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Title:
A SCENT RELEASING CORROSION OR CORROSIVE ENVIRONMENT INDICATING COATING SYSTEM, A METAL STRUCTURE WITH THE SYSTEM AND A METHOD FOR DETECTING CORROSION
Document Type and Number:
WIPO Patent Application WO/2017/179990
Kind Code:
A1
Abstract:
The present invention relates to a corrosion or corrosive environment indicating coating system. The coating system includes a curing or setting binder or matrix, and a corrosive environment or corrosion indicating scent releasing material. The scent releasing material develops or releases a scent substance upon exposure to the corrosion indicating fluid or the corrosive environment, dispersed in said curing or setting binder or matrix.

Inventors:
OEN EIVIND ROBERT (NO)
Application Number:
PCT/NO2017/050084
Publication Date:
October 19, 2017
Filing Date:
April 07, 2017
Export Citation:
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Assignee:
OCEANEERING ASSET INTEGRITY - LCI (NO)
International Classes:
C09D5/08; C09D7/12
Domestic Patent References:
WO2013009873A22013-01-17
WO2009126802A12009-10-15
Foreign References:
RU2020363C11994-09-30
EP1854850A12007-11-14
Other References:
SCHOON, A. ET AL.: "Using dogs to detect hidden corrosion", APPLIED ANIMAL BEHAVIOUR SCIENCE, vol. 153, 2014, pages 43 - 52, XP055432629, Retrieved from the Internet
Attorney, Agent or Firm:
BRYN AARFLOT AS (NO)
Download PDF:
Claims:
Claims

1 . A corrosion or corrosive environment indicating coating system comprising a curing or setting binder or matrix; and

a corrosive environment or corrosion indicating scent releasing material, developing or releasing a scent substance upon exposure to said corrosion, corrosion indicating fluid or corrosive environment, dispersed in said curing or setting binder or matrix.

2. The coating system of claim 1 , further including a corrosion inhibiting composition.

3. The coating system of claim 1 or 2, wherein the binder is an epoxy resin binder.

4. The coating system of any of the preceding claims wherein the corrosive environment or corrosion indicating scent developing material includes scent substance filled micro beads with micro bead walls, suspended in said binder, and whereupon said micro bead walls rupture upon contact with said corrosive environment or corrosion indicating fluid, releasing said scent substance.

5. The coating system of any of the preceding claims wherein the scent substance includes at least one halogenated compound.

6. The coating system claim 5 wherein the at least one halogenated compound includes one of chlorinated alkanes and fluorinated chemicals or a combination thereof.

7. The coating system of claim 5, wherein the chlorinated alkanes include 1 - chlorotetradecane or 1 ,2-dichlorotetradecane, or a combination thereof.

8. The coating system of claim 5, wherein the fluorinated chemicals are selected from the group 1 -(perfluoro-n-hexyl)decane, 1 -(perfluoro-n-hexyl)-dodecane, and 1 -(perfluoro-n-hexyl)tetradecane.

9. The coating system of one of claims 1 -4 wherein the corrosive environment or corrosion indicating fluid sensitive scent developing material is a substance reacting chemically with said corrosive environment or corrosion indicating liquid to produce the scent substance.

10. A metal structure including a corrosive environment indicating coating system comprising a curing or setting binder or matrix, and a corrosive

environment or corrosion indicating fluid sensitive scent material, developing or releasing a scent substance upon exposure to said corrosive environment or corrosion, applied onto a metal surface of the metal structure; and

a layer of sealing paint applied to said layer of corrosive environment indicating coating system.

wherein the corrosive environment or corrosion indicating scent developing material includes scent substance filled micro beads with micro bead walls, suspended in said binder, and whereupon said micro bead walls rupture upon contact with said corrosive environment or corrosion indicating fluid, releasing said scent substance.

1 1 . A metal structure of claim 10, wherein the scent substance includes at least one halogenated compound.

12. A metal structure of claim 1 1 wherein the at least one halogenated compound includes one of chlorinated alkanes and fluorinated chemicals or a combination thereof.

13. A metal structure of claim 12, wherein the chlorinated alkanes include 1 - chlorotetradecane or 1 ,2-dichlorotetradecane, or a combination thereof.

14. A metal structure of claim 12, wherein the fluorinated chemicals are selected from the group 1 -(perfluoro-n-hexyl)decane, 1 -(perfluoro-n-hexyl)-dodecane, and 1 -(perfluoro-n-hexyl)tetradecane. , 15. A method for detecting the presence of corrosion on a metal structure including applying at least a corrosive environment indicating coating system of any of claims 1 -3 onto the metal structure;

covering the metal structure with covering elements;

exposing the coated and covered metal structure to a corrosive environment; providing scent samples from the coated and covered structure;

installing the scent samples in a scent sample rack; and

exposing said scent samples to a trained dog or a sniffing sensor.

Description:
A scent releasing corrosion or corrosive environment indicating coating system, a metal structure with the system and a method for detecting corrosion

The present invention relates to a coating system such as a primer for monitoring the occurrence of specific substances, in particular corrosion or corrosion products or corrosive substances. The coating system of the invention releases a specific scent upon contact with the above suggested substances.

Corrosion protection and monitoring is an important labor and cost intensive task frequently performed on all sorts of mechanical structures. Offshore structures are particularly exposed to corrosive environments, and failures of such structures are potentially catastrophic.

From WO2013009873 it is known methods to produce pH-sensitive microparticles that have an active agent dispersed in a polymer matrix have certain advantages over microcapsules with an active agent encapsulated in an interior

compartment/core inside of a polymer wall. WO2013009873 relates to pH- sensitive microparticles that have a corrosion-detecting or corrosion-inhibiting active agent or active agents dispersed within a polymer matrix of the

microparticles. The pH-sensitive microparticles can be used in various coating compositions on metal objects for corrosion detecting and/or inhibiting. The corrosion indicators can be color or fluorescence indicators, which indicate corrosion through color change or change of their fluorescent properties. The corrosion indicators can be chosen to detect pH or ion concentration changes as a result of the corrosion process.

Pipes, process equipment and other components on offshore or onshore structures are often covered with insulating materials, cladding or are of other reasons impossible to inspect visually without removing the covering with the possible consequence of taking the structure out of service. Visual inspection through small openings in the cover will not provide a reliable indication for an entire structure. An insulated pipe system used in connection with production of hydrocarbons is a typical system that can be monitored according to the present invention.

It is the purpose of the present invention to provide a coating system and a method involving said coating system for detecting corrosion or a potentially corrosion inducing situation at the onset, before the corrosion has become a major problem.

Furthermore it is an object of the present invention to monitor or indicate corrosion on structures that are difficult to inspect. Such structures will typically include insulated or otherwise covered structures that not easily can be monitored by visual inspection without substantial disassembly, downtime of components, restructure work etc.

Furthermore it is an object of the invention to monitor or indicate corrosion on structures without the use of electricity, wired systems, or visual detection through optical sensors or direct visual inspection.

It is known to use trained dogs to smell and indicate the occurrence of specific substances, and dogs have been trained to smell rust. It is however easier for a dog to smell substances or tracers with a specific scent that can be used for a plurality of purposes, for instance for scented explosives. The present invention could provide a coating system that will allow dogs trained for indicating specific substances to also indicate the occurrence of corrosion, corrosion products or corrosive substances. It is also a purpose of the present invention to facilitate the indication for the dog or a detector and to reduce the risk of false detection.

Indicating the scent of rust or other types of corrosion directly may also create difficulties if for some reason steel or other metal parts inadvertently have been included inside a covered structure.

It is a purpose of the present invention to provide a method of indicating the integrity or sealing ability of a corrosion inhibiting top coat preventing the coating system of the invention from being exposed to liquids such as water, in particular saline water.

Accordingly, the present invention relates to a coating system for application directly onto a metal surface, or for application onto a different coating. The coating system should also allow a top coat to be applied on top of the coating system. Accordingly, the coating system of the invention includes a scent substance or tracer that releases a scent/smell/odour upon contact with the substance to be indicated and a binder that will set after application of the coating system on an object to be monitored. The coating system in itself may have corrosion inhibiting properties.

The substance to be indicated may include pure water, saline water, Fe(aq), an alkaline solution etc.

The scent substance or tracer may be enclosed in micro capsules or

microcapsules with a shell that dissolves upon contact with the substance to be indicated. WO2013009873 discloses such microcapsules. Alternatively, may the substance to be indicated initiate a chemical reaction with the scent substance that produces the scent.

The scent substance or tracer could satisfy several requirements:

A dog or instruments should be able to detect it;

It should be of medium volatility as it will disappear to quickly if it is too volatile unless it can be released gradually, and as it not easily can be detected if it not is volatile enough;

It could be a-polar, so it does not have the tendency to stick to the insulation material or anything else while still being possible to collect air samples;

It could be different from the chemicals produced or handled in the environment of the structure typically in oil and gas plants to prevent contamination issues; It should remain stable, not react to other chemicals, water, heat, and other environmental factors on oil and gas plants/platforms, so that the instrument/dog has a fair chance of detecting it.

According to the present invention

Appropriate chemicals should fulfill the following demands:

1 ) Do not occur in nature or in crude oil and gas processing

2) Have very little water solubility

3) Are semivolatile (saturated vapor pressure roughly in the range of 0.01 to 0.1 Pa)

4) Are stable against any kind of reaction up to 150° C

5) Are ideally already in commercial use and have gone through the process of registration under the EU chemical legislation (REACH) and are affordable.

The conditions 1 , 2, and 4 can be met by chlorinated and/or fluorinated hydrocarbons. Chlorinated and fluorinated aromatic chemicals are not further considered here, because they tend to be very toxic. This leaves chlorinated and fluorinated alkanes. The desired saturated vapor pressure can be achieved by selecting an appropriate chain length and degree of halogenation.

Chemicals with iodine or bromine have not been considered because organic chemicals with these halogens can occur naturally in an ocean-environment.

Specific embodiments for use with the invention:

Chlorinated alkanes:

1 -chlorotetradecane ( CAS 2425-54-9) C14H29CI, estimated water solubility of 0.01 mg/L and estimated vapor pressure of 0.09 Pa; both values at 25°C, this chemical is a liquid at room temperature. 1 ,2-dichlorotetradecane (CAS 701920-83-4) C14H28CI2, estimated water solubility of 0.005 mg/L and estimated vapor pressure of 0.04 Pa; both values at 25°C, this chemical is a solid at room temperature.

Both chemicals are available. Both chemicals are toxic to a certain extent.

In general, all alkanes with 13 to 15 carbon atoms and one or two chlorines in any position should fulfill the requirements 1 , 2, 3 and 4. Chlorinated alkanes with less carbon atoms and more chlorines than those named here would also fulfill requirements 1 -4. Not all of these chemicals can be listed here because their number is huge.

Fluorinated chemicals:

(The following chemicals ( and other representatives of the same family) are used in Ski-Wax. In total they make up up to 15 % of a typical wax.)

The estimated water solubility of these chemicals range from 0.002 mg/L for 1 - perfluorohexyloctane to 0.0000001 mg/L for 1 -perfluorohexyltetradecane and the estimated vapor pressure ranges from 1 Pa for 1 -perfluorohexyloctane to 0.1 Pa for 1 -perfluorohexyldecaneane, to 0.01 Pa for perfluorohexyldodecane to 0.001 Pa for 1 -perfluorohexyltetradecane.

1 -perfluorohexyloctane is likely to be too volatile for the desired purpose but the other three chemical fulfill the requirements in an almost perfect way. These chemicals are less toxic than the chlorinated chemicals and they will sorb to a much lesser extend to the mineral fibers that are used as insulation material.

In an embodiment of the invention it is suggested to use a mixture of 1 -(perfluoro- n-hexyl)decane, 1 -(perfluoro-n-hexyl)-dodecane, and 1 -(perfluoro-n- hexyl)tetradecane. These chemicals are extremely stable, have an extremely low water solubility, are likely non-toxic, have the smallest sorption to mineral fibers compared to other chemicals of similar vapor pressure and water solubility and are in commercial use. If the volatility of the suggested chemicals not are in a suitable range for the detection by dogs or instrumental analysis then analogue chemicals of the same class with either longer or shorter alkyl chain length should be selected.

A dog may indicate on the structure to be detected directly, or may be indicating on smell /scent samples taken from the structure. The smell/scent sample may include a liquid sample wiped or otherwise collected from the structure. The sample may alternatively include a pad having received air or gas blown over the structure, (typically hot air).

Alternatively, may the scent or tracer be detected by suitable detectors, and the scent substance may be particularly designed for being detected by such a detector.

In the following description is "smell developing material" meant to indicate the material that is added into the coating system, and "smell substance" or "tracer" is intended to mean the actual substance the dog or sensor reacts to. The scent developing material may for instance include micro beads and the scent substance is then the material inside the beads. The scent developing material may alternatively be a substance reacting chemically with for instance water or water with Fe Ions and the product of the chemical reaction is then the scent substance.

Accordingly, the present invention includes a corrosive environment indicating coating system comprising a curing or setting binder or matrix and a corrosive environment or corrosion indicating, scent developing material. The corrosion indicating scent developing material is a material developing or releasing a scent substance upon exposure to the corrosive environment, upon exposure to corrosion or to a corrosion indicating fluid. The scent substance may be

considered as a tracer. The corrosion indicating scent developing material is dispersed in/mixed with said curing or setting binder.

The coating system may further include a corrosion inhibiting composition.

The binder may be an epoxy resin binder.

The corrosive environment or corrosion indicating scent developing material may be contained in micro beads with micro bead walls, suspended in the binder. The micro bead walls rupture upon contact with the corrosive environment or the corrosion indicating liquid.

The scent substance may include at least one halogenated compound.

The at least one halogenated compound may include one of chlorinated alkanes and fluorinated chemicals or a combination thereof.

The chlorinated alkanes may include include 1 -chlorotetradecane or 1 ,2- dichlorotetradecane, or a combination thereof. The fluorinated chemicals may be selected from the group 1 -(perfluoro-n- hexyl)decane, 1 -(perfluoro-n-hexyl)-dodecane, and 1 -(perfluoro-n- hexyl)tetradecane.

The corrosive environment or corrosion indicating fluid sensitive scent developing material may be a material reacting chemically with the corrosive environment or the corrosion indicating fluid to produce the scent substance.

The invention furthermore relates to a metal structure including corrosion or a corrosive environment indicating coating system comprising a curing or setting binder or matrix, and a corrosion or corrosive environment indicating scent developing material, developing or releasing the scent substance upon exposure to the corrosive environment or corrosion indicating fluid applied directly onto a metal surface of the metal structure.

The scent substance may be one of the scent substances mentioned above.

A layer of sealing paint may be applied to the layer of the corrosive environment indicating coating system.

Furthermore, the invention relates to a method for detecting or controlling the presence of corrosion on a metal structure. The method includes applying at least a corrosive environment indicating coating system as defined above onto the metal structure, coating and covering the metal structure with required covering elements, exposing the coated and covered metal structure to a corrosive environment, providing scent samples from the coated and covered structure, installing the scent samples in a scent sample rack, and exposing the scent samples to a trained dog or a sniffing sensor.

The required elements covering the metal structure will typically include various corrosion preventing paints, insulating materials and metal cladding structures. The scent developing material could also develop a scent substance upon contact with bare metal such as bare steel. Coatings with different scent substances can be utilized to separate different areas of a structure. For instance can a specific scent substance be used for particularly critical components whereas a different scent substance is used on less critical components. Similarly, different coatings can be used on top of each other to indicate the thickness of a coating or if a coating layer is worn away.