Pipeline element to the pipeline system, the corresponding pipeline system and method of protecting coating of pipeline element

 

(57) Abstract:

The invention relates to construction and is used for corrosion protection of underground pipelines from cast iron pipes. On the pipe cause the outer multi-layer protective coating. The first layer is zinc, the second one zincaluminum alloy, and the outer porous organic-based binder. Recommendations for methods of coating to the thickness of the layers. Improves the reliability of the pipeline through effective protection against corrosion. 3 S. and 7 C.p. f-crystals.

The invention relates to corrosion protection of pipeline systems, pipeline educated elements of ferrous metals, in particular iron. Under pipeline elements imply pipes, and various pipe fittings, such as elbows, pipe connections, etc.

In the patent JP-A-23010357 described known method of coating steel pipe, in which the "sacrificial" coating of an alloy of zinc and aluminum is applied by sputtering, followed by deposition of epoxy resin. It is obvious that the coating resin should be impervious to liquid.

This method applies the coating on the pipe, RAS is S="ptx2">

Closest to the claimed are known pipeline element and the system (see EP A1 0178404, CL F 16 L 58/02, 1985), and in part of the way - the solution known from the application FR, A1 2575765, CL F 16 L 58/02, 1985

The invention applies mainly to buried in the soil pipeline systems, but can also be used for suspended piping.

Soil corrosion of ferrous metals by nature different from atmospheric corrosion and is mainly in the creation of the oxidation zones, electrically connected with rehabilitation areas that may be located some distance.

So there are localized, and therefore, significant destruction of black metal.

Corrosion protection laid in soil piping elements is thus a considerable challenge, especially as the site is heterogeneous and have different nature, piping elements, depending on their destination pass different environments at different temperatures, changing conditions, corrosion, and transportation piping elements intended for laying in the ground, often causes damage to the I pipeline element, in particular, grounded, black metal, which is at an acceptable cost, provides effective protection against corrosion, regardless of the destination of the pipeline system, in particular, for the supply of water and wastewater, and for most sites.

The object of the present invention is a pipeline element of black metal, particularly iron, in particular, laid in the soil pipeline system, characterized in that it has an outer coating comprising the first zinc layer, a second porous layer of zincaluminum alloy containing 5 to 55% aluminum and placed on the second layer, the third porous layer, called putty, which includes an organic binder, in particular, water paint, bitumen varnish or epoxy resin.

Pipeline element may have one or more of the following characteristics: first layer is made porous; the first layer is applied in an amount of not less than 130 g /m2in particular not less than 200 g/m2; alloy layer deposited in an amount of not less than 130 g/m2in particular not less than 150 g/m2; putty layer has a thickness of from 80 to 150 microns.

The subject invention is also pipeline the way to protect the pipeline element of black metal in particular cast iron from corrosion, in particular of the soil, which includes the following steps : a) deposition by arc metallization of the first zinc layer; b) applying by arc second metallization layer zincaluminum alloy containing 3 - 55% aluminum; C) applying a third porous layer, called putty, which includes an organic binder, in particular, water paint, bitumen varnish or epoxy resin.

Below is a specific example of carrying out the invention as applied to pipeline element for water supply or wastewater from kokovoko iron.

In this example, the above-described coating is applied in three stages on the iron passed through a furnace, i.e., with the crust formed by the oxides of iron.

In the first phase precipitated the first zinc layer by metallization in electrical arc.

Then a second layer formed zincaluminum alloy, is deposited by metallization in an electric arc on the first layer.

Finally, is applied by spraying the finishing layer, called putty, which includes an organic binder, in particular a water-based paint, bitumen varnish or epoxy resin. This is the atom the air.

Basically, this coating performs the following function.

The zinc layer, the so-called sacrificial compared to cast iron, may be gradually consumed by oxidation under the action of the electrochemical cell formed by iron, zinc and soil, to protect the underlying or exposed iron in places defects or damage to the coating by the formation of a protective layer of corrosion products that form a stable deposition in the place where they appeared.

Corrosion products clog and close up the injuries, but with the depletion of zinc this layer gradually degrade over time, not vozobnovlyali, and this iron is already protected. Therefore, the main factor leading to the depletion of zinc, is samarraie zinc, which consumes the metal.

The second layer of zincaluminum alloy protects the zinc layer from this phenomenon, being a place of samarraie.

The interaction between the first zinc layer and the second layer of the alloy stabilizes each metal layer to form a protective layer for long periods.

Since the alloy layer is applied by metallization in electrical the and occurrence of precipitation of the corrosion of zinc this gradual movement of the electrolyte from the surface to a layer of pure zinc is retarded in the alloy layer. In addition, the porosity of this layer alloy promotes the effective pinning layer of putty.

It should be noted in this regard that the migration of corrosion products of the first zinc layer to the second layer of the alloy allows you to score the second layer, thereby reducing the diffusion of the active constituents of soils in cast iron. In this regard, the protective layer formed by a regulated transformation of various layers of coating provides better long-term stability than the transition layers derived from one or the other metal comprising zinc or alloy coating according to the invention.

The porous nature of the zinc layer also important, as it increases the active surface of the zinc, and thus the effectiveness of galvanic protection, and in addition, it promotes the effective pinning layer of alloy.

The zinc layer and the layer zincaluminum alloy perform consequently, in the main, additional functions, and indicate that the overlap in the respective quantities of preferably not less than 200 g/m2and 150 g/m2efficiency is samarrai zinc, and therefore contributes to the creation of compact and dense layer of corrosion products of zinc to maintain their protective effect. The thickness of the filler should be sufficient to ensure effective braking samarraie zinc, but low enough to ensure effective action of the galvanic protection and formation of corrosion products.

In addition, too large thickness of the putty would lead to the capture of water under it and to the formation of suchevane.

Thus, it was determined that the thickness of the filler should be from 80 to 150 μm.

1. Pipeline element of black metal, in particular made of cast iron, having the outer coating consisting of several layers, the first of which is the zinc layer, and an outer organic layer, characterized in that the first layer of zinc deposited second layer, porous, zincaluminum alloy containing from 5 to 55% aluminum, and the outer organic layer located on the second layer is a coating is porous and includes an organic binder, in particular a water-based paint, bitumen varnish or epoxy resin.

2. Item under item 1, characterized in that the first layer is porous.

2.

4. Item one by one from PP.1 to 3, characterized in that the alloy layer deposited in an amount of not less than 130 g/m2in particular 150 g/m2.

5. Item one by one from PP.1 to 4, characterized in that the layer of coating has a thickness of from 80 to 150 microns.

6. Pipeline system, in particular embedded in the ground, consisting of pipeline elements of black metal, in particular made of cast iron, each of which has an outer coating consisting of several layers, the first of which is the zinc layer, and an outer organic layer, characterized in that the first coating layer of each pipeline element deposited second layer, porous, zincaluminum alloy containing from 5 to 55% aluminum, and the outer organic layer located on the second layer is a coating is porous and includes an organic binder, in particular, water paint, bitumen varnish or epoxy resin.

7. The way to protect the pipeline element of black metal, in particular of iron from corrosion, in particular from soil, which is sprayed on a substrate a first layer of zinc by metallization and then sprayed layer, called a filler, characterized in that crutem metallization in the arc second layer zincaluminum alloy, containing from 5 to 55% aluminum, up to spray putty, which is porous and includes an organic binder, in particular a water-based paint, bitumen varnish or epoxy resin.

8. The method according to p. 7, characterized in that the layer of zinc is sprayed in an amount of not less than 130 g/m2in particular 200 g/m2.

9. The method according to p. 7 or 8, characterized in that the layer of alloy sprayed in an amount of not less than 130 g/m2in particular 150 g/m2.

10. The method according to one of paragraphs.7 to 9, characterized in that the third layer is sprayed, in particular, to a thickness of from 80 to 150 μm.

 

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