Valve Identification
How to use valves correctly, weld valve parts, repair valve parts and replace valve parts when valve drawings and materials are missing, nameplates are lost and valve parts are incomplete? Valve identification, material identification and valve recognition are particularly important.
According to the nameplate and logo on the valve and the paint color on the valve, the type, structure, nominal diameter, nominal pressure (or working pressure), material, medium, temperature and closing direction of the valve can be directly identified.
1. The nameplate is fixed on the valve body or handwheel. The data on the nameplate is relatively complete and reflects the basic characteristics of the valve. According to the use conditions provided on the nameplate, determine the material and form of the replacement gasket and packing and determine the material for replacing other valve parts. According to the manufacturer's name on the nameplate, ask the manufacturer for relevant drawings and information of the valve, and refer to the repair content according to the factory date.
2. The mark is to use casting and printing methods to mark the valve nominal pressure, working pressure, nominal diameter and medium flow direction on the valve body.
There is another mark on the valve - the opening indicator, which has a scale line indicating opening or an arrow indicating opening and closing. The throttle valve and concealed stem gate valve are equipped with an opening indicator. A straight groove is engraved on the end of the valve stem, which is consistent with the valve channel to indicate opening, and the groove is 90° to the channel to indicate closing. The arrow on the handwheel indicates the closing direction.
3. The valve is painted with various paints, not only for rust prevention and good looks. It is to facilitate the identification of valves, valve bodies, and sealing surface materials. Paint the valve body, handwheel and flange outer edge with different colors as required. For valves with lining, additional identification paint should be applied on the outer surface of the connecting flange. The colors are as follows:
Enamel lining--red paint Rubber and hard rubber lining--green plastic lining--blue aluminum alloy lining--yellow aluminum lining--aluminum white
Examples of meanings on valves
Meaning of DN on valves
DN: refers to the nominal diameter of the valve, which is usually followed by a number. For example, if the nominal diameter is 200mm, it should be marked as DN200. Normally, the channel diameter of the valve is the same as the nominal size, but when the valve body adopts a pipe welding structure or the pipe connected to it is connected with a standard steel pipe flange, the actual channel diameter of the valve is not equal to the value of the nominal size DN.
Meaning of WCB on valves
WCB: Indicates that the valve body material is a carbon steel casting (W-weldable: the first letter of welding, indicating that the material has good welding performance; C-cast steel: the first letter of cast steel; B-the mechanical properties of steel are Class B). Together, it means: weldable cast steel parts with Class B mechanical properties. (It is ordinary carbon steel, equivalent to 25 or 35 carbon steel.)
The meaning of PN on the valve
PN: The nominal pressure of the valve, which is composed of the integer number immediately following it. In my country, when it comes to nominal pressure, for the sake of clarity, the unit of measurement is usually given, expressed as "MPa". For example, PN100 means the nominal pressure is 10Mpa, which is 100Kgf/cm2;
