US4298416A — Protection of substrates against corrosion

Claim 1

Independent Claim 220 words

In a method of imparting improved corrosion resistance to a substrate which is susceptible to corrosion by action of a corrosive chemical containing and gas containing medium, with which said substrate comes into contact, wherein said substrate is coated with an elastomeric material of a known gas permeability, and which is resistant to the corrosive action of said corrosive chemical containing and gas containing medium and which coating prevents said corrosive medium from reaching said substrate and wherein said coating may suffer loss of adhesion caused by gas build-up between said coating and said substrate the improvement which comprises providing means for escape of said gases carrying gas build-up from between said coating and the supporting substrate, said means for escape of gases including a porous backing material upon which said elastomeric coating is deposited, said backing material being adhesively secured to said substrate and serving to prevent a build-up of said gases between said coating and said substrate which would tend to dislodge the coating from the substrate, and thereby maintaining the adhesive of the coating to the substrate, said elastomeric coating having a suitable viscosity during application to said porous backing material so that the rate of escape of gases through the porous backing will be substantially greater than the rate of permeation of gases through the coating.

Claim 2

Dependent Claim 220 words

In a method of imparting improved corrosion resistance to a substrate which is susceptible to corrosion by action of a corrosive chemical containing and gas containing medium, with which said substrate comes into contact, wherein said substrate is coated with an elastomeric material of a known gas permeability, and which is resistant to the corrosive action of said corrosive chemical containing and gas containing medium and which coating prevents said corrosive medium from reaching said substrate and wherein said coating may suffer loss of adhesion caused by gas build-up between said coating and said substrate the improvement which comprises providing means for escape of said gases carrying gas build-up from between said coating and the supporting substrate, said means for escape of gases including a porous backing material upon which said elastomeric coating is deposited, said backing material being adhesively secured to said substrate and serving to prevent a build-up of said gases between said coating and said substrate which would tend to dislodge the coating from the substrate, and thereby maintaining the adhesive of the coating to the substrate, said elastomeric coating having a suitable viscosity during application to said porous backing material so that the rate of escape of gases through the porous backing will be substantially greater than the rate of permeation of gases through the coating.

Claim 3

Dependent Claim 25 words

A method according to claim 1 wherein the substrate comprises metal parts which may be cathodic to corrosive liquids, and generate gas at their surface.

Claim 4

Dependent Claim 15 words

A method according to claim 1 wherein said porous backing material is a textile material.

Claim 5

Dependent Claim 15 words

A method according to claim 1, wherein said porous backing material is woven glass cloth.

Claim 6

Dependent Claim 46 words

A method according to claim 4 wherein said elastomeric coating is applied to a woven glass cloth backing which is in turn applied to the solvent-dissolved surface of a PVC substrate, said backing adhering to the PVC substrate upon removal of the solvent from said surface.

Claim 7

Dependent Claim 20 words

A method according to claim 5 wherein the thickness of elastomeric coating is in the range of 1/16" to 1/8".

Claim 8

Dependent Claim 28 words

A method according to claim 6 wherein a PVC substrate is cleaned with xylol and then primed with a silanecontaining primer before application of said elastomeric coating thereto.

Claim 9

Independent Claim 204 words

A method of imparting improved corrosion resistance to a substrate which is susceptible to corrosion by action of a corrosive chemical and gas-containing medium or by a corrosive chemical and gas-generating medium with which said substrate comes into contact, said method comprising: applying an elastomer coating to a porous backing material, said elastomer being of a known gas permeability, and being resistant to the corrosive action of said corrosive medium, the elastomer having a suitable viscosity during application to said porous material to enable said elastomer to penetrate into the porous backing in a controlled manner, so that the rate of escape of gases through the porous backing will be substantially greater than the rate of permeation of gases through the coating, and adhesively securing said backing material to said substrate, said coating thereby preventing said corrosive medium from reaching the substrate, and said porous backing material providing means for escape of gases permeating said coating, from between said coating and the supporting substrate, said means for escape of gases serving to prevent a build-up of gases between said coating and said substrate which would tend to dislodge the coating from the substrate, whereby the adhesion of said coating to said substrate is maintained.

Claim 10

Independent Claim 204 words

A method of imparting improved corrosion resistance to a substrate which is susceptible to corrosion by action of a corrosive chemical and gas-containing medium or by a corrosive chemical and gas-generating medium with which said substrate comes into contact, said method comprising: applying an elastomer coating to a porous backing material, said elastomer being of a known gas permeability, and being resistant to the corrosive action of said corrosive medium, the elastomer having a suitable viscosity during application to said porous material to enable said elastomer to penetrate into the porous backing in a controlled manner, so that the rate of escape of gases through the porous backing will be substantially greater than the rate of permeation of gases through the coating, and adhesively securing said backing material to said substrate, said coating thereby preventing said corrosive medium from reaching the substrate, and said porous backing material providing means for escape of gases permeating said coating, from between said coating and the supporting substrate, said means for escape of gases serving to prevent a build-up of gases between said coating and said substrate which would tend to dislodge the coating from the substrate, whereby the adhesion of said coating to said substrate is maintained.

Claim 11

Dependent Claim 25 words

A method according to claim 1 wherein the substrate comprises metal parts which may be cathodic to corrosive liquids, and generate gas at their surface.

Claim 12

Independent Claim 136 words

A method of imparting to a substrate improved resistance to corrosion thereof by a corrosive chemical and gas-containing medium or by a corrosive chemical and gas-generating medium, which method comprises: (1) applying to a porous backing material an elastomeric coating having a permeability of at least 10 -4 ml/cm 2 hr. atm. at room temperature for oxygen and an uncured elastomer viscosity of 100-2000 poises, and (2) adhesively securing said porous backing to said substrate; said porous backing providing means for escape of gases permeating said coating, from between said coating and the supporting substrate, said means for escape of gases serving to prevent a build up of gases between said coating and said substrate which would tend to dislodge the coating from the substrate, whereby the adhesion of said coating to said substrate is maintained.

Claim 13

Independent Claim 136 words

A method of imparting to a substrate improved resistance to corrosion thereof by a corrosive chemical and gas-containing medium or by a corrosive chemical and gas-generating medium, which method comprises: (1) applying to a porous backing material an elastomeric coating having a permeability of at least 10 -4 ml/cm 2 hr. atm. at room temperature for oxygen and an uncured elastomer viscosity of 100-2000 poises, and (2) adhesively securing said porous backing to said substrate; said porous backing providing means for escape of gases permeating said coating, from between said coating and the supporting substrate, said means for escape of gases serving to prevent a build up of gases between said coating and said substrate which would tend to dislodge the coating from the substrate, whereby the adhesion of said coating to said substrate is maintained.

Claim 14

Dependent Claim 136 words

A method as in claim 10 wherein said elastomeric coating is applied to said porous backing material in a controlled way so that the backing material is held mechanically by the coating and yet its porous body is substantially free from coating material so that 70 to 97% of the pores of the backing material remain open, to thereby form a laminate which is then adhered to said substrate by adhesive bonding means, said adhesive bonding means having a viscosity in the range of 1 to 200 poise and filling the remaining open pores of said porous backing material which are not filled with said elastomeric coating so that 10 to 50% of the open pores remaining in said porous backing material of said laminate remain open to the atmosphere after the elastomer has been applied.

Claim 15

Dependent Claim 75 words

A method as in claim 10 wherein said elastomer coating which is applied to a porous substrate is selected from the group consisting of: (a) RTV (room temperature vulcanizing) polysiloxane adhesive adhesive sealants utilizing an acetoxy cure system, and incorporating a filler and an acyloxy silane; (b) RTV silicone rubber made with a tin-catalyzed condensation cure system, said silicone rubber comprising a silicone polymer, a cross-linking agent and a filler material; and (c) fluorocarbon elastomers.

Claim 16

Dependent Claim 13 words

A method as in claim 12 wherein the porous substrate is porous brick.

Claim 17

Dependent Claim 19 words

A method as in claim 10 wherein the escape of gases is further provided for by perforating said substrate.

Claim 18

Dependent Claim 12 words

A method according to claim 10 wherein said substrate is of metal.

Claim 19

Dependent Claim 19 words

A method according to claim 10 wherein said substrate is a metal electrical conductor submerged in a corrosive electrolyte.

Claim 20

Dependent Claim 246 words

A resealable pressure relief valve capable of relieving the excessive build-up of internal pressure within the closed container of an energy cell by venting gas from within the container to the atmosphere and resealing the container after venting, said valve comprising: an outer cover plate; an inner base plate joined to the outer cover plate, a central cavity being formed therebetween; and a compressed, resilient, elastomeric member interposed in the cavity between said plates whereby said elastomeric member is positioned to overlie a vent orifice located in the inner base plate, said elastomeric member being compressed to a degree whereby the elastomeric member forms an air-tight seal over the vent orifice when the internal container pressure is less than a predetermined limit, the shape of the elastomeric member being such that the stress-strain curve of the compressed elastomeric member with respect to the sealing forces over said vent orifice exhibits a relatively flat region; whereby said elastomeric member is capable of becoming deformed or distorted with respect to the inner base plate and breaking its seal over the vent orifice when the internal container pressure exceeds a predetermined limit for the container, said break in the seal over the vent orifice in the inner plate forming a passageway for gases to exit from the interior of the container to the atmosphere, and whereby the elastomeric member has sufficient memory to reseal the vent orifice, when the internal pressure of the container falls below the predetermined limit.

Claim 21

Dependent Claim 246 words

A resealable pressure relief valve capable of relieving the excessive build-up of internal pressure within the closed container of an energy cell by venting gas from within the container to the atmosphere and resealing the container after venting, said valve comprising: an outer cover plate; an inner base plate joined to the outer cover plate, a central cavity being formed therebetween; and a compressed, resilient, elastomeric member interposed in the cavity between said plates whereby said elastomeric member is positioned to overlie a vent orifice located in the inner base plate, said elastomeric member being compressed to a degree whereby the elastomeric member forms an air-tight seal over the vent orifice when the internal container pressure is less than a predetermined limit, the shape of the elastomeric member being such that the stress-strain curve of the compressed elastomeric member with respect to the sealing forces over said vent orifice exhibits a relatively flat region; whereby said elastomeric member is capable of becoming deformed or distorted with respect to the inner base plate and breaking its seal over the vent orifice when the internal container pressure exceeds a predetermined limit for the container, said break in the seal over the vent orifice in the inner plate forming a passageway for gases to exit from the interior of the container to the atmosphere, and whereby the elastomeric member has sufficient memory to reseal the vent orifice, when the internal pressure of the container falls below the predetermined limit.

Claim 22

Dependent Claim 15 words

A method according to claim 10 wherein said substrate is of fiberglass reinforced polyester (FRP).

Claim 23

Dependent Claim 26 words

A method according to claim 10 wherein an RTV silicone rubber of category (a) is employed as the silicone rubber which is applied to said substrate.

Claim 24

Dependent Claim 26 words

A method according to claim 10 wherein an RTV silicone rubber of category (b) is employed as the silicone rubber which is applied to said substrate.

Claim 25

Dependent Claim 18 words

A method according to claim 10 wherein a fluorocarbon elastomer of category (c) is applied to said substrate.

Claim 26

Dependent Claim 20 words

A method according to claim 10 wherein the elastomeric coating has a thickness ranging from about 0.002" to about 0.5".

Claim 27

Dependent Claim 24 words

A method according to claim 10 wherein said substrate is cleaned by use of an organic solvent before application of the elastomeric coating thereto.

Claim 28

Dependent Claim 23 words

A method according to claim 10 wherein a silane in solvent primer is applied to the substrate before application of said elastomeric coating

Claim 29

Dependent Claim 50 words

A method according to claim 10 wherein the elastomeric coating is applied to a substrate comprising walls of vessels or surfaces of equipment, valves, fitting piping and the like, for use in producing and handling corrosive chemicals or food products in liquid, mixed phase or gaseous form, or by-products thereof.

Claim 30

Dependent Claim 20 words

A method according to claim 25 wherein the substrate comprises apparatus for carrying out the electrolysis of alkali metal halides.

Claim 31

Dependent Claim 27 words

A method according to claim 25 wherein the substrate comprises apparatus for the electrolysis of sodium chloride, or for the handling of electrolysis products of sodium chloride.

Claim 32

Dependent Claim 31 words

A method according to claim 25 wherein the substrate comprises linings for gas and vapour ducting, piping and exhausters and fans and vessels in which corrosive liquors are entrained in gases.

Claim 33

Dependent Claim 29 words

A method according to claim 10 wherein the elastomeric coating is applied to the porous backing by a technique selected from the following: airless spraying, trowelling, painting and coating.

Claim 34

Dependent Claim 25 words

A method according to claim 10 wherein the substrate comprises metal parts which may be cathodic to corrosive liquids, and generate gas at their surface.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1984-11-02	1985-05-04	1985-11-03	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1988-11-02	1989-05-04	1989-11-03	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1992-11-02	1993-05-04	1993-11-03	$7700.00	Window Closed / Lapsed

Protection of substrates against corrosion

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