Lined element for pipe or tank

Abstract

The present invention relates to a lined element for a pipe or a tank, comprising an unworked element made of steel, concrete or ductile cast iron for a pipe or a tank, and an inner liner situated on an inner wall of the unworked element for a pipe or a tank, the inner liner being made from a mortar composition comprising a cement and a magnesium-based additive. The invention also relates to a pipe or a tank comprising one or more of these lined pipe or tank elements, the pipe or the tank preferably being intended for the supply, distribution or storage of drinking water.

Description

[0001] Description

[0002] Title: Coated pipe or tank element

[0003] The present invention relates to a pipe or reservoir element comprising a particular mineral interior coating, said element being advantageously adapted to the supply, distribution or storage of drinking water. It also relates to a pipe or reservoir comprising such an element.

[0004] Pipe or tank elements made of ductile iron, steel or concrete have been used for many years for the supply, distribution or storage of drinking water. The inner wall of these elements is generally covered with mortar to ensure protection by a passivation mechanism. During commissioning, the water gradually soaks into the mortar, and is enriched with alkaline elements and thus becomes non-corrosive when it reaches the wall of the pipe or tank element.

[0005] However, it has been found that certain metals present in the composition of the mortar, such as chromium, vanadium, antimony, or aluminum, were released into the water in contact with the latter. Regulations impose increasingly strict constraints regarding the metal content in water, particularly drinking water.

[0006] Thus, there remains a real need for a pipe or tank element coated with a mortar that releases fewer metals into the water.

[0007] SUMMARY OF THE INVENTION

[0008] In this context, the inventors demonstrated that adding a magnesium-based additive to the cement mortar composition used to coat the inner wall of the pipe or tank element made it possible to substantially reduce the levels of certain metals released into the water. The inventors were able to observe that these performances could be achieved even with low levels of magnesium-based additive.

[0009] Advantageously, it has been shown that the coating retains good mechanical properties. Thus, the present invention relates to a coated pipe or tank element comprising:

[0010] - a raw pipe or tank element made of ductile iron, steel or concrete, and

[0011] - an inner coating located on an inner wall of the raw pipe or tank element, the inner coating being formed from a mortar composition comprising:

[0012] - a cement and

[0013] - a magnesium-based additive.

[0014] The invention also relates to a pipeline or reservoir comprising one or more coated pipeline or reservoir elements as described in the present application, the pipeline or reservoir preferably being intended for the supply, distribution or storage of drinking water.

[0015] FIGURES

[0016] [Fig 1]: Schematic cross-sectional representation of a coated pipeline or tank element, in a particular embodiment of the invention.

[0017] DETAILED DESCRIPTION

[0018] The coated pipeline or tank element according to the invention comprises:

[0019] - a raw pipe or tank element made of ductile iron, steel or concrete, and

[0020] - an interior coating located on an interior wall of the raw pipe or tank element.

[0021] The coated pipe or tank element defines an interior space in which the liquid (typically water) can circulate in contact with the interior coating.

[0022] The raw pipe or tank element may, for example, be a pipe or a branch, or form a tank. In certain embodiments, the coated pipe or tank element further comprises an outer coating located on an outer wall of the raw pipe or tank element. The outer coating is advantageously suitable for contact with a ground. The outer coating, well known to those skilled in the art, is advantageously configured to increase the corrosion resistance of the raw pipe or tank element. This outer coating is generally formed of a metallic protective layer, in particular based on sacrificial zinc, covered with a pore-filling paint based on an organic resin.

[0023] The inner coating advantageously covers the entire inner wall of the raw pipe or tank element.

[0024] The interior coating advantageously has a nominal thickness of 2 to 15 mm, preferably 2.5 to 9 mm.

[0025] The interior coating is a mortar formed from a mortar composition comprising:

[0026] - a cement and

[0027] - a magnesium-based additive.

[0028] More particularly, the inner coating is a mortar, typically formed by applying said mortar composition to the inner wall of the raw pipe or tank element and then curing (or setting) said mortar composition. The application of the mortar composition may be by centrifugation, spraying or hand coating.

[0029] A cement is a hydraulic mineral compound, that is, one that sets upon contact with water by hydration. Cement generally comprises clinker, and preferably one or more constituents chosen from blast furnace slag, steel slag, fly ash, pozzolan, silica fume, limestone, and calcined clay.

[0030] The cement may, for example, be Portland cement, composite Portland cement, blast furnace slag cement, composite cement, pozzolanic slag cement, calcined limestone and clay cement, aluminous cement, sulfo-aluminous cement, supersulfated cement, quick-setting cement, or a mixture thereof.

[0031] The cement is advantageously a cement as defined by standard EN 197-1 or standard EN 197-5. Unless otherwise stated, the weight contents indicated for the constituents of a cement defined by standard EN 197-1 or standard EN 197-5 are as defined by standard EN 197-1 or standard EN 197-5 respectively.

[0032] In some embodiments, the cement is a CEM I Portland cement of EN 197-1. The clinker content of a CEM I Portland cement of EN 197-1 is at least 95% by weight.

[0033] In some embodiments, the cement is a CEM II Portland cement of EN 197-1. A CEM II Portland cement of EN 197-1 results from the mixture of clinker in an amount at least equal to 65% by weight and other constituents such as blast furnace slag, fly ash, pozzolans, silica fume, the total of which does not exceed 35% by weight.

[0034] In some embodiments, the cement is a CEM ll / AS or CEM ll / BS Portland slag cement of EN 197-1. The CEM ll / AS cement comprises 80 to 94% by weight of clinker and 6 to 20% by weight of blast furnace slag. The CEM ll / BS cement comprises 65 to 79% by weight of clinker and 21 to 35% by weight of blast furnace slag.

[0035] In some embodiments, the cement is a CEM ll / CM composite Portland cement of EN 197-5, including a CEM ll / CM (SP), CEM ll / CM (SV), CEM ll / CM (S-L), CEM ll / CM (S-LL), CEM ll / CM (PL), CEM ll / CM (VL), CEM ll / CM (P-LL), or CEM ll / CM (V-LL) cement of EN 197-5. The CEM ll / CM cement typically comprises 50 to 64% by weight of clinker, and at least two other constituents selected from blast furnace slag, pozzolan, fly ash, calcined clay, and limestone.

[0036] In some embodiments, the cement is a CEM lll / A, CEM lll / B, or CEM lll / C blast furnace slag cement of EN 197-1. CEM lll / A cement comprises 35 to 64% by weight of clinker and 36 to 65% by weight of blast furnace slag. CEM lll / B cement comprises 20 to 34% by weight of clinker and 66 to 80% by weight of blast furnace slag. CEM lll / C cement comprises 5 to 19% by weight of clinker and 81 to 95% by weight of blast furnace slag.

[0037] In some embodiments, the cement is a CEM V / A or CEM V / B slag cement of EN 197-1. The CEM V / A cement comprises 40 to 64% by weight of clinker, 18 to 30% by weight of blast furnace slag and 18 to 30% by weight of pozzolan or fly ash. The CEM V / B cement comprises 20 to 38% by weight of clinker, 31 to 49% by weight of blast furnace slag and 31 to 49% by weight of pozzolan or fly ash.

[0038] In some embodiments, the cement is a CEM VI slag pozzolanic cement of EN 197-5, including a CEM VI (SP), CEM VI (SV), CEM VI (SL) cement. The CEM VI (SP, V or L) cement comprises 35 to 49% by weight of clinker, 31 to 59% by weight of blast furnace slag and 6 to 20% by weight of pozzolans, fly ash or limestone.

[0039] In some embodiments, the cement is a mixture comprising (preferably consisting of) CEM I Portland cement and a blast furnace slag, the weight content of CEM I Portland cement preferably being 5 to 64% (or even 20 to 50%) relative to the weight of the mixture.

[0040] In some embodiments, the cement is a mixture comprising (preferably consisting of) CEM I Portland cement, silica fume and blast furnace slag, the weight content of CEM I Portland cement preferably being 30 to 60% (or even 40 to 60%) based on the weight of the mixture and the weight content of silica fume preferably being 5 to 35% (or even 10 to 30%) based on the weight of the mixture. In some embodiments, the cement is a mixture comprising (preferably consisting of) CEM I Portland cement or CEM lll / B cement, and silica fume, the weight content of CEM I Portland cement or CEM lll / B cement preferably being 50 to 94% (or even 60 to 80%) based on the weight of the mixture.

[0041] In some embodiments, the cement is a mixture comprising:

[0042] - a cement as defined by standard EN 197-1 or standard EN 197-5 (for example a CEM I or CEM lll / B cement), and

[0043] - an addition having a Blaine specific surface area of ​​at least twice the specific surface area of ​​the cement of said mixture.

[0044] The Blaine specific surface area of ​​the addition is advantageously greater than 0.6 m 2 / g, for example greater than 0.8 m 2 / g, greater than 1.0 m 2 / g, greater than 1.2 m 2 / g, and preferably less than 5 m 2 / g. The addition typically consists of inorganic particles, particularly SiO2, the inorganic particles being finer and / or less dense than the cement of said mixture. More particularly, the addition may comprise (or even consist of) one or more of the following compounds: diatomite, moler, expanded perlite, andalusite, bentonite, chamotte, activated carbon, biochar, feldspar, graphite, graphene, halloysite, kaolin, mica, molochite, mullite, carbon black, talc or wollastonite.

[0045] The Blaine specific surface area is determined according to the Blaine method (defined by standard NF EN 196-6).

[0046] The cement used in the present invention may comprise secondary constituents in a content of less than 5% by weight. The secondary constituents are as defined in standard EN197-1 or EN 197-5. Specifically, they are generally compounds derived from the clinker production process, or blast furnace slag, fly ash, pozzolan, silica fume, limestone, or calcined clay.

[0047] In a preferred embodiment, the cement is a CEM lll / B cement of standard EN 197-1.

[0048] Cement may include magnesium in its composition, and in particular magnesium oxide. When present in cement, magnesium-based components, particularly magnesium oxide, are generally amorphous (or essentially amorphous).

[0049] The weight content of magnesium-based components (expressed as oxide by convention) in cement is generally less than 20%, preferably less than 10%, or even less than 5%, relative to the total weight of the cement.

[0050] The cement content by weight (based on its dry weight) is advantageously 15 to 60%, for example 20 to 60%, preferably 25 to 50%, or even 25 to 45%, relative to the total dry weight of the mortar composition.

[0051] The mortar composition further includes a magnesium-based additive.

[0052] Cement may include magnesium in its composition. It is understood that said additive is distinct from the cement, and more particularly distinct from any magnesium-based components that may be present in the cement.

[0053] The magnesium additive can be organic or inorganic.

[0054] Examples of organic magnesium additives include magnesium carboxylates, such as magnesium acetate, magnesium lactate, magnesium malate, or magnesium citrate.

[0055] However, it is preferred that the magnesium-based additive be inorganic.

[0056] In some embodiments, the magnesium-based additive is selected from a magnesium halide (e.g., magnesium chloride, magnesium bromide), a magnesium hypohalite (e.g., magnesium hypochlorite), a magnesium perhalate (e.g., magnesium perchlorate), a magnesium sulfate, a magnesium carbonate, a magnesium silicate, a magnesium nitrate, a magnesium phosphate, a magnesium sulfonate, a magnesium thiosulfate, a magnesium hydroxide (e.g., a hydrotalcite or Mg(OH)2), a magnesium oxide (e.g., MgO), a hydrate thereof, and a mixture of at least two of these. In a preferred embodiment, the magnesium-based additive comprises a magnesium oxide (eg MgO), advantageously in a weight content greater than 50%, or even greater than 60%, or even greater than 70%, or even greater than 80%, for example greater than 90% (relative to the total weight of the magnesium-based additive).

[0057] In a more preferred embodiment, the magnesium-based additive is magnesium oxide. More preferably, the magnesium-based additive is MgO.

[0058] The magnesium-based additive is advantageously crystalline (or essentially crystalline).

[0059] In a preferred embodiment, the magnesium-based additive is crystalline (or essentially crystalline) magnesium oxide. More preferably, the magnesium-based additive is crystalline (or essentially crystalline) MgO.

[0060] Preferably, the magnesium-based additive has a reactivity to citric acid at 23°C of at most 2,000 s, in particular 5 to 2,000 s, or even 10 s to 1,500 s, or even 20 to 1,000 s. The reactivity to citric acid is measured according to standard YB / T 4019-2020 (Determination of chemical activity of light calcined magnesia). Such a criterion of reactivity to citric acid contributes advantageously to an optimization of the performances of the additive (i.e. optimal reduction of the levels of certain metals released into the water).

[0061] The specific surface area of ​​the magnesium-based additive is advantageously at least 1 m 2 / g, for example 1 m 2 / g at 100 m 2 / g, or even 5 m 2 / g at 50 m 2 / g, as determined by the BET method (typically using nitrogen as the adsorption gas).

[0062] The weight content of magnesium-based additive (based on its dry weight) is advantageously from 0.02 to 10%, for example from 0.05 to 10%, from 0.1 to 10%, from 0.2 to 10%, from 0.4 to 10%, from 0.1 to 8%, from 0.1 to 5%, from 0.2 to 5%, or from 0.4 to 3%, relative to the total dry weight of the mortar composition. When said additive is a hydrate, it is understood that the reference weight for the weight content is that of the hydrate and not of the corresponding anhydrous compound. Typically, the mortar composition further comprises mineral fillers. Preferably, the mineral fillers are chosen from fillers, sand, gravel, or a mixture of at least two of these.

[0063] By "filler" we mean in particular fines, or addition fines, that is to say a fine aggregate. The sand and gravel are preferably of siliceous or calcareous nature.

[0064] Advantageously, at least 95% by mass of the fillers have a diameter less than or equal to 8 mm. Such a diameter can be measured according to standard EN 933-1, using the test for determining the geometric characteristics of aggregates (Part 1: Determination of granularity - Granulometric analysis by sieving).

[0065] The mass ratio of the quantity of mineral fillers to the quantity of dry cement is preferably 0.5 to 5, or even 1 to 4, or even 1.5 to 3.

[0066] Typically, the mortar composition further comprises water. The mass ratio of the amount of water to the amount of dry cement is preferably 0.2 to 1, or even 0.3 to 0.6, or even 0.35 to 0.5.

[0067] In some embodiments, the mortar composition further comprises one or more admixtures. The admixtures may be organic or mineral. Examples include setting (or hardening) accelerators, setting retarders, viscosity modifiers, and superplasticizers.

[0068] A superplasticizer has the role of increasing the fluidity of the mortar composition at a constant water dosage or of reducing the water content at constant fluidity. The superplasticizer can, for example, be a polycarboxylate solution advantageously having a dry extract of 10 to 50%, preferably 20 to 35%.

[0069] The mass ratio of the quantity of admixture(s) to the quantity of dry cement is preferably from 0.0001 to 0.1, for example from 0.0001 to 0.05, or even from 0.0005 to 0.04, or even from 0.001 to 0.03.

[0070] It is understood that the magnesium-based additive is not encompassed by the term "adjuvant" used in the present application. Figure 1 is a schematic cross-sectional representation of a coated pipe or tank element, in a particular embodiment of the invention. In this embodiment, the coated pipe or tank element 10 comprises:

[0071] - a raw pipe or tank element 12 made of ductile iron, steel or concrete,

[0072] - an inner coating 18 located on an inner wall 14 of the raw pipe or tank element 12, the inner coating 18 being formed from a mortar composition as defined in the present application, and

[0073] - advantageously, an external coating 20 located on an external wall 16 of the raw pipe or tank element 12.

[0074] The coated pipe or reservoir element 10 defines an interior space 22 in which the liquid (typically water) 5 circulates in contact with the interior coating 18.

[0075] The outer covering 20 is advantageously adapted to contact with a ground 24.

[0076] The present invention also relates to a pipeline or tank comprising one or more coated pipeline or tank elements as defined in the present application.

[0077] The pipeline or reservoir is advantageously intended for the supply, distribution or storage of drinking water.

[0078] Examples of metals whose release can be limited by means of the inner coating of the invention include those mentioned in EU Directive 2020 / 2184. Examples include the following metals: antimony (Sb), arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mg), mercury (Hg), nickel (Ni), lead (Pb), selenium (Se), vanadium (V), zinc (Zn), aluminum (Al), and uranium (U).

[0079] It further relates to a method of manufacturing a coated pipeline or tank element as defined in the present application, comprising: i) applying a mortar composition to an inner wall of a raw pipeline or tank element made of ductile iron, steel or concrete, to form a wet inner coating, and ii) curing the wet inner coating to obtain said coated pipeline or tank element comprising a cured inner coating, characterized in that the mortar composition is as defined in the present application.

[0080] The following examples illustrate the present invention, in a non-limiting manner.

[0081] EXAMPLES

[0082] Test specimens were made by coating sections of cast iron pipe with a nominal diameter of 200 mm with mortar compositions of different formulations. This mortar is implemented by centrifugation at 175 G. The sand used is silica sand with a grain size of 0 to 2 mm.

[0083] These specimens were tested according to the leaching protocol of standard EN 14944-3, describing the implementation of three successive migrations. The rates indicated in Table 1 below are the rates obtained at the end of the third migration. The rates indicated for the reference (i.e. without magnesium-based additive) are by default set at 100% and those indicated for the invention (i.e. with magnesium-based additive) are calculated relative to the reference.

[0084] [Table 1]

[0085] * weight content of MgO expressed in relation to the total dry weight of the mortar composition and MgO characterized by reactivity to citric acid at 23°C (measured according to standard YB / T 4019-2020).

[0086] Table 1 shows that the use of a mortar formed from a composition including a magnesium-based additive makes it possible to substantially reduce the levels of aluminum, vanadium, and antimony released into the water.

Claims

CLAIMS 1. Coated pipeline or tank element (10) comprising: - a raw pipe or tank element (12) made of ductile iron, steel or concrete, and - an inner coating (18) located on an inner wall (14) of the raw pipe or tank element (12), the inner coating (18) being formed from a mortar composition comprising: - a cement and - a magnesium-based additive.

2. A coated pipeline or tank element (10) according to claim 1, characterized in that the cement is a Portland cement, a composite Portland cement, a blast furnace slag cement, a composite cement, a pozzolanic slag cement, a calcined limestone and clay cement, an aluminous cement, a sulfo-aluminous cement, a supersulfated cement, a quick-setting cement or a mixture thereof.

3. Coated pipeline or tank element (10) according to claim 1 or 2, characterized in that the cement is a CEM lll / B cement according to standard EN 197-1.

4. Coated pipe or tank element (10) according to any one of claims 1 to 3, characterized in that the dry cement weight content is 15 to 60%, for example 20 to 60%, preferably 25 to 50%, or even 25 to 45%, relative to the total dry weight of the mortar composition.

5. A coated pipe or tank element (10) according to any one of claims 1 to 4, characterized in that the magnesium-based additive is chosen from a magnesium halide, a magnesium hypohalite, a magnesium perhalogenate, a magnesium sulfate, a magnesium carbonate, a magnesium silicate, a magnesium nitrate, a magnesium phosphate, a magnesium sulfonate, a magnesium thiosulfate, a magnesium hydroxide, a magnesium oxide, a hydrate thereof, and a mixture of at least two of these.

6. Coated pipe or tank element (10) according to claim 5, characterized in that the magnesium-based additive is MgO.

7. Coated pipe or tank element (10) according to any one of claims 1 to 6, characterized in that the weight content of magnesium-based additive is 0.02 to 10%, for example 0.05 to 10%, 0.1 to 10%, 0.2 to 10%, 0.4 to 10%, 0.1 to 8%, 0.1 to 5%, 0.2 to 5%, or 0.4 to 3%, relative to the total dry weight of the mortar composition.

8. Coated pipeline or tank element (10) according to any one of claims 1 to 7, characterized in that the mortar composition further comprises mineral fillers, where the mass ratio of the quantity of mineral fillers to the quantity of dry cement is preferably 0.5 to 5, or even 1 to 4, or even 1.5 to 3.

9. Coated pipeline or tank element (10) according to claim 8, characterized in that the mineral fillers are chosen from fillers, sand, gravel, or a mixture of at least two of these.

10. Coated pipeline or tank element (10) according to any one of claims 1 to 9, characterized in that the magnesium-based additive has a reactivity to citric acid at 23°C of at most 2,000 s, in particular 5 to 2,000 s, or even 10 to 1,500 s, or even 20 to 1,000 s.

11. Pipeline or reservoir comprising one or more coated pipe or reservoir elements as defined in any one of claims 1 to 10, the pipe or reservoir preferably being intended for the supply, distribution or storage of drinking water.

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