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  • Brief Introduction of Ball Valve
    Brief Introduction of Ball Valve Feb 13, 2020
    Ball valve is a kind of valve that uses a ball with a circular channel as the opening and closing parts, and the ball rotates with the valve stem to realize the opening and closing action. We supply various trunnion mounted ball valve,floating ball valve,fully welded ball valve and other multi way ball valve. Ball valve is evolved from plug valve. They have the same 90 degree rotation action, the difference is that ball valve has a ball with circle port, while plug valve has a plug in the shape of cylindrical or conical. In a cylindrical plug, the channel is generally rectangular; in a conical plug, the channel is trapezoidal. The main feature of ball valve is its compact structure, easy to operate and maintain and suitable for not only general working media such as water, solvents, acids and natural gas, but also for media with harsh working conditions, such as oxygen, hydrogen peroxide, methane and ethylene. Besides, ball valve body can be integrated or combined. Generally speaking, ball valves are most suitable for directly opening and closing, but recently, ball valves have been developed and designed to throttle and control flow. Ball valves are one of the most supplied valves at dvsvalve.com.
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  • High Performance Double Eccentric Butterfly Valve
    High Performance Double Eccentric Butterfly Valve Feb 13, 2020
    Double eccentric butterfly valve is further improved on the basis of single eccentric butterfly valve. Its structural feature is that the axis of the valve stem deviates from both the center of the disc and the center of the body. The effect of double eccentricity enables the butterfly plate to detach from the valve seat immediately after the valve is opened, which greatly eliminates unnecessary excessive squeezing and scraping of the disc and seat, reduces the opening resistance, extends valve seat life. The double eccentric butterfly valve also adopts metal seat, which improves the application in high temperature field. Double eccentric butterfly valve is also called high performance butterfly valve. It is mainly used for drainage of water plants, power plants, steel plants, chemical engineering, water source engineering, environmental facilities and other systems. Structural features of high performance double eccentric butterfly valve: 1. Reasonable design, compact structure, easy assembly and disassembly, and easy maintenance. 2.Eccentric structure is adopted to reduce the friction of the seal ring and prolong the service life of the valve. 3, Completely sealed, zero leakage. Can be used in ultra-high vacuum conditions. 4. Replace the seal ring, disc, shaft to different materials, which can be used for a variety of media and different temperatures.
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  • SPE, DPE, DBB and DIB of Ball Valves
    SPE, DPE, DBB and DIB of Ball Valves Dec 16, 2019
    SPE and DPE are different types of ball valve seats. Ball valve with DPE (Double Piston Effect) seals both at upstream or/and at downstream. When ball valves with DPE seats needs to achieve cavity over-pressure automatically, a extra pressure relief device need to be installed. Ball  valves with SPE ( Single Piston Effect) seals only at upstream. And will release the cavity over-pressure automatically to the pipeline. DBB ( Double Block and Bleed) and DIB(Double Isolation and Bleed) are different forms of valves. The ISO/API definition of DBB reads as follows: "single valve with two seating surfaces that, in the closed position, provides a seal against pressure from both ends of the valve with a means of venting/bleeding the cavity between the seating surfaces".  The definition for DIB reads as follows: "single valve with two seating surfaces, each of which, in the closed position, provides a seal against pressure from a single source, with a means of venting/bleeding the cavity between the seating surfaces".   The definition of DIB isn't very clear all by itself, so it's best to read it concurrently with the requirements of the DIB testing in Annex B for clarification. In short, DBB is valve with both side SPE seat, and DIB-1 is valve with both side SPE seat, and DIB-2 is valve with one side SPE seat and one side DPE seat. DIB-1 is a test performed on a valve where both seats are uni-directional (DPE) and a DIB-2 test is performed on a valve with one seat uni-directional (SPE) and one seat bi-directional (DPE).  Both DIB-1 and DIB-2 are optional tests, and must be requested in order for the test to be performed.  So, either a DIB-1 or a DIB-2 test will test the effectiveness of a DPE seat. DBB Trunnion Mounted Ball Valve
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  • Installation and Maintenance of Ball Valve
    Installation and Maintenance of Ball Valve Nov 21, 2019
    The Preparation of Ball Valve before Installation 1. Ensure that the pipeline at the installation position of the ball valve is in the coaxial position. The two flanges on the pipeline should be parallel, and confirm that the pipeline can bear the weight of the ball valve. 2. Check whether there are impurities and welding slag in the pipeline, and the regulating valve must purge the pipeline. 3. Check the nameplate of the ball valve, and fully open and close the ball valve for several times to confirm that the valve can work normally, and thoroughly check all the details of the valve to ensure that the valve is intact. 4. Remove the protective cover at both ends of the valve, check whether the body is clean, clean the body cavity, because the sealing surface of the ball valve is ball shape, even small debris may cause damage to the sealing surface. Installation of Ball Valve 1. Any section of the ball valve can be installed in the upstream end, Shanghai nimei ball valve handle ball valve can be installed in any position of the pipeline, if equipped with actuator (such as gear box, electric-pneumatic actuator) ball valve, it must be installed vertically, valve inlet and outlet in a horizontal position. 2. Between the ball valve flange and the pipeline flange according to the design requirements of the pipeline with sealing gasket. 3. Bolts on the flange shall be tightened symmetrically, successively and uniformly. 4. If the ball valve with pneumatic, electric and other actuators, according to the manual to complete the installation of air source, power supply. Inspection After Installation Of Ball Valve 1.After installation, start the ball valve open and close several times, should be flexible, uniform force, ball valve work normally. 2. According to the design requirements of pipeline pressure, test the sealing performance of the joint surface of ball valve and pipeline flange after passing through pressure. Ball Valve Maintenance 1. Only by removing the pressure before and after the ball valve can the ball valve be disassembled and decomposed. 2. In the decomposition and reassembly process of the ball valve, it is necessary to protect the sealed parts, especially non-metallic parts, such as o-ring and other parts, with special tools. 3. Bolts must be tightened symmetrically, step by step and evenly when the ball valve body is reassembled. 4. Cleaning agent should be compatible with rubber parts, plastic parts, metal parts and working medium (such as gas) in the ball valve.When the working medium is gas, gasoline (gb484-89) can be used to clean the metal parts.Clean nonmetallic parts with purified water or alcohol. 5. The decomposed individual parts can be cleaned by immersion washing.The metal parts that have not been decomposed can be cleaned by a clean and fine dip silk cloth with cleaning agent (to avoid fiber falling off and sticking to the parts).When cleaning, remove all the grease, dirt, glue, dust etc. 6, non-metallic parts should be imm...
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  • How to select valves for hydrongen service
    How to select valves for hydrongen service Nov 07, 2019
    Hydrogen service is a condition in which the medium contains hydrogen. Hydrogen-dependent equipment refers to the equipment containing hydrogen in the medium, including the hydrogenation reactor, the hydrogenation heat exchanger and the hydrogenation separator. Under high temperature and high pressure conditions, hydrogen is easy to produce hydrogen and hydrogen sulfide corrosion with steel equipment, resulting in steel strength reduction, or even damage to equipment It can be divided into hydrogen-dependent process and non-hydrogen-dependent process. Due to the particularity of hydrogen medium (small molecule, easy penetration, hydrogen embrittlement, explosive, etc.), high quality requirements are required for the valve body and valve cover: Forgings are preferred for body & bonnet material. Casting can be selected for large-caliber valves, but RT secondary sheet standard is required. Valve design and manufacturing can not have sharp chamfering, all chamfering needs to be smooth, parts processing accuracy and surface are very high requirements; Valves need to be cleaned strictly; During the pressure test, the strength test should be done for gas strength test, not just for water strength test. In the case of hydrogen valve, the requirements will be higher. The material of valve shall control the content of C, S and P, and conduct crystal phase test, etc. Valves with hydrogen media can also be tested with hydrogen according to SHELL 77/308 specifications. Must pay attention to fire safe, blow-out proof, and anti - static.
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  • Introduction of Jacket Valve
    Introduction of Jacket Valve Oct 31, 2019
    The jacket valve has good heat preservation and cold preservation characteristics, and the diameter of the valve is consistent with the diameter of the pipe, and at the same time, the heat loss of the medium in the pipeline can be effectively reduced. It has good thermal insulation properties and can effectively reduce the heat loss of the medium in the pipeline. Insulation valves are widely used in various systems such as petroleum, chemical, metallurgy, and pharmaceuticals, effectively reducing the loss of heat in the pipeline and preventing the appearance of crystals and solidification of the medium. The function of the heat preservation valve is that when the valve passes through the valve at a high or low temperature, the material in the heat preservation valve has a heat insulation effect on the medium, so that the medium does not condense or stick to the inside of the valve body, so that the opening and closing of the valve can operate normally.
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