Corrosion-resistant nodular cast iron water supply pipeline

Abstract

A corrosion-resistant nodular cast iron water supply pipeline relates to the technical field of water supply pipe design and comprises a nodular cast iron pipe base body layer and an alloy corrosion-resistant layer arranged on the inner side of the nodular cast iron pipe base body layer, and the alloy corrosion-resistant layer is formed by metallurgical bonding of a corrosion-resistant alloy material and the nodular cast iron pipe base body layer through a centrifugal casting process. A plurality of sets of double-spiral micro-ribs are arranged on the inner wall of the alloy anti-corrosion layer along the circle center of the pipeline in an equal-angle array mode, each set of double-spiral micro-ribs are two single-spiral micro-ribs opposite in rotation direction, and the connecting line of the two single-spiral micro-ribs on the section perpendicular to the axis of the pipeline passes through the circle center of the pipeline. The problem of interface failure is solved through the metallurgical bonding layer, the turbulent flow design is formed by superposing the double-spiral micro-ribs, local sediment attachment to the inner wall of the pipeline is reduced, corrosion resistance is indirectly improved, although the initial investment cost is higher than that of a traditional process, frequent excavation and maintenance are not needed, and the composite pipe has good application prospects in high-added-value industrial scenes and areas with poor water quality. The method has remarkable technical advantages and economic value.

Description

TECHNICAL FIELD

[0001] The utility model relates to water supply pipe design technical field, concretely is a kind of corrosion-resistant nodular cast iron water supply pipeline. BACKGROUND

[0002] Nodular cast pipe is widely used in municipal water supply, industrial water delivery and fire-fighting pipe network, and the inner wall of nodular cast pipe is prone to corrosion phenomenon for long-term contact with water body, and the traditional anticorrosion measure is that the inner lining of nodular cast pipe adopts cement mortar or epoxy coating, but there is the problem of coating easy to fall off, leading to anticorrosion failure, which needs regular maintenance, and each maintenance needs excavation, which is troublesome, and in some areas with poor water quality or high-value industrial scenarios, the downtime cost of single maintenance far exceeds the cost of maintaining nodular cast pipe. SUMMARY

[0003] To solve the technical problems in the above background art, the utility model provides a kind of corrosion-resistant nodular cast iron water supply pipeline.

[0004] The utility model technical scheme is as follows:

[0005] A kind of corrosion-resistant nodular cast iron water supply pipeline, including nodular cast pipe base layer and the alloy anticorrosion layer of its inner side setting, alloy anticorrosion layer is formed by metallurgical combination of corrosion-resistant alloy material and nodular cast pipe base layer by centrifugal casting process, and the inner wall of alloy anticorrosion layer is also provided with multiple groups of double helix micro-rib along the equiangular array of the center of circle of pipeline, each group of double helix micro-rib is two single helix micro-rib with opposite rotation direction, and the connecting line of two single helix micro-rib passes through the center of circle of pipeline on the cross section perpendicular to the axis of pipeline.

[0006] The embodiment realizes the metallurgical combination of alloy anticorrosion layer and nodular cast iron base by centrifugal casting process, and the interface strength of metallurgical combination is much higher than the adhesion of traditional cement mortar or epoxy coating, and the bonding strength can be significantly improved, to avoid coating peeling problem, at the same time, Dean vortex is formed by double helix micro-rib to induce water flow, to reduce the attachment of local deposits (such as corrosive substances or microorganisms) on the inner wall of pipeline, to indirectly improve corrosion resistance.

[0007] Further, the height of double helix micro-rib is 0.3mm-0.8mm, and the pitch is 20mm-50mm, through test, the height of double helix micro-rib is too low to effectively induce vortex, and too high will significantly increase flow resistance, and the pitch of double helix micro-rib is too dense to increase vortex energy consumption, and too sparse will weaken shear stress, so the above design is more reasonable.

[0008] In general, the height of the double helix micro-rib is preferably 0.5 mm and the pitch is 30 mm to balance the vortex intensity and flow resistance; and the helix angle of the double helix micro-rib is 15°-30° to avoid the vortex intensity being reduced by too small an angle and the axial flow stability being weakened by too large an angle.

[0009] Preferably, the cross-sectional shape of the double helix micro-rib is a symmetrical trapezoidal structure to enhance the structural rigidity, and a fillet transition structure is provided between the root of the double helix micro-rib and the alloy corrosion-resistant layer to reduce stress concentration.

[0010] To facilitate the processing of the double helix micro-rib and ensure high bonding strength with the anti-fouling layer, the double helix micro-rib is preferably made by laser cladding process, and the spacing angle between adjacent two double helix micro-ribs is 15°-45°.

[0011] Further, the double helix micro-rib and the alloy corrosion-resistant layer are of the same material, and the alloy corrosion-resistant layer is a nickel-based alloy corrosion-resistant layer. The nickel-based alloy is Ni-Cr-Mo, which not only has high corrosion resistance, but also has a thermal expansion coefficient matching that of the ductile cast pipe, thereby relieving the interfacial thermal stress.

[0012] The corrosion-resistant ductile cast iron water supply pipeline described above has a thickness ratio of the ductile cast pipe base layer to the alloy corrosion-resistant layer of 20:1-35:1.

[0013] Further, the inner wall of the alloy corrosion-resistant layer and the surface of the double helix micro-rib are also provided with a wear-resistant and hydrophobic coating. The wear-resistant and hydrophobic coating is preferably a chromium carbide reinforced fluoropolymer composite coating among commercially available materials. The wear-resistant and hydrophobic coating can be made by spraying, dipping or vapor deposition process, and during the manufacturing process, it is necessary to ensure that the hydrophobic coating uniformly covers the inner wall of the alloy corrosion-resistant layer and the surface of the double helix micro-rib, and the thickness is 10-50 μm.

[0014] Traditional ductile cast pipe corrosion prevention mainly uses a single coating. The present design solves the interface failure problem through a metallurgical bonding layer, and superimposes a double helix micro-rib to form a vortex design, which reduces the attachment of local deposits on the inner wall of the pipeline and indirectly improves the corrosion resistance. Although the initial investment is higher than that of traditional processes, frequent excavation and maintenance are not required, and it has significant technical advantages and economic value in high-value-added industrial scenes and areas with poor water quality. BRIEF DESCRIPTION OF DRAWINGS

[0015] In the drawings:

[0016] Figure 1 is a schematic diagram of the internal structure of the present embodiment (radial cross-sectional view of the ductile cast pipe);

[0017] Figure 2 is an enlarged schematic view of A of Figure 1

[0018] Figure 3 ​The setting path schematic diagram of the single group of double helix micro-ribs of the embodiment.

[0019] The components represented by the reference numerals in the figures are:

[0020] 1, ductile cast iron pipe base layer; 2, alloy corrosion-resistant layer; 3, double helix micro-rib. DETAILED DESCRIPTION

[0021] In combination Figure 1 and Figure 2 , the embodiment provides a corrosion-resistant ductile cast iron water supply pipe, which comprises a ductile cast iron pipe base layer 1 and an alloy corrosion-resistant layer 2 arranged on the inner side of the ductile cast iron pipe base layer 1.

[0022] The alloy corrosion-resistant layer 2 is metallurgically combined with the ductile cast iron pipe base layer 1 by a centrifugal casting process, and a plurality of groups of double helix micro-ribs 3 are arranged on the inner wall of the alloy corrosion-resistant layer 2 at equal angles along the center of the pipe.

[0023] The metallurgical combination of the alloy corrosion-resistant layer 2 and the ductile cast iron base by the centrifugal casting process has an interface strength much higher than the adhesion of traditional cement mortar or epoxy coating, and can significantly improve the bonding strength to avoid coating peeling problems. At the same time, the double helix micro-ribs 3 induce water flow to form Dean vortex, thereby reducing the attachment of local deposits (such as corrosive substances or microorganisms) on the inner wall of the pipe, indirectly improving corrosion resistance.

[0024] Specifically, the height of the double helix micro-rib 3 is 0.3mm-0.8mm, and the pitch is 20mm-50mm. Through tests, the height of the double helix micro-rib 3 is too low to effectively induce vortex, and too high to significantly increase flow resistance. The pitch of the double helix micro-rib 3 is too dense to increase vortex energy consumption, and too sparse to weaken shear stress, so the above design is reasonable.

[0025] In general, the height of the double helix micro-rib 3 is preferably 0.5mm, and the pitch is 30mm, to balance the vortex intensity and flow resistance; and the helix angle of the double helix micro-rib 3 is 15°-30°, to avoid the angle being too small to reduce the vortex intensity, and the angle being too large to weaken the axial flow stability.

[0026] In combination Figure 2 , the cross-sectional shape of the double helix micro-rib 3 is a symmetrical trapezoidal structure to enhance the structural rigidity, and a round corner transition structure is provided between the root of the double helix micro-rib 3 and the alloy corrosion-resistant layer 2 to reduce stress concentration.

[0027] For the convenience of processing of the double-helix micro-rib 3 and ensuring high bonding strength with the anti-fouling layer, the double-helix micro-rib 3 is preferably made by laser cladding process, and the interval angle of the adjacent two double-helix micro-ribs 3 is 15°-45°.

[0028] The double-helix micro-rib 3 and the alloy corrosion-resistant layer 2 can be of the same material, and the alloy corrosion-resistant layer 2 is a nickel-based alloy corrosion-resistant layer 2. The nickel-based alloy is preferably Ni-Cr-Mo, which is a commonly used corrosion-resistant material in the prior art. In the present patent, not only its high corrosion resistance is utilized, but also its coefficient of thermal expansion is matched with the ductile cast pipe, thereby relieving the interface thermal stress. The thickness ratio of the ductile cast pipe base layer 1 and the alloy corrosion-resistant layer 2 is 20:1-35:1.

[0029] It should be noted that the specific element content of each layer structure in the present embodiment is designed according to the actual working condition and demand, so as to meet the needs while avoiding material waste, and will not be described in detail here.

[0030] In some cases, the inner wall of the alloy corrosion-resistant layer 2 and the surface of the double-helix micro-rib 3 are also provided with a wear-resistant and hydrophobic coating. The wear-resistant and hydrophobic coating can be a chromium carbide enhanced fluoropolymer composite coating in commercially available materials, which is made by spraying (thickness 20-50 μm), vapor deposition (thickness 10-30 μm) or controllable immersion process. Before coating, the surface of the alloy layer needs to be sandblasted and roughened (Ra=3-5 μm) and plasma activated, and multi-axis linkage spraying or rotary immersion technology is used to ensure uniform coating of the double-helix micro-rib 3 at the root and top, so as to finally form a wear-resistant and hydrophobic protective layer with a thickness of 10-50 μm and a contact angle of ≥150°.

[0031] Traditional ductile cast pipe corrosion is mainly based on a single coating, while the present design solves the interface failure problem through a metallurgical bonding layer, and superimposes a double-helix micro-rib 3 to form a vortex design, thereby reducing the attachment of local deposits on the inner wall of the pipe and indirectly improving the corrosion resistance. Although the initial investment cost is higher than that of traditional technology, frequent excavation and maintenance are not required, and in high-value-added industrial scenes and areas with poor water quality, the present design has significant technical advantages and economic value.

Claims

1. A corrosion-resistant ductile cast iron water supply pipe, characterized by, The alloy anticorrosion layer (2) is metallurgically combined with the ductile cast iron pipe base layer (1) by centrifugal casting process; The alloy anticorrosion layer (2) is metallurgically combined with the ductile cast iron pipe base layer (1) by centrifugal casting process; The inner wall of the alloy anticorrosion layer (2) is further provided with a plurality of groups of double helix micro-ribs (3) arranged along the center of the pipe at equal angles; Each group of double helix micro-ribs (3) is two single helix micro-ribs with opposite rotation directions, and the connecting line of the two single helix micro-ribs passes through the center of the pipe in the cross section perpendicular to the pipe axis.

2. The corrosion resistant ductile cast iron water supply pipe according to claim 1, wherein The height of the double helix micro-rib (3) is 0.3mm-0.8mm, and the pitch is 20mm-50mm.

3. A corrosion resistant ductile cast iron water supply pipe as claimed in claim 2, wherein, The helix angle of the double helix micro-rib (3) is 15°-30°.

4. The corrosion resistant ductile cast iron water supply pipe according to claim 1, wherein The cross-sectional shape of the double helix micro-rib (3) is a symmetrical trapezoidal structure.

5. The corrosion resistant ductile cast iron water supply pipe according to claim 1, wherein A round corner transition structure is arranged between the root of the double helix micro-rib (3) and the alloy anticorrosion layer (2).

6. The corrosion resistant ductile cast iron water supply pipe according to claim 1, wherein The double helix micro-rib (3) is made by laser cladding process.

7. The corrosion resistant ductile cast iron water supply pipe according to claim 1, wherein The interval angle of adjacent two double helix micro-ribs (3) is 15°-45°.

8. A corrosion resistant ductile cast iron water supply pipe according to any one of claims 1 to 7, characterized in that The alloy anticorrosion layer (2) is a nickel-based alloy anticorrosion layer (2).

9. A corrosion resistant ductile cast iron water supply pipe as claimed in claim 8, wherein The nickel-based alloy is Ni-Cr-Mo.

10. The corrosion resistant ductile cast iron water service pipe as claimed in claim 8 wherein, The inner wall of the alloy anticorrosion layer (2) and the surface of the double helix micro-rib (3) are further provided with a wear-resistant and hydrophobic coating.

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