Design Phase

Research and development

Design phase

Products released by GREENPIPE Srl are the result of an accurate design phase conducted by long-time experienced technicians, assisted by cutting-edge CAD 3D software.

Gratings

After being designed and before making a mould, gratings undergo parametric simulations, which reproduce loading and displacement tests according to the EN 1433 standard. By means of this procedure, the exact loading class can be established for each designed grating. Gratings are available in ductile iron or in galvanised iron steel S385J.

Preview of digital test results on grating class E600. It is possible to have a realistic preview of calculated loading stress in MPa, according to criterion of von Mises, which must always be less than a value of 500 Mpa.

Residual displacement (deformation) after five cycles at 2/3 of the maximum load (<0.11 mm, maximum value accepted 1mm).

Channels

Concrete and reinforced concrete channels are the result of meticulous design carried out internally (in partnership with Italian universities).

Focus on concrete channels

GREENPIPE Srl type M drainage channels are made of high resistance concrete drainage channels are made of high resistance vibrocompressed concrete:

  • Minimum compression strength class C 35/45 ((NSC – Normal Strength Concrete, according to EN 206:2006 and UNI11104:2004, Rck = 45 N/mm2)
  • Frost and defrost cycle (classification +R according to EN 1433:2008)
  • Weather and atmospheric agent (classification W according to EN1433:2008).

The mixture consists of inert (granulometry from 0,2 to 10 mm) and Portland cement characterized by a low water to concrete ratio, and in fact it is also known as “moist soil”.
The products, made in moulds fi lled with moist concrete, are at the same time mechanically vibrated, hydraulically compressed and extracted in few seconds.

The GREENPIPE Srl self-supporting drainage channels (type I) are made with reinforced concrete which is resistant to weather conditions and to the frost and defrost cycle (W+R) with minimum strength class C35/45. The mixture is fluid and self-levelling designed for the use of stone aggregates, suitable granulometry (with appropriate quantity of filler which diminishes the percentage of empty spaces in the conglomerate thanks to its reduced dimensions). The water to cementratio must be defined according to standard and be constant during production.
The mixture is poured by gravity into moulds. The extraction of the piece is deferred for a few hours to enable the concrete to begin a chemical grip and hardening reaction in order to ensure, after 28 days, the best mechanical performance.
Initially, the products made from this kind of material look particularly smooth (the filler has a fundamental role) and have a Gauckler-Stickler coefficient of 100 (similar to a clay pipe) which is beneficial for water outflow.
The steel reinforcement is properly calculated to react to the tension and shearing stress.

What does self- supporting mean?

Drainage channels can be described as “self-supporting”, or type I according to the EN1433 standard, “they do not require additional support for horizontal and vertical loads”. (EN1433, §3.2.).

Focus on ductile cast iron

Ductile cast iron is a ferrous alloy with standard carbon ratio of more than 2%, which can, in its free state, be graphite (grey cast iron) or can be in the form of ferrous carbide Fe3C (cementite or white cast iron).
Grey cast iron is preferable for the production of gratings and covers.
White cast iron is very brittle and has elevated hardness. This kind of cast iron is used for producing tools.
In the group of Grey Cast Iron, two categories can be distinguished: lamellar cast iron and ductile cast iron.
Lamellar cast ironis formed by thousands of lamellae which interrupt the continuity of the metallic matrix compromising mechanical resistance and facilitating cracks and breakages.
Ductile cast iron has a composition made up of spheroids obtained by introducing, before casting, a certain amount of magnesium in the bath.

Lamellar Cast Iron

Ductile Cast Iron

Minimum tensile strength Rm: 500 N/mm²
Unit load proof strength at 0,2 Rp: 320 N/mm²
Min.stretching %: 7
Brinell hardness: 170÷230 (Ferrite+Pearlite)

This addition gives the product a high breaking load and high elasticity.
The graphite spheroidal shape produces a minor stress concentration than the lamellar type.
The spherical shape has a smaller surface, consequently its cast iron matrix turns out to be less damaged, and manages to properly exploit its mechanic characteristics.
From the comparison it appears that spheroidal cast iron has a higher safety coeffi cient to breakage because it deforms without breaking and remains in its initial state when stress decreases.
It takes more mass to produce a lamellar cast iron product with the same loading class than it does to produce a cast iron product: therefore, the product will be heavier and the cost of transport will be higher.

In conclusion, ductile cast iron is a construction material of considerable value. Because of its mechanic characteristics which are similar to those of a well-made steel product.

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