Pipe wrap for preventing microbiologically influenced corrosion in buried conduits

• US 6,488,998 B1
• Filed: 08/01/2000
• Issued: 12/03/2002
• Est. Priority Date: 06/24/1996
• Status: Expired due to Term

• Current Assignee: The Ductile Iron Pipe Research Association
• Original Assignee: Fulton Enterprises, Inc.
• Inventors: Crook, John A.
• Primary Examiner(s): TARAZANO, DONALD LAWRENCE
• Application Number:
  US09/630,195
• Time in Patent Office: 854 Days
• Field of Search: 428/515, 428/516, 428/523, 428/36.91, 428/461, 424/411, 424/412, 138/141, 138/146, 138/DIG.6
• US Class Current: 428/36.91
• CPC Class Codes: A01N 25/34 Shaped forms, e.g. sheets, not provided for in any other sub-group of this main group
• CPC Class Codes: F16L 58/1054 the coating being placed outside the pipe
• CPC Class Codes: F16L 58/109 the coating being an extruded layer
• CPC Class Codes: Y10T 428/1393 Multilayer [continuous layer]
• CPC Class Codes: Y10T 428/31692 Next to addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31909 Next to second addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31913 Monoolefin polymer
• CPC Class Codes: Y10T 428/31938 Polymer of monoethylenically unsaturated hydrocarbon

Abstract

An improved anti-corrosive material used to protect buried conduits from corrosion. The anti-corrosive material is comprised of a conduit contacting layer of polyolefin having the anti-corrosive agents impregnated therein. The preferred embodiment of the material is a multi-layered co-extruded, calendered, or laminated polyolefin. The material has an outer layer, or environment contacting layer, preferably comprised of a low density polyethylene having characteristically strong tensile strength and elongation properties to provide conventional protection from soil, water, air, or other potentially damaging elements. The material has a center layer preferably comprised of a high density polyethylene having superior tensile strength to provide a high density barrier between the outer layer and an inner layer. The inner layer, or conduit contacting layer, is preferably comprised of a low density polyethylene impregnated with one or more antimicrobial additives. The antimicrobial additives are incorporated into and dispersed throughout the conduit contacting layer for killing corrosion-inducing bacteria on the surface of the conduit. The antimicrobial additives are able to migrate through the low density polymer matrix but the rate of migration of the biocide is considerably slowed through the high density polymer. Thus, the antimicrobial agents are substantially prevented from escaping into the surrounding environment, but rather, are trapped within a “protection zone” immediately adjacent the conduit surface to provide extended protection against corrosion.

Claims

1. An apparatus for carrying fluids, comprising:

a conduit comprising a material selected from the group consisting of metal, and concrete with metal reinforcements;

a polyolefin film comprising an anti-corrosive film layer in abutment with a surface of said conduit, said anti-corrosive film layer having an antimicrobial additive incorporated into and dispersed throughout said anti-corrosive film layer for killing corrosion-inducing bacteria on the surface of said conduit, said antimicrobial additive being selected from the group consisting of bromonitropropanediol, 2,4,4′

-trichloro-2′

-hydroxy diphenyl ether, and diiodomethyl-p-tolyl sulfone.

2. The apparatus described in claim 1 wherein said polyolefin film further comprises a barrier film layer having a permeability resistant to migration of said antimicrobial additive therethrough adjacent said anti-corrosive layer to maintain said antimicrobial additive in an anti-corrosion zone comprising said anti-corrosive layer and the surface of said conduit.

3. The apparatus described in claim 2 wherein said polyolefin film further comprises an outer protective film layer adjacent said barrier film layer.

4. The apparatus described in claim 1, 2 or 3 wherein said antimicrobial additive is between 0.01% to 10.0% by weight of said anti-corrosive layer.

5. The apparatus described in claim 1, 2 or 3 wherein said anti-corrosive layer comprises a material selected from the group consisting of low density, medium density, and high density polyethylenes.

6. The apparatus described in claim 1, 2 or 3 wherein said barrier layer comprises a material selected from the group consisting of low density, medium density, and high density polyethylenes.

7. The apparatus described in claim 3 wherein said outer layer comprises a material selected from the group consisting of low density, medium density, and high density polyethylenes.