General Features: The descaling system is made from different equipment connected together to supply high pressure water in the Mill in order to remove scale from the strip. The main components are: Suction Backwashing Filter Descaling Pumps Unloading Valves Pneumatic Compressor Descaling Valves Instrumentation The feeding water for this system is taken from the low pressure (3 to 6 bar or ~45 to 90 psi). Backwashing Filter: This filter is mounted on the pump suction common header. The purpose of this filter is to avoid that large objects entered into the cooling system damage the pumps. Its mechanical design provides for an automatic removal of solids thanks to a backwashing mechanism. The backwashing time period is activated by a differential pressure limit or by time. The normal pressure drop is 0.3 - 0.8 Kg/cm2. Main Pumps: The design of the pumps is centrifugal multistage heavy duty. The motor, the gear box and the pump are mounted on a common steel frame. The supporting and thrust bearings are forced lubricated with low viscosity oil. The axial balancing of the shaft is hydraulically made with a drum bushing. Each pump has also an oil forced lubrication system for the bearings and for the gear box consisting from: (1) Reservoir (1) Auxiliary Oil Pump Motor Driven (1) Oil pump Driven by a Gear Low Speed Shaft (1) stainless Steel Heat Exchanger for Oil Cooling Reservoir, circuit valves and instrumentation for oil temperature, level and pressure monitor and control The lubrication units are located in the nearby of each pumping groups. During idling time the pump is discharging about 25% of its nominal flow to the bypass line to remove heat. A magnetic flow transmitter is mounted on each pump suction line to stop the operation in case of low flow, to avoid damages and or water boiling inside the pump. Unloading valves: The pump is started loadless by opening an on/off bypass valve on a line coming out from the delivery pipe right down flow the pump. When the pump is working in a bypass mode, the pressure of the system is bellow 10 bar. The bypass unloading valve is air piloted by a solenoid valve, Each pump also protected by a pressure relief valve, in the event of a downstream system complete clogged. Pneumatic Compressor: The air compressor supplies air to the pneumatic and part of the hydro pneumatic accumulators. It is started manually after a complete depressurization or in the case of air losses. The system checks the combination of level and pressure and alerts the operator whenever it is time to fill up the system with air. Descaling Valves: The descaling valves are: Automatic On/Off High Pressure Automatic Accumulator Safety Shut-Off Manual On/Off High Pressure Check Valves for High Pressure Safety Relief Valves High Pressure All valves are poppet type to provide quick accessibility to all internal parts. The valve bodies are made from forged steel block. Internal sleeves and poppet are in stainless steel / bronze. Water hammer eliminated by a poppet design with progressive opening/closing. Instrumentation: Magnetic flow meters with transmitters are installed on the pump suction lines. Pressure gauges are installed before and after the suction filter, on pump suction and delivery lines, on accumulators, on compressors, before and after the automatic descaling valves on the ramps, on low pressure prefilling lines. Pressure switches are mounted on suction filter and delivery lines, on accumulators, after each automatic descaling valve on the ramps, on low pressure prefilling lines. Pressure transducer is mounted on the accumulators. A temperature gauge is mounted after the suction filter. Limit switches are mounted on all automatic on/off valves. Electrical Parts: There are available electrical cabinets with switch breakers for the pump motors and for all the auxiliary equipment. Also there are available all the controls for the pumping station. 10. Components Table: Flow rate GPM/m3/h 1004/230 each Min pressure PSI/bar 3407/235 Capacity l/min 600 High Pressure Descaling Valves:


Stock NumberVX-22720
DutyTo feed the descaler headers located in the Hot Strip Mill.
FluidContact cooling water
Descaling pumps3 pcs
Pump electrical motor3 pcs
Power2885/2150 HP/Kw each
Voltage6000 Volt
Speed3600 RPM
Compressors2 pcs
Pressure4350/300 PSI/bar
Electrical motor power15 Kw
Electrical motor speed3600 RPM
Backwashing filter1 pc
Flowrate1922/440 GPM/m3/h
Filtration100 µm
Pressure design4350/300 PSI/bar
Automatic on/off for primary descaler1
Automatic on/off for rougher descaler1
Automatic on/off for fm descaler2