FR2597117A1 - ANTI-CORROSION COMPOSITION - Google Patents

Abstract

THE INVENTION IS ABOUT ANTI-CORROSION COMPOSITIONS. ITS SUBJECT TO AN ANTI-CORROSION COMPOSITION CONTAINING 60 TO 98 BY WEIGHT OF A LIQUID HYDROCARBON FILLING MATERIAL, 1 TO 30 BY WEIGHT OF A CORROSION INHIBITOR AND 1 TO 10 BY WEIGHT OF A GELING AGENT WHICH OVER TIME GIVES THE COMPOSITION A VISCOSITY OF AT LEAST 650 CST AT 25C WITH ALL PERCENTAGES BY WEIGHT TAKEN FROM THE TOTAL OF FILLING MATERIAL, CORROSION INHIBITOR AND GELLING AGENT. USE OF THE COMPOSITION IN PIPING FITTINGS.

Description

The present invention relates to an anti-corrosion composition and its

  use in pipe fittings. Oil and gas production off the coast has become very important. It gave birth to several problems. One of these problems is related to the fact that pipelines such as pipelines, risers, drill pipes, etc., are in continuous contact with seawater. form a very corrosive environment. Especially where parts of a pipe are connected together (fittings), corrosion is quite severe. Due to corrosion, the mechanical strength of the pipe is drastically reduced, so that there is a risk of pipe breakage. To avoid this risk, costly pipe repair and fitting replacement operations are

a relatively short period.

  Thus, there is a great need for a good anti-corrosion means for such fittings. Conventional greases containing or not containing a corrosion inhibitor have not been satisfactory. In conventional fittings having threads, the grease is removed during assembly of the connector members. In more sophisticated fitting systems, for example as described in United Kingdom Patents Nos. 1,573,945 and 2,064,041, it is very difficult to apply an anti-corrosion composition between the male elements.

and female fitting.

  The present invention overcomes the above difficulties. It relates to an anti-corrosion composition containing from 60 to 98% by weight of a liquid hydrocarbon filler, from 1 to 30% by weight of a corrosion inhibitor and from 1 to 10% by weight of a gelling agent. Which over time gives the composition a viscosity d'of at least 650, preferably 750 cSt at 250 ° C, all percentages being based on the total of the filler, the corrosion inhibitor and the gelling agent. The anti-corrosion composition is prepared by mixing the hydrocarbon filler, the gelling agent and the corrosion inhibitor, resulting in a low viscosity mixture which can be easily pumped to the desired surfaces and / or applied to them. . After a certain period of time, the gelling agent

  causes an increase in the viscosity of the composition.

  Preferably, the desired viscosity is obtained after 60 to 600 minutes from the mixing of the constituents.

  The liquid filler must not be corrosive in itself. In addition, for safe handling, it must not be easily flammable. Accordingly, the filler is preferably a hydrocarbon material having an initial boiling point of at least 80 ° C. It can be selected from a wide range of hydrocarbons; particular alkanes or alkylenes such as alkylbenzenes, toluenes or -xylenes are usable. On the

  From an economic point of view, the hydrocarbon filler is preferably a gas oil, which includes diesel fuels 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 the seawater environments. Corrosion inhibitors selected from fatty acid and alkanol salts are preferred. or alkylamines. The gelling agent must be able to give the required viscosity. If the viscosity were lower, there could be a risk that the composition could be flushed out of the surface to be protected. If desired, the amount of gelling agent may be adjusted to provide a composition having the desired viscosity. Highly usable gelling agents are chosen from organic phosphates, in particular

C1-C15 alkyl phosphates.

  The composition according to the invention contains the constituents in the amounts described above. Preferably the composition contains from 65 to 85% by weight of the filler, from 5 to 25% by weight of the corrosion inhibitor and from 1 to 5% by weight of the gelling agent. If desired, it may also contain a catalyst which has an influence on gelation. The catalysts that can be used include aluminates of

  alkali metals, whether or not in combination with hydroxides.

  Their amount is conveniently from 5 to 20% by weight, by

relative to the gelling agent.

  The present invention also relates to the use of the anti-corrosion composition in a pipe fitting comprising a male tubular member and a female tubular member, the inner surface of which is

  substantially to the outer surface of the male member, each surface having raised and recessed portions that are engageable with each other.

  The invention also relates to a process for applying the anti-corrosion composition between the male element and the female element of a pipe fitting, wherein the filler, the gelling agent and the corrosion inhibitor are mixed together. the pressure mixture is forced through an orifice in the female element to cause expansion of the female element and / or contraction of the male element, thereby creating a space between the elements which is filled by the mixture And the mixture between the elements is allowed to reach an increased viscosity of at least 650 cSt at 25 C. The pressure on the fluid can be released before or after gelation of the mixture; preferably, this is done before

gelation.

  The invention will be explained with reference to the drawings. FIG. 1 is a view partly in axial section and partially in elevation of a coupling of

  piping showing a male element and a female element 10 completely assembled.

  Figure 2 is a partial view in axial section showing a portion of the pipe fitting in more detail. As shown in FIGS. 1 and 2, the pipe connection 15 comprises a male tubular element 1 to be fastened, for example by welding, to the end of a pipe 2, and a female tubular element 3 to be fixed, for example by welding, at the end of a pipe 4 to be assembled with the pipe 2. The male and female elements can be telescopically coupled and have outer and inner peripheral surfaces 5 and 6, respectively, of generally frustoconical shape which rest one on the other when the male member is fully telescopically pushed into the female member, as shown in FIG. 1. The members 1, 3 have surfaces 7, 8 extending radially at their free outer ends and, when they are completely telescopically assembled, one of the radially extending surfaces 7, 8 abuts a radially extending surface, 9 or 10, respectively, of a shoulder provided at the end inner diameter of the frustoconical surface of the female and male elements, respectively, for the transmission of axially directed forces, for example of driving forces of piles, between the elements 1, 3. As shown, the surface 8 of the element female and the surface 10 of -5

  the male element are abutting.

  The generally frustoconical peripheral surfaces 5, 6 comprise frustoconical end portions 11, 12 and 13, 14, respectively, at the inner and outer ends of the frustoconical surfaces and, between these intermediate end portions, the surfaces comprise projecting means and

  in hollow 15 and 16 coming into mutual engagement.

  An orifice 17 is provided in the female element 3 opening into the region provided with projecting and recessed means for communication with a source of fluid

under pressure.

  To assemble the coupling, the male and female elements are moved axially towards each other. Through port 17, a pressurized fluid is introduced to expand the female member and / or to contract the male member in a manner such that

  that the elements can be moved further relative to each other for complete telescopic assembly.

  The pressurized fluid, which is generally a hydraulic fluid, is replaced by a composition according to the invention. The low viscosity composition, obtained after mixing the constituents, is introduced under pressure through the orifice 17 so that it arrives between the surfaces and 6 and 9 and 10 of the elements 1 and 3. The pressure is released and the pressure is closed. orifice 17 with a plug. After a certain period of time, the composition arrives at the desired viscosity. Because of the high viscosity, the composition will not leak from the fitting, but will exhibit

  long lasting anti-corrosive action.

Example I

  To create stable anti-corrosion compositions according to the invention, the following starting materials have been used:

:::::::

  ::: 5 :: 5: :: 0 -6- 1) a hydrocarbon solvent, available under the trade name "Corexit 8811", based on a gas oil, containing C9-C30 hydrocarbons; 2) a corrosion inhibitor, available under the trade name "Corexit 8466", comprising a 73% by weight solution of fatty acid-alkanol / alkylamine salt in a mixture of an aromatic hydrocarbon and butoxyethanol; 3) a gelling agent comprising phosphoric esters of ethanol, octanol and decanol in an aromatic solvent, available under the trade name "J 292";

  4) a catalyst consisting of sodium aluminate and sodium hydroxide available under the trade name "J 242".

  The following compositions gave gels which had a viscosity of more than 750 cSt at 25 C and which were stable after 9 months: Corexit 8811 Corexit 8466 Composition J 292 J 242 (% by weight) (% by weight) (% by weight) % in

1 65.6

weight) 4.0 weight 0.4, 0

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-corrosive behavior, metal samples, coated with a layer of 50 Nm thick of composition 2 of Example 1 having a viscosity of 760 cSt at 25 C, were immersed in water aerated sea for 6 months. They remained free of corrosion. Based on impedance measurements over the entire exposure period, it was determined that the corrosion rate of the metal samples is less than 0.004 mm per year. Uncoated samples showed a corrosion rate of 1-2 mm per year.

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Claims (8)

  1. An anti-corrosion composition containing from 60 to 98% by weight of a liquid hydrocarbon filler, from 1 to 30% by weight of a corrosion inhibitor and from 1 to 10% by weight of a gelling agent which over time gives the composition a viscosity of at least 650 cSt at 25 C, all percentages by weight being taken from the total of the filler,   the corrosion inhibitor and the gelling agent.   2. An anti-corrosion composition according to claim 1, characterized in that the viscosity of at least 650 cSt at 25 ° C is obtained after 60 to 600 minutes from of the mixture of constituents.   3. An anti-corrosion composition according to claim 1 or 2, characterized in that the filling material is a hydrocarbon having an initial point boiling at least 80 C.   4. An anti-corrosion composition according to claim 3, characterized in that the filling material is a gas oil.   5. An anti-corrosion composition according to any one of claims 1 to 4, characterized in that   the corrosion inhibitor is selected from salts   fatty acids and alkanol- and / or alkylamines.   6. An anti-corrosion composition according to any one of claims 1 to 5, characterized in that   the gelling agent is chosen from organic phosphates.   7. The use of an anti-corrosion composition   according to any one of claims 1 to 6 in a   pipe fitting comprising a male tubular element and a female tubular element, the inner surface of which substantially corresponds to the outer surface of the male element, each surface comprising -8 means   protruding and recessed that come into mutual engagement.   8. A method for applying an anticorrosion composition according to any one of claims 1 to 6   between the male element and the female element of a pipe connection, according to which the filling material, the corrosion inhibitor and the gelling agent are mixed, the mixture is forced under pressure by an orifice in the element female to cause expansion of the female element and / or contraction of the male element, thus creating a space between the elements which is filled by the mixture, and the mixture is left between the elements   achieve an increased viscosity of at least 650 cSt at 250C.