AU592420B2

AU592420B2 - Anti-corrosion composition

Info

Publication number: AU592420B2
Application number: AU71165/87A
Authority: AU
Inventors: Philip Albert Attwood; Douglas Miller; Stephen Paetke
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1986-04-09
Filing date: 1987-04-07
Publication date: 1990-01-11
Anticipated expiration: 2007-04-07
Also published as: IT8720012A0; IT1203871B; AU7116587A; GB2189501B; NO871463L; GB8608656D0; GB8708272D0; FR2597117B1; FR2597117A1; DE3711611A1; GB2189501A; NO871463D0; NL8700821A

Description

r FORM 10 592420 SPRUSON FERGUSON COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: y//1,5 Class Int. Class Complete Specification Lodged: c, Accepted: t 4 44 4l P o F4 Published: Priority: Related Art: This document contains the amendments made unud-r Section 49 and is Lorrect i or printing.

Name of Applicant: Address of Applicant: Actual Inventor(s): Address for Service: SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ

B.V.

Carel van Bylandtlaan 30, 2596 HR The Hague, the Netherlands PHILIP ALBERT ATTWOOD, DOUGLAS MILLER and STEPHEN PAETKE Spruson Ferguson, Patent Attorneys, Level 33 St Martins Tower, 31 Market Street, Sydney, New South Wales, 2000, Australia ar i" r: k Complete Specification for the invention entitled: "ANTI-CORROSION COMPOSITION" The following statement is a full description of this invention, including the best method of performing it known to us SBR/JS/0199F ii i 1! II

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ABSTRACT

ANTI-CORROSION COMPOSITION Anti-corrosion composition conntaining from 60 to 98%w of a liquid hydrocarbon filling material, from 1 to 30%w of a corrosion inhibitor and 5 from 1 to 10%w of a gelling agent which 60 to 600 minutes after mixing of the composition gives the composition a viscosity of at least 650cSt. at all weight percentages being based on the total of the filling material, corrosion inhibitor and gelling agent, in particular suitable for use in pipe connectors.

0 00 0000 0 0 o 0 Oo0 0000 0 0 0. 0 0000 0 0000 0 0 0000 0 0 a t I ii1 r TMR/591y la ANTI-CORROSION COMPOSITION The present invention relates to an anti-corrosion composition and to the use thereof in pipe connectors.

Offshore production of oil and gas have become very important. It gave rise to several problems. One of these problems is related to the fact that pipes such as pipelines, risers, drilling rods etc., are in continuous contact with sea water. Sea water tends to form a very corrosive environment. Especially in the places where parts of a pipe are connected together (connectors), the corrosion appears to be rather severe. Due to the corrosion the strength of the pipe is decreased tremendously so that there is a risk of a rupture of the pipe. To avoid o this risk expensive repair of the pipe or replacement of the connector is 0 necesseary in a relatively short period of time.

o So, there is a great need of a good anti-corrosion means for such connectors. Conventional greases, irrespective of whether or not they co contain a corrosion inhibitor were not satisfactory. In conventional pipe connectors having screw threads the grease is removed by assembling the parts of the connectors. In more sophisticated connector systems, e.g. as described in U.K. patent specifications Nos. 1,573,945 and 2,064,041 it is very difficult to apply an anti-corrosion composition between the male and 0 female parts of the connector.

000.The present invention overcomes the above problems. It relates to an anti-corrosion composition containing from 60 to 98%w of a liquid hydrocarbon filling material, from 1 to 30%w of a corrosion inhibitor and from 1 to 10%w of a gelling agent which 60 to 600 minutes after mixing of the composition gives the composition a viscosity of at least 650cSt. at 0 C, all weight percentages being based on the total of the filling niaterial, corrosion inhibitor and gelling agent.

The anti-corrosion composition is prepared by mixing the hydrocarbon filling material, the gelling agent and the corrosion inhibitor, yielding a low-viscous mixture which can easily be pumped to and/or applied on the desired surfaces. After a while the gelling agent causes a viscosity incease of the composition. The desired viscosity is obtained after 60 to 600 min after mixing of the components.

The liquid filling material should not be corrosive in itself.

Moreover, for the sake of safe handling, it should not be easily 2 ignitable. Therefore, the filling material is preferably hydrocarbon having an initial boiling point of at least 80 0 C. It can be selected from a wide range of hydrocarbons; specific alkanes or alkylarenes such as alkylbenzene, -toluene or -xylene are feasible. From an economic point of view the hydrocarbon filling material is preferably a gas oil, which includes diesel oil and heavier fuel oils.

Many corrosion inhibitors can be used in the composition according to the invention. Suitably they are very effective so that they can counteract the corrosive action of sea-water environments. Preferred are S corrosion inhibitors selected from salts of fatty acids and alkanol- and/or o o alkylamines.

So'o The gelling agents used needs to be able to yield the required viscosity. If the viscosity would be lower there might be a chance that S the composition can be flushed away from the surface it is to protect. If desired, the amount of gelling agent can be adjusted to yield a composition having the required viscosity. Very suitable gelling agents are selected from organic phosphates, in particular from C 1 15 alkyl phosphates.

1 i| f tr -3- The caposition according to the invention contains the components in the amounts as described above. Preferably, the composition contains from 65 to 85%w of the filling material, A from 5 to 25%w of the corrosion inhibitor and from 1 to 3%w of the gelling agent. If desired, it may also contain a catalyst which influences the gelation. Suitable catalysts include alkali metal aluminates, whether or not in combination with hydroxides. The amount thereof is conveniently from 5 to based on the gelling agent.

The present invention also relates to a use of the anti-corrosion composition in a pipe connector comprising a tubular pin member and a tubular box member, the inner surface of which substantially corresponds with the outer surface of the pin member, each surface being provided with interengageable 15 projection and groove means.

i The invention further relates to a method for applying the anti-corrosion composition between the pin member and the box member of a pipe connector, in which method the filling material, the gelling agent and the corrosion inhibitor are 20 mixed, the mixture is pumped under pressure through a port in I the box member to cause expansion of the box member and/or :i contraction of the pin member, thereby creating a space between the members which is filled with the mixture, and allowing the mixture between the members to obtain an increased viscosity of at least 650 cSt at 25 0 C. The fluid may be depressurized before or after the gelation of the mixture; preferably it is done before gelation.

The invention will be elucidated with reference to the Sdrawings. Fig. 1 is a part axial section, part elevation, of a pipe connector showing a pin and box member fully interengaged.

Fig. 2 is a part axial section showing part of the pipe connector in greater detail.

As shown in Figures 1 and 2, the pipe connector comprises a tubular pin member 1 for connection, e.g. by welding, to the end of a pipe 2, and a tubular box member 3 for connection, e.g. by welding to the end of a pipe 4 to be connected to pipe 2. The BN39.001 4 pin and box members are telescopically engageable and have generally frusto-conical outer and inner peripheral surfaces 5,6 respectively which overlie one another when the pin member is fully telescoped into the box member, as shown in Figure 1. The members 1, 3 have radially extending surfaces 7, 8 at their free outer ends and, when fully telescoped together, one of the radially extending surfaces 7, 8 respectively abuts a radially extending surface 9 or 10 of a shoulder provided respectively at the inner end of the frusto-conical surface of the box and pin members, for the transmission of axially directed forces, for example pile-driving forces, between the members 1, 3. As shown the surface 8 of the box member and the surface 10 of the pin member are in abutment.

SThe generally frusto-conical peripheral surfaces 5,6 camprise frusto-conical end portions 11, 12 and 13, 14 respectively at the inner and outer ends of the frusto-conical surfaces and, intermediate these end portions, the surfaces are provided with interengageable projection and groove means 15 and I16.

A port 17 is provided in the box member 3 opening into the I' region provided with the projection and groove means for connection to a source of fluid under pressure.

To assemble the connector the box and pin member are moved axially together. Through the port 17 a fluid is supplied under pressure to expand the box member and/or contract the pin member so that the members can be moved further to get telescoped fully Stogether. The pressurized fluid, which generally is a hydraulic 1. fluid, is replaced by a composition according to the invention.

The low-viscous composition, obtained after mixing the components, is fed under pressure through the port 17 to get between the surfaces 5 and 6 and 8 and 10 of the members 1 and 3. The pressure is released and the port 17 is sealed with a plug. After a while the composition gets the required viscosity. Due to the high viscosity the composition will not BN39. 001 leak out of the connector but will show a long-lasting anti-corrosive action.

Example I In order to create stable anti-corrosion compositions according to the invention the following starting materials were used: 1) a hydrocarbon solvent, available under the trade name "Corexit 8811", based on a diesel oil, containing C 9

-C

30 o 00 00 0 000 0 0 00 0 0 0 0000 001000 o 0 103 lit 0 0 0.r

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hydrocarbons; 2) a corrosion inhibitor, available under the trade name "Corexit 8466", comprising a 73%w solution of fatty acid-alkanol/alkylamine salts in a mixture of an aromatic hydrocarbon and butoxyethanol; 3) a gelling agent comprising phosphate esters of ethanol, 15 octanol and decanol in an aromatic solvent, available under the trade name "J 292"; and 4) a catalyst being sodium aluminate and sodium hydroxide available under the trade name "J 242".

The following composition resulted in gels which had a viscosity above 750cSt at 25'C and which were stable after 9 months: Conposition Corexit 8811 Corexit 8466 J 292 J 242 1 65.6 30.0 4.0 0.4 2 81.7 15.0 3.0 0.3 3 80.6 15.0 4.0 0.4 Example II To show the excellent anti-corrosion behaviour metal specinens, coated with a 50 im thick film of composition 2 of Example 1 having a viscosity of 760 cSt at 25'C, were immersed in aerated sea water for 6 months. They remained corrosion-free. Fran impedance measurements carried out BN39.001

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1 1 1.

-6throughout the exposure period it was determined that the corrosion rate of the metal specimens is less than 0. 04nmn/year. Uncoated specimens showed a corrosion rate of l-2mm/year.

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Claims

1. Anti-corrosion composition containing from 60 to 98%w of a liquid hydrocarbon filling material, from 1 to 30%w of a corrosion inhibitor and from 1 to 10%w of a gelling agent which 60 to 600 minutes after mixing of the composition gives the composition a viscosity of at least 650cSt. at 25 0 C, all weight percentages being based on the total of the filling material, corrosion inhibitor and gelling agent.

2. Anti-corrosion composition according to claim 1, in which the filling material is a hydrocarbon having an initial boiling point of at least 80 0 C.

3. Anti-corrosion composition according to claim 2, in which the filling material is a gas oil.

4. Anti-corrosion composition according to any one of claims 1 to 3, in which the corrosion inhibitor is selected from salts of fatty acids and alkanol- and/or alkylamines. r

5. Anti-corrosion composition according to any one of claims 1-4, in which the gelling agent is selected from organic phosphates.

6. A method of inhibiting corrosion in a pipe connector using an anti-corrosion composition according to any one of claims 1 to 5, wherein said pipe connector comprises a tubular pin member and a tubular box member, the inner surface of which substantially corresponds with the outer surface of the pin member, each surface being provided with interengageable projection and groove means, the anti-corrosion composition being between said inner and outer surfaces.

7. Method for applying an anti-corrosion composition according to any one of claims 1-5, between a pin member and a box member of a pipe connector, in which method the filling material, the corrosion inhibitor and the gelling agent are mixed, the mixture is pumped under pressure through a port in the box member to cause expansion of the box member and/or contraction of the pin member, thereby creating a space between the members which is filled with the mixture, and allowing the mixture between the members to obtain an increased viscosity of at least 650 cSt at 25 0 C.

8. Anti-corrosion composition, substantially as hereinbefore described with reference to Example 1 and any one of Compositions 1 to 3. 0 C (N TMR/591y -8- DATED this FIFTH day of OCTOBER 1989 lit IIShell International Research Maatschappij BV Patent Attorneys for the Applicant SPRUSON FERGUSON 6 ~o TMR /591 y