Claims:We Claim:
1. A system for lifting top spray headers used as laminar cooling system at run out table prior to coiling at Hot Strip Mills comprising:

pneumatic system having pneumatic lifting cylinders for each top spray bank adapted to lift gooseneck type top headers fitted with respect to mounting arrangementsand surrounding equipments;

a compressed air source to supply compressed air to operate said pneumatic lifting cylinders;

an air drier to supply dry air to the pneumatic system;

an air booster to boost the air pressure in case of lower line pressure;

non return valve (NRV) to avoid free fall of top headers in case of air failure during lowering the headers

pneumatic valves (ON/OFF switch) for operating the pneumatic system locally with or without cooperative

solenoid valves for operating the system from control panel at remote location (Operator’s desk) ; and
an air accumulator to favour lifting even during air failure

2. A system for lifting top spray headers as claimed in claim 1 wherein saidair booster comprise twin pressure type pneumatic booster operable with compressed air;

said pneumatic valves (ON/OFF switch) comprising of 3/2 pneumatic valve.

3. A system for lifting top spray headers as claimed in anyone of claims 1 or 2 wherein said pressure boosters comprises of a double piston system and directional control valve for continuous operation whereby the input pressure is automatically doubled with or without a pressure regulator to selectively boost the pressure.

4. A system for lifting top spray headers as claimed in anyone of claims 1 to 3 wherein said pneumatic lifting cylinder is a double acting cylinder capable of operating at a pressure range of 0.6 to 10bar, having the size based on the calculated load of 1519 Kgf comprises cylinder diameter of 250mm, Rod diameter of 42 mm, eye to eye distance of the cylinder 1641 mm and stroke 1070mm so that the cylinder can be fitted in existing mounting.

5. A system for lifting top spray headers as claimed in anyone of claims 1 to 4 wherein said air accumulator is of 5000 liters capacity with working pressure of 12.5 kgf/cm2.

6. A system for lifting top spray headers as claimed in anyone of claims 1 to 5 wherein said pneumatic cylinder is adapted to start responding to minimal pressure of 0.6 bar indicating a low level of friction between the cylinder and piston head due to superior surface finishing comprising “U” shape piston for lesser contact area, superior internal surface finish to reduce friction (Min. force required for 0 mm stroke: 30 kg) and heat resistant seal for temp. up to 120 °C.

7. A system for lifting top spray headers as claimed in anyone of claims 1 to 6wherein the system is adapted to lift the header assembly to 90 degree, with available pressure (3.5~4.0 bar) with jerk free operation within 1 minute.

8. A system for lifting top spray headers as claimed in anyone of claims 1 to 7comprising pneumatic failure operability whereby even at zero bar pressure headers can be maintained in lifted position and not fall by gravity and maintained in stay put condition.

9. A system for lifting top spray headers as claimed in anyone of claims 1 to 8 wherein 3/2 solenoid valves enable system operation from control panel installed at remote location (Operator’s desk) in case of cobble in ROT area.

10.A system for lifting top spray headers as claimed in anyone of claims 1 to 9 having swivel joint with modification by offsetting the center by 16 mm such that cylinder base can be accommodated in available space and swivel joint bolted to cylinder base.

11. A system for lifting top spray headers as claimed in anyone of claims 1 to 10 comprising means to accommodate the variation in eye to eye distance in different top spray banks, threaded end connection involving a threaded portion providing for eye rod to adjust the modified cylinder in the existing mountings.

Dated this the 1st day of December, 2015
Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)
, Description:FIELD OF THE INVENTION

The present invention relates to an improved system for lifting top spray headers of laminar cooling system at run out table (ROT) at Hot Strip Mill prior to coiling at coilers. More particularly, the present invention is directed to provide a system for controlled pneumatic lifting of top headers of cooling system at run out table of hot strip mill at steel plants. Importantly, the system for lifting top headers of laminar cooling at run out table involves novel features like selectively configured pneumatic lifting cylinders with associated mountings adapted to be fitted in existing cylinder mounting arrangement, compressed air source, air drier to supply dry air to the pneumatic system, air booster to boost the air pressure in case of lower line pressure comprising a double piston system and a directional control valve for continuous operation whereby the input pressure is automatically doubled and Non Return Valve (NRV) has been incorporated in the system to avoid free fall of top headers in case of air failure during lowering the headers. The system can be operated locally as well as remotely from control panel installed at remote location (Operator’s desk) in case of cobble in ROT area. The modified system for lifting top headers are capable of lifting the top header assembly at 90 degree, with available pressure (3.5~4.0 bar) with jerk free operation within 1 minute. Advantageously, the system for lifting of top headers in laminar cooling according to the present invention is capable of lifting all four top spray banks in tandem having goose neck type top headers with about 36% higher weight than previous box type cooling headers in a safe and reliable manner during cobble in the ROT area and/or during shutdown days for repair/ changing of ROT rolls or other shutdown related activities.

BACKGROUND OF THE INVENTION

The Hot Strip Mill(HSM) at Rourkela Steel Plant(RSP) of the applicants is Semi-continuous mill (1700 mm) with a production capacity of 1.5 million ton Hot Rolled(HR) coils per annum. The finished hot rolled strip coming out of the last finishing stands passes over a long roller table called Run Out Table (ROT) prior to coiling at coilers. On this ROT, both the sides of the strip surfaces are cooled by controlled water spray from top and bottom spray banks to control the grain size, hardness and other mechanical & metallurgical properties of the HR strip.

The ROT cooling system at HSM, RSP is divided into 4 spray banks, each spray bank having top and bottom spray arrangement separately. The ROT laminar cooling system at HSM, RSP has been modified in order to achieve high heat transfer coefficient for improved productivity and product quality. Previously, top ROT cooling headers were box type which have been later on modified to goose neck type headers. Total weight of individual previous box type header, including weight of contained water was around 204 kg. Total weight of the modified header, including weight of contained water will be around 278 kg. The weight of top headers (goose-neck type) is ~36% more than the previous box type headers.

Each top spray bank has a pneumatic lifting cylinder arrangement for lifting the banks:
(a) During cobble in the ROT area.
(b) During shutdown days for repair/changing of ROT rolls or other shutdown related activities.

The previous lifting system consisted of two number of 300mm rotary swivel joints, 178 mm bore lifting cylinder and a counter weight. The arrangement of top spray bank include more than one lifting cylinder. The location of pneumatic cylinder w.r.to top bank are positioned alongwith counter weights so that all four (4) top banks covering the ROT cooling area are supposed to be lifted in tandem. Each bank is provided with two limit switches to indicate the up/down position of the top headers to the mill operators at operator pulpit. The lifting cylinders are operated pneumatically at 3.5~4.0bar pressure. The previous lifting systems were controlled with manual pneumatic valves. There is overflow arrangement in each top bank which has a provision of maintaining a minimum water flow in the top banks. The lifting system was not capable of lifting even the lower weight top headers (box type). The headers were lifted with the aid of crane.

There has been thus a need in the existing ROT cooling system in HSM to develop improved pneumatic lifting system for top spray bank having goose neck type headers with higher weight in fast, safe and reliable manner avoiding failure due to pressure drop or pneumatic failure to ensure safe plant operation during cobble or usual shut down activities.

OBJECTS OF THE INVENTION

The basic object of the present invention is directed to provide asystem for lifting top headers for laminar cooling at run out table (ROT) at Hot Strip Mill prior to coiling at coilers which would be capable of lifting of all four top spray banks involving goose neck type headers in a safe and reliable manner.

A furtherobject of the present invention is directed to provide asystem for lifting top headers for laminar cooling at run out table (ROT) at Hot Strip Mill which is capable of lifting the modified top headers of goose neck type with nearly 36% additional weight compared to existing box type headers in top spray banks reliable avoiding any failure due to pressure drop.

A still further object of the present invention is directed to provide asystem for lifting top headers for laminar cooling at run out table (ROT) at Hot Strip Mill wherein the pneumatic cylinders deployed for lifting purpose are selectively configured for installing with existing mounting arrangement and for lifting higher weight of headers with available air pressure.

A still further object of the present invention is directed to provide asystem for lifting top headers for laminar cooling at run out table (ROT) at Hot Strip Mill wherein air drier and air booster is involved to favour easy lifting of spray banks with existing available compressed air source at 3.5~4.0bar pressure and with pressure boosting even in case of pressure drop.

A still further object of the present invention is directed to provide asystem for lifting top headers for laminar cooling at run out table (ROT) at Hot Strip Mill wherein the booster consists of a double piston system and a directional control valve for continuous operation such that the input pressure can be boosted upto twice a particular value.

A still further object of the present invention is directed to provide asystem for lifting top headers for laminar cooling at run out table (ROT) at Hot Strip Mill wherein in case of pneumatic failure, i.e. even at zero bar pressure and headers to be in lifted position and shall not fall by gravity and remain in stay put condition.

A still further object of the present invention is directed to provide asystem for lifting top headers for laminar cooling at run out table (ROT) at Hot Strip Mill wherein the system enable modified header assembly to be lifted 90 degree, with available pressure (3.5~4.0 bar) with jerk free operation within 1 minute.

A still further object of the present invention is directed to provide asystem for lifting top headers for laminar cooling at run out table (ROT) at Hot Strip Mill whereinNon Return Valve (NRV) has been incorporated in the system to avoid free fall of top headers in case of air failure during lowering the headers.

A still further object of the present invention is directed to provide a system for lifting top headers for laminar cooling at run out table (ROT) at Hot Strip Mill wherein operation of lifting system is provided from remote location (speed cabin), so that lifting system can be immediately operated during any cobble.

SUMMARY OF THE INVENTION
The basic aspect of the present invention is directed to a system for lifting top spray headers used as laminar cooling system at run out table prior to coiling at Hot Strip Mills comprising:

pneumatic system having pneumatic lifting cylinders for each top spray bank adapted to lift gooseneck type top headers fitted with respect to mounting arrangements and surrounding equipments;

a compressed air source to supply compressed air to operate said pneumatic lifting cylinders;

an air drier to supply dry air to the pneumatic system;

an air booster to boost the air pressure in case of lower line pressure;

non return valve (NRV) to avoid free fall of top headers in case of air failure during lowering the headers

pneumatic valves (ON/OFF switch) for operating the pneumatic system locally with or without cooperative

solenoid valves for operating the system from control panel at remote location (Operator’s desk) ; and
an air accumulator to favour lifting even during air failure

A further aspect of the present invention is directed to a system for lifting top spray headers as claimed in claim 1 wherein saidair booster comprise twin pressure type pneumatic booster operable with compressed air;

said pneumatic valves (ON/OFF switch) comprising of 3/2 pneumatic valve.

A still further aspect of the present invention is directed to a system for lifting top spray headers wherein said pressure boosters comprises of a double piston system and directional control valve for continuous operation whereby the input pressure is automatically doubled with or without a pressure regulator to selectively boost the pressure.

Another aspect of the present invention is directed to a system for lifting top spray headers wherein said pneumatic lifting cylinder is a double acting cylinder capable of operating at a pressure range of 0.6 to 10bar, having the size based on the calculated load of 1519 Kgf comprises cylinder diameter of 250mm, Rod diameter of 42 mm, eye to eye distance of the cylinder 1641 mm and stroke 1070mm so that the cylinder can be fitted in existing mounting.

Yet another aspect of the present invention is directed to a system for lifting top spray headers wherein said air accumulator is of 5000 liters capacity with working pressure of 12.5 kgf/cm2.

A further aspect of the present invention is directed to a system for lifting top spray headers wherein said pneumatic cylinder is adapted to start responding to minimal pressure of 0.6 bar indicating a low level of friction between the cylinder and piston head due to superior surface finishing comprising “U” shape piston for lesser contact area, superior internal surface finish to reduce friction (Min. force required for 0 mm stroke: 30 kg) and heat resistant seal for temp. up to 120 °C.

A still further aspect of the present invention is directed to a system for lifting top spray headers wherein the system is adapted to lift the header assembly to 90 degree, with available pressure (3.5~4.0 bar) with jerk free operation within 1 minute.

A still further aspect of the present invention is directed to a system for lifting top spray headers comprising pneumatic failure operability whereby even at zero bar pressure headers can be maintained in lifted position and not fall by gravity and maintained in stay put condition.

A still further aspect of the present invention is directed to asystem for lifting top spray headers wherein 3/2 solenoid valves enable system operation from control panel installed at remote location (Operator’s desk) in case of cobble in ROT area.

Another aspect of the present invention is directed to a system for lifting top spray headers having swivel joint with modification by offsetting the center by 16 mm such that cylinder base can be accommodated in available space and swivel joint bolted to cylinder base.

Yet another aspect of the present invention is directed to a system for lifting top spray headers comprising means to accommodate the variation in eye to eye distance in different top spray banks, threaded end connection involving a threaded portion providing for eye rod to adjust the modified cylinder in the existing mountings.

The above and other objects and advantages of the present invention are described hereunder in greater details with reference to the following accompanying non limiting illustrative drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Figure 1: shows the photographic image of Box Type top ROT cooling headers previously installed.
Figure 2: shows the photographic image of modified Gooseneck Type Headers with 36% higher weight presently installed replacing the box type headers in ROT cooling area.
Figure 3: shows the photographic image of lifted position of existing box type top headers during cobble in the ROT area.
Figure 4: schematically illustrates the general Arrangement of a top spray bank showing the various components like swivel joint, overflow line, hinge for lifting cylinder etc and their locations.
Figure 5: is the photographic image showing the location of Pneumatic Cylinder w.r.t Top spray Bank.
Figure 6:schematically shows the Top Header Lifting Cylinder Arrangementfitted in existing cylinder mounting arrangement.
Figure 7: shows a schematic sectional Elevation of Top Headers with modified headers indicating its C.G and weight.
Figure 8: shows the schematic arrangement of modified lifting system for top spray headers according to the present invention indicating the different components used in the system.
Figure 9: shows the photographic image of the system with Top Headers in “Down” Position.
Figure 10: shows the photographic image of the system with Top Headers in “UP” Position.
Figure 11: shows the photographic image of selectively configured Pneumatic Cylinder and Air Booster used in the system.
Figure 12: schematic view of the modified swivel joint to accommodate cylinder base in available space.
Figure 13: schematic view of the threaded End Connection provided for eye rod to accommodate variation in eye to eye distance in spray banks.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS

The present invention is directed to provide asystem for lifting top headers for laminar cooling at run out table (ROT) at Hot Strip Mill prior to coiling at coilers which would be capable of lifting of all four top spray banks involving goose neck type headers in a safe and reliable manner with adequate protection in case of pressure drop or failure of compressed air supply.

It has already been discussed that ROT cooling system is divided into 4 spray banks, each spray bank having top and bottom spray arrangement separately. The ROT laminar cooling system has been modified in order to achieve high heat transfer coefficient for improved productivity and product quality. Previously, top ROT cooling headers were box type as illustrated in Figure 1 and have been modified to goose neck type headers as illustrated in Figure 2. Total weight of individual previous header, including weight of contained water was around 204 kg. Total weight of the modified header, including weight of contained water will be around 278 kg. Thus the weight of modified top headers of goose-neck type presently in use is ~36% more than the previous box type headers.

This modification of top headers in the ROT cooling system required improvement of the lifting mechanism which involved pneumatic lifting cylinders and its associated operating accessories including compressed air supply in desired magnitude. It is to be noted that each top spray bank has a pneumatic lifting cylinder arrangement for lifting the banks under the following situations:
(i) During cobble in the ROT area as illustrated in Figure 3.
(ii) During shutdown days for repair/ changing of ROT rolls or other shutdown related activities

The general arrangement of existing one top bank is shown in Figure 4comprising oftwo (2) nos 300mm rotary swivels joint, 178 mm bore lifting cylinder and a counter weight. The location of pneumatic cylinder w.r.to top bank is shown in Figure 5. All four (4) top banks are supposed to be lifted in tandem by the lifting mechanism involving pneumatic lifting cylinders. Each bank is provided with two limit switches to indicate the up/down position of the top headers to the mill operators at operator pulpit. The lifting cylinders are operated pneumatically at 3.5~4.0bar pressure.

Further, based on the torque calculation required to lift the modified headers (goose-neck type), it was envisaged that the previous lifting system was totally insufficient for lifting modified top headers due to increased weight. Thus, the previous lifting system needed to be modified due to increased weight of top header assembly by approx 36%. In view of this lifting system was modified so that it can lift the modified headers during strip cobble and shutdown days.

Following design considerations thus formed the basis of modifying the lifting system for desired lifting of goose neck type headers in top spray banks:
(i) The modified lifting system to be capable to lift modified gooseneck type top headers. The weight and CG of modified system considered for sizing the pneumatic cylinder and air pressure required for lifting the modified headers. The load and torque required for selection of the system was calculated based on the new weight and CG of modified headers.
(ii) Pneumatic system to be designed for modified system. Available air pressure considered for designing lifting system is 3.5~4.0bar.
(iii) The eye to eye distance of the pneumatic cylinder taken as 1641 mm and stroke taken as 1070mm so that the cylinders can be fitted in existing cylinder mounting arrangement as illustrated in Figure 6. The diameter of the cylinders selected based on the designed load. The new cylinder to be accommodated at the dimensions mentioned above without any modification in existing ROT table and surrounding equipments.
(iv) The modified lifting systems to be operated from finishing stand operator’s pulpit (speed cabin). Thus control of solenoid valve given at speed cabin.
(v) In case of pneumatic failure, i.e. even at zero bar pressure and headers to be in lifted position and shall not fall by gravity and remain in stay put condition.
(vi) The modified header assembly to be lifted 90 degree, with available pressure (3.5~4.0 bar) with jerk free operation within 1 minute.

Accordingly the calculation of lifting force for designing the system was done as follows:

The previous top ROT cooling headers were box type laminar headers and have been modified to goose neck type headers. The existing lifting cylinder arrangement for lifting each bank needed to be modified due to increased weight of the top headers and top header assembly by approx 36% more. The sectional elevation of top headers with modified headers indicating its C.G and weight is illustrated in Figure 7. Considering new C.G and weight, the load/torque calculation with modified header vis-a-vis lifting force requirement of pneumatic cylinder for lifting of headers is given below:

A. Calculation of Torque by headers (with water) in One Bank
Weight of 1 header with water (Considering Sch. 40 pipes) = 278 Kg
Composite CG of a single header from centre of rotation = 1.92 m
Weight of Mounting Brackets + valves = 150 Kg
Composite CG of a mounting from centre of rotation = 0.356 m
Torque developed by a single header = 278 *1.92 = 533.76 Kgm
Torque developed by a Mounting Brackets + valves = 150 *0.356 = 53.4 Kgm
Torque developed by one header + valves+ mountings = 587.16 kgm
Total Torque by 6 headers of 1 bank = 587.16* 6 = 3522.96 Kgm

B. Calculation of Torque by Counterweight in One Bank
Dimension of Counter Weight (measured manually) = 0.8m x 0.6m x 0.6 m
Volume of Counter weight = 0.288 m3
Density of mild steel = 7850 kg/m3
Weight of Counterweight = Volume x Density = 0.288 * 7850 = 2261 Kg
Distance of Counterweight CG from Centre of rotation = 1.2 m
Torque by Counterweight = 2261 * 1.2 = 2713Kgm

C. Calculation of Force on Lifting Cylinder
Torque required on lifting cylinder = 3522.96 - 2713 = 810 Kgm
Distance from Centre of rotation to centre of lifting cylinder = 0.533 m
So, Force on Cylinder = 810/0.533 = 1519 Kgf

Sizing of pneumatic cylinder decided based on the calculated load: (Dia-250mm, Rod dia- 42 mm). The eye to eye distance of the cylinder-1641 mm and stroke -1070mm, so that the cylinder can be fitted in existing mounting.

The schematic arrangement of modified lifting system for spray banks of goose neck type top headers according to the present invention is illustrated in accompanying Figure 8. It can be seen in Figure 8 that an air drier is incorporated to supply dry air to the pneumatic system and an air booster is provided to boost the air pressure in case of lower line pressure. The air booster is of twin pressure type pneumatic booster. The pressure booster requires no other source of compressed air than compressed air. Pressure boosters are classified as twin-piston pressure boosters and are intended solely for compressing air. The basic variant of the booster consists merely of a double piston system and a directional control valve for continuous operation. With this design, the input pressure is automatically doubled; it is not possible to adjust the pressure to a lower value. Pressure boosters which also have a pressure regulator can boost the pressure to less than double the set value. In this case the pressure regulator reduces the pressure in the outside chambers. This is important for the pressure amplification achieved. Depending on the function, however, the pressure cannot be boosted to more than twice a particular value. Air accumulator of 5000 liters capacity with working pressure of 12.5 kgf/cm2 was introduced so that all the four lifting system can be operated once, even during air failure. Newer design pneumatic valves (ON/OFF switch) was provided for operating the pneumatic system locally. Further 3/2 solenoid valves were provided, so that the system can be operated from control panel installed at remote location (Operator’s desk) in case of cobble in ROT area. Non Return Valve (NRV) has been incorporated in the system to avoid free fall of top headers in case of air failure during lowering the headers.

Major components of the Lifting System according to the present invention as described above are having the respective structural/operational features as follows:
a) Pneumatic Cylinder:
-Stroke- 1070 mm (selected so that it can be fitted in existing mountings without any modification).
-Diameter: 250mm
-Pneumatic cushioning (cushioning length: 60 mm) adjustable to both end provided to take care of the jerks during lifting the headers.
-Operating pressure: 0.6- 10 bar
-Mode of operation: Double acting
-Operating medium: Compressed air
-Ambient temperature: 120 C
-Force at 6 bar during return stroke: 28270 N
-Force at 6 bar during advance stroke: 29450 N
-MOC of piston rod & cylinder: High alloy steel

b) Air Reservoir:
-Capacity: 5000 liters
-Working pressure: 12.5 kgf/cm2
-Design pressure: 13.75 kgf/cm2
-Hydrostatic test pressure: 21 kgf/cm2
-Allowable stress value: 14 kgf/mm2
-Shell thickness: 8 mm
-MOC: IS 2062

c) Refrigerant Air Dryers:
-Inlet air capacity: 72 l/s
-Working pressure: 13 kgf/cm2

d) Pressure Booster:
-Piston diameter: 100 mm
-Design structure: Twin piston pressure booster
-Inlet pressure: 2- 10 bar
-Output pressure: 4-16 bar
-Ambient temperature- 60 C

The above modified system was installed in phased manner at Hot Strip Mill, at applicant’s Rourkela Steel Plant. Trials were conducted by lifting the new gooseneck type headers with increased weight. The headers were lifted with ease both from local panel (pneumatic valve/ switch) and remote location (solenoid valve). The modified lifting system is able to lift the headers with increased weight at 3.5-4 bar pressure effortlessly. State of art control system has been selected for operating the lifting system. The manual valves are operated through push buttons. Additionally, an electrical control panel has been provided in the speed cabin to operate lifting system remotely, in case of any cobble in ROT area. The operation of modified system in “Down” position is shown in Figure 9 and operation of modified system in “Up” position is shown in Figure 10.

The various aspects and inventive features involved in the lifting system for top headers in ROT cooling in HSM according to the present invention are as follows:
i) Sizing of pneumatic cylinder and designing the total system based on the calculated load / torque of modified system involving:
(a) Calculation of CG of modified header;
(b) Calculation of torque by headers (with water);
(c) Calculation of torque by Counterweight;
(d) Calculation of force on lifting cylinder (1519 Kgf);
(e) Sizing of pneumatic cylinder based on the calculated load (Dia-250mm, Rod dia- 42 mm);
(f) The eye to eye distance of the cylinder-1641 mm and stroke -1070mm maintained so that the cylinder can be fitted in existing mounting.
ii) Selection of suitable cylinder with min. operating pressure of 0.6 bar(as shown in Figure 11) comprising
(a) “U” shape piston for lesser contact area
(b) Superior internal surface finish to reduce friction (Min. force required for 0 mm stroke: 30 kg)
(c) Heat resistant seal for temp. up to 120 °C

iii) Incorporation of pneumatic booster thatIncreases the line pressure by 2 times

iv) Modified swivel joint so that cylinder base can be accommodated in available space (as shown inFigure 12)
(a) Available space between cylinder mounting and roller table: 120 mm;
(b) Swivel joint modified by offsetting the center by 16 mm;
(c) Swivel joint bolted to cylinder base.

v) Since, there was variation in eye to eye distance in different banks, threaded end connection are provided for eye rod to adjust the modified cylinder in the existing mountings (as illustrated in Figure 13)
(d) ~30 mm variation observed in eye to eye distance in different banks;
(e) 65 mm threaded portion provided to accommodate variation;

vi) Size of air reservoir is selected such that, all the four bank can be operated once even during air failure.
vii) Pneumatic circuit is designed to avoid free fall of top headers in case of air failure during lowering the headers.
viii) Operation of lifting system is provided from remote location (speed cabin), so that lifting system can be immediately operated during any cobble.

It is thus possible by way of the present invention to provide an improved lifting system for top headers of ROT cooling system in HSM involving selectively designed lifting pneumatic cylinder, compressed air source, air drier, air booster and means to operate the system in case of pressure drop or failure of compressor wherein
a) Special care is taken in designing cylinder bottom end eye, so that it can fit into the existing mounting and cylinder can be accommodated in the available space. Offset of 20 mm is provided to centre of cylinder bottom end eye so that it can be accommodated in the available space.
b) Since, there was variation in eye to eye distance in different banks, threaded end connection are provided for top eye to adjust the modified cylinder in the existing mountings.
c) Pneumatic cylinder starts responding to minimal pressure of 0.6 bar indicating a low level of friction between the cylinder and piston head due to superior surface finishing technology. It helps in optimum design of cylinder diameter for lifting higher load.
d) Air booster was provided to operate the system even during lower line pressure.
e) Operation of lifting system was provided from remote location (speed cabin), so that lifting system can be immediately operated during any cobble.
f) This kind of lifting system can be utilized in other ROT cooling system for lifting top headers, where cantilever type top headers are installed.
g) This system can be utilized for any other application where cantilever type headers/ other system needs frequent lifting.