Characteristics of Liquid Gas Storage Tank Penetrant Testing
Time:2022-11-08
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Liquefied gas storage tank belongs to Class III pressure vessel. It is a storage tank containing liquefied gas and belongs to special equipment. Its quality requirements are particularly strict. The tank body is made of Q345R steel plate specially used for Class III pressure vessels. It has undergone penetrant flaw detection, overall heat treatment, hydro pneumatic test, on-site inspection by the Technical Supervision Bureau, issuance of pressure vessel inspection certificate, and completion of external rust removal and painting.
Penetrant testing (abbreviated as PT), also known as penetrant testing, is a surface nondestructive testing method and one of the five conventional nondestructive testing methods. Then the penetrating liquid is sucked out to the surface by the developer to show the existence of defects. This nondestructive testing method is called penetrant testing.
Features of PT:
1. Penetrant flaw detection method can be used for inspection of open defects on the surface of non loose porous materials.
2. It is not limited by the workpiece shape, and can be roughly inspected in one operation.
3. One operation can simultaneously detect defects with complex shape in all directions.
4. Simple equipment, portable spray irrigation dye penetrant flaw detection, no water and electricity, very convenient for on-site use.
5. Only open surface defects can be detected, and buried defects or closed surface defects cannot be detected.
6. The surface finish of the test piece has great influence.
7. There are many detection procedures and the speed is slow.
8. The detection cost is high.
9. Some test materials are flammable and toxic.
10. The detection sensitivity is lower than that of magnetic particle inspection.
Any nondestructive testing method is not omnipotent, and each method has its own advantages and disadvantages. As much as possible, several detection methods should be used to learn from each other‘s strengths and complement each other‘s weaknesses to ensure the safe operation of pressure equipment.
Disadvantages of penetrant inspection:
a. It can only detect surface opening defects.
b. It is not suitable for checking workpieces made of porous and loose materials and workpieces with rough surfaces.
c. Penetrant testing can only detect the surface distribution of defects, and it is difficult to determine the actual depth of defects, so it is difficult to make a quantitative evaluation of defects. The detection result is also greatly affected by the operator. Since various testing methods have certain characteristics, in order to improve the reliability of testing results, the most appropriate nondestructive testing method shall be selected according to the equipment material, manufacturing method, working medium, service conditions and failure mode, and the type, shape, position and orientation of possible defects.
Advantages of penetrant inspection:
a. Various materials can be tested; Metal and non-metallic materials; Magnetic and non-magnetic materials; Welding, forging, rolling and other processing methods.
B. High sensitivity (0.1 can be found μ M wide defects).
c. The display is intuitive, the operation is convenient, and the detection cost is low.
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