What should be paid attention to when using forged steel valves?

What should we pay attention to when using self-sealing forged steel valves?

  1. Forged steel valves often ignore the problem of grease injection. After the grease gun is refueled, the operator selects the valve and the grease injection method after the low temperature shut-off valve, and then performs the grease filling operation. There are two kinds of conditions for the forged steel gate valve: on the one hand, the amount of grease is less than that of the grease, and the sealing surface is accelerated by the lack of lubricant. On the other hand, excessive fat injection causes waste. There is no accurate calculation of the different valve sealing capacities based on the valve type category. The sealing capacity can be calculated in terms of valve size and type, and a proper amount of grease can be injected reasonably.

2, forged steel gate valves often ignore pressure problems. In the grease injection operation, the grease-loaded regular semi-free float-type steam trap has a peak-to-valley change. The pressure is too low, the seal leaks or the safety valve fails, the pressure is too high, the grease port valve manufacturer is clogged, the seal grease hardens or the seal ring and the valve ball and the valve plate are locked. Usually, when the grease pressure is too low, the injected grease flows into the bottom of the valve cavity, which usually occurs in a small gate valve. The pressure of the grease flow control valve is too high. On the one hand, the grease gate valve is inspected and the grease nozzle is inspected. If the grease remote control float valve hole is blocked, the spring seal is replaced with a wrench. The other plunger valve is a grease. For hardening, use a cleaning solution, repeatedly soften the failed sealing grease, and inject a new grease to replace it. In addition, the sealing type and sealing material also affect the grease filling pressure. Different sealing forms have different grease filling pressures. Generally, the hard sealing grease pressure is higher than the soft sealing.

Forged steel globe valves pay attention to the problem of the valve in the switch position. The ball valve is normally in the open position during maintenance and maintenance. In special cases, the maintenance is turned off. Other valves cannot be discussed in terms of opening. Forged steel shut-off valves must be closed during maintenance to ensure that the grease fills the seal groove along the seal. If it is open, the seal grease will fall directly into the runner or valve cavity, causing waste. When the valve is greased, the problem of grease injection is often ignored. The pressure, grease injection amount and switch position are normal during the grease filling operation. However, in order to ensure the grease filling effect of the valve, it is sometimes necessary to open or close the valve to check the lubrication effect and confirm that the valve ball or the surface of the valve is evenly lubricated.

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What are the uses and types of stainless steel sight glass?

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Direct impeller viewing sight glass (impeller indicator; impeller viewing sight glass; flow indicator; oil flow observer; liquid flow display; flow observer) belongs to the category of viewing sight glass, which is a necessary accessory to observe the flow of medium in pipeline. The flow indicator of impeller sight glass is widely used in cooling system, lubrication system, fuel supply system, petroleum, chemical industry, chemical fiber, medicine, food and other industrial production devices. It can observe the flow reaction of liquid, gas, steam and other media at any time, and it is an indispensable accessory to ensure normal production. The connection mode of flow indicator includes threaded flow indicator, welding flow indicator and flange flow indicator.

Flow indicator can also be used in automatic sprinkler fire extinguishing system. It can be installed on the main water supply pipe or the horizontal pole water pipe to give the medium flow value in a small area in a certain subregion. The flow value can be sent to the electronic control box to start the control switch of the fire pump。

  1. Characteristics of stainless steel sight glass products:

The integrated casting design of the valve body conforms to the manufacturing process of instrument valves, with beautiful appearance, high precision and stronger compression resistance.

The manufacturing process is numerically controlled and the quality is more reliable.

The diversified connection mode adapts to the industry standard more widely.

The installation mode is vertical and horizontal, and the disassembly is more convenient.

It is more convenient to observe the structure of double windows with high perspective.

The click window is easy to disassemble, and the integrated design of maintenance and maintenance is more reasonable.

  1. Material of stainless steel sight glass instruments:

Main material: carbon steel, stainless steel and copper

Windows Material: Tempered Borosilicate Glass, Quartz Glass, Aluminum Silicon Glass

Temperature Resistance of Tempered Borosilicate Glass to Pressure 2.5 MPa < 200 Temperature

Quartz glass withstands pressure 10 MPa and temperature less than 1000 C

Aluminum-silicon glass withstands pressure 6.4 MPa and temperature less than 450 C

Sealing material: nitrile rubber, polytetrafluoroethylene

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What are the methods for non-destructive testing of steel castings?

Non-destructive testing is one of the most commonly used methods in the production of steel castings. Non-destructive testing is the detection of defects in surface and internal quality and precision while ensuring that castings are not damaged. . This article will introduce the non-destructive testing according to the testing method of steel castings.

There are many methods for nondestructive testing, and there are four main types commonly used in production: magnetic particle inspection, ultrasonic flaw detection, radiographic inspection, and liquid penetrant inspection.

-VT (Visual Testing)
The Visual Testing is one of the most widely used test method to investigate the surface aspect and observe potential discontinuities or failures, which should be detected under proper lighting conditions, monitored by an instrument able to measure the light intensity, the light meter.
-UT (Ultrasonic Testing)
The Ultrasonic testing is often performed on raw materials but can be also performed on critical areas to have an accurate and reliable detection of material discontinuities: an ultrasonic transducer (Ultrasound test instrument) sends high-frequency vibrations into a material section to find discontinuities which, if found, reflect the vibrations back to the transducer; the result is translated and displayed on an oscilloscope to reveal their extent and location.
-PT (Penetrant Testing)
The Penetrant testing, also called Liquid or Dye Penetrant Inspection, is generally used to locate and detect surface defects (cracks, porosity, leaking points) on non-ferrous and ferrous materials: testing fluid (penetrant) penetrates into the surface-breaking discontinuities and, after adequate penetration time, a developer should be applied: the penetrant is drawn out by capillary action so that an invisible crack becomes visible.
-MT (Magnetic Particle Testing)
The Magnetic Particle Testing is generally used to locate and detect surface sub-surface discontinuities in ferromagnetic materials. The area to be tested is magnetized by direct electric current transmission by a magnetic joke; in case of discontinuity, the magnetic field flowing through the specimen is interrupted and leakage field occurs, iron particles are then applied to the detected area and cluster to form an indication directly over the discontinuity. The indication can be visually detected under proper lighting conditions.

-PMI (Positive Material Identification)
The Positive Material Identification is the elemental identification and quantitative determination in percentage of metallic alloys, without regard to form, size and shape,

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How to solve the problem of water leakage or rust in the forged steel check valve

  1. Forging steel check valve storage environment should be noted, should be stored in a dry and ventilated room, and block both ends of the passage.
  2. The forged steel check valve should be inspected regularly, and the dirt on it should be removed, and the anti-rust oil should be applied on the surface.
  3. Forged steel check valves after installation should be regularly inspected to ensure their normal operation.
  4. Check the valve sealing surface for wear and repair or replace it according to the situation.
  5. Check the trapezoidal thread wear of the valve stem and stem nut of the forged steel stop valve, whether the packing is out of date, etc., and make necessary replacement.
  6. Test the sealing performance of the valve to ensure its performance.
  7. The valve in operation should be in good condition, the bolts on the flange and the bracket are complete, the thread is not damaged, and there is no looseness.
  8. If the handwheel is lost, it should be timely and not replaced by a spanner wrench.
  9. The packing gland is not allowed to be skewed or has no pre-tightening clearance.
  10. If the valve is used in a harsh environment and is susceptible to dirt such as rain, snow, dust, sand, etc., a protective cover should be installed for the valve stem.
  11. The scale on the forged steel stop valve should be complete, accurate and clear, and the valve seal and cap.
  12. The problem of depression and crack of the insulated forged steel stop valve.
  13. Forging steel check valve in operation, avoid knocking on it, or supporting heavy objects.

What is the principle of selection for forged steel globe valves?

The principle of selection for forged steel globe valves is:

  1. The globe valves should be used on the pipeline or device of high temperature and high pressure medium. Such as thermal power plants, nuclear power plants, high-temperature, high-pressure pipelines of petrochemical systems.
  2. On the pipeline where the flow resistance is not strict on the pipeline. That is, the place where the pressure loss is not considered.
  3. Small valves can be used with needle valves, instrument valves, sampling valves, pressure gauge valves, etc.

4, there are flow adjustment or pressure regulation, but the adjustment accuracy is not high, and the pipeline diameter is relatively small, such as the nominal diameter of ≤ 50mm pipeline, should be used.

  1. For small chemical fertilizers and large chemical fertilizers in synthetic industrial production, high-pressure angle shut-off valves or high-pressure angle throttle valves with nominal pressure PN160 nominal pressure 16MPa or PN320 nominal pressure 32MPa should be used.
  2. In the desiliconization workshop and the easy coking pipeline in the production of alumina Bayer method, it is easy to select the DC type
    globe valves valve or the DC type throttle valve with the valve body separated, the valve seat can be removed, and the carbide seal pair.
  3. In the water supply and heating projects in urban construction, it is known to pass through smaller pipelines, and the cut-off, balance valve or plunger valve can be used, such as the pipeline passing the nominal less than 150mm.

Forged steel globe valves valves pay attention to the problem of the valve in the switch position. The ball valve is normally in the open position during maintenance and maintenance. In special cases, the maintenance is turned off. Other valves cannot be discussed in terms of opening. Forged steel globe valves must be closed during maintenance to ensure that the grease fills the seal groove along the seal. If it is open, the seal grease will fall directly into the runner or valve cavity, causing waste. When the valve is greased, the problem of grease injection is often ignored. The pressure, grease injection amount and switch position are normal during the grease filling operation. However, in order to ensure the grease filling effect of the valve, it is sometimes necessary to open or close the valve to check the lubrication effect and confirm that the valve ball or the surface of the valve is evenly lubricated.

What is the purpose and structural characteristics of the swing check valve?

Swing check valve is suitable for nominal pressure PN1.0MPa~42.0MPa, CLASS150Lb~2500Lb; nominal diameter DN15mm~1200mm, NPS1/2″~48″; working temperature -196C~540C for various pipelines, used for Prevent the media from flowing backwards. By using different materials, it can be applied to a variety of media such as water, steam, oil, nitric acid, strong oxidizing medium and urea.
The structure length is short, and its structure length is only 1/4~1/8 of the traditional flange check valve;
Small in size and light in weight, its weight is only 1/4~1/20 of the traditional flange check valve;
The valve flap is closed quickly and the water hammer pressure is small;
Both horizontal and vertical pipes can be used for easy installation;
Flow to smooth, fluid resistance is small;
Sensitive action and good sealing performance;
The valve flap has a short stroke and a small impact force;
The overall structure is simple and compact, and the shape is beautiful;
Long service life and high reliability

Introduction of operation after installation of stainless steel valve

Stainless steel valves refer to valves made of stainless steel. Stainless steel valves are used in the industry: food biscuit industry, instant noodles and rice noodle industry, various quick-frozen food dewatering line equipment, and glass products industry. So how do stainless steel valves work?

Opening and closing of the valve: The stainless steel valve is the most widely used valve. Its hand wheel or handle is designed according to ordinary manpower, considering the strength of the sealing surface and the necessary closing force. Therefore, you cannot use long levers or long wrenches to move. Some people are accustomed to using the wrench, should pay careful attention, do not use too much force, otherwise it is easy to damage the sealing surface, or the plate breaks the hand wheel, handle. When opening and closing the valve, the force should be stable and not impact. Some components of high-pressure valves that have been opened and closed by impact have been considered such that the impact force cannot be equal to that of a general valve. For steam valves, pre-heating should be carried out before opening, and condensed water should be removed. When opening, it should be as gentle as possible to avoid water hammer. When the valve is fully open, the handwheel should be reversed a little to make the threads tightly tight to avoid loose damage.

For open-end valves, keep in mind the position of the stem when fully open and fully closed to avoid hitting the top dead center when fully open. And it is easy to check whether it is normal when fully closed. If the valve is detached or a large debris is embedded between the valve plug seals, the position of the valve stem will change when fully closed.

Some media, after the valve is closed, cool, the valve member shrinks, the operator should close again at the appropriate time, so that the sealing surface does not leave a slit, otherwise, the medium flows through the slit at a high speed, it is easy to erode the sealing surface. .

When the stainless steel valve is operated, if it is found that the operation is too laborious, the reason should be analyzed. If the packing is too tight, it can be loosened properly. If the valve stem is skewed, the person should be notified to repair it. In some cases, when the valve is closed, the closing member is heated and expanded, which makes opening difficult. If it must be opened at this time, the bonnet thread can be loosened by half a turn to one turn, the stem stress is eliminated, and then the hand wheel is driven.

What is the reason for the forced sealing of stainless steel forged steel valves?

The reason why the stainless steel forged steel valve adopts the forced sealing is that when the stainless steel forged steel valve is closed, the external force is forced to press the ram to the valve seat to ensure the sealing of the sealing surface. Stainless steel forged steel valves should generally be installed horizontally in the pipeline. When the gate valve is closed, the sealing surface can be sealed only by the medium pressure, that is, the sealing surface of the ram is pressed against the valve seat on the other side by the medium pressure to ensure the sealing of the sealing surface, which is self-sealing.

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What is the difference between a forged steel valve and a cast steel valve?

Forged steel valves are better than cast steel valves and can withstand large impact forces. Plasticity, toughness and other mechanical properties are also higher than steel castings, but the nominal diameter is relatively small, generally below DN50. Casting valves have lower pressure ratings. Commonly used nominal pressures are PN16, PN25, PN40, 150LB-900LB. Forged steel valve grade: PN100, PN160, PN320, 1500LB-3500LB, etc. Cast steel is mainly used to make parts that are complex in shape, difficult to forge or cut, and require high strength and plasticity.

       Casting is liquid molding, and forging is a plastic deformation process. The forged workpiece can improve the internal structure of the structure, the mechanical properties are good, the grains are uniform, and the important laborious workpiece must be forged. The casting will cause structural segregation, structural defects, and of course, casting has its advantages. The forming of complex workpieces is not easy to mold and has been cast.
Forged steel globe valves are available in three bonnet designs. The first type is a bolt type valve cover. The valve body designed according to this design has a valve body and a valve cover connected by bolts and nuts, and a wound type gasket (made of 316 clip flexible graphite). Metal rings can also be used when customers have special requirements. The second design form is a welded bonnet. According to this design, the valve body and the bonnet are screwed and fully welded. All welded connections are also available when the customer has special requirements. The third type is a pressure self-tightening valve cover. The valve designed according to this design form has a valve body and a valve cover which are screwed, and an internal pressure is sealed from the sealing ring.