SY/T 0546-1996 Collection and identification of corrosion products

SY/T 0546-1996 Collection and identification of corrosion products SY/T0546-1996 standard download decompression password: www.bzxz.net

Petroleum and Natural Gas Industry Standard of the People's Republic of China SY/T 05461996
Collection and identification of corrosion products
Collection and identification of corrosion products1996-11-15Promulgated
China National Petroleum Corporation
Implementation on 1997-06-01
Description of corrosion conditions
Collection of corrosion product samples
Storage and transportation of samples
5 Analysis and identification methods
Appendix A (suggestive appendix) Example A of inspection list for items related to corrosion product collection
Through research and investigation, it was found that the standard KP0173-73 of the National Association of Corrosion Engineers (NACE) was still adopted in the 1992 data. It can be seen that the standard has strong adaptability and a long application period: The purpose of this standard non-equivalently adopting NACE P0173-73 is to help personnel engaged in corrosion protection work in understanding When solving the problem, the corrosion product samples can be collected correctly, so that the analysts can take appropriate measures in the laboratory for classification and identification. This standard mainly provides methods and techniques for collecting corrosion product samples: In Chapter 5, some commonly used analysis and adjustment methods are briefly listed for reference by personnel engaged in anti-corrosion work and personnel engaged in classification. Analysis and identification methods, such as electron probe, electron energy spectrum, ESCA (chemical spectrometry), etc. are not listed in this standard, but sometimes they are very useful for analyzing corrosion products. When necessary, relevant information can be consulted. At the same time, new technologies and new methods should be adopted as they are constantly generated and developed. The appendix A of this standard is a reminder, which lists a checklist for items related to the collection of corrosion products. This standard was proposed and approved by the Oil and Gas Field and Pipeline Construction Design Professional Standardization Committee. : This standard was drafted by the Central Plains Petroleum Exploration Bureau Survey and Design Institute. The main drafter of this standard is Yue Jingying Ban Peijie 1 Scope
Petroleum and Natural Gas Industry Standard of the People's Republic of China Collection and Identification of Corrosion Products
SY/ T 05461996
Collection and identification of corrosion products This standard specifies the basic requirements for the collection and identification of corrosion products. This standard applies to the collection and identification of steel corrosion products. 2 Description of corrosion conditions
2.1 Original data
Collect the original data of the corroded parts (components), including the part number, manufacturing, installation, use date, corrosion time, corrosion environment, metals and non-metals related to corrosion in the parts, metals in adjacent areas, and other data related to the maintenance conditions of the parts.
2.2 Surface inspection
2.2.1 Inspect the corrosion area and corrosion products, record the color structure, the degree of corrosion and other relevant data. 2.2.2 Observe and describe with a 5x or 10x magnifying glass. 2.3 Photography
Before and after the corrosion products are removed, take photos of the corroded area. If necessary, draw a schematic diagram to indicate the relevant materials, component names, numbers and component features shown in the photos. 2.4 Magnetic inspection
Use a magnet to check whether there are magnetic substances in the corrosion products. 2.5 Bacterial inspection
When the presence of bacteria is suspected, bacterial culture should be carried out. 3 Collection of corrosion product samples
3.1 Collection of corroded parts
3.1.1 When possible: the entire corroded part should be sent to the laboratory; otherwise, a representative part should be selected. 3.1.2 To prevent the loss or contamination of corrosion products, special steps should be taken when cutting or transferring (see Appendix A (instructive Appendix) for inspection examples and Chapter 4 for storage and transportation of samples).
3.2 Determination of pH value
Use pH test paper (wet with deionized water when the deposit is too dry) to determine the pH value of water-soluble substances in the corroded area or adjacent areas.
3.3 Preparation of leaching solution
When necessary, use deionized water or other special solutions to diffuse the adjacent area. The leaching solution is collected in a clean, dry glass bottle or plastic bottle. The bottle stopper or screw cap lining should be made of materials that do not react with the solution, such as cork, rubber stopper or plastic-lined screw cap. 3.4 Collection of corrosion product samples
3.4.1 When the corrosion product has attachments, the attachments should be removed as much as possible; if the corrosion product is tightly combined with the attachments and is difficult to separate, they can be collected together; when the corrosion product is in the form of flakes or blocks, its structure should be kept intact during sampling. China National Petroleum Corporation Approved on November 15, 1996, implemented on June 1, 1997
SY/ T 05461996
3.4.2 Sampling should be representative. When the color and appearance of the corrosion products are different, they should be sampled separately and collected in different containers, and described by visual inspection (see 2.2) and photography, drawing and other methods (see 2.3). 3.4.3 When taking dry corrosion products, porcelain spatulas, spoons, screwdrivers, hacksaw blades or tweezers can be used: when taking wet corrosion products, porcelain spatulas should be used; when the liquid part is known to be weakly corrosive, screwdrivers, hacksaw blades, tweezers and other tools can also be used. The container for the sample can be a wide-mouthed glass bottle or plastic bottle with a stopper (or lid); when strong acid or strong alkali exists in the sample, a plastic bottle should be used. 3.4.4 When the corrosion products are taken from an aerobic environment, the dry corrosion product samples can be directly placed in the container; for wet corrosion products, after collecting the corrosion product samples, the medium sample should also be collected. After the collection is completed, the stopper (or lid) of the container should be covered and wax sealed. 3.4.5 When corrosion products are taken from an oxygen-free environment, more samples should be collected for dry corrosion products or smaller containers should be used so that the samples can fill the entire container as much as possible; for anaerobic corrosion products: after the collected samples are placed in the container, the remaining space in the container should be filled with the medium sample. After sampling, the sample container should be immediately plugged (or covered) and sealed with wax. 3.4.6 The collection of corrosion products should always meet the requirements of analysis and identification, and the volume should generally reach 30mL. 4 Storage and transportation of samples
All containers for storing corrosion products should be fixed with tape to prevent loosening: when corrosion products are easily affected by factors such as light and air temperature, consider taking appropriate protective measures during storage and transportation. 5 Analysis and identification methods
Under normal circumstances. Corrosion products can be identified directly: if organic matter is attached to the corrosion products, they should be cleaned with appropriate solvents first.
5.1 Microscope method
5.1.1 Optical microscope method
a) Place the corrosion specimen under a binocular microscope to observe whether the specimen has signs of pitting, cracks or metal erosion; b) Use a metallographic microscope to observe the cross-section of the corrosion specimen to determine the type and extent of corrosion. The types of corrosion can be divided into uniform corrosion, pitting corrosion, intergranular corrosion, transgranular corrosion, etc.; the corrosion degree report should include the erosion depth, the number of pits per unit area, the estimated weight loss of the entire section, etc.
5.1.2 Electron microscopy method
a) An electron microscope can be used to observe the shape, size and morphology of an object, and can also observe the size of grains and subgrains, phase distribution, and the type and uniformity of crystal defects;
b) An electron microscope can be used to observe the direction of crystallization, and sometimes reliable identification results can be obtained. 5.1.3 Scanning electron microscopy method
) The shape, size and morphology of the substance can be observed, and the particle size distribution and surface size can also be measured; b) In combination with energy spectrum analysis: qualitative and quantitative analysis of elements with atomic numbers greater than 11 can be performed. 5.2 X-ray diffraction method
5.2.1 X-ray diffraction patterns of powdered materials are widely used to identify the compounds and phases present in solid samples. The test data can also provide information about the degree of crystallite, grain size and particle orientation. 5.2.2 If X-ray diffraction is used directly to detect corrosion products on metal surfaces, the interpretation of the spectrum must take into account that the X-rays will penetrate to 10~20μm of the surface layer: if the corrosion product layer is thicker than this thickness, then the diffraction spectrum will not reflect the information of the matrix. 5.2.3 Sample requirements and analysis capabilities:
a) In general, a 10mg powder sample is sufficient for qualitative identification; b) Under appropriate circumstances, samples less than 11ng or single particles with a diameter of 10~100um can also be identified: c) For the properties of the root material, the quantitative detection limit is 0.1%~10%, and the accuracy is usually 5%~10% of the total amount; d) The measurement range of grain size is usually (30~5000)×10-\m5.3 Flame spectrometry
SY/T 05461996
5.3.1 Depending on the situation, atomic emission spectroscopy (FE) or atomic absorption spectroscopy (AA) can be used, and the two complement each other. 5.3.2More than 60 metal elements can be analyzed by flame spectrometry, of which about 1/3 are more sensitive to FE, 1/3 are more sensitive to AA, and the remaining 1/3 have the same sensitivity to the two methods. Among the elements that make up the corrosion products, Al and Cα are more sensitive to FE, Cd, Fe.MgNi.PbZn are more sensitive to AA; Cr, Cu, Mo.Ta.Ti.V.Zr are equally sensitive to the two methods.
5.4 Chemical analysis method
5.4.1 After dissolving the corrosion products with appropriate solvents, qualitative and quantitative tests can be carried out. 5.4.2 Chemical spot test is applicable to qualitative tests of all metal elements and most non-metal elements. 5.4.3 Gravimetric, volumetric, and colorimetric methods can be used to quantitatively analyze the corrosion product solution. 5.5 Other methods
When conditions permit, electronic probe, electron energy spectrum, spark source mass spectrometry, infrared spectrum, ultraviolet/visible spectrum, and other instruments can be used to conduct supplementary tests on corrosion products.
Appendix A (Suggestive Appendix)
A1 Components subject to corrosion
A1.1 Description of corroded components bzxZ.net
a) Photographs before and after cleaning
Example of an inspection list for items related to corrosion product collection b) Record the weight of the component d) Observe (magnifying glass can be used) and describe the appearance (local corrosion, uniform corrosion), color, crystallinity, color spot pattern, whether there is stratification, pitting, nodule, etc. of the corrosion site; e) Investigate other metals or steels with different structures and components in the system: When possible, cut off part of the corroded parts and collect samples of the surrounding medium A1.2 Material analysis a) Chemical composition analysis b) Metallographic structure analysis c) Inclusion analysis A1.3 Check the surface of the corroded parts a) Check the surface pH distribution inside and outside the corrosion area and the color spot pattern in different areas b) Collect the solid corrosion products on the surface and send them to the laboratory for identification c) Check whether there are bacteria in the corrosion products d) Wash the surface with water, measure the pH value and conductivity, and measure CI, SO ions and calculate the concentration on the surface. A1.4 Evaluation of pitting corrosion
a) Calculate the number of pits per unit area and observe whether there is a regular distribution of pitting corrosion; ) Measure the maximum pitting depth. When the component is large enough, it should be divided into several areas for separate measurement: c) The shape characteristics of the pit;
d) Measure the pitting activity, measure the pH value, and observe whether the corrosion product is dry or colloidal. A1.5 Metallographic examination
a) The degree of intergranular corrosion;
b) The size and structure of the grains;
c) Precipitation at the grain boundaries;
d) Whether there are other foreign substances on the surface or in the pits. A1.6 Test the mechanical properties of the component
a) Tensile strength and elongation;
b) Hardness of different parts, especially around the weld. A2
Liquid environmental samples
A2.1 Measure conductivity
A2.2 Measure pH value, bacteria, dissolved gas, anions and cations, etc. A2.3 When there is a galvanic couple, measure the potential of each metal. A2.4 Take this liquid for corrosion test: a) Weight loss, pitting rate
b) Galvanic corrosion (measure galvanic potential):
c) Pitting probability test
A3 Solid environmental samples
Buried plate test, test corrosion.
A3.2 Measure water-soluble components, pH value, bacteria. A3.3 Measure resistivity.
A3.4 Test stray current
4 Gas environmental samples
1 Test the concentration of corrosive components such as H, S.COO2: SO, CI in the gas. A4.1
A4.2 Test the temperature and humidity of the medium.
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