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Valve Continuous Improvement Of Equipment Process And Performance
Oct 30, 2017

The adjustment and action performance of the Valve is controlled by the stem thread, which is ensured by the rotation of the handwheel to the material properties and the process of each part. In order to avoid the occurrence of titanium in some medium crevice corrosion phenomenon. Structural design to maximize the elimination of gaps and can be stored in the concave place. The gap between titanium plate and titanium plate is also susceptible to corrosion, especially the gap between titanium and PTFE. Because titanium has a small amount of soluble fluoride in the solution is not corrosion-resistant fluoride causes blunt state damage. Therefore, the use of PTFE plastic pads, fluorine-containing rubber washers and binders should be particularly cautious.

Because titanium at room temperature also has the creep phenomenon and the stress relaxation problem, the choice of titanium bolts, it is best not to use titanium bolts for forced sealing connectors. When titanium bolts are used for corrosion resistance, structural design should be considered easy to tighten bolts regularly to ensure sealing. Titanium and stainless steel, as well as friction bonding, occlusal phenomenon. The titanium thread is easy to bite, may use the dissimilar kind of data or the larger clearance thread to cooperate or solves with the suitable lubricant. Should be less use of tapping the internal thread, as far as possible with the groove of the car with a knife-screw structure. The cutting process can be used in general cutting process, because of the high chemical activity and special physical and mechanical properties of titanium rods and titanium alloys. But with other commonly used metal ratio, also has its special request, grasps certain processing technology, the processing process to pay attention to. For economic and rational use of titanium materials, titanium is more expensive. The parts that do not contact with the corrosive medium should be as far as possible without titanium. It is larger than normal carbon steel and alloy steel. The strength index decreases with the temperature rise, and the mechanical properties of TI change with the temperature. such as 250-300 ℃ when the tensile strength and yield intensity is at room temperature half. Even in the case of a low design temperature, so. should also be selected according to the strength value of the design temperature. The flexural strength of titanium is higher than that of durability, and when the design temperature is below 316 ℃, it is decided that the intensity index of the design is usually the tensile strength value under the temperature. For industrial pure titanium, the thermal expansion coefficient of titanium can not be improved by heat treatment to increase the strength index value when titanium and other materials are used together. Pay attention to the stress caused by the expansion difference. Prone to rupture. And the increase of deformation speed, reduce the deformation temperature and so on can lead to the process of rupture. Therefore, the plastic deformation range of industrial pure titanium and α-titanium alloy is less. It is best not to design a large deformation of cold processing parts, the need to turn the edge of the place, the bending radius as far as possible to achieve a larger, with the strength of the pipe and tube plate tube hole between the gap tolerance should be small, so as to avoid the titanium tube swelling crack.

The valve is the control part of the industrial fluid transmission system, which has the functions of diversion, medium, regulation, anti-countercurrent, shunt and pressure relief. There are many kinds of valves, and with the continuous improvement of the process and performance of various complete sets of equipment, the type of valve is also increasing. Today we will take a look at the characteristics of common valves, and applicable occasions.

Single seat valve metal seal leakage of ≤10-4CV, soft seal when ≤10-7CV, with a small allowable pressure difference, flow complex, simple structure characteristics, it is suitable for leakage requirements strict, working pressure difference small clean media occasions. But the small size of the valve (such as DN1/2, 3/4, 20) can also be used for larger pressure difference occasions, is the most widely used valve. The shape of the spool determines the flow characteristics and loses its original characteristics after being washed. Changing the valve core can change the flow characteristic. Select this valve should pay attention to the pressure difference check, to prevent the top open, because the flow path is complex, do not adapt to the unclean medium, bulky, the bigger the caliber more obvious.

Contrary to the single seat valve, the leakage is large, allow the characteristics of large pressure difference, suitable for leakage requirements are not strict, work pressure is large clean media occasions, is the most widely used valve, select the valve, should pay attention to check whether the leakage volume to meet the requirements of the process, but also should pay attention to the prevention of plugging and heavy impact.

The sleeve valve has a single seal, double seal two kinds of structure, the former is equivalent to the single seat valve, is suitable for the single seat valve occasion; the latter is equivalent to two-seater valve, suitable for two-seater valve occasion. In addition, the sleeve valve has a good stability, easy to install features, but the price ratio of single, double seat valve 50-200%. is second only to single, double seat valves more widely used valves, but for the unclean media should not choose this valve, but also should pay attention to the prevention of plugging and heavy impact.

Throttle type is equivalent to a single seat valve, but the valve body flow is simple, it is applicable to the leakage requirements of small, pressure difference is not very clean media occasions and requirements of the right angle piping.

Three-way valve with three channels, can replace two straight-through single seat valve for shunt and confluence two sets of flow and temperature difference ≤150℃ occasions, when dn≤80, the confluence valve can be used for diversion occasions.

Diaphragm valve flow path is simple, the diaphragm has certain corrosion resistance, so it is suitable for the two-bit cut-off occasions of the unclean medium and the weak corrosive medium. When the regulation accuracy requirements and requirements of strong corrosive (such as water treatment valve) is not suitable to select the valve. The fatal weakness of the valve is that the diaphragm is easily damaged.

Butterfly valve is equivalent to take a section of straight pipe to do the valve body, and valve body is equivalent to the valve seat, so "self-cleaning" performance, small size, light weight, suitable for the unclean medium and large diameter, large flow, low pressure situation. When dn>300, the butterfly valve is usually done, and the larger the caliber, the more prominent the features.