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5.Chemical Treatment Department

 

5.1.Pre-treatment Area

5.1.1.Acid Degreasing Tank


Inside dimensions 14.50 x 2.25 x 3.00 (h) mtr
Outside dimensions to be determined
Liquid volume 90.60 mc
Total weight of the tank 18 tons
Polypropylene lining thickness 20 mm
Solution in the tank acid degreaser solution,
Working temperature room temp

Thanks to their consistent steel frames and to the thickness of polypropylene lining, these tanks are perfectly suitable for the use in Hot Dip Galvanizing industry. Each tank has the following components:

Supporting steel frame in welded steel profiles and plates, coated with bituminous fibre glass epoxy-resin paint.

The polypropylene lining of the tank including: Polypropylene 20-mm-thick sheets for five walls, cut, chamfered and pre-welded to be installed and welded according to DVS 2205 standards inside the supporting steel frame.

Manhole strengthened stub pipe with a PVC free flange. Pipes, pipeline fittings and flanges in PVC to furnish the tank.


5.1.2.Pickling Tank


Inside dimensions 14.50 x 2.25 x 3.00 (h) mtr
Outside dimensions to be determined
Liquid volume 90.60 mc each
Total weight of the tank 18 tons each
Polypropylene lining thickness 20 mm
Solution in the tank acidified water HCL 15 -16 %
Working temperature Room Temperature

5.1.3.Rinsing Tank


Inside dimensions 14.50 x 2.25 x 3.00 (h) mtr
Outside dimensionsto be determined
Liquid volume 90.60 mc
Total weight of the tank 18 tons
Polypropylene lining thickness 20 mm
Solution in the tank Water
Working temperature Room Temperature

5.1.4.Fluxing tank


Inside dimensions 14.50 x 2.25 x 3.00 (h) mtr
Outside dimensionsto be determined
Liquid volume90.60 mc
Total weight of the tank 18 tons
Polypropylene thickness20 mm
Solution in the tank Zinc ammonium chloride at 28/30 Baume
Working temperature 55C

5.1.5.Agitation Process


5.2.Post-Treatment area

5.2.1.Cooling tank

Inside dimensions 14.50 x 2.25 x 3.00 (h) mtr
Outside dimensions to be determined
Liquid volume 90.60 mc
Total weight of the tank 18 tons
Solution in the tank potable water
Working temperature Room Temperature

5.3Service equipment for chemical treatment area

5.3.1.Integrated Heating unit for Fluxing tanks


This heating system consists of a heat-exchanging unit, which is installed inside the tanks. The heating fluid (water) is supplied by a heat economizer. The hot water which is produced in this way is pumped to an insulated storage facility having the suitable capacity. This fluid is ready to be utilized by the heating unit.

The water inside the pipes recirculates with the help of pumps until it gets the exchanging units which are immerged into the pre-treatment tanks, and in this way there takes place a turnover between the water and the liquid inside the tank. Once the fluid rejected all the caloric, it turns back through the pipe to the insulated storage facility.

The working temperature is controlled by control devices which are installed in Control Unit.

Once they read the temperature data through the thermocouples inside the tanks, they operate a three-way water supplying valve.

Heat capacity400,000 Kcal/h
Heating fluidHot water at 65-75C
Temperature of the solution in tank 25-45C
Given electric power 2 HP

5.3.2.Containment pit for tanks, absorbing wells, grill flooring,LipSuction


All pre-treatment tanks are set on a single above ground pit, where they are positioned side-by side.

The upper level of the tanks overhangs 1,000 mm the operators walking level, so that the operator working in this area finds himself further away from the surface of the liquids in the tanks and this has some advantages, such as the better visibility of the racks with the items during the working process.

The pit is provided with safety wells which assist in absorbing and distribution of the liquid discharge from the tanks. A safety well is a basin where all the acid solutions poured out, or overflowed, or dripped from the various pretreatment tanks, are entrapped. Inside the well are set 3 floating liquid-level switches in PVC which bring into action a pneumatic pump in polypropylene as soon as the liquid inside the safety well reaches the limit-level. The pump works until the well is emptied completely.

The acid solution which is pumped from the well is decanted into exhausted acid storage facility.

The pump which is used for decanting is the same pump which is used for pump over and emptying of the tanks: thanks to various switches it can be defined if the pump will work for absorbing or for pump over, and from which well it will pump.

Standard pit dimensions 27 x 20 m
Number of safety absorbing wells 3

Grill flooring made of glassfiber grates which are positioned between the tanks, are useful as access pathways. They have a nonskid surface and are essential in such an acid environments only a pretreatment area can be.. The walls are coated with anti acid paint totally


5.3.3.Polypropylene covers to close the tanks

Covers to close the pre-treatment tanks are required for degreasing, pickling and fluxing tanks and consist of a 12 mm polypropylene fully-lined iron frame which acts to protect against the corrosive action of acid solutions. Every cover consists of 4 lifting screws for their handling and with a system of wheels, in order to slide along the iron guides.


5.3.4.Moving translation block for covers

Every cover slides along iron guides placed in the upper side of the tanks. This movement becomes possible because every cover is provided with 2 air pistons (one each side) and a locking system that stops their stroke, as well as from mechanical retainers that prevent the cover to come out from guides.