Metals – Heat Galvanisation
Heat galvanisation is a zinc coating technique which involves emerging the metallic items in a bath of molten zinc kept at an average temperature of 450°C, which results in the coating, for example of steel, with a solid layer of zinc. Heat galvanisation guarantees a much greater thickness of coating than electro-galvanisation.
The heat galvanisation process is sub-divided into different phases: Degreasing and pickling, which is achieved through the use of surfactants and hydrochloric acid; Flushing: immersion in ammonium chloride and zinc chloride; Galvanisation: immersion, after pre-heating to 100°C, in a bath of molten zinca at 450°C for the time necessary for the metal to reach that of the zinc.
Cooling in the air or in water and which may be followed by passivation treatment.
The bath which contains the molten zinc is subject to a slow and constant process of erosion, due to the high temperature reached and to the chemical agents which are released during the operational phase, which come into contact with the sides.
The state of corrosion is therefore evaluated through the use of diagnostic technologies that elaborate the thickness parameters of the bath with an ultrasound probe which is covered in alluminium and is connected to an external computer. This is to guarantee the client the best result.
The speed of corrosion of the heat galvanised items may vary between 0.1 and 2 microns per annum when subject to normal useage, whereas in extreme conditons it may go above this limit.
On the basis of this information, excluding scenarios of extreme or rare useage, it is reasonable to state that the protection offered by heat galvanisation varies from a minimum of 40 years to well over a century. Galv.Ar is able to guarantee optimum results with items treated through heat galvanisation thanks to the company’s vast experience in this field spanning three decades.
Objects treated enjoy enhanced durability and reliability. The company is able to carry out the procedure rapidly whilst respecting fully all applicable norms. Galv.Ar can organise and supply the logistics of uplift and delivery of materials to be heat galvanised at the client’s domicile; such material is brought by an external supplier for the treatment.