Corrosion-resistant nodular cast iron pipe

Abstract

The utility model provides a corrosion-resistant nodular cast iron pipe, which belongs to the technical field of corrosion-resistant pipelines and comprises an inner corrosion-resistant layer, a nodular cast iron base layer and an outer corrosion-resistant layer which are sequentially arranged from inside to outside. The inner anti-corrosion layer comprises a chemical excitation cementing material enrichment layer which is in direct contact with a conveying medium, and a chemical excitation cementing material mortar layer which is positioned between the chemical excitation cementing material enrichment layer and the nodular cast iron base layer; according to the cast iron pipe, the cast iron pipe has good erosion resistance and corrosion resistance through the chemical excitation cementing material enrichment layer, and the ductile iron base material can maintain a passivation environment by combining the chemical excitation cementing material enrichment layer with the chemical excitation cementing material mortar layer, so that the service life of the cast iron pipe is indirectly prolonged.

Description

Technical Field

[0001] This utility model relates to the field of anti-corrosion pipeline technology, specifically to a corrosion-resistant ductile iron pipe. Background Technology

[0002] Ductile iron pipes are widely used in municipal water supply and drainage networks and industrial fluid transportation due to their excellent mechanical properties and good casting performance.

[0003] Traditional ductile iron pipes for wastewater treatment typically employ a single coating or a simple composite coating for protection, and their structure often includes basic anti-corrosion measures such as an inner cement lining and an epoxy coating. However, under conditions of long-term transportation of highly corrosive media (such as industrial wastewater and seawater) or complex geological environments (such as saline-alkali land and acidic soil), existing anti-corrosion systems reveal significant limitations.

[0004] In other words, there is a phenomenon of reduced internal corrosion protection: although traditional cement linings can provide initial protection, they are prone to forming microcracks and causing localized corrosion under long-term erosion and media penetration. Although epoxy coatings have good density, they are subject to the risk of peeling due to the difference in thermal expansion coefficients with the substrate, and their impact resistance is insufficient, making them prone to damage after long-term water flow, resulting in substrate exposure. Utility Model Content

[0005] In view of this, the present invention provides a corrosion-resistant ductile iron pipe. The present invention can make the cast iron pipe have good erosion resistance and corrosion resistance by chemically activated cementitious material enrichment layer. Combined with the chemically activated cementitious material mortar layer, it can also maintain the passivation environment of the ductile iron substrate, thereby indirectly improving the service life of the cast iron pipe.

[0006] To solve the above-mentioned technical problems, this utility model provides a corrosion-resistant ductile iron pipe, which consists of an inner anti-corrosion layer, a ductile iron base layer, and an outer anti-corrosion layer arranged sequentially from the inside to the outside.

[0007] The internal anti-corrosion layer consists of a chemically activated cementitious material enrichment layer that is in direct contact with the conveying medium, and a chemically activated cementitious material mortar layer located between the chemically activated cementitious material enrichment layer and the ductile iron base layer.

[0008] The external anti-corrosion layer is made of one of the following: high-chlorinated polyethylene, acrylic, epoxy resin, polyurethane, or fiber cement mortar. The external anti-corrosion layer can effectively resist the erosion of the external environment and enhance the anti-corrosion performance of the pipe.

[0009] It also includes a zinc-based coating located between the ductile iron base layer and the outer anti-corrosion layer, with the zinc-based coating serving as an intermediate transition layer.

[0010] The zinc-based coating is made of metallic zinc.

[0011] The zinc purity of the metallic zinc is ≥99%, and the coating quality is ≥130g / m². 2 .

[0012] The zinc-based coating is made of a zinc alloy.

[0013] The zinc-aluminum mass ratio of the zinc alloy is 85:15, and the coating mass is ≥130g / m². 2

[0014] The zinc-based coating is a zinc-rich paint coating.

[0015] The zinc content of the zinc-rich coating is ≥85%, and the equivalent metallic zinc mass is ≥130g / m². 2 .

[0016] Zinc, zinc alloy, and zinc-rich coatings are all formed by arc spraying zinc, which can enhance the adhesion between the outer anti-corrosion layer and the ductile iron substrate, and further improve the corrosion resistance of ductile iron pipes.

[0017] In summary, compared with the prior art, this application includes at least one of the following beneficial technical effects:

[0018] 1. Multi-level synergistic anti-corrosion system: Through the dual structure design of the chemically activated cementitious material enrichment layer and mortar layer of the inner anti-corrosion layer, the enrichment layer directly contacts the corrosive medium and has high density and erosion resistance, which can effectively block the medium penetration; the mortar layer provides chemical passivation and inhibits the corrosion activity of ductile iron substrate. The two work together to significantly improve the long-term effectiveness of the inner anti-corrosion and avoid the problem of substrate exposure caused by cracking and peeling of traditional coatings.

[0019] 2. Wide compatibility of external anti-corrosion layer materials: The external anti-corrosion layer uses a variety of materials such as high-chlorinated polyethylene, acrylic, and epoxy resin, which can be flexibly selected according to different corrosive environments (such as saline-alkali soil and acidic media), to specifically enhance the ability to resist chemical corrosion and mechanical damage, and broaden the application scenarios of pipelines.

[0020] 3. Significantly extended overall service life: The synergistic effect of the inner and outer anti-corrosion layers and the zinc-based transition layer increases the service life of the pipeline by more than 30% under highly corrosive media (such as industrial wastewater and seawater) and harsh geological environments (acidic soil), reducing maintenance costs.

[0021] 4. Environmental and construction advantages: Chemically activated cementitious materials do not require high-temperature sintering, reducing energy consumption; the electric arc zinc spraying process is highly efficient and controllable, and the coating uniformity is better than traditional coating, which is in line with the trend of green manufacturing. Attached Figure Description

[0022] Figure 1 This is a structural schematic diagram of a corrosion-resistant ductile iron pipe according to the present invention.

[0023] Explanation of reference numerals in the attached figures:

[0024] 10. Inner anti-corrosion layer; 11. Chemically activated cementitious material enrichment layer; 12. Chemically activated cementitious material mortar layer; 20. Ductile iron base layer; 30. Zinc-based coating; 40. Outer anti-corrosion layer. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the following will be described in conjunction with the accompanying drawings of the embodiments of this utility model. Figure 1 The technical solutions of the embodiments of this utility model are clearly and completely described herein. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the described embodiments of this utility model are within the protection scope of this utility model.

[0026] This embodiment provides a corrosion-resistant ductile iron pipe, such as Figure 1 As shown, it consists of an inner anti-corrosion layer 10, a ductile iron base layer 20, a zinc-based coating 30, and an outer anti-corrosion layer 40 arranged sequentially from the inside out.

[0027] The inner anti-corrosion layer 10 comprises a chemically activated cementitious material enrichment layer 11 that is in direct contact with the conveying medium, and a chemically activated cementitious material mortar layer 12 located between the chemically activated cementitious material enrichment layer 11 and the ductile iron base layer 20.

[0028] Specifically, the preparation of the chemically activated gel material mortar layer requires precise mass proportioning. Weighed sand, chemically activated cementitious material, additives, and water are sequentially added to a mixer and thoroughly mixed to form the chemically activated material mortar. The mixed mortar is then evenly distributed onto the inner wall of the ductile iron pipe and centrifuged to adhere it to the pipe's inner wall under centrifugal force. Curing is then performed, with a maximum steam curing temperature of 40-50℃. After curing, the chemically activated anti-corrosion layer is polished to remove surface laitance, yielding the chemically activated gel material mortar layer.

[0029] That is, the aforementioned chemically activated cementitious material enrichment layer 11, in contact with the conveying medium, has good erosion resistance and corrosion resistance, providing the first layer of protective barrier. The chemically activated cementitious material mortar layer 12 is bonded to the ductile iron substrate, which can maintain the passivation environment of the ductile iron substrate and further protect the ductile iron substrate; the two work together to significantly improve the long-term effectiveness of internal corrosion protection and avoid the problem of substrate exposure caused by cracking and peeling of traditional coatings.

[0030] Zinc-based coating 30: An electric arc zinc spraying process is used, where compressed air atomizes molten zinc-based material and sprays it onto the surface of the ductile iron pipe. During the spraying process, the distance between the spray gun and the substrate surface is maintained at 200-300 mm, resulting in a uniform and dense zinc-based coating 30.

[0031] When the zinc-based coating 30 is metallic zinc, it is zinc with a purity of not less than 99%, and the zinc layer is formed by arc spraying, with a zinc layer weight of not less than 130 g / m³. 2 .

[0032] When the zinc-based coating 30 is a zinc alloy, it is an alloy of zinc and aluminum in a ratio of 85:15. The zinc alloy layer is formed by arc spraying, and the weight of the zinc alloy layer is not less than 130 g / m³. 2 .

[0033] When the zinc-based coating 30 is a zinc-rich coating, the zinc content is not less than 85%, and the coating weight is not less than 150 g / m2, equivalent to 130 g / m2. 2 Quality of zinc coating.

[0034] The zinc-based coating 30 serves as an intermediate transition layer, providing protection for the ductile iron pipe substrate. It enhances the adhesion between the outer anti-corrosion layer 40 and the ductile iron substrate, further improving the corrosion resistance of the ductile iron pipe.

[0035] The outer anti-corrosion layer 40 is made of one of the following: high-chlorinated polyethylene, acrylic, epoxy resin, polyurethane, or fiber cement mortar.

[0036] When the outer anti-corrosion layer 40 is made of high-chlorinated polyethylene, acrylic or epoxy resin, the coating thickness is 60-150μm.

[0037] When polyurethane is selected for the external anti-corrosion layer 40, the coating thickness is approximately 1000μm.

[0038] When fiber cement is selected as the external anti-corrosion layer 40, the coating thickness is 3000-5000μm.

[0039] Specifically, before spraying the external anti-corrosion layer 40, the ductile iron pipe needs to be preheated. The preheating process is adjusted according to different materials. Then, the external anti-corrosion layer 40 is sprayed. After spraying, the coating is cured or maintained (the curing or maintenance process also needs to be adjusted according to different materials).

[0040] The above description is the preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. A corrosion resistant ductile cast iron pipe characterized by: It comprises an inner anticorrosion layer (10), a ductile cast iron base layer (20) and an outer anticorrosion layer (40) arranged in sequence from inside to outside. The inner anticorrosion layer (10) comprises a chemical excitation cementitious material enrichment layer (11) in direct contact with the conveying medium and a chemical excitation cementitious material mortar layer (12) between the chemical excitation cementitious material enrichment layer (11) and the ductile cast iron base layer (20).

2. A corrosion resistant ductile iron pipe as claimed in claim 1, wherein: The outer anticorrosion layer (40) is made of one of high-chlorinated polyethylene, acrylic acid, epoxy resin, polyurethane or fiber cement mortar layer.

3. A corrosion resistant ductile iron pipe according to claim 1 or 2, characterized in that: It further comprises a zinc-based coating layer (30) between the ductile cast iron base layer (20) and the outer anticorrosion layer (40).

4. A corrosion resistant ductile iron pipe as claimed in claim 3, wherein: The zinc-based coating layer (30) is made of metal zinc.

5. A corrosion resistant ductile iron pipe as claimed in claim 4, wherein: The metal zinc has a purity of zinc ≥ 99%, a coating mass ≥ 130 g / m 2 .

6. A corrosion resistant ductile iron pipe as claimed in claim 3, wherein: The zinc-based coating layer (30) is made of metal zinc alloy.

7. A corrosion resistant ductile iron pipe as claimed in claim 6, wherein: The mass ratio of zinc and aluminum of the metal zinc alloy is 85:15, and the coating mass is ≥130 g / m 2 .

8. A corrosion resistant ductile iron pipe as claimed in claim 3, wherein: The zinc-based coating layer (30) is a zinc-rich coating layer. The zinc-based coating layer (30) is a zinc-rich coating layer.

9. A corrosion resistant ductile iron pipe as claimed in claim 8, wherein: The zinc content of the zinc-rich coating is > 85%, equivalent metal zinc mass > 130 g / m 2 .

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