GOOD RESISTANCE TO CORROSION
Upon request we can produce special flanges.
Being less heavy (over30%) than steel, aluminium is more functional in installation, maintenance, loading, unloading, storage and transport.
In most cases the physical and chemical characteristics of aluminium allow the use of these flanges without any surface preservative treatement. Optionally you can cover the flanges with a coat of epoxy paint.
Relied by technical proofs of resistance and by years of usage of this metal.
The use of the flanges, as component of pipes joint, is generally necessary for the assembly and disassembly of equipment or pipes parts.
The loose flanges are slipped on the pipe and lean against a ring or a collar welded at pipe, which is the only part of joint that comes in contact with the fluid. Their use appears economic for aggressive fluids which need pipes in expensive materials (stainless steel, etc.) as the flanges can be in less valuable material, like aluminium, carbon steel or other.
The flanges are aluminium allo die-casted and present EN AC-47000 Al Si 12(Cu) discrete mechanical properties and sufficient corrosion resistance.
Mechanical properties at room temperature are as follows (UNI EN 1706:2010) part 3 table 7.1:
|Tensile strength||170 N/mm2|
|Feld strength||90 N/mm2|
|Brinell hardness||55 HB|
Usually the aluminium flanges are supplied with blank surfaces and, without any treatment, are installed on stainless steel or aluminium or plastic pipes as, in normal atmosphere, the natural film of aluminium oxide (Al2O3) that forms on the flange surface shows a sufficient resistance to corrosion.
In humid atmosphere it forms a thick layer of oxide whose outside is porous and hydrates with small particles or white deposits, while the side adherent to the surface is a continuous porous film durable and insoluble in 4.5 to 8 ph field.
This natural passivation allows, in most cases, to use aluminium flanges with blank surfaces. On the surface of contact between stainless steel and aluminium is not produced any phenomenon of corrosion for contact.
Our aluminium flanges follows the dimensions according to the UNI EN 1092-1:2013 PN10, PN16, EN1759-4 Class 150 (ANSI TYPE) and DIN 16963 (TP-TYPE) regarding both the outer diameter of the flanges and the interaxis space number of the holes for the bolts. These dimensions apply with the UNI 2223-67 6092-67, DIN 2501 and DIN 2527 norms.
Thickness: over ND 25 up to ND 250 according to UNI 6089 (DIN 2642) standards, over ND 250 see the dimensional tables. For the thickness of the TP-TYPE flanges (strengthened and reg. form) see the relative dimensional tables.
Tests carried out from official corporations at our factory attest, for flanges of our production (ISO and METRIC flanges up to DN 500 and LITE flanges) the tightness up to 10 or 16 bar and various tests from our quality service attest the tightness of TP-TYPE flanges (hydrostatic test up to ND 300).
As information from DN 500 the maximum allowable pressure changes from 6 to 4 bar.
The practical use of millions of gea flanges for several years and a business system of production technology certified by the prestigious ISO 9001:2015 demostrate that our aluminium flanges afford an absolutely reliability.
THERMAL CONDUCTIVITY AT 20°C EN-47000 → 130 - 150 W/(mK).
The resistance of the aluminium alloy to various temperatures is the following:
up to 50°C
|100 °C||150 °C|
|Tensile strength N/mm2||170||150||120|
On this matter we can note that the temperature of the aluminium flanges is always very lower than the one of the pipes because there is a rapid dispersion of the absorbed heat as the capacity of heat conduction of aluminium is 3 times better than carbon steel alloys and 6 times than stainless steels.
G-ITALY flanges prooved a rapid, previously absorbed, heat loss.
When flanges are installed in very humid places, in grounds or when the white oxides must be excluded for aesthetics reasons, are used flanges covered by an enamel composed of powders that has high mechanical resistances and good chemical resistances.
First the surface of the flange is prepared with a mechanical (sand-blasting) or chemical treatment to guarantee the maximum adhesion of the covering thick and the best resistance to corrosion.
Powders are so applied in electrostatics way and, after baking in the furnace, form a very adherent and resistant film, but sufficiently elastic as to follow the thermic dilatations of the flange.
We report here below, only like information title, the characteristics of the covering concerning the standard tests for applications on laminations treated with phosphates.
|Type of coating||EPOXI-POLYESTER|
|Mechanical properties of the coating|
|Thickness (ISO 2360)||60 micron|
|Adherence (ISO 2409)||GT 0|
|Hardness (EN ISO 2815)||> 90|
|Collision Resistance (ECCA T8)||> 2,5 Nm|
|Shaping (ISO 1520)||> 3 mm|
|Bending (ISO 1519)||5 mm|
|Brightness||80 - 90 glos|
|Resistance to corrosion|
|Saline fog (ASTM B117)||500 hours (1 mm. of penetration on the cross)|
|Humidity resistance (IUNI 8744)||500 hours: no change|
|Demineralized water (ASTM D870)||500 hours: no change|
|Resistance to solvents|
|Ethyl alcohol - Buthyl alcoh||No softening|
|Toluene - Xylene||Light softening|
|Trichloroetane - Perchloroetane||Hard softening|
|Methylethylketone - Acetone||Hard softening|
- Temperature of use: from -25°C to 50°C
- Standard colour: RAL 7031