RU2296149C1 - Sealing paste for stop valve (variants) - Google Patents

Abstract

FIELD: sealing pastes for pipeline stop valve.

SUBSTANCE: claimed paste contains (mass pts): polydimethylsiloxanes 3.0-30.0; petroleum oil and/or polyalkylbenzene 10.0-30.0; alpha-olefins or propylene tetramer, or polyethylenesiloxane liquid 5.0-20.0; perlite 1.0-4.0; kaolin 0-3.5; bentonite 0-3.5; mica 2.5-5.5; low molecular or high molecular resin in form of oil solution 8.0-9.5; 14 % LiOH solution 1.75-3.0; CaO 0.07-0.29; tall oil fat acids and/or stearic acid 5.0-13.0. In another embodiment claimed paste contains colloidal graphite in amount of 1-28 mass pts instead of mineral fillers. Paste has penetration of 170-225 U, colloidal stability of 3-7, contains not more than 0.4 % of water, is resistant to gas condensate components in wide temperature range and is characterized with low viscosity-temperature dependence.

EFFECT: improved sealing paste for stop valve.

10 cl, 2 tbl, 14 ex

Description

The invention relates to sealing sealing pastes (UP) used in valves of pipelines.

Sealing pastes used in the operation of pipelines to eliminate leakage during transportation should provide increased sealing of the gas pipeline fittings, resistance to transported substances and related components, temperature stability in the range from -40 to + 60 ° C, increased service life up to 0.5 years without additional refueling.

Known sealing non-curing material for valves, described in and.with. USSR No. 1181309, based on polydimethylsiloxane, silica gel and polyisobutylene, additionally containing methylene chloride and oligophenl-2-ethyl (hexoxy) siloxane. This composition with an penetration rate of 160-180 units. can be used as a sealing paste, but it does not provide the required resource for the paste's working life due to the fact that oligophenyl-2-ethyl (hexoxy) siloxane is soluble in gas condensate components. The consequence of this is that the paste loses its consistency and requires frequent filling of new portions of the paste.

Known sealing paste for valves of gas pipelines described in the patent of the Russian Federation No. 2101332, including a dispersion medium, lithium stearate, talc and other fillers. As a plastic base, it contains petroleum instrument oil or polydimethylsiloxane fluid with a viscosity of 100 to 1000 mm ² / s, and polytetrafluoroethylene and α-naphthylamine as additional fillers. This paste has a penetration rate in the range of 180-230 units. The main disadvantage of this paste is that it has high penetration at low temperatures (90-120 units), which limits its use in the winter period and in the North-Eastern regions of Russia, reduces its sealing ability to gas condensate components. The paste has a low stability during operation, since liquids with a low viscosity, which require additional stabilization, are used as its plastic base.

From Japanese application No. 57-180656, it is known to use mineral fillers and synthetic oils in sealing pastes, which provides increased resistance of the seals to pressure and temperature drops, protecting them from dust. However, such pastes are not intended for pipelines operating at low temperatures, since at these temperatures they have a high penetration rate.

From Japan application No. 61-264080 known sealing material containing mineral oils and fillers, providing high corrosion and water resistance. However, this material is ineffective at temperature extremes and does not provide satisfactory sealing of gas pipelines.

From Japan application No. 63-152688 a sealing lubricant for use in the field of ultra-low temperatures is known, containing a silicone base, as well as salts of fatty acids and bentonite as thickeners. However, this lubricant loses its sealing properties at temperatures of about 0 ° C and above.

A common drawback of the pastes and greases described in the above Japanese applications is the high dependence of penetration on temperature, which is unacceptable if they are used at daily temperature differences, in the winter and in the North-Eastern regions of Russia.

Known mastic for filling joints between building elements, described in RF patent No. 2241726, containing a mineral filler - perlite, as a hydrophobic agent - siloxanes and a silicate agent - mica. This mastic can be used both as filling and finishing, it has good adhesion to paper and building structures, provides easy application of paint, has slight shrinkage, but it loses its properties when in contact with gas condensate, which makes it unsuitable for use in seals shutoff valves of pipelines.

RF patent No. 2181372 describes a sealing lubricant containing a dispersion medium — petroleum oils or polydimethylsiloxanes, an additive based on lithium stearate, a filler — chalk, and aerosil, stearin, rosin, and rubber. This paste is non-toxic, low-combustible, explosion-proof, efficient in a wide range of temperatures (from -60 to + 120 ° C) and pressures (from 1 to 10 MPa). However, due to the low compatibility of the silicone and oil components of the dispersion medium, it is subject to delamination in the working area, which reduces the tightness of the seal.

Closest to the claimed invention is the paste described in the patent of the Russian Federation No. 2218384, obtained on the basis of organosilicon oligomer. A mixture of petroleum oils and high viscosity polydimethylsiloxane (polymethylsiloxane with a viscosity of 10,000 to 100,000 cP) was used as a dispersion medium (plastic base) in this paste, and composite mixtures of bentonite, chemically precipitated chalk, kaolin, aerosil, and soot were used as thickeners. fluoroplastic and mica, as well as components providing the adhesive properties of the composition, which are used as a mixture of high molecular weight rubbers (styrene-butadiene, isoprene, ethylene-propylene, butyl rubbers, etc.) and n zkomolekulyarnyh rubbers (polyisobutene, polybutadiene, carboxylated nitrile rubbers, etc.). This paste has high consumer properties, but has a low colloidal stability (at least 10), which leads to the separation of liquid components due to the incompatibility of polydimethylsiloxane and petroleum oils. This, in turn, leads to thickening of the paste in the sealed gap and, as a result, to clogging of the locking unit. In addition, the composition of the paste used scarce and expensive components - granular fluoroplastic, aerosil.

The aim of the present invention is to provide a sealing plastic composition with high performance properties - sealing ability, stability over a wide temperature range, high resistance to gas condensate components, high resistance to delamination, which should ensure its long-term performance in various climatic zones. Another objective of the invention is the replacement of scarce, expensive raw materials with less scarce and cheaper.

According to one embodiment of the invention, this goal is achieved in that the claimed sealing paste comprising a dispersion medium - polydimethylsiloxanes and mineral oils, mineral fillers and thickeners based on low molecular weight and high molecular weight rubbers, characterized in that it contains at least one of the polydimethylsiloxanes with viscosity from 5 to 100,000 cSt, as a mineral oil it contains petroleum oil and / or polyalkylbenzene, and the dispersion medium of said paste additionally contains an α-olefin s, or propylene tetramer, or polyethylsiloxane liquid, as fillers, said paste contains at least three of a series including perlite, mica, kaolin, bentonite, and the composition of thickeners additionally includes the reaction products of a solution of LiOH, CaO, tallow fatty acids oils and / or stearic acid.

The claimed paste preferably contains I-40A oil (GOST 20788-88) or MGE-10A (OST 38.01281-82), and, as α-olefins, preferably C ₁₂ -C ₁₄ olefin fractions (TU 2411-058- 05766801-96) or C ₁₆ -C ₁₈ (TU 2411-067-05766801-97).

The claimed paste according to the first embodiment contains the above components in the following proportions, parts by weight:

Polydimethylsiloxanes 3.0-3 0.0 petroleum oil and / or polyalkylbenzene 10.0-30.0 α-olefins, or propylene tetramer, or polyethylsiloxane liquid 5.0-20.0 perlite 1.0-4.0 kaolin 0-3.5 bentonite 0-3.5 mica 2.5-5.5 low molecular weight and high molecular weight rubbers in the form of their solutions in oil 8.0-9.5 14% LiOH solution 1.75-3.0 Cao 0.07-0.29 tallow oil fatty acids and / or stearic acid 5.0-10.0

The introduction into the dispersion medium of additional components — α-olefins, or propylene tetramer, or polyethylsiloxane liquid — PES-5 or PES-5M, provides conditions for the mutual solubility of organosilicon and mineral components and for their combination in any proportions, which ensures the stability of the paste when it long operation and storage. Mixtures of fillers and thickeners provide the necessary rheological and structural properties of the compositions, namely, the penetration rate in the range from 140 to 190 units. at 20 ° C and from 65 to 90 at minus 30 ° C, which determines their high sealing properties for a long time without additional stuffing under conditions of exposure to variable temperatures. The introduction of composite mixtures of mineral fillers, taken in various ratios, as described above, each of which is itself known in sealing compounds, nevertheless leads to an unexpected result - structuring of the sealing layers in the sealed gaps of the reinforcement. The inclusion in the claimed composition of additional thickeners - salts of fatty acids, in the above ratios, ensures the adhesion of the paste in the gap, its high thixotropy and performance for a long time. It also significantly improves the sealing ability of the claimed paste. The use of all of the above components in the indicated ratios provides an unexpected effect on operational characteristics, which consists in increasing the sealing ability, the working life of the paste, the stability of its behavior at temperature extremes, and also in ensuring high colloidal stability.

In another embodiment, the claimed paste contains instead of mineral fillers: perlite, kaolin, bentonite, mica, colloidal graphite in the following components, parts by weight:

Polydimethylsiloxanes 3.0-30.0 petroleum oil and / or polyalkylbenzene 10.0-30.0 α-olefins, or propylene tetramer, or polyethylsiloxane liquid PES-5 or PES-5M 5.0-20.0 colloidal graphite 1.0-28.0 low molecular weight or high molecular weight rubber 8.0-9.5 a mixture of calcium and lithium tall oil fatty acid salts 0-5.0 a mixture of calcium and lithium stearic acid salts 5.0-13.0

In order to improve the anticorrosion properties, both types of pastes can include oil-soluble type corrosion inhibitors that perform the functions of surface-active substances (surfactants) in an amount up to 2 parts by weight It was found that the best results are achieved when using phosphate-type corrosion inhibitors such as alkyl phosphate, FOS, tricresyl phosphate.

Another objective of the invention is the replacement of scarce expensive raw materials - fluoroplastic and aerosil, with cheaper and less scarce ones was solved by using mineral fillers such as kaolin, perlite, mica and bentonite, as well as by their complete or partial replacement with colloidal graphite.

The authors are not aware of a similar or close technical solution providing a range of such operational properties as reliable sealing of valves, stability of operational properties in a wide temperature range from minus 40 to plus 120 ° C and high colloidal stability (no more than 7).

Sealing paste is prepared as follows.

The required amount of a dispersion medium, including polydimethylsiloxanes with a viscosity of 5 to 100,000 cSt, mineral oil, for example, I-40, VMGZ, MTB-10, polyalkylbenzene, additional components of the dispersion medium, providing the mutual dissolution of the silicone and mineral components, is loaded into the mixer apparatus. α-olefins, propylene tetramer, polyethylsiloxane liquid PES-5 or PES-5M. The mixture is stirred until a homogeneous mass is obtained, after which half of the resulting dispersion medium is poured into an additional container, and the mass remaining in the mixer is heated. With constant stirring, the components of the thickeners are loaded - stearic acid, tall oil fatty acids, then LiOH and CaO to obtain salts of fatty acids. The resulting mixture was heated to 120 ° C, stirred for 1.5 h and the remaining half of the dispersion medium was added from an additional container. Then load corrosion inhibitors with a surfactant function, and, gradually, the remaining components of the thickeners are rubbers of various molecular weights. Stirring is carried out for 3-5 hours, then the mixture is slowly cooled and colloidal graphite and / or mineral fillers — perlite, kaolin, mica, bentonite — are loaded with constant stirring. The final product is discharged into prepared containers. It is allowed to pass the resulting paste through a wiper machine for better dispersion of fillers. In order to intensify the process, rubbers are introduced in the form of solutions in mineral oil.

The invention is illustrated by the following examples.

Example 1

In the apparatus, equipped with a heated jacket, stirrer and thermocouple, the required amount of dispersion medium: 20 kg of PMS-1000 polydimethylsiloxane, 20 kg of C ₁₂ -C ₁₄ α-olefin and 20 kg of I-40A oil. The mixture is stirred until a homogeneous mass. 50% of the resulting mass is poured into an additional container. The mass remaining in the apparatus is heated to 80 ° C and, with stirring, 10 kg of stearic acid are added. The temperature of the reaction mass is increased to 120 ° C and 1750 g of a 14% solution of LiOH and 245 g of CaO are introduced. The mixture is stirred for 1.5 hours. Then, the remaining half of the dispersion medium is added from the additional container, 1 kg of perlite is added, and after 0.5 hours of stirring, 2 kg of alkyl phosphate are added. The mixture is stirred again for 0.5 hours. After obtaining a homogeneous mass, 2.4 kg of a 10% solution of styrene-butadiene-thermoelastoplast (DST, Kraton, Europren, etc.) in polyalkylbenzene are added to the apparatus. In this case, the temperature is maintained from 100 to 120 ° C and after stirring for 0.5 h, 6 kg of KP-20 product is introduced (polyisobutylene solution TU 38.303-02-107-2002). The reactor heating is turned off and after mixing and obtaining a homogeneous mass, 3.5 kg of mica with a dispersion of not more than 100 μm, 3.5 kg of bentonite and another 3.5 kg of perlite are loaded into the apparatus. The mixture is stirred until smooth, cooled and discharged.

Properties of the resulting paste:

- penetration - 180 units;

- colloidal stability - 6;

- water content - 0.2%;

Example 2

In a device equipped with a heated jacket, stirrer and thermocouple, load 10 kg of PMS-100 polydimethylsiloxane, 20 kg of C ₁₆ -C ₁₈ α-olefin and 30 kg of polyalkylbenzene. The mixture is stirred until a homogeneous mass. 50% of the resulting mass is poured into an additional container. The mass remaining in the apparatus is heated to 80 ° C and, with stirring, 10 kg of stearic acid are added. The temperature of the reaction mass is increased to 120 ° C and 2500 g of a 14% solution of LiOH and 140 g of CaO are introduced. The mixture is stirred for 1 hour. Then, the remaining half of the dispersion medium, 1 kg of perlite are added from the additional container, and after 0.5 hours of stirring, 2 kg of tricresyl phosphate are added. The mixture is again stirred for 0.5 hours. After obtaining a homogeneous mass, 2.4 kg of a 10% solution of styrene butadiene-styrene thermoplastic elastomer (DST, Kraton, Europren, etc.) in I-40A oil is added to the apparatus. In this case, the temperature is maintained from 100 to 120 ° C and after stirring for 0.5 h, 6 kg of KP-20 product (polyisobutylene solution) is introduced. The reactor heating is turned off and after mixing and obtaining a homogeneous mass, 3.5 kg of mica with a dispersion of not more than 100 μm, 3.5 kg of bentonite and 3.5 kg of kaolin are loaded into the apparatus. The mixture is stirred until smooth, cooled and discharged.

Properties of the resulting paste:

- penetration - 170 units;

- colloidal stability - 7;

- water content - 0.2%.

Example 3

A device equipped with a heated jacket, stirrer and thermocouple is charged with 10 kg of PMS-60000 polydimethylsiloxane, PMS-20 polydimethylsiloxane, 20 kg of C ₁₂ -C ₁₈ α-olefin, 10 kg of I-40A oil and 10 kg of polyalkylbenzene. The mixture is stirred until a homogeneous mass. 50% of the resulting mass is poured into an additional container. The mass remaining in the apparatus is heated to 80 ° C and, with stirring, 5 kg of stearic acid and 5 kg of tall oil fatty acids are added. The temperature of the reaction mass is increased to 120 ° C and 1750 g of a 14% solution of LiOH and 245 g of CaO are introduced. The mixture is stirred for 1 hour. Then, from the additional container, the remaining dispersion medium, 1 kg of perlite are added, and after 0.5 hours of stirring, 2 kg of Neonol-10 is added. The mixture is stirred again for 0.5 hours. After obtaining a homogeneous mass, 2.4 kg of a 10% solution of styrene-butadiene-thermoelastoplast (DST, Kraton, Europren, etc.) in polyalkylbenzene are added to the apparatus. The temperature is maintained from 100 to 120 ° C and, after stirring for 0.5 h, 6 kg of the product KP-20 (polyisobutylene solution) are introduced. The reactor heating is turned off and after mixing and obtaining a homogeneous mass, 3.5 kg of mica with a dispersion of not more than 100 μm, 3.5 kg of kaolin and another 3.5 kg of perlite are loaded into the apparatus. The mixture is stirred until smooth, cooled and discharged.

Properties of the resulting paste:

- penetration - 180 units;

- colloidal stability - 5;

- water content - 0.2%.

Similarly receive the composition of the pastes according to examples 2-9.

Example 10

The number of components, sequence and modes according to example 1, but instead of mineral fillers enter colloidal graphite in an amount of 1 wt.h.

Example 11

Everything, as in the previous example, but the amount of colloidal graphite is 28 parts by weight.

Partial replacement of mineral fillers with colloidal graphite is also possible, while the claimed paste retains its advantages over known analogues.

Table 1 shows the composition of the claimed paste with different contents and variants of its components.

Table 1 Name of downloadable components The number of downloadable components in the examples, kg one 2 3 four 5 6 7 8 9 12 13 fourteen PMS-5 - - - 3.0 - - - - - - - - PMS-20 - - 10.0 - - - - - - - - 10.0 PMS-100 - 5,0 - - - - - - - - 5,0 - PMS-400 - - - - 10.0 - - - - - - - PMS-1000 20,0 - - - - 10.0 - 30,0 30,0 20,0 - - PMS-60000 - - 10.0 - 20,0 - 15.0 - - - - 10.0 PMS-100000 - - - 7.0 - - - - - - - - I-40A oil 20,0 - 10.0 15.0 - 30,0 10.0 - - 20,0 - - Polyalkylbenzene 30,0 10.0 15.0 10.0 - 15.0 10.0 - - 30,0 10.0 MGE oil - - - - - - - - 30,0 - - -

10A Stearinov. K-ta 10.0 10.0 5,0 5,0 5,0 8.0 10.0 6.0 10.0 10.0 10.0 5,0 Fatty oils of tall oil - - 5,0 5,0 5,0 4.0 - 4.0 - - - 5,0 14% solution of LiOH 1.75 2,5 1.75 1.8 1.75 2.1 1.75 3.0 1.75 1.75 2,5 1.7 CaO 0.245 0.14 0.245 0.14 0.245 0.29 0.245 0,07 0.245 0.245 0.14 0.24 α-olefin C ₁₂ -C ₁₈ 20,0 - 20,0 - - - - - - 20,0 - 20,0 α-olefin C ₁₆ -C ₁₈ - 20,0 - - - - - - - - 20,0 - Propylene tetramer - - - 20,0 10.0 - - - 20,0 - - - PES-5 or PES-5M fluid - - - 10.0 20,0 5,0 - - - - Perlite 4,5 1,0 4,5 2,5 4.0 1,0 4.0 1,0 4,5 4,5 1,0 4,5 Kaolin - 3,5 3,5 3.0 3.0 - 3.0 3.0 - - 3,5 3,5 Bentonite 3,5 3,5 - 3.0 - 5,0 3,5 5,0 3,5 3,5 3,5 - Mica 3,5 3,5 3,5 4.0 4.0 5.5 4.0 2,5 3,5 3,5 3,5 3,5 KP-20 6.0 6.0 6.0 7.0 6.0 6.0 7.0 6.0 6.0 - - - 10% DST solution in I-40A - 2,4 - 2,5 - 2,4 2.2 - - - - - 10% DST solution in polyalkylbenzene 2,4 - 2,4 - 2.0 - - 2,4 2,4 - - - Alkyl Phosphate 2.0 - - - 2.0 - - 2.0 2.0 2.0 - - FOS - - - 2.0 - - - - - - - - Tricresyl phosphate - 2.0 - - 2.0 - - - - - 2.0 Neonol-10 - - 2.0 - - - - - - - - 2.0 PBN (30% solution in I-40 oil) - - - - - - - - - 7.0 - 6.0 Nitrile carboxylate - - - - - - - - - - 6.0 - SKN-18-1A rubber (30% solution in I-40 oil) 10% rd SKEPT-40 in I-40 - - - - - - - - - - 2,4 -

The properties of the paste composition in accordance with examples 1-11 are presented in table 2.

table 2 Example No. Properties of the resulting paste Penetration at 20 ° C * Colloidal stability Water content,% Corrosion activity one 180 6 0.2 Withstands 2 170 7 0.2 Withstands 3 180 5 0.2 Not withstand four 200 7 0.3 Withstands 5 180 6 0.3 Withstands 6 190 four 0.2 Withstands 7 170 5 0.4 Not withstand 8 190 3 0.2 Withstands 9 200 6 0.3 Withstands 10 190 5 0.2 Withstands eleven 225 5 0.2 Withstands 12 170 5 0.2 Withstands 13 170 6 0.2 Withstands fourteen 180 5 0.2 Withstands * At negative temperatures - up to -40 ° C, penetration in all examples is not lower than 120, which is acceptable for applying the declared paste in both cases at low temperatures, as well as at temperature extremes.

From the data presented in table 2, it follows that the claimed paste is characterized by high colloidal stability, low penetration at both positive and negative temperatures, has a low moisture content and is corrosion-resistant. In addition, it is characterized by a low temperature dependence of viscosity. Due to the above properties, the declared paste is efficient in a wide range and at temperature differences, insoluble in gas condensate and provides reliable sealing of shut-off valves, which makes it promising for use in the winter period and in the North-Eastern regions of Russia. The paste according to example 3 does not contain phosphate-type corrosion inhibitors, and according to example 7 does not contain corrosion inhibitors at all. These pastes, having advantages over known analogues in penetration and colloidal stability, have insufficient corrosion resistance and, as a result, may have limited use in pipelines.

Claims (10)

1. Sealing paste for valves, including dispersion medium - polydimethylsiloxanes and mineral oils, mineral fillers and thickeners based on low molecular weight or high molecular rubbers, characterized in that it contains at least one of polydimethylsiloxanes with a viscosity of 5 to 100,000 cSt, as a mineral oil, it contains petroleum oil and / or polyalkylbenzene, and the dispersion medium of said paste further comprises α-olefins, or propylene tetramer, or polyethylsiloxane liquid, the filler specified paste contains at least three of the series, including perlite, mica, kaolin, bentonite, and the composition of the thickeners further includes the reaction products of a solution of LiOH, CaO, tall oil fatty acids and / or stearic acid or stearic acid acid, with the following content of these components, parts by weight: Polydimethylsiloxanes 3.0-30.0 Petroleum oil and / or polyalkylbenzene 10.0-30.0 α-olefins, or propylene tetramer, or polyethylsiloxane liquid 5.0-20.0 Perlite 1.0-4.0 Kaolin 0-3.5 Bentonite 0-3.5 Mica 2.5-5.5 Low molecular weight or high molecular weight rubber in the form of their solutions in oil 8.0-9.5 14% LiOH solution 1.75-3.0 Cao 0.07-0.29 Tall Oil Fatty Acids and / or stearic acid 5.0-13.0 2. The sealing paste for valves according to claim 1, characterized in that it contains I-40A or MGE-10A as petroleum oils. 3. The sealing paste for valves according to claim 1, characterized in that as α-olefins it contains fractions of C ₁₂ -C ₁₄ or C ₁₆ -C ₁₈ olefins. 4. The sealing paste for valves according to claim 1, characterized in that it contains a polyethylsiloxane liquid PES-5 or PES-5M. 5. Sealing paste for valves according to any one of claims 1 to 4, characterized in that it further comprises oil-soluble type corrosion inhibitors with the function of surfactants from a series including alkyl phosphate, FOS, tricresyl phosphate, Neonol-10. 6. Sealing paste for valves, including dispersion medium - polydimethylsiloxanes and mineral oils, mineral fillers and thickeners based on low molecular weight or high molecular rubbers, characterized in that it contains at least one of polydimethylsiloxanes with a viscosity of 5 to 100,000 cSt, as a mineral oil, it contains petroleum oil and / or polyalkylbenzene, and the dispersion medium of said paste further comprises α-olefins, or propylene tetramer, or polyethylsiloxane liquid, the filler specified paste contains colloidal graphite, and the composition of the thickeners further includes the reaction products of a solution of LiOH, CaO, tall oil fatty acids and / or stearic acid or stearic acid, with the following contents of these components, parts by weight: Polydimethylsiloxanes 3.0-30.0 Petroleum oil and / or polyalkylbenzene 10.0-30.0 α-olefins, or propylene tetramer, or polyethylsiloxane liquid 5.0-20.0 Colloidal graphite 1.0-28.0 Low molecular weight or high molecular weight rubber in the form of their solutions in oil 8.0-9.5 14% LiOH solution 1.75-3.0 Cao 0.07-0.29 Tall Oil Fatty Acids and / or stearic acid 5.0-13.0 7. The sealing paste for valves according to claim 6, characterized in that it contains I-40A or MGE-10A as petroleum oils. 8. The sealing paste for valves according to claim 6, characterized in that it contains fractions of C ₁₂ -C ₁₈ or C ₁₆ -C ₁₈ olefins as α-olefins. 9. The sealing paste for valves according to claim 6, characterized in that it contains a polyethylsiloxane liquid PES-5 or PES-5M. 10. Sealing paste for valves according to any one of claims 6 to 9, characterized in that it further comprises oil-soluble type corrosion inhibitors with the function of surfactants from a series including alkyl phosphate, FOS, tricresyl phosphate, Neonol-10.