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A kind of preparation method of strong acid and strong alkali resistant nodular cast iron pipe

A technology for ductile iron pipes and strong acid resistance, which is applied in pipeline protection, mechanical equipment, pipeline anticorrosion/rust protection, etc. Corrosion and other problems, to achieve good corrosion resistance, good protection, and prolong the service life

Active Publication Date: 2011-12-07
XINXING DUCTILE IRON PIPES CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The aluminum sprayed coating has good corrosion resistance in the environment medium of PH=4~9. In the case of low pH value (P﹤4) and high pH value (PH﹥12), the aluminum-zinc sprayed coating None of them can play a good anti-corrosion effect. In addition, in the environment of > 60 ℃, the potential of the zinc layer exceeds the potential of the iron layer, and the protective effect of the sacrificial anode is lost.
[0004] The pH of the soil in the pipe explosion area of ​​Guangdong is about 5.5, which is beyond the use range of zinc coating with a pH of 6 to 12. If zinc-sprayed bottom layer + asphalt topcoat coating ductile iron pipes are still used, the corrosion of ductile iron pipes will be accelerated, and the short-term perforated squib

Method used

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  • A kind of preparation method of strong acid and strong alkali resistant nodular cast iron pipe

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] (1) Shot blasting is performed on the surface of the ductile iron pipe substrate to reach the Sa2.5 level;

[0018] (2) Spray stainless steel alloy bottom layer: purge the outer surface of the ductile iron pipe substrate with nitrogen, use 316L stainless steel wire as the two melting electrodes of the arc, and spray on the outer surface of the ductile iron pipe to form a stainless steel alloy bottom layer, the unit of the stainless steel alloy bottom layer The area weight is 130g / m 2 .

[0019] After the surface of the ductile iron pipe base is shot blasted, the stainless steel alloy bottom layer is sprayed within four hours. The diameter of the wire is 2mm. The process parameters are shown in Table 1.

[0020] Table 1 Spraying process parameters

[0021]

[0022] (3) Coating an anti-corrosion paint coating on the outer surface of the nodular cast iron pipe sprayed with a stainless steel alloy bottom layer. The layer is applied by brushing.

Embodiment 2

[0024] (1) Shot blasting is performed on the surface of the ductile iron pipe substrate to reach the Sa2.5 level.

[0025] (2) Spray stainless steel alloy bottom layer: Blow the outer surface of the ductile iron pipe base with dry and clean compressed air, use 304 stainless steel wire as the two melting electrodes of the arc, and spray on the outer surface of the ductile iron pipe to form a stainless steel alloy bottom layer, stainless steel The weight per unit area of ​​the alloy bottom layer is 400g / m 2 .

[0026] The surface of the ductile iron pipe substrate is subjected to shot blasting treatment, and the stainless steel alloy bottom layer is sprayed within four hours. The diameter of the wire material is 4mm. The process parameters are shown in Table 2.

[0027] Table 2 Spraying process parameters

[0028]

[0029] (3) Coating an anti-corrosion paint coating on the outer surface of the nodular cast iron pipe sprayed with a stainless steel alloy bottom layer, the th...

Embodiment 3

[0031] (1) Shot blasting is performed on the surface of the ductile iron pipe substrate to reach the Sa2.5 level.

[0032] (2) Spray stainless steel alloy bottom layer: purge the outer surface of the ductile iron pipe substrate with nitrogen gas, use the nickel-based alloy stainless steel wire as the two melting electrodes of the arc, and spray on the outer surface of the ductile iron pipe to form a stainless steel alloy bottom layer, a stainless steel alloy bottom layer The weight per unit area is 200g / m 2 .

[0033] After the surface of the ductile iron pipe base is shot blasted, the stainless steel alloy bottom layer is sprayed within four hours. The diameter of the wire is 3 mm. The process parameters are shown in Table 3.

[0034] Table 3 Spraying process parameters

[0035]

[0036] (3) Coating an anti-corrosion paint coating on the outer surface of the ductile iron pipe sprayed with a stainless steel alloy bottom layer, the coating thickness is 100 microns, the ma...

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Abstract

The invention discloses a method for preparing a ductile cast iron tube with strong acid and alkali resistance. The method comprises the following steps: (1) performing ball blast treatment on the surface of a ductile cast iron tube substrate; (2) spraying a stainless steel alloy bottom layer; and (3) coating an anti-corrosion coating layer on the outer surface of the ductile cast iron tube with the stainless steel alloy bottom layer. The method provided by the invention is used for reducing the uniform corrosion speed of the stainless steel alloy. on the basis of a formed synergetic anti-corrosion system of the stainless steel alloy bottom layer and the anti-corrosion coating layer, the ductile cast iron tube still has excellent anti-corrosion property under the conditions of lower pH value (PH<4) and higher PH value (PH<12), thereby greatly prolonging the service life of the ductile cast iron tube under strong acid and alkali conditions.

Description

technical field [0001] The invention relates to a preparation method of a ductile iron pipe resistant to strong acid and strong alkali. Background technique [0002] Ductile iron pipes have always been made of zinc as the base, and then sprayed with a sealing layer on the composite anti-corrosion system ductile iron pipes. This is a sacrificial anode plus cathodic protection anti-corrosion system. It has the advantage of long anti-corrosion years and has been satisfied by users Well received and widely used all over the world. However, some problems were also found in use. For example, after the application of zinc-sprayed bottom layer + asphalt topcoat coating ductile iron pipe in a coastal Guangdong area, a perforation and water leakage accident occurred in just two or three years. After various studies and analysis, The main cause of the accident was found. First, the soil was highly acidic, with a pH of 5.5 (water extract) after testing. Second, Cl - Ions and SO4 2- H...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B05D7/14C23C4/08C23C4/02F16L58/04C23C4/06C23C4/131
Inventor 信绍广李军张永杰王恩清
Owner XINXING DUCTILE IRON PIPES CO LTD
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