FR2655682A1 - Safety rung intended to be anchored in the wall of a masonry construction - Google Patents

Abstract

It is made from an aluminium alloy having a high elastic strength, covered with a coating consisting of an epoxy resin, and its two branches (1) and (2), closed at their end, each include, near the said end, two pinches (5, 6) (7, 8) which are each arranged in a vertical plane and positioned at a distance from each other.

Description

 The subject of the present invention is a safety rung intended to be anchored in the wall of a masonry structure to allow access to the interior of wells, reservoirs, underground galleries, etc.

 The steps known to date for this type of use generally comprise a tubular element approximately in the shape of a U, the end of the branches of which is intended to be inserted into the wall of the masonry work.

 The tubular elements constituting these rungs are most often made of iron or steel, but their use in humid or corrosive atmospheres requires that they be provided with a protective coating such as a synthetic material.

However, such a coating cannot be securely joined to the tubular element, and on the other hand it can be fairly easily deteriorated during use, allowing local corrosion of the tubular element which leads to progressive degradation. of the rung.

 In order to remedy this drawback, steps have been proposed made of aluminum, which have a higher resistance to corrosion. However, such steps offer the disadvantage of not having any dielectric insulation, which prohibits their use in atmospheres where there are risks of sparks.

 Finally, the establishment of these various steps generally involves plastic insulating and blocking sleeves, intended to be previously inserted in recesses formed in the masonry wall, in order to receive the end of the branches of the step, forcefully inserted into said sleeves. However, the use of such sleeves has the disadvantage of being able to give rise to a partial deterioration of the external surface of the branches of the rung, when they are forcefully introduced into said sleeves, this deterioration possibly causing that of the anchoring of the rung in the wall.

 The object of the present invention is to remedy these various drawbacks of known steps by proposing a safety step which combines the advantage of easy installation in the masonry wall that of excellent resistance to corrosion and of '' not less good resistance to loosening.

The subject of the present invention is therefore a safety rung which is essentially characterized
- On the one hand, in that it consists of a tubular element whose shape is approximately that of a U and whose two branches are closed at their ends, in the vicinity of which they have two pinches spaced a few centimeters , arranged in a vertical plane
- on the other hand, in that it is made of an aluminum alloy whose composition, specially studied, gives it an elastic resistance greater than that of common aluminum alloys
- secondly and finally, in that said tubular element is entirely covered with a material of the epoxy resin type which gives it excellent resistance to corrosion and eliminates the possibility of creating a galvanic couple.

 The aluminum alloy in which the safety rung according to the invention is produced is an alloy adapted to give it an elastic resistance of approximately 2 to 3 daN / mm2.

 To this end, the alloy used, of determined composition, is subjected to a heat treatment of quenching and tempering which increases said elastic resistance.

 The best alloy suitable for achieving the safety step according to the invention is an aluminum alloy containing from 0.30 to 0.60% by weight of silicon and from 0.4 to 0.80% by weight magnesium, as well as small amounts of iron, copper, manganese, chromium and zinc.

 Preferably, the proportions of these metals are at most 0.35% iron, 0.25% copper, 0.20% manganese, 0.20% chromium and 0.10% zinc.

 The anti-corrosion coating of the safety rung according to the invention preferably consists of an epoxy resin used in the form of a paint which is applied to the entire surface of the rung, constituting a dielectric insulation efficient and thereby giving it the best possible resistance to corrosion, especially when coming out of concrete.

 In order to provide said coating with the best adhesion to the aluminum alloy used, said epoxy resin is deposited on the surface of the rung by an electrostatic process.

 Among the epoxy resins which can be used, the one giving the best results is the epoxy resins of bisphenol A type crosslinked with a cyclic amidine.

 Corrosion resistance tests carried out revealed that this type of coating gives the level a corrosion resistance of at least 600 hours in salt spray, the test being carried out according to standard NFX 41002.

 The two branches of the rung according to the invention are closed at their ends by means of a plastic shutter so as to avoid the penetration of concrete into these branches during the establishment of the rung, which is intended to be inserted into fresh concrete.

 The advantages and characteristics of the safety rung according to the invention will emerge more clearly on reading the description which follows made with reference to the appended drawing which represents an embodiment thereof, it being understood that this description has no limiting character vis-à-vis the invention.

 In the single figure of the appended drawing, it can be seen that the safety rung according to the invention affects the approximate shape of a U, the two branches 1 and 2 of which each have a closure element 3 at their end, respectively 4, and in the vicinity of said end two pinches 5 and 6, respectively 7 and 8, each arranged in a vertical plane so as to provide the rung with the best possible resistance to tearing while avoiding reducing its resistance to bending.

 The rung also has non-slip grooves on its surface intended to increase the safety conditions attached to its use.

 By design, both in terms of form and materials used for its realization, the safety rung according to the invention can be implemented under the best safety conditions in more or less corrosive humid atmospheres, such as those sewers or certain large capacity tanks.

 Of course, the present invention cannot be limited to the foregoing description of one of its embodiments, liable to undergo a certain number of modifications without departing from the scope of the invention.

Claims (6)

1) Safety rung intended to be anchored in the wall of a concrete structure, of the type consisting of a U-shaped tubular element, characterized in that it is made of an aluminum alloy having an elastic resistance greater than that of current aluminum alloys, covered with a coating consisting of an epoxy resin, and in that its two branches (1) and (2), closed at their end each have, in the vicinity of said end, two pinches (5, 6) (7, 8) each arranged in a vertical plane and positioned at a distance from one another. 2) Safety step according to claim 1, characterized in that the aluminum alloy is an alloy having an elastic resistance of 2 to 3 daN / mmZ and containing from 0.30 to 0.60% by weight of silicon, and from 0.4 to 0.80% by weight of magnesium as well as small amounts of iron, copper, manganese, chromium and zinc. 3) Safety step according to claim 1 or claim 2, characterized in that the aluminum alloy used contains at most 0.35% iron, 0.25% copper, 0.20% manganese , 0.20% chromium and 0.10% zinc. 4) Safety step according to any one of the preceding claims, characterized in that the coating consists of an epoxy paint of the bisphenol A type crosslinked with a cyclic amidine.  5) Safety rung according to any one of the preceding claims, characterized in that the coating is deposited on the surface of the rung by an electrostatic process. 6) Ladder according to any one of the preceding claims, characterized in that its branches are closed by means of two shutters (3, 4) made of plastic.