JB/T 6902-1993 Liquid penetration inspection method for valve steel castings
Some standard content:
Machinery Industry Standard of the People's Republic of China
Liquid Penetration Inspection Method for Valve Steel Castings
1 Subject Content and Scope of Application
JB/T 6902—93
This standard stipulates Liquid paint penetration inspection method for surface defects and grade classification of defect display marks. This standard is applicable to liquid penetration inspection of valve steel castings. 2 Reference standards
GB5097 Indirect evaluation method of black light source
ZBH24002 Type A sensitivity comparison test block for penetrant testing 3 Flaw detection personnel and protection
3.1 Liquid penetrant testing of valve steel castings shall be carried out by Candidates with certain basic knowledge and experience in flaw detection of steel castings, and who have obtained qualification certificates recognized by relevant departments after examination, will be appointed.
3.2 The corrected visual acuity at close range of penetrant inspection personnel should be above 1.0, and the color vision should be able to distinguish the color contrast related to penetrant inspection.
3.3 During penetrant inspection, there are volatile gases and ultraviolet rays that can harm human health. Ventilation should be strengthened and corresponding safety protection measures should be established. 4 Penetrant flaw detection device and penetrant flaw detection agent
4.1 Penetrant flaw detection device
4.1.1 Penetrant flaw detection device is mainly composed of penetration, emulsification, cleaning, imaging, drying and observation devices. 4.1.2 The ultraviolet wavelength of the black light lamp used should be 320~400mm, and the black light radiation illumination at a distance of 400mm from the black light filter plate should not be less than 800uW/cm. The visible illumination in the dark room should not be greater than 20lx. 4.2 Penetrant flaw detection agent
4.2.1 Control of penetrant
4.2.1.1 Reference penetrant: Take 500mL of each new batch of penetrant and store it in a sealed glass container as a sample up as a reference. The storage temperature is 16~~52℃, and sunlight should be avoided. 4.2.1.2 The penetrant should be packed in a sealed container and stored in a low temperature and dark place. The specific gravity of various penetrants should be checked frequently using a hydrometer according to the manufacturer's instructions, and the specific gravity should be kept unchanged. 4.2.1.3 The concentration of the penetrant should be checked frequently according to the manufacturer's instructions. The calibration method is to inject 10 ml of calibration penetrant and reference penetrant into a measuring cup containing 90 mL of colorless kerosene or other solvents, and stir evenly. Then the two reagents were placed in colorimeter nanotubes to compare the color concentrations. If the difference in color concentration between the penetrant being tested and the reference penetrant exceeds 2.0%, it shall be deemed unqualified.
4.2.1.4 Conduct visual inspection of the penetrant in use. If there is obvious turbidity or sediment, discoloration or difficulty in cleaning, it should be scrapped.
4.2.1.5 Use a comparison test block and a reference penetrant to perform performance comparison tests on various penetrants. When the ability of the tested penetrant to show defects is lower than that of the reference penetrant, it should be scrapped.
The Ministry of Machinery Industry of the People's Republic of China approved 418 on 1993-07-13
Implemented on 1994-07-01
JB/T 6902 -- 93
4.2.1.6 Fluorescence The fluorescence efficiency of the penetrant shall not be less than 75%, and the test method shall be in accordance with the relevant provisions in Appendix A of GB5097. 4.2.2 Control of imaging agents
4.2.2.1 Formulated imaging agents should be checked frequently. If particles are found to be agglomerated, have significant residual fluorescence or have low performance, they must be discarded. 4.2.2.2 The concentration of the developer should be maintained within the working concentration range specified by the manufacturer, and its specific gravity should be calibrated frequently. 4.2.3 Regulations on oxygen and fluorine content in penetrant flaw detection agents 4.2.3.1 For austenitic stainless steel, the sum of the chlorine and fluorine element contents in penetrant flaw detection agents generally shall not exceed 1%. If there are higher requirements, they can also be negotiated by both parties.
4.2.3.2 The fluorine and fluorine content of the flaw detection agent can be measured according to the following method. Take 100g of the flaw detection agent sample, place it in a surface evaporator with a diameter of 150mm, heat it in a boiling water bath for 60 minutes, and evaporate. If the residue left after evaporation exceeds 0.005g, its oxygen and fluorine content should be analyzed. The sum of the chlorine and fluorine contents in the residue should not exceed 1% of the weight of the residue. 4.2.4 Precautions
The penetrant must be packed in a closed container and stored in a low temperature and dark place. The developer and quick-drying developer must be stored in airtight containers, and different types of penetrant flaw detection agents cannot be mixed. 5 Comparative test blocks and their applications
5.1 Comparative test blocks are divided into two types: chromium-plated comparison test blocks and aluminum alloy comparison test blocks. 5.1.1 The specifications and dimensions of the chromium-plated comparison test block are shown in Figure 1. Electroplating is performed on the surface of copper or steel, and then appropriate force is applied to the electroplated test block until cracks occur in the coating. Use a reference penetrant to conduct penetrant testing on the test block, and take photos or copy the testing results. A
100mm
Chrome plating
IA
Chrome plating A—A rotation
10:
Figure 1 Chrome-plated comparison test block| |tt||5.1.2 Aluminum alloy comparison test block shall comply with the provisions of ZBH24002. 5.2 Application of comparison test blocks
5.2.1 Under the interphase test conditions, use the comparison test block to check whether the performance and operation method of the penetrant flaw detection agent are suitable, and its ability to show traces of defects. A comparison test block should be used for verification before each flaw detection or when operating conditions change. 5.2.2 The comparison test block that has been subjected to color flaw detection cannot be subjected to fluorescence flaw detection test, and vice versa. 5.2.3 The comparison test block must be thoroughly cleaned after use to remove any remaining penetrant on the surface of the test block. After cleaning, soak it in acetone solution for 30 minutes, dry it and store it in a closed container. 6 Penetration inspection methods
6.1 General requirements
6.1.1 Inspection parts
All parts that can be inspected should be subject to penetration inspection, and the flange roots and pouring risers should be focused on. Roots and parting surfaces are prone to defects.
6.1.2 Inspection timing
Generally, inspection should be carried out after all processing and heat treatment processes are completed, but inspections between certain processes determined by negotiation between the supply and demand parties are not subject to this restriction.
6.1.3 Check temperature
419
JB/T 6902-93
The penetration flaw detection overflow should be controlled within the range of 16~52℃. If due to site conditions If this indicator is not met, correction should be made according to the requirements of Appendix A (Supplement).
6.1.4 Inspection method
When inspecting, the type and size of defects that may appear on the surface of steel castings, the use of steel castings, surface roughness, quantity and size should be considered, according to Table 1 and Table 1 2Select the flaw detection method and combine the codes in Table 1 and Table 2 to represent a certain flaw detection method. Table 1
Name
Name
Fluorescent penetrating flaw detection
Pulse color penetrating flaw detection
Method
Method
Water-washable fluorescent sea-permeable liquid method
Post-emulsification fluorescent sea-permeable liquid method
Solvent-removal fluorescent sea-permeable liquid method
Water-washable colored sea-permeable liquid method
Solvent removal Colored penetrant method
Note: The emulsifiers of post-emulsified fluorescent penetrant are oil-based and water-based. Table 2
Name
Name
Dry imaging method
Wet imaging method
No imaging method
6.2 Flaw detection operation Procedure
Form
Thousand-type developer method
Wet developer method
Quick-drying developer method
No developer method
The operating procedures for various flaw detection methods are determined according to Table 3. Table 3 | | tt | Fluorescent sea-permeable liquid
or water-washable color sea-permeable liquid
wet developer
water-washable fluorescent penetrant
or water-washable colored sea-permeable liquid||tt ||One-speed imaging agent
Water-washable fluorescent penetrating fluid
No developer required
Post-emulsified fluorescent penetrating fluid
"Dry imaging Agent
Post-emulsified fluorescent penetrant
-Wet imaging agent
420
Flaw detection method
Symbol
FA-D| |tt||FA-W
VA-W
FA-S
VA-S
FA-N
FB-D||tt ||FB-W
processing
C
O
O
sea
through
C||tt ||OO:
method
milk
chemical
exploration
clear
wash
C
O|| tt||Change
Go
Divide
Make
Thousands
Dry
O
Cheng||tt| |O
generation
generation
order
display
like
FA
FB
FC
VA
vC
D
w
s
N
No.
No.|| tt||Yu
Dry
Observation
Observation
Destiny
Processing
C)
OlO||tt ||Penetrant used
Type of developer
Post-emulsified fluorescent penetrant
Quick-drying developer
Solvent removal type fluorescent penetrant
Dry developer
Solvent-removable fluorescent penetrant
or solvent-removable latent penetrant
Mixed developer
Solvent Removable fluorescent penetrating fluid
or solvent removable coloring penetrating fluid
- Quick-drying developer
Solvent removable fluorescent penetrating fluid
No developer required
6.3 Pretreatment
Flaw detection method
Symbol
FB-S
FC-D
FC-W
cw
FC-S
VC-S
FC-N
JB/T 6902 -- 93
Continued Table 3
Pre-
Process
O
O
Through
Breast
Chemistry
Flaw detection
Fuck| |tt||clear
wash
remove
make
day
dry
program
program||tt ||Show
Dry
Drybzxz.net
Observe
Observe
After
Processing
6.3.1 Steel castings Grease, paint, rust spots, oxide scale and dirt that hinder penetrant inspection must be removed. Solvent cleaning, steam cleaning, coating film stripping, alkali cleaning and pickling are generally used for cleaning. 6.3.2 When the qualification level of the steel casting is 1 to 2, the surface roughness value Ra of the flaw detection surface is 6.3 μm; when the qualification level of the steel casting is set to level 3 to 4, the surface roughness value Ra of the flaw detection surface is is 25μm. 6.3.3 It is not advisable to carry out shot peening treatment before penetrating flaw detection of steel castings. If shot peening treatment is necessary due to technical reasons, pickling treatment must be carried out before penetrating flaw detection.
6.3.4 When local flaw detection is performed on the surface of steel castings, the pre-treatment range should be extended outward by 25mm from the required flaw detection area. 6.3.5 The surface of steel castings must be fully dry after pre-treatment, and the drying time should be at least 5 minutes. 6.4 Penetration treatment
6.4.1 Penetration treatment can use methods such as dipping, spraying wine and painting according to the quantity, size, shape and type of penetrant of steel castings. The flaw detection part must be completely moistened by the penetrant, and the penetration must be sufficient. 6.4.2 The penetration time depends on the type and penetration method of the penetrant. The penetration time should be no less than the time recommended by the penetrant manufacturer, which is generally 1030 minutes.
6.4.3 When performing emulsification or cleaning treatment, the residual penetrant attached to the surface of the casting should be dripped as cleanly as possible. 6.5 Emulsification treatment
6.5.1 Wash with water before emulsification treatment, and then apply emulsifier to the surface of steel castings by spreading, spraying wine, etc. The emulsification must be uniform.
6.5.2 The emulsification time depends on the performance of the emulsifier and penetrant and the surface roughness of the steel casting. Generally, the emulsification time of oil-based emulsifiers is within 2 minutes, and the emulsification time of water-based emulsifiers is within 5 minutes. 6.6 Cleaning and removal
6.6.1 Cleaning is to remove the residual penetrant attached to the surface of the workpiece to be inspected. During the treatment process, it is necessary to prevent insufficient treatment from causing difficulty in identifying defective traces. It is also necessary to prevent excessive processing so that the penetrant that penetrates into the defect is also washed away. When using fluorescent penetrant, the degree of cleaning can be observed under ultraviolet irradiation. 6.6.2 Both water-washable and post-emulsified penetrants should be washed with water. The water pressure when using the nozzle is not greater than 340kPa, and the water temperature is generally 40~421
500.
JB/T 6902 93
6.6.3 When using cleaning agents to remove permeate, you should Use cloth or paper dipped in cleaning agent to wipe in the same direction. Do not immerse the inspected parts in cleaning agent or use excessive cleaning agent.
6.7 Drying treatment
6.7.1 The drying temperature on the surface of steel castings should be controlled below 52°C. 6.7.2. When using dry or quick-drying developer, the drying treatment should be Carry out before imaging processing. 6.7.3 When using cleaning agents, they should be dried naturally or wiped with cloth or paper in the same direction. Do not heat and dry. 6.8 Development processing
6.8.1 The interval between cleaning of the penetrant and application of the developer shall not exceed 30 minutes. 6.8.2 When using the dry imaging method, bury the steel casting in the developer or spray it into powder mist to evenly cover the surface of the repaired steel casting. 6.8.3. When using a quick-drying developer, spray alcohol or apply the developer after drying. However, do not soak the cleaned steel castings in the developer. After spraying the developer, it should be dried naturally or blown dry with room temperature air. 6.8.4 When using wet and quick-drying developers, the developer should be sprayed evenly so that the surface of the steel casting can be seen slightly. Do not apply it repeatedly to the same part. It should then be dried naturally or blown dry with room temperature air. 6.8.5 The development time depends on factors such as the type of developer, the type and size of expected defects, and the processing temperature. In the range of 16 to 52C, the general development time is 7 to 15 minutes, but it cannot be lower than the development time specified by the developer manufacturer. 6.9 Observation
6.9.1 Observation of traces displayed should be carried out within 7 to 30 minutes after application of the developer. If the size of the trace does not expand excessively, observation can be carried out beyond the above time.
6.9.2 During fluorescent penetrant inspection, observe under a black light. Before observation, you must allow your eyes to adapt to the darkroom environment for more than 5 minutes. 6.9.3 During color penetrant inspection, the illumination of visible light on the surface being inspected shall not be less than 5001x6. 9.4·When traces appear, it must be determined whether the traces are true defects or false defects. If it cannot be determined, retest or other methods should be used for verification.
6.10 Re-inspection
It is necessary to re-inspect the pre-processing if the following conditions are found: a.
There is an error in the operation method;
b. It is difficult to determine whether traces are real defects or false defects; c. Have other needs.
6.11 Post-processing
6.11.1 After observation, in order to prevent the residual penetrant and developer from causing magic corrosion on the surface of the steel casting or affecting its use, the method in 6.6 should be used to remove it| |tt||6.11.2 After removing the developer from the processed surface of the steel casting, the workpiece should be dried and protected against corrosion if necessary. 7 Grade classification of defect display traces
7.1 Types of defect display traces
Defect display traces can be divided into three categories according to their shape and properties: linear defect display traces and point-like defect display traces Traces, cracks, 7.1.1 Linear defect indication traces are defect indication traces whose length is greater than or equal to 3 times the width. Point-like defect traces are defect display traces whose length is less than 3 times the width. 7.1.2
7.1.3 Except for cracks, any defect group formed by 3 or more defect marks with a distance of less than or equal to 3mm can be regarded as a large defect. The perimeter is the scope of the defect, and its types are distinguished according to the provisions of Articles 7.1.1 and 7.1.2. 7.2 Defect display traces will be evaluated and graded according to their maximum displayed length. Defects showing traces with a maximum length of less than 0.5mm will not be counted.
7.3 The classification of linear defect display traces is shown in Table 4. 422
Grade
1
2
3
4|| tt||different
13
A0.5
2
4
JB/T 6902 — 93
Table 4|| tt||Wall
Thickness
>13～25
A0.5
5
8
13
Greater than level 4
>25
<0.5
13
18
mm
Note: Two linear defects are on a line, and the adjacent spacing is less than the maximum length of the smaller defect should be regarded as one linear defect To evaluate, the length should be expressed as the sum of the length and spacing of each defect
7.4 See Table 5 for the classification of point defect traces. Table 5
level
4
5
different
13
2
5
thick
Those greater than level 4
Note: Four or more point-like defects show traces on - lines. When the adjacent spacing is less than 3 mm, it is classified as level 5, 7.5 crack-like The display traces are rated as level 5.
8Acceptance level
>13
1
5
8
13
mm
Those with defective traces of level 5 are considered unqualified. Users and designers can also choose a higher level as the qualified level of valve steel castings according to their needs. Valve steel castings after welding repairs should be inspected with emphasis on the welding repair location and heat-affected zone. The inspection methods and ratings are still in accordance with the provisions of this standard.
9 Records and Reports
9.1 According to the quality acceptance level requirements of steel castings, the type, location and size of all unqualified defects showing traces should be recorded. Defects can be recorded by covering them with transparent tape, taking photos or drawings. 9.2 Flaw detection report
The penetrant flaw detection report should include the following contents: 9.2.1 Name, number, material, heat treatment status, surface roughness, and qualification level of steel castings. 9.2.2 Flaw detection methods and operating procedures, types and grades of flaw detection agents. 9.2.3
Operating conditions
a.
b.
a.
Penetration time and penetration temperature;
Emulsification time:
Cleaning water pressure and temperature;
Drying temperature and time:
Development time and observation time.
423
9.2.4
Flaw detection results
a.
c
d.
e.|| tt | | 9.2.5 | | tt | |Whether there are cracks;
Flaw detection conclusion.
Operator qualifications, signature, and issuance date. JB/T6902-93
A1 Overview
JB/T 6902-93
Appendix A
Validation of flaw detection methods for non-standard temperatures [Supplement]
When the flaw detection cannot be carried out in the temperature range of 16~52C, it is required to identify the flaw detection method at lower or higher temperature. Usually an aluminum alloy comparison test block is used, as shown in Figure A1. 76
38
F
ilt
E
St.5||tt| |Figure A1
A2 identification method
A2.1 The identification of penetrant testing method when the temperature is lower than 16C is all
After the test block and all materials used have dropped to the predetermined temperature, Apply the proposed low-temperature inspection method to Area B. Then heat the test block to between 1652C, conduct inspection in area A using standard methods, and compare the crack traces in areas A and B. If the traces are basically the same, the method to be adopted can be considered feasible. A2.2 Identification of penetrant testing methods when the temperature is higher than 52C. If the temperature test is higher than 52C, heat the test block to this temperature and use the proposed high-temperature test method for testing in area B. The test block is then cooled to between 16 and 52C, and tested in area A using standard methods. Compare the crack display traces in areas A and B. If the traces are basically the same, the method to be adopted can be considered feasible. Additional notes:
This standard is proposed by the National Valve Standardization Technical Committee. This standard is under the jurisdiction of Hefei General Machinery Research Institute of the Ministry of Machinery Industry. This standard is drafted by Hefei General Machinery Research Institute of the Ministry of Machinery Industry and Kaifeng High Pressure Valve Factory. The main drafters of this standard are Nang Rong and Fang Jianzhou. 425
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