General Requirements for Iron valves Used for Water Supply in Urban Water Supply
1. General
1.1 Iron valves used for water supply in urban water supply are divided into low-voltage valve core, butterfly valve core and other valve cores according to their structures. Among them, the butterfly valve core is an important part of the circulating water system of buildings such as air conditioning and heating. The low pressure valve core is mostly made of gray cast iron and is the most widely used valve in urban water supply.
1.2 Iron valves used for urban water supply must meet the requirements of GB/T12221-1989 General Technical Conditions for Pipe Valves.
2. Design requirements
2.1 Low-pressure valve core must ensure that when the pressure difference on both sides is 0.63 MPa, the surface will not leak or blow through.
2.2 The airtightness of the butterfly valve core must meet the requirements of GB/T12221-1989 General Technical Conditions for Pipe Valves, that is, when the pressure difference is 0.6 MPa, the air tightness must be better than 0.02 MPa, and when the pressure difference is 0.3 MPa, the air tightness must be better than 0.01 MPa.
2.3 The torque performance of the butterfly valve core must meet the requirements of GB/T12221-1989 General Technical Conditions for Pipe Valves, that is, the opening and closing torque of the nominal diameter of 50mm and below should be within 15N.m, and the nominal diameter of more than 50mm should be within 25N.m.
3. Manufacturing requirements
3.1 The requirements of materials for low-pressure valve core shall meet the requirements of GB/T1179-2006 Gray Cast Iron for Valves and their chemical compositions shall be strictly controlled.
3.2 The butterfly valve core shall be made of austenitic stainless steel or grey cast iron as the body material, carbon steel as the valve stem, and stainless steel as the operating components.
4. Technical Requirements for On-site Installation
4.1 Low-pressure valve core should be installed in the horizontal pipeline. Its lower surface should be embedded with 600mm*600mm reinforced concrete foundation, and its pipeline should be connected with flange.
4.2 The butterfly valve core should be installed in the vertical pipeline. Its lower surface should be embedded with 400mm*400mm reinforced concrete foundation, and its pipeline should be connected with flange.
5. Pressure Test Requirements
5.1 Prior to installation of the low-pressure valve core, pressure test shall be carried out in accordance with the requirements of GB/T10251-1989 Technical Conditions for Casting Valves.
5.2 Prior to installation of butterfly valve core, pressure test shall be carried out in accordance with the requirements of GB/T 24175-2009 Low Pressure Anticorrosive Butterfly Valve.
In conclusion, the above are the general technical requirements for the use of iron valves for water supply in urban water supply. For the detailed use requirements, please refer to the corresponding national standards.
