The production of welded cylinders:
The production of welded cylinders takes place at the Vitkovice Milmet plant in Siemianowice Śląskie - Poland. The first stage of production is the cutting out of discs from metal sheet coils, from which later in the process of pressing are created lower parts of cylinders. After pressing, the lower parts are cut at the edges, mold and washed.
The next step is welding the cylinder elements. In the first place, the upper part is welded with a neck ring, then the entire cylinder is completed in the chamber of the welding machine, in which all welds are made at the same time.
Welded cylinders are subjected to a heat treatment process, which is aimed at removing the stresses arising in the cold pressing process and in the welding process. After heat treatment, the cylinders are subjected to a leakproofness test, the purpose of which is to detect possible leaks in welded connections. Then the cylinders are marked with a serial number and other additional signs depending on the customer's requirements.
The cylinders prepared in this way are subjected to a shot-blasting and powder coating process. After leaving the powder paint shop, the cylinders are checked for cleanliness of the internal Surface. The next step is the installation of valves, followed by a leak check of the cylinder-valve connection. In accordance with the customer's order, different types of graphics are applied to the cylinders by screen printing. The final stage is packing of the cylinders according to the customer's specification.
The production of seamless steel cylinders:
The production of seamless steel cylinders takes place at the Vitkovice Milmet plant in Sosnowiec-Poland.
The first stage of production is the cutting of the input material - steel rods for billets, which after heating to a temperature of approx. 1200°C are subjected to two-stage pressing – backward extrusion and hot-drawing.
The next step is ultrasonic inspection of the moldings and then cutting to a specific length. Closing of the cylinder's shell and neck formation takes place in the spinning process. In order to increase the mechanical properties, cylinders are subjected to a heat treatment in the form of hardening and tempering. After strengthening the material, the cylinders external surface is cleaned (shot blasting) and then the hardness test is carried out.
The next stage of production is the threading in the neck of the cylinder and a pressure hydraulic test, where are determined the capacity and weight of the finished cylinder. After testing, the cylinders are marking in accordance with the applicable standards. After marking, the neck rings are applied to the neck of the cylinder, which are used to mount the accessories of the cylinder (e.g. caps), after which the inner surface of the tanks is shot-blasted.
Before the last stage of production, i.e. painting, the final ultrasonic inspection of finished cylinders is performed. Painting takes place - depending on the customer's requirements - using the powder method or APS Extreme technology.