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  • Special Cleaning Requirements for Cryogenic Valves
    Special Cleaning Requirements for Cryogenic Valves Dec 30, 2020
    Cryogenic valves are intended for very cold applications. The term "cryogenic" refers to temperatures below -50゜C.   Valve materials for cryogenic service are required for good ductility. Sealing parts, gaskets and other fittings should also be adapted to these extremely cold conditions on demand.   Industries associated with liquefied and compressed natural gas, as well as liquid oxygen, nitrogen or helium, rely on these special valves for the frequent, safe and reliable transport of cryogenic liquids and gases.   Special Cleaning Needs & Concerns To Be Stressed   The valve manufacturers are required to remove grease and all organic contaminants from the valve with a special solvent, keeping the valve clean. Ultrasonic cleaning is a common choice.   Some cleaning gases such as oxygen or chlorine require a very high level of cleanliness to ensure that no organic material or fiber breaks remain on the valve after the cleaning. The cleaned and certified valves are placed in double-sealed polyethylene bags to ensure that the valves are stored in a clean environment until they are installed and used.   Operators should perform a thorough inspection when installing cryogenic valves. This is critical to ensure that no lubricants or grease are accidentally introduced into the valve. Some specialty lubricants are available for use in cryogenic environments, and whether or not they are allowed should depend on the specific application requirements.   As mentioned earlier, cryogenic valves must avoid staining with fiber breaks. As a general rule, fibers longer than 1/8 inch are not allowed in the valve. In many cases, fibers or breaks of any length are not allowed in the valve.   Finally, inspectors should regularly check cryogenic valves and oxygen systems to see if there are internal or external leaks. Internal valve leaks can be prevented by installing the valve properly and a reliable seal design. Cryogenic service requires robust and stable seals to ensure long-lasting and reliable operation of the equipment. Here at Dervos, we’re a leading provider for products inindustrial valve, and we’re certified with the CE, ISO, API and other institutions. We strive to offer the best quality products and customer service through our extensive experience. Contact us today for more information.
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    The biggest valve Dervos has made ever. This is a DN3750 butterfly valve Dervos made forBombay Municipal Corporation in 2017 which is a government project. The project is special and challenging for its operation for suchalarge size of DN3750. As its torque isup to 989954N.m,it isbetter to be automatically actuated instead of manual operation. But as where it was going to serve is outreach of electrical power, manual operation is the only choice we have. After accurate calculation of the torque, finally we came up with a solution that DN3750 would be operated by a combination of total four gearboxes,which reduced theinput torqueinto incredible117N.m. What an amazing job we did! Andfor this valve, many tests had been carried out, including but not limited to below: We had done DP to the seat ring, UT to flanges, disc and stem, and RT to the welding. Besides, we had done strength tests to disc, adhesive tests to the painting, and IP68 Submergence Test by merging the gearboxes into 3-metre deep water by 72hours. And movement tests were also witnessed, it took about 9 hours from fully open to fully close position. Eventually,The completed valve was made out as about 58 tons weight and 82.4 CBM. Besides the remarkable work we did, we're so proud that its successful put-in-use was even reported by the local newspaper in Mumbai. As you can conclude, Dervos is indeed a professional and reliable valve provider. Contact us today, and get you the quality products and outstanding services Dervos offers.
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  •  Installation and Maintenance of Pneumatic Butterfly Valve
    Installation and Maintenance of Pneumatic Butterfly Valve Dec 12, 2020
    Pneumatic butterfly valve is a newly developeddurable energy-friendly butterfly valve.This kind of butterfly valve adopts new technologies such astriple eccentric design, elastic sealing,multilevel hard and soft sealing processing, so that the butterfly valves are more than reliable and they can achieve no leakageingas sealing. The pneumatic actuator adopts curved arm conversion structure, which has the characteristics of large output torque, small volume, stable and reliable performance, etc. It can be used with valve positioner. Or used in conjunction with solenoid valves, the device can achieve proportional regulation or switching control and is suitable for media such as gases, solid particles and liquids. Pneumatic butterfly valve can be widely used in paper, petrochemical, chemical, metallurgy, electric power, environmental protection, petroleum, light industry, building automation and automation control system of otherindustrial sectors. Installation and maintenance of pneumatic butterfly valve. 1. When installing the butterfly valve, you should pay attention to the flow direction mark on the valve body to avoid the wrong direction of flow and affect the use. 2. Beforethe use ofthepneumatic butterfly valve, you should flush the pipeline with the valve fully open to avoid the sealing surface being scratched by debris such as welding slag. 3. Generally, bypass piping will be set next to the butterfly valve so that when the butterfly valve is serviced or replaced, the bypass piping can be used to carry out the process as usual. 4. Pneumatic butterfly valve can be installed vertically within 180°。And do not install the pneumatic actuator upside down. 5. If you find that the stuffing box is leaking during use, tighten the gland bolts to solve the problem. Here atDervos, we’re a leading provider for products inindustrial valve, and we’re certified with theCE, ISO, API and other institutions. We strive to offer the best quality products and customer service through our extensive experience. Contact us today for more information—we can’t wait to work with you!
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  • Six Factors to Consider When Selecting Valve Seal Face Material
    Six Factors to Consider When Selecting Valve Seal Face Material Dec 02, 2020
    There are six major factors to consider when selecting valve sealing face materials. The sealing surface is the most critical working surface of the valve, the quality of the sealing surface directly affects the service life of the valve, and the sealing surface material is an important factor to ensure the quality of the sealing surface. Therefore, the following factors should be considered when selecting the valve sealing surface material. Corrosion Resistance. "Corrosion" is the process by which the surface of a sealingpart is damaged by medium. If the surface is damaged in this way, the sealability cannot be guaranteed; therefore, the sealing face material must be corrosion resistant. The corrosion resistance of a material depends mainly on its tensile strength and its chemical stability. Abrasion resistance. "Abrasion" is the damage caused by friction during the relative movement of the sealing surface. This damage will inevitably lead to the destruction of the sealing surface, therefore, the sealing surface material must have good anti-scuffing properties, especially the gate valve. The abrasion resistance of the material is often determined by the internal properties of the material. Erosion resistance."Erosion"refers thatthe medium flows through the sealing surface at high speed, so that the sealing surface is damaged. This damage is more obvious in the high temperature, high pressure steam medium used in the globe valve, safety valve. the sealing damage has a great impact, therefore, erosion resistance is also one of the important requirements of the sealing surface material. It should have acertain hardness, and the hardness decreases greatly under the specified working temperature. The coefficient of linear expansion of the sealing face and the body material should be similar, which is more important for the structure of the inlaid seal, in order to avoid additional stress and lose under high temperature. For use at high temperatures, there should be adequate resistance to oxidation, thermal fatigue, andthermal cycling issues. In the current situation, it is very difficult to find a sealing surface material that fully meets the above requirements. For example, for valves used in high speed media, specific attention should belaidto the requirements of erosion resistance of the sealing surface; when the medium contains solid impurities, sealing surface materials with higher hardness should be selected. Here at Dervos, we’re a leading provider for products inindustrial valve, and we’re certified with the CE, ISO, API and other institutions. We strive to offer the best quality products and customer service through our extensive experience. Contact us today for more information—we can’t wait to work with you!
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  • Ball Valve, 2 Piece or 3 Piece, That's a Question
    Ball Valve, 2 Piece or 3 Piece, That's a Question Nov 07, 2020
    Just like there are different advantages between lug or wafer type butterfly valves, 2 piece type and 3 piece type ball valves also have their edges. What below are some of the important factors when considering choices between the two types.   1. Design 2. End connections 3. Installation 4. Performance 5. Ease of maintenance   Design As their names imply, a 2-piece ball valve has two distinct pieces – one piece is an end connection and the body and a second piece, which has the other end connection as well as the valve trim.   A 3-piece ball valve has three body pieces – 2 ends and a center section that holds the valve trim. The three parts are bolted together around the three sections.   End Connections Because of their designs, two-piece ball valves are limited in the type of end connections they can make. They are usually limited to threaded end connections.   Three-piece ball valves have a swing design that allows for welded end connections, so socket and butt weld ends are often feasible.   Installation Its simple design makes 2-pc ball valve one of the most common types in many industries. Due to this simple design, the 2-pc ball valve is a lightweight solution for manual and automatic fluid or gas control.   If the end connection is threaded, the installation of the 3-pc type is also very straightforward. When it is necessary to weld the end, in order to prevent the valve seat and the sealing ring from being heat damage, the device have to be partially disassembled during the installation.   Performance The simplistic design of 2-pc valve allows itself, generally, a better Cv value. The seats, seals, applications and other parts in performance are more decisive than the design type.   Ease of Maintenance The oscillating design of the 3-piece valve allows the body section to remain in place while the valve section swings up and out of the line for cleaning or servicing. This feature makes the 3-pc stand out from the 2-pc, whose design does not allow for any maintenance. Applications where the media is thick or viscous, or where lines must be cleaned between batches, are almost always the domain of the 3-pc valve.   summary Based on the above information, the consideration of 2-pc or 3-pc must include various factors, including the length of the production line through its medium, flow, weight, and maintenance plan. The good news is that our technical sales staff will be more than happy to discuss these factors so that you can make the right decision.   Xiamen Dervos has served countless industrial, commercial, and municipal clients for over 10 years. We have supplied thousands of common valves, customized products, electric and pneumatic actuators and so on to customers worldwide.   If you would like to know more about our valves, services, or other products, any message or inquiries are welcomed.
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    PLUG VALVE VS. BALL VALVE Oct 16, 2020
    Generally speaking, a plug valve and a ball valve may absolve the same function (fluid shut-off). The main differences are:   Plug valves are more economical than ball valves, generally, due to their simpler design   Plug valves are less prone to contamination by debris, and accumulation of dirt in the interstitial spaces, compared to ball valves (an issue that is frequently faced by ball valves, due to the spaces existing between the sphere and the body of the valve)   Ball valves require more maintenance than plug valves, especially after planned or unplanned plant shut-downs   Plug valves have a full port design, without pressure drops, ball valves may be reduced or full port (a full port ball valve would be heavier and bulkier than a plug valve of the same size)   In general, plug valves are good alternatives to ball valves, even if ball valves are still considered industry standard for shut-off operations at least in the oil & gas industry.
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