Process & Facilities
SSI’s maximum production capacity for hot-rolled steel sheet is 4 million tonnes per year. This is the greatest single-facility capacity in Southeast Asia.
The process begins with high-quality steel slab. One piece of slab, weighing 5-32 tonnes and 160-250 mm thick, is heated in a furnace until it reaches a temperature of 1,250°C. The heated slab is rolled until it becomes a steel sheet of 1.0 – 19.0 mm thick and 750 – 1,550 mm wide and then coiled.
Various quality grades are produced to meet the varying needs of clients. With one of the most state-of- the-art technology in the world, SSI’s hot rolling mill can produce hot rolled steel sheet of 1.0 mm thick.
SSI’s production of hot-rolled steel sheet may be characterized as a stand-alone hot rolling mill of flat steel, comprising two sections:
SLAB
Slab, raw material used in the production, is weighed and measured before lifted by a walking beam into a furnace.
| Weight | 15 – 32 tonnes |
| Width | 800 – 1,550 mm |
| Thickness | 160 – 250 mm |
WALKING BEAM REHEATING FURNACE
Modern furnance heats continuous cast slabs to a rolling temperature of approximately 1,250-1,300°C, for 3-4 hours. This furnace can process approximately 275 tonnes per hour.
HIGH PRESSURE DE-SCALING BOX
After departing the reheat furnace, the slab enters a high pressure water spray descaling unit at a pressure of 160 bars or 180 times atmospheric pressure to remove oxide formed during reheating for rolling in the roughing stands.
VERTICAL EDGER AND REVERSING ROUGHING MILL
The slab with a clean surface condition is subject to a vertical edger to control its desired width, and a roughing mill to reduce its thickness from 160-250 mm to 26-40 mm. These two machines work simultaneously, passing back and forth over the slab from five to seven times until the desired thickness and width are obtained. Having completed this stage, the output is referred to as steel bar.
COIL BOX AND CROP SHEAR
Steel bar is longer and thinner than steel slab. Consequently, the surface of the steel exposed to air is greater, as is the heat loss, which leads to rapid stiffening. The advantage of the coil box is to coil the steel bar and to provide a nearly constant temperature. The bar’s head and tail ends that lose heat so rapidly are sheared prior to entering the finishing mill.
FINISHING MILL
The 7 finishing stands reduce the bar’s thickness to meet customer specifications.
COOLING BED
DOWN-COILER
The finished strip is then coiled in a down-coiler, bound with a strapping band, weighed, and given a product number. Product samples are taken to measure output quality. The coils are then stored until the steel cools to room temperature. Finally we have coiled hot-rolled steel sheet ready for delivery to customers or futher processing.
HOT ROLLED COIL
| Weight | 15 – 31 tonnes |
| Width | 750 – 1,550 mm. |
| Thickness | 1.0 – 19.0 mm. |
Hot Strip Mill (HSM)
SSI’s maximum production capacity for hot-rolled steel sheet is 4 million tonnes per year. This is the greatest single-facility capacity in Southeast Asia.
The process begins with high-quality steel slab. One piece of slab, weighing 5-32 tonnes and 160-250 mm thick, is heated in a furnace until it reaches a temperature of 1,250°C. The heated slab is rolled until it becomes a steel sheet of 1.0 – 19.0 mm thick and 750 – 1,550 mm wide and then coiled.
Various quality grades are produced to meet the varying needs of clients. With one of the most state-of- the-art technology in the world, SSI’s hot rolling mill can produce hot rolled steel sheet of 1.0 mm thick.
SSI’s production of hot-rolled steel sheet may be characterized as a stand-alone hot rolling mill of flat steel, comprising two sections:
SKIN-PASS MACHINE
This machine gives the product a fine surface finish, using rollers to press the strip as it passes. It is also used to cut the sheet into sections according to the customer’s weight specifications.
SHEARING LINE MACHINE
The main purpose of this machine is to cut large sections of steel into smaller coils as specified by the customer, or to reshape these coils.