Method of manufacture of special parts
Tubes in “ T ”
The steel core and armor are placed in a vertical position, and concreted with the aid of a fixed mold, thereby forming up the core tube. On the wall of this core is left a negative consisting of polystyrene and caught between the two molds (interior and exterior). The diameter of this negative must have a measure of the outer diameter of the extension plus 400mm, in order to simplify the coupling plate and the lashings of the extension to the core armor.
The core remains in the vertical position until the concrete reaches the required minimum resistance allowing its displacement, so that can proceed to the next step, the manufacture of the extension.
This extension shall have circular section and it will be fresh concrete castings when the core tube is in a horizontal position. This concreting will be done with concrete designed to appeal only on the outer wall of the extension, since it does not have indoor coverage. In the figure one can see the division effected in stages of concreting.
The termination of the extension, will always be composed of a phalanx. For the finishing, these special pieces follow exactly the same processes running on a standard tube, as described above, with the addition of carrying an epoxy based paint protective plate for the extension of future corrosion protection.
Upon completion of the tubes in “ T ”, these are again inspected macroscopically in order to find possible flaws in the design or openings slots for cracking of concrete.
Curvs
The steel core of curved, unlike conventional tubes is performed by means of ferrules welded together and then coupled to the nozzles by welds performed manually. The perimeters of these ferrules are of variable size, and always controlled by an employee in order to avoid deviations from the desired angle.
The armor of the curves is also performed manually because of the limitations imposed by the armor machine. Steel is purchased in rolls, having itself a spiral formed when released from its original position. thus facilitating its positioning by welding the guidelines which have already been calendered with varying curvature, according to the desired angle of bend.
After positioning both in the vertical parts, they are welded together with metal spacers to confer rigidity to the assembly.
Then the set (steel armor and soul) is positioned so that the male nozzle is horizontal for the purpose of a perfect leveling of the concrete, and formed through two reinforced centering, a lower and an upper, so to avoid ovalizações the mouthpieces.
The formworks are made of pressed hardboard boards with textile tapes, the outer side and the inner side anchored by steel adjustable turnbuckles. The overlap between the armature and the workpiece surface is provided by plastic spacers of 40 mm.
Part of the concreting It follows that runs simultaneously on both sides of the piece.
For the finishing, these special pieces follow exactly the same processes running on a standard tube, as described above. Upon completion of the curves, these are again inspected macroscopically in order to find possible flaws in the design or openings slots for cracking of concrete.
Cones
As the tubes bend, the tubes cone, are performed through welding of various ferrules together until they make up the desired length and then attached to the respective nozzles, all by manual process. Due to the cone shape of these parts, it is impossible to perform hydraulic test factory, to compensate for this fact penetrant testing is enhanced and the welds undergo a double control such as to avoid any porosity. The closing angle of these cones are explained in the image below.
- D – Larger diameter
- d – Smaller diameter
- C – 4X (D-d) – Length conica part
- A1 – Length nozzle female
- A2 – Length nozzle male
The reinforcement is performed analogously to the process of the tubes being curved hand made and welded to the plate for the purpose of conferring rigidity to the assembly.
These parts are positioned vertically, they are placed centering (upper and lower) and envolved with hardboard. The spacing is done with the help of plastic spacers.
Part of the concreting It follows that runs simultaneously on both sides of the piece.
For the finishing, these special pieces follow exactly the same processes running on a standard tube, as described above. Upon completion of the curves, these are again inspected macroscopically in order to find possible flaws in the design or openings slots for cracking of concrete.