# US 5,706,866 A · Pipe member for buried conduit with corrosion protection and process therefor

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- Number: US 5,706,866 A
- Document ID: US5706866A
- Status: Granted
- Kind: A
- Application number: 08/516,063
- Filed: 1995-08-17
- Granted: 1998-01-13
- Earliest claimed: 1993-02-18
- Assignees: Pont-A-Mousson S.A.
- Inventors: Jean-Marc Pedeutour; Gerard Nouail; Jean Bello
- Web page: https://patentgrep.com/patent/US5706866A

## CPC

- F16L 58/04: Coatings characterised by the materials used (F16L58/16 takes precedence)
- C23C 4/18: After-treatment
- C23C 28/021: {including at least one metal alloy layer}
- C23C 28/025: {with at least one zinc-based layer}
- C23C 28/028: {Including graded layers in composition or in physical properties, e.g. density, porosity, grain size}
- Y10T 428/12611: Oxide-containing component
- Y10T 428/1393: Multilayer [continuous layer]
- F16L: PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A cast iron piping system element has an outer coating comprising a first, inner porous layer consisting of zinc/aluminum alloy containing from 5 to 60% of aluminum, and a second, outer pore occluding layer of an organic or mineral binder in an aqueous, solvent or powder phase with a thickness of 100-140 .mu.m.

## Claims

### Claim 1

An iron pipe member for a piping system buried in the earth, provided with an external coating for galvanic protection against soil corrosion, said coating comprising:
a) a porous inner coat of zinc-aluminum alloy containing 5% to 60% of aluminum applied directly to an outer surface of the pipe member; and
b) a porous outer pore-sealing coat of one of an organic and mineral binder in one of an aqueous, solvent, and powder phase, and having a thickness between 100 and 140 .mu.m applied over the inner coat.

### Claim 2 (depends on 1)

An iron pipe member as recited in claim 1, wherein said member is made of cast iron.

### Claim 3 (depends on 2)

A pipe member as recited in claim 2, wherein the organic binder is one of a bitumen varnish, a coal pitch, and a synthetic organic product.

### Claim 4 (depends on 3)

A pipe member as recited in claim 3, wherein the synthetic organic product is an epoxy resin.

### Claim 5 (depends on 2)

A pipe member as recited in claim 2, wherein the pore-sealing coat is a water-based paint.

### Claim 6 (depends on 2)

A pipe member as recited in claim 2, wherein the alloy coat has a density of at least 200 g/m.sup.2.

### Claim 7 (depends on 2)

A pipe member as recited in claim 2, further comprising an intermediate coat of at least one of zinc chromate and zinc phosphate between the inner and outer coats.

### Claim 8 (depends on 2)

An iron pipe member as recited in claim 2, wherein the alloy coat is deposited by electric-arc spraying.

### Claim 9 (depends on 8)

An iron pipe member as recited in claim 8, wherein the outer coat is deposited by spraying.

### Claim 10

A method for protecting an iron pipe member for galvanically a buried piping system against soil corrosion, comprising the steps of:
a) applying a porous inner coat of zinc-aluminum alloy containing 5% to 60% of aluminum directly to an outer surface of the pipe member, and
b) applying a porous outer pore-sealing coat of one of an organic and mineral binder in one of an aqueous, solvent, and powder phase, and having a thickness between 100 and 140 .mu.m over the inner coat.

### Claim 11 (depends on 10)

A method as recited in claim 10, wherein the pipe member is made of cast iron.

### Claim 12 (depends on 11)

A method as recited in claim 11, wherein the organic binder is one of a bitumen varnish, a coal pitch, and a synthetic organic product.

### Claim 13 (depends on 12)

A method as recited in claim 12, wherein the synthetic organic product is an epoxy resin.

### Claim 14 (depends on 11)

A method as recited in claim 11, wherein the pore-sealing coat is a water-based paint.

### Claim 15 (depends on 11)

A method as recited in claim 11, wherein the alloy coat has a density of at least 200 g/m.sup.2.

### Claim 16 (depends on 11)

A method as recited in claim 11, further comprising the step of applying an intermediate coat of at least one of zinc chromate and zinc phosphate between the inner and outer coats.

### Claim 17 (depends on 11)

A method as recited in claim 11, wherein the alloy coat is deposited by electric-arc spraying, and the outer coat is deposited by spraying.