CN109540775B

CN109540775B - Method for detecting and evaluating quality of zinc coating of power grid equipment

Info

Publication number: CN109540775B
Application number: CN201811337278.2A
Authority: CN
Inventors: 边美华; 彭家宁; 尹立群; 梁世容; 梁庆国; 张兴森; 卢展强; 李君华; 刘桂婵
Original assignee: Electric Power Research Institute of Guangxi Power Grid Co Ltd
Current assignee: Electric Power Research Institute of Guangxi Power Grid Co Ltd
Priority date: 2018-11-12
Filing date: 2018-11-12
Publication date: 2021-06-22
Anticipated expiration: 2038-11-12
Also published as: CN109540775A

Abstract

The invention belongs to the technical field of power equipment detection, and particularly relates to a method for detecting and evaluating the quality of a zinc coating of power grid equipment, which comprises the following steps: (1) detecting each evaluation index of a zinc coating of the power grid equipment; (2) determining the corrosion grade of the service environment of the power grid equipment; (3) and judging whether the zinc coating of the power grid equipment is qualified or not according to the determined corrosion grade of the service environment of the power grid equipment and the detection result of the zinc coating. The invention increases the key indexes of zinc coating quality evaluation: the corrosion grade of the service environment of the power grid equipment determines the evaluation index of the zinc coating according to the service environment of the power grid equipment, and the defect that the quality of the zinc coating is judged by adopting a unified detection evaluation index at present is overcome. Meanwhile, under the condition of meeting the corrosion grade requirement of the service environment, partial evaluation index values are reduced, and a large amount of investment cost is saved for the power grid.

Description

Method for detecting and evaluating quality of zinc coating of power grid equipment

Technical Field

The invention belongs to the technical field of power equipment detection, and particularly relates to a method for detecting and evaluating the quality of a zinc coating of power grid equipment.

Background

The hot dip coating technique is a method for protecting the anticorrosion coating layer of metal, which is to be dipped in the molten metal or alloy to be coated, and then the surface of the substrate is taken out after the substrate is kept in contact with the molten metal for a period of time, so that the substrate is adhered with a layer of uniform and smooth metal coating layer firmly combined with the substrate. At present, hot-dip galvanizing is widely used for corrosion prevention of power grid equipment, and has a plurality of detection standards. The detection items include four aspects of appearance, thickness, uniformity and adhesive force of the zinc coating. The appearance requires continuous and complete surface without defects of acid washing, plating leakage, nodulation, zinc accumulation, burrs and the like. The uniformity adopts a copper sulfate test, the zinc immersion resistant times are not less than 4, and iron is not exposed. The adhesion test adopts a drop hammer test, and after the drop hammer test, the zinc coating does not bulge and peel. The thickness of the galvanized layer of the power transmission line tower is determined according to the thickness of the plated part, when the thickness t of the plated part is more than or equal to 5mm, the minimum value of the thickness is 70 mu m, and the average minimum value is 86 mu m; when the thickness t of the plated part is less than 5mm, the minimum value of the thickness is 55 μm, and the average minimum value is 65 μm. The thickness of the zinc coating of the hardware fitting is determined according to whether the workpiece is a steel workpiece or an iron workpiece and the thickness of the workpiece, when the workpiece is the steel workpiece, the thickness t is more than or equal to 6mm, the minimum thickness of monomer zinc is 70 mu m, the minimum thickness of total zinc is 85 mu m, the thickness t is less than 6mm, the minimum thickness of monomer zinc is 55 mu m, and the minimum thickness of total zinc is 70 mu m; when the workpiece is an iron casting, the thickness t is more than or equal to 6mm, the minimum thickness of the monomer zinc is 70 mu m, the minimum thickness of the total zinc is 80 mu m, the thickness t is less than 6mm, the minimum thickness of the monomer zinc is 60 mu m, and the minimum thickness of the total zinc is 70 mu m. The thickness of the galvanized layer of the bolt and the nut requires that the thickness of the monomer zinc is not less than 40 mu m, and the thickness of the total zinc is not less than 50 mu m.

However, the existing detection evaluation standards are not distinguished according to the degree of corrosion grade, and all adopt uniform detection evaluation standards. In addition, the detection of the passivation effect of hot-dip galvanizing is not considered in the detection standard, because the passivation effect directly determines the corrosion resistance of galvanizing, white corrosion products are easy to appear due to poor passivation, and corrosion is accelerated. In the actual detection test process, the resistance value of the galvanized part with poor passivation effect is lower than 8000 ohm, and the corrosion acceleration test is 100h, and the galvanized part begins to generate red rust; the galvanized part with good passivation effect has the impedance value higher than 10000 ohms, and the red rust begins to appear after 200 hours of corrosion acceleration test. Therefore, the power grid equipment in the severely corroded area begins to be corroded gradually after being put into operation for 5-6 years, part of the power grid equipment is corroded seriously and even completely, and great threat is brought to safe and stable operation of the power grid. Therefore, the method for improving the existing method for detecting and evaluating the quality of the galvanized layer is necessary to improve the key indexes for evaluating the quality of the galvanized layer and carry out differential treatment according to the corrosion grade degree.

Disclosure of Invention

In order to solve the problems, the invention provides an evaluation method for a power distribution network equipment provider, which comprises the following specific technical scheme:

the method for detecting and evaluating the quality of the zinc coating of the power grid equipment comprises the following steps:

(1) detecting each evaluation index of a zinc coating of the power grid equipment; the evaluation indexes comprise 2 first-level evaluation indexes, and specifically comprise the following steps: the service environment index of the power grid equipment and the performance evaluation index of the zinc coating; the service environment indexes of the power grid equipment comprise 4 secondary indexes, specifically: atmospheric moisture time, dust content in air, sulfur compound content in air, and chloride salt content in air; the zinc coating performance evaluation indexes comprise 5 secondary indexes, specifically: appearance, thickness, uniformity, adhesion, and resistance;

(2) determining the corrosion grade of the service environment of the power grid equipment according to the detection result of the service environment index of the power grid equipment;

(3) and judging whether the zinc coating of the power grid equipment is qualified or not according to the determined corrosion grade of the service environment of the power grid equipment and each secondary evaluation index result of the detected zinc coating performance evaluation indexes, and judging that the corresponding zinc coating of the power grid equipment is unqualified as long as the detection result of any one secondary evaluation index of the zinc coating performance evaluation indexes does not accord with the corresponding corrosion grade requirement.

Preferably, the monitoring period for detecting the service environment index of the power grid equipment is 3-12 months.

Preferably, the corrosion grade is C1, C2, C3, C4, C5; the thickness requirements of the zinc coating of the power grid equipment under the corresponding corrosion grade are shown in the following table 1.

TABLE 1 list of the requirements of the galvanized layer thickness of the power grid equipment under each corrosion grade

Preferably, the resistance requirements of the zinc coating of the grid equipment at the corresponding corrosion levels are as shown in table 2 below.

TABLE 2 resistance requirement detailed table for zinc coating of power grid equipment under each corrosion grade

Grade of corrosion	C1	C2	C3	C4	C5
						Minimum value of impedance (omega)	8000	8000	8000	10000	10000

The invention has the beneficial effects that: the invention increases the key index of evaluating the quality of the zinc coating, determines the evaluation index of the zinc coating according to the service environment of the power grid equipment, solves the defect that the quality of the zinc coating is evaluated by adopting a unified detection evaluation index at present, avoids the problem that the power grid equipment starts to be corroded gradually after being put into operation for 5-6 years in a severely corroded area, or part of the power grid equipment is corroded seriously or even is corroded completely, can estimate the corrosion degree of the power grid equipment in advance by adopting the method, further discovers the defect of the power grid equipment and reduces the operation risk of the power grid. Meanwhile, under the condition of meeting the corrosion grade requirement of the service environment, partial evaluation index values are reduced, and a large amount of investment cost is saved for the power grid.

Drawings

FIG. 1 is a schematic flow chart of the present invention.

Detailed Description

For a better understanding of the present invention, reference is made to the following detailed description taken in conjunction with the accompanying drawings in which:

as shown in fig. 1, a method for detecting and evaluating the quality of a zinc coating of a power grid device includes the following steps:

(1) detecting each evaluation index of a zinc coating of the power grid equipment; the evaluation indexes comprise 2 first-level evaluation indexes, specifically: the service environment index of the power grid equipment and the performance evaluation index of the zinc coating; the service environment indexes of the power grid equipment comprise 4 secondary indexes, specifically: atmospheric moisture time, dust content in air, sulfur compound content in air, and chloride salt content in air; the zinc coating performance evaluation indexes comprise 5 secondary indexes, specifically: appearance, thickness, uniformity, adhesion, and resistance; the monitoring period for detecting the service environment indexes of the power grid equipment is 3-12 months. The appearance detection of the zinc coating of the power grid equipment is visual detection, a 10x magnifier can be used, the surface is required to be continuous and complete, and the defects of acid washing, plating leakage, nodulation, zinc accumulation, burrs and the like are avoided. The thickness of the zinc coating is detected by a metal coating thickness meter according to the GB/T4956 standard requirements; the specific requirements are as follows in table 2. The uniformity adopts a copper sulfate test, the zinc immersion resistant times are not less than 4, and iron is not exposed. The adhesion test adopts a drop hammer test, and after the drop hammer test, the zinc coating does not bulge and peel. The impedance measurement was measured using an impedance analyzer, with the specific requirements as shown in table 3 below.

(2) Determining the corrosion grade of the service environment of the power grid equipment according to the detection result of the service environment index of the power grid equipment; the corrosion grade of the service environment of the power grid equipment is graded according to the standard GB/T19292.1-2003 classification of corrosion atmospheric corrosion of metals and alloys, and the corrosion grade is divided into 5 corrosion grades such as C1, C2, C3, C4 and C5; specifically, the following table 1 shows.

TABLE 1 atmospheric corrosiveness rating

Rank of	Corrosiveness of
		C1	Is very low
C2	Is low in
		C3	Medium and high grade
C4	Height of
		C5	Is very high

The thickness requirements of the zinc coating of the grid equipment at the corresponding corrosion levels are shown in table 2 below.

TABLE 2 fine-listing of the galvanized layer thickness requirements of the power grid equipment under each corrosion grade

The resistance requirements of the zinc coating of the grid equipment at the corresponding corrosion levels are shown in table 3 below.

TABLE 3 resistance requirement detailed table for zinc coating of power grid equipment under each corrosion grade

The present invention is not limited to the above embodiments, which are merely preferred embodiments of the present invention, and the present invention is not limited thereto, and any modifications, equivalents and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting and evaluating the quality of a zinc coating of power grid equipment is characterized by comprising the following steps: the method comprises the following steps:

(2) determining the corrosion grade of the service environment of the power grid equipment according to the detection result of the service environment index of the power grid equipment; the corrosion grades are C1, C2, C3, C4 and C5; the thickness requirements of the zinc coating of the power grid equipment under the corresponding corrosion grade are shown in the following table 1:

The impedance requirements of the zinc coating of the grid equipment at the corresponding corrosion levels are shown in table 2 below:

2. The method for detecting and evaluating the quality of the zinc coating of the power grid equipment as claimed in claim 1, wherein the method comprises the following steps: the monitoring period for detecting the service environment indexes of the power grid equipment is 3-12 months.