Installation points and maintenance details of forged steel gate valve
date：2017/11/25 11:00:24 source：
As a kind of gate valve, all the gate valves processed by forging materials are referred to as forged steel gate valves. The forging materials are A105, F11, F5, 304, 304L, 316, 316L and so on. Forged steel gate often say that the country usually refers to forged steel gate, small bore diameter range: DN10~DN50; pressure range: PN16~PN320 GB, American Standard: Class150 ~ 2500, recoverable American Standard or dimension of production and processing, manufacturers are in stock. More than DN50 caliber forged steel gate valves need to be customized, domestic demand is less.
Forged steel gate valve is suitable for Class150 to 2500, working temperature -29 ~ 425 degrees C (Tan Gang) or -29 ~ 500 C (stainless steel) on the small caliber pipeline, used to cut off or connect the pipeline medium. More applications in oil pipelines.
1, installation position, height, import and export direction must comply with the design requirements, the connection should be firm and tight.
2, all kinds of manual valves installed on the insulated pipe, the handle shall not be downward.
3, the valve must be installed before the appearance inspection, valve nameplate should be in line with the current national standard "general valve signs" GB 12220 provisions. For the valve with working pressure greater than 1 MPa and cutting off on the main pipe, the strength and tight performance test should be carried out before installation. Strength test, the test pressure is 1.5 times the nominal pressure, duration of not less than 5min, the valve shell and filler should be no leakage qualified. In the tightness test, the test pressure is 1.1 times of the nominal pressure; the test pressure in the test duration should meet the requirements of GB 50243 standard, and the gate seal surface without leakage is qualified.
Design specifications: JB/T 7746, API602
Structural length: JB/T 7746, factory specification
Socket / Thread: JB/T1751/GB7306, ANSI B16.11/B2.1
Test and test: JB/T 9092, API598
Pressure temperature: GB/T 9131, ANSI B16.34
Product identification: GB/T 12220, MSS SP25
Supply specification: JB/T 7928
The standards produced by the major manufacturers in China are different. Forging steel gate valve often ignores the pressure problem. In the operation of grease injection, the half pressure free floating ball steam trap with the injection pressure has a peak and valley variation. Low pressure safety valve, seal leakage or failure, the pressure is too high, the injection port valve manufacturing plug seal within the lipid hardening or sealing ring and the ball valve, valve plate locking. Usually, when the injection pressure is too low, the grease injected into the bottom of the valve cavity usually occurs in the small gate valve. The grease flow control valve pressure is too high, a check valve check insulation grease mouth, such as grease is a remote control float valve hole blocking satisfied feeling spring closed with a condition to replace the plunger valve wrench; the other hand is the lipid hardening, to use the cleaning fluid, repeated failure to soften the seal fat, and injection new grease replacement. In addition, the sealing type and sealing material, also affect the injection pressure, different sealing forms have different injection grease pressure, in general, hard sealing grease injection pressure is higher than the soft seal.
In the maintenance of forged steel valves, attention should also be paid to the electric head and its transmission mechanism. Especially in the rainy season infiltration of rainwater. One is to make the transmission mechanism or transmission shaft rust, and the two is winter freezing. Electric valve operation caused by excessive torque, damage drive components will make the load or super torque motor protection tripped electric operation can not be achieved. The transmission parts are damaged and can not be operated manually. After the operation of the torque protection, manual operation is also unable to switch, such as forced operation, will damage the internal alloy parts.
Iron and steel are based on iron, carbon as the main addition elements of the alloy, collectively referred to as iron carbon alloy
Put the casting pig iron smelting in cupola, to obtain iron (liquid), the liquid casting
Iron is cast into a cast iron called a cast iron. And where is the difference between cast steel and carbon steel?. First of all, steel is classified according to chemical composition
(1): A. carbon steel low carbon steel (C = 0.25%); B. (C = 0.25~0.60%) in carbon steel high carbon steel; C. (C = 0.60%). Steel is classified according to forming methods: (1) forged steel; (2) cast steel; (3) hot rolled steel; (4) cold drawn steel. All gates of the gate have two sealing surfaces, which are determined by the structure of the gate, otherwise it is not called gate valve. The most commonly used gate form is wedge type gate. The two sealing surfaces of the gate form wedge and wedge angles vary with valve parameters, usually 50, and medium temperature is 2 degrees 52'. Wedge gate valve can be made into a whole, called the rigid gate, using "1" as Z41H; can also be made to produce micro deformation of ram, in order to improve its process, make up the sealing surface angle deviations arising during processing, the gate is called the flexible gate, using "0" such as type Z40H.