve has a lot of bakelite directivity, such as closing valves, throttle valves, check valves, etc., if the anti-loaded flip, it will affect the use of effects with life (such as the throttle) or simply does not work (such as a valve), or even pose a risk (such as a check valve). Usually bakelite valve, the valve body directional signs; there is no case, should be based on bakelite valve works correctly identified. Cut-off valve left-right asymmetry of the valve chamber, the fluid through the valve port to make its bottom-up, so fluid resistance (determined by the shape), open the effort (due to media pressure up), after the closure of the media do not pressure filler, easy to repair . That's why the cut-off valve shall An anti-truth. Other bakelite valve also have their own characteristics. Bakelite valve installation position must be easy to operate; even install some temporary difficulties, but also for the sake of the operation of permanent staff. Bakelite hand wheel with the best valve chest aligner (generally from operating floor 1.2 meters), so that the valve opening and closing bakelite strength compared to the province. Floor bakelite hand wheel valve should be facing up, do not tilt, in order to avoid awkward operation. Wall machine by bakelite valve device, leaving a reasonable operator standing room. To avoid his back operation, especially in acid, toxic media, otherwise very safe. Do not flip gate (ie handwheel down), otherwise it would be retained in the media long bonnet space, easy to stem erosion and taboo for certain process requirements. At the same time replace the packing very inconvenient. Rising stem gate valve, do not install in the ground, or because of wet and corrosive exposed stem. Lift check valve, the installation should ensure the valve perpendicular to lift and flexible. Swing check valve, the installation should ensure that its pin level in order to swing flexible. To install the valve upright in horizontal pipelines, do not tilt in all directions.

(B) Installation construction work must be careful and avoid the impact of brittle material bakelite valve. Before installation, you should make a check valve bakelite, check the specifications, identification of damage, especially for stem. Also a few turns to see if skewed, since transportation experience, most likely to hit the crooked stem. But also to clear the debris inside the valve. When bakelite valve lifting, rope not tied hand wheel or stem to avoid damage to these components, this should be tied to the flange. For pipes bakelite valve is connected, it must be cleaned. Available compressed air to remove iron oxide particles, silt, welding slag with other debris. These sorts of things, not only easy to scratch the sealing surface bakelite valve, which large particles of debris (such as weld slag), but also blocked the small bakelite valve, it can be disabled. When you install screw bakelite valve should seal packing (leaded hemp oil or Teflon tape), including on the pipe threads, do not get bakelite valve, the valve in order to avoid memory product, the impact medium flow. When bakelite valve mounting flange, pay attention to the symmetry evenly tighten bolts. Bakelite valve flange must be parallel with the pipe flange, reasonable gap, bakelite valve in order to avoid excessive pressure, even cracking. For brittle materials with low strength bakelite valve, with particular attention. Shall bakelite valve with pipe welding, spot welding should be, then the closure member open, and then welded shut.

(Iii) the protection of some facilities bakelite valve must have external protection, which is guaranteed with cold insulation. Sometimes within the insulation layer plus heating steam line. What should the insulation bakelite valve or cold, according to the production requirements. Principle to say that in the medium where the valve to lower the temperature too much can affect productivity or frozen bakelite valve, you need heat, even heating; where bakelite valve nudity, production caused by adverse or negative phenomena such as frost, it needs cold. Asbestos insulation materials, slag wool, glass wool, perlite, diatomaceous earth, Vermiculite, etc.; cold materials cork, perlite, foam and plastics. Long without water, steam bakelite valve must let go of water.

(Iv) bypass valve bakelite with some instrument, in addition to the necessary protection facilities, but also with the bypass meter. Installed bypass, easy trap maintenance. Bakelite other valves, there are installed bypass. Installed bypass valve depends on the requirements of bakelite case, with the importance of the production may be.

(V) a filler valve replacement stock, and some filler has been so bad, and some do not match with the use of the media, which need to replace the packing. Bakelite valve manufacturer can not consider the use of units of one thousand million class is not the same medium, the stuffing box is always filled with ordinary packing, but when used, must be allowed to adapt to packing with medium. When replacing the packing, to circle around pushed. Each lap joints 45 degrees is appropriate, with the circle ring joints staggered 180 degrees. To consider the height of packing gland constantly pressing room, now we have to let the lower part of the gland packing chamber pressure proper depth, this depth is generally 10 to 20% of the total depth of the packing room. For demanding bakelite valve seam aspect of 30 degrees. Between the ring with ring joints staggered 120 degrees. In addition to the Office of the filler, also based on the specific situation, the adoption of a rubber O-ring (natural rubber resistant to 60 degrees Celsius weak base, NBR oil resistant to 80 degrees Celsius, fluorine rubber resistant to many corrosive media 150 degrees Celsius) three stacked PTFE ring (resistant to 200 degrees Celsius and strong corrosive media) nylon bowl rings (resistant to 120 degrees Celsius ammonia, alkali) and other forming filler. Outside the ordinary asbestos packing, including a layer of Teflon tape, can enhance the sealing effect, reduce the electrochemical corrosion of the stem. When compression packing, the valve stem to rotate simultaneously to four weeks evenly and prevents too dead, tighten the gland to force uniform, not tilted.

Maintenance Section of bakelite valve maintenance, can be divided into two conditions; one is to maintain custody, the other is the use of maintenance.

(A) keeping custody of the maintenance goal is to keep in custody bakelite valve damage, or reduce the quality. In fact, improper storage is one of the important reasons bakelite valve damaged. Bakelite valve custody, this should be well-organized, small bakelite valve on the shelves, big bakelite valves can be neatly arranged on the warehouse floor, not random heaps pile, do not let the flange surface contact with the ground. This is not only for aesthetic reasons if the main valve will not damage the protection of bakelite. Because keeping with improper handling, hand wheel broken, crooked stem touch the hand wheel with the valve stem retaining nut loose loss, etc., these unnecessary losses, this should be avoided. To temporarily use the short-term bakelite valve, remove asbestos packing, in order to avoid electrochemical corrosion, damage to the stem. Of bakelite valve entered the library, to be checked, such as rain or dirt into the transportation experience, to Wipe clean, re-storage. Importers use waxed paper or plastic bakelite valve sealed to prevent dirt into it. Of energy in the atmosphere bakelite rusty valve working surface to be coated with anti-rust oil, to protect them. Place outdoor bakelite valve, must be covered with linoleum or Tarpaulins like rain, dust articles. Bakelite valve storage warehouse to continue clean and dry.

(Ii) the use of maintenance using the maintenance goal is to extend the life of bakelite valve open and close with a reliable guarantee. Stem threads, often with stem nut friction, to be painted little yellow grease, molybdenum disulfide or graphite, a lubricant. Not often open and close the valve of bakelite, also regularly turn the hand wheel, valve stem thread lubricant to prevent the bite. Outdoor bakelite valve to add protective sleeve on the stem, with rain, snow, dust, rust pollution. Such as the Department of Mechanical bakelite valve to be fixed, to be on time for the gearbox lubrication. Always continue bakelite valve clean. Always check valves and other components continued bakelite integrity. The hand wheel retaining nut off, to be filled and can not improvise using, otherwise it will grind the upper part of the stem garden square, with the gradual loss of reliability, can not even start. Do not rely on bakelite valve support other heavy objects, do not stand on bakelite valve. Stem, especially threaded portion to regular cleaning of the dust has been soiled lubricant must be replaced with new, since the dust contains hard debris, easy to wear with the surface of the threaded stem, affecting the service life.

For the third quarter operating bakelite valve, not only to be installed with the maintenance, and also will operate.

(A) manually bakelite valve opening and closing the manual valve is the most widely used bakelite bakelite valve, hand wheel or handle it, in accordance with the ordinary human design, taking into account the intensity with the necessary closing force of the sealing surface. So you can not use a long lever or long wrench to board moving. Some people are accustomed to using a wrench, should be strictly careful not to force too much too fast, or easy to damage the sealing surface, broken plates or hand wheels, handles. Bakelite open and close the valve, this force should be stable, must not shock. The impact of closing certain high pressure bakelite valve components have considered this impact with the general bakelite valve can not wait Gang. Bakelite valve for steam, before opening, should be pre-heated, and the exclusion of condensing water, and when opened, should try to move slowly to avoid water hammer phenomenon. When bakelite valve is fully open, the hand wheel reverse a little, so that between the threads tight, so as not to loose damage. For the next shot bakelite valve, to remember the fully open position with the stem fully closed and fully open to avoid the impact on the dead. And easy to check whether it is normal when fully closed. If the valves do fall off, or embedded in the larger debris between the valve seal, valve stem when fully closed position will change. The early use of the pipeline, the internal dirt more, you can bakelite valve slightly parted, use medium speed flow, which was washed away, and then gently close (not closing fast, fierce close, to prevent residual impurities crush the sealing surface) , opened again, so repeated several times, rinse the dirt, and then put to work. Bakelite normally open valve, sealing surface may stick dirt, closed by the above method should be washed away, and then officially shutting. Such as hand wheels, handles damaged or lost, immediately filled and can not be replaced by active wrench, to avoid damage to the stem of the Quartet, hoist ineffective, the accident that occurred in production. Some of the media, after cooling bakelite valve closed, the valve member contraction, the operator should be closed once again at an appropriate time, so that the sealing surface without leaving slit Otherwise, medium speed flowing from the slit, it is easy to seal erosion surface. In operation, the operation is too strenuous if found, should analyze the reasons. If the packing is too tight, it may be appropriate to relax, such as stem skew, repair personnel should be notified. Some bakelite valve in the closed state, the closure member to thermal expansion, resulting in open difficulties; as a child must turn in this, you can loosen the bonnet thread half circle to circle, eliminate stress stem, then board the handwheel.

(B) Notes

Bakelite temperature above 1,200 ℃ valve, as installed at normal temperature, and after normal use, temperature, thermal expansion bolts, expansion of the gap, and therefore must be tightened again, called "heat tight", the operator should pay attention to this work otherwise prone to leakage.

2, when the cold weather, long-closed valve stops, the water valve should be ruled out. After steam steam stop valve, but also exclude condensing water. Bottom valve like plugs, it can open the drain.

3, non-metallic valve bakelite, some hard and brittle, some low intensity, operation, opening and closing force can not be too much, especially not to Meng Jin. Also note that the provision of free objects bump.

4, the use of new bakelite valve, filling not too tight, so as not to leak for the degree, in order to avoid too much pressure stem, accelerate wear, open and close but strenuous. Check Chapter bakelite valve repair with the use of new life both bakelite valve, or the use of bakelite valve repaired and must be pressure test leak testing prior to installation.

The first section, pressure test leak pressure test, referring to the body strength test. Leak testing, referring to the sealing surface of the tightness test, this test is to check on the two main bakelite valve performance. Test medium, typically room temperature water, it is important to use bakelite valve kerosene. Safety valve constant pressure test, can use nitrogen more stable gas, steam or air can also be substituted. For the diaphragm, the use of air for testing.

(A) The test pressure bakelite valve pressure strength test, the following relationship with nominal pressure PN (Mpa) Strength test pressure (Mpa) 0.1 0.2 0.25 0.4 0.4 0.6 0.6 0.9 1.0 1.5 1.6 2.4 2.5 3.8 4.0 6.0 6.4 9.6 10.0 15.0 16.0 24.0 20.0 30.0 25.0 38.0 32.0 48.0 As seen above, the nominal pressure from 0.4Mpa-32Mpa, these common pressure bakelite valve, the strength test pressure 1.5 times. Bakelite valve sealing test pressure is equal to nominal pressure.

(B) Test Method for leak testing pressure test, the test bench. The structure, a test rig above a pressing member, here are a test pump in communication with the tubing. After pressing the valve, pressure test pump, pump from the pressure test gauge, can be read bakelite valve under pressure numbers. Caulking valve when the test timber filled with water, the air inside to drain valve. Test bench unit pressure plate, exhaust hole, with a small bakelite valve opening and closing. Air drain sign of vent holes are all out of the water. After closing the vent and start boosting. Boost experience slowly, not abruptly. After reaching a predetermined pressure, for 3 minutes, the pressure constant for qualified

Pressure test leak testing procedures can be in three steps:

1. Open the bakelite valve passages with water (or kerosene) filled with the valve chamber, and pressurized to the required pressure strength test, check valve, valve cover gaskets, packing leaks.

2, shut valve road, in pressurized to nominal bakelite side of the valve, the other side to check for leaks.

3, the valve bakelite reversed, the opposite side of the test.

Section II, general overhaul program bakelite valve removed, the word on the steel flange with bakelite bakelite valve and valve connected on the lay overhaul numbers and record the bakelite valve working medium, working pressure with temperature, in order to choose the appropriate material for repairs. When servicing bakelite valve requires a clean environment. First, clean up the outer surface of the valve bakelite, or blowing with compressed air or kerosene. But to keep track nameplate and other identification. Check the appearance of damage to health, and for the record. Then disassemble bakelite valve member each other, with kerosene (do not use gasoline to clean, so as not to cause a fire), check the status of the other damaged parts, and recorded. Bonnet valve body strength test. Bakelite case of high-pressure valves, but also for non-destructive testing such as ultrasonic flaw detection, x-ray detection. Ring Available on red lead powder inspection, seat, gate (valve Office) goodness of fit. Check that the stem bending, whether corrosion, thread galling how. Check the stem nut wear. Inspection to deal with the problem. Body repair welding defects. Surfacing or update seals. Straightening or replace the valve stem. All other parts should be repaired repairs; wearers can not be replaced. Reassemble bakelite valve. When assembled, gaskets, packing to replace them all. Strength test with sealing tests. Section III, often see failure and Prevention (a) general bakelite valve

1, packing box leakage which is run, run, the angle of the main drain, in the factory by often to see. Cause packing box leakage of the following points:

1), corrosive packing with the working medium, temperature, pressure incompatible; 2), filling the wrong way, especially screwed into the entire root filler spare, the most prone to leaking;

3), stem or precision surface finish is not enough, or ovality, or nicks;

4), the stem is due to the lack of open-air protection and rust pitting, or;

5), bent stem;

6), the use of fillers long aging.

7), the operation is too fierce.

2, the closure member leaking stuffing is usually called the leak leak, the leak is called internal leakage closure member, the closure member leak in the valve inside the bakelite, difficult to find. Closing member leaks can be divided into two categories; one is the sealing surface leakage (the other is the root of the seal leak

(Cause leakage are:

1>, the sealing surface grinding poorly;

2>, seals with the valve seat, a valve do not meet stringent;

3>, do not connect securely with the valve stem;

4>, stem bending and torsion, the upper and lower closing member misalignment;

5>, closed too quickly, or had a bad contact sealing surface damage;

6>, improper material selection, unable to withstand the corrosive medium;

7>, the closing valves, valve for regulating use of the seal surface withstand the impact of high-speed flow of medium;

8>, some media, bakelite valve closed after gradually cooling, the sealing surface appears slit, will produce the phenomenon of erosion;

9>, the adoption of certain seal between the valve seat with the valve do threaded connections, easy to produce oxygen concentration cell corrosion loose;

10>, because the welding slag, rust, dust and other impurities embedded, or production system with a mechanical valve block off the other pieces, so that the valve can not shutting bakelite.

3, stem down failure. The reasons are:

1>, the threaded operating excessive damage;

2>, the lack of lubricant or lubricant failure;

3>, stem bending and torsion;

4>, surface finish is not enough;

5>, with tolerances allowed, bite tight;

6>, stem nut tilt;

7>, improper material selection; for example, stem nut with the valve stem of the same material, easy to bite;

8> Thread wave medium corrosion (means dark bar bakelite valve or valve stem in the lower part of bakelite);

9>, the lack of protection outdoor bakelite valve stem threads caked sand dust, rust, etc. or by rain and frost.

4 Other body cracking: generally caused by freezing. Cold weather, the valve must be bakelite insulation heating measures, otherwise should be discontinued after bakelite valve and connecting pipe in the water drain (if the bottom wire blocking valve, open the drain plugs). Hand wheel damage: impact or long lever operation caused violently. As long as the operator or other persons concerned attention, could have been avoided. Gland Fracture: uneven force when the compression packing, gland or defective. Compression packing, to symmetrically rotate the screw can not be skewed. Just do not pay attention to the production of large parts with the core, but also pay attention gland times like elements, or affect the use. The stem is connected with the gate failure: valve stem rectangular head with the adoption of ram T-shaped groove connection form large, T-shaped groove sometimes not working, so make stem rectangular head wear faster. Mainly from the manufacturing point of view to solve. But the use of the unit can also be carried out on the T-line slots fill processing, so she has a certain finish. Bakelite double plate valve gate voltage can not close the cover: double plate tension is generated by the top wedge, some gate, the top wedge material poor (low grade iron), use of worn or broken soon. Top of the wedge is a small member, replaced the original cast iron.

(Ii) automatic valve bakelite

1, one of the spring-loaded safety valve failure, the sealing surface leakage. The reasons are:

① sandwiched between the sealing surface debris;

② damage the sealing surface. This failure to rely on regular maintenance to prevent.

The second failure, the sensitivity is not high. The reasons are:

① spring fatigue;

② spring improper use. Spring fatigue, no doubt this should be replaced. Improper use of the spring, is the use of those who pay no attention to the nominal one kind of spring-loaded safety valve, pressure has several segments, each segment there is a corresponding pressure spring. As for the safety valve nominal pressure 16 kg / cm 2, the use of pressure is the pressure section 2.5 to 4 kg / cm 2, the installation of the spring 10 to 16 kg / cm 2, although can improvise on, but the peaks and valleys , very sensitive. 2, check to see long faults: ① disc break; ② medium back. Cause broken valve do is: before and after the valve pressure medium is close to balance but to each other "see-saw" state, often to do with the valve seat beat, some brittle materials (such as cast iron, brass, etc.) made Office was broken valve. Preventive approach is adopted for the valve to do valve toughness. Media reflux causes are: ① sealing surface damage; ② sandwiched impurities. Repair the sealing surface with the removal of impurities, you can prevent backflow. Often see on the above described failures and methods of prevention, can only play a role in enlightenment, practice, will encounter other faults, to be flexible and proactive in preventing the occurrence of Bakelite valve failure, the most fundamental one is familiar its structure, operation principle with the material. Section IV, bakelite valve service life due to the bakelite valve widely used in the field, using the medium range, corrosion status of each is not exactly the same, so no use for life bakelite valve made from the provisions of national standards to industry standards, the machinery industry in 1980 section in order to enhance the quality of industrial products and machinery with the high-quality products and competitions, developed a "product quality grading bakelite valve industry regulations," which for the valve, cutting off the first-class products, superior product provides life test requirements; as Dn≤200 400 High school wood adhesive valve First grade scratch times 2000 times, 4000 times superior product. Because of the special nature of nuclear power plants, nuclear power countries to use bakelite valve life have made provisions; such as the US, France has 40, Japan 30 years to 40 years prescribed. Chapter VI Development bakelite valve technology development bakelite valve technology, depending on materials science, the development of structural studies. In recent years, the development of China synthetic materials, new steel and new technology, new materials, the use of the metal, gained great progress, these are the development of bakelite valve technology has added new content. Such as the development of titanium because titanium has a high affinity for oxygen with force, can generate a layer of solid oxide protective film, so that was passive in many highly corrosive media, it exhibits excellent corrosion resistance in acid , with the organic base is widely used, mixing in some organic acids in stainless steel cutting only use twelve weeks, and the titanium valve can be long-term use. In addition, the metal zirconium materials, is another good corrosion-resistant metal. Synthetic material is endless, such as polypropylene, polycarbonate esters, nylon and other materials bakelite valve has been used in the chemical industry. New ceramic bakelite valve is gradually promote the use of. The new structure, but also continue to introduce, such as the introduction of hard sealing butterfly valve, in the country is nearly 10 years of things. High temperature high pressure power station valve bakelite development, application and so on. New sealing materials; flexible graphite applications.

It is immersed in the graphite lattice in a liquid, and then forced to vaporize, changing the lattice arrangement direction, thereby changing the graphite become brittle and soft material, he can do with the packing washer, because of the high purity graphite, resistant to almost all chemical species, if the increase in the strength of nickel wire clip which can be used in high temperature and pressure control valves made of bakelite packing, gaskets. World countries in order to reduce costs, improve competitiveness, complete sets of equipment to large-scale development; current maximum is 1.3 million kilowatts thermal power generating units (USA, Switzerland made) a 600,000-kilowatt generator group with three 200,000 kilowatts generating units, equipment power down the unit cost of 10 to 20%, the cost of establishing power plants, power units, manufacturing hours, a 20% reduction in consumption of steel 6 million tons / year refinery with two 3 million tons / year refinery compared with the equivalent of only after investments 69% of those, 53% of steel consumption, covers an area of ​​54%, the production cost is 75%, while labor productivity has improved by 170% foreign refineries current maximum of 36.4 million tons / year, and 20 million tons / It has more than 20 years or more. With the oil refining industry has also been rapid development pipeline. The moment has been built up to 4830 km oil pipeline (Iran). The longest gas pipeline 7680 km (from Alaska through Canada to the United States) with the largest diameter 1420mm 1620mm. The maximum line pressure 9 ~ 12MPa these lines of Bakelite valve has strict requirements are adopted by remote control. With thermal power units also increased, in order to enhance the efficiency of its operating parameters are increasing; regulate temperature and pressure subcritical temperatures from 566 ° C 16.9MPa critical temperature 583 ° C 24.6MPa supercritical temperature above 650 ° C 35MPa review by a large-scale equipment for bakelite valve material, structure, reliability stand more stringent requirements.