Inspection Standards of Small-diameter Seamless Steel Pipes

Small-diameter seamless steel pipe refers to seamless steel pipe with smaller outer diameters. Usually, steel pipes with an outer diameter of less than 89mm and a wall thickness of more than 4mm are called small-diameter seamless steel pipes. This type of steel pipe is often used to manufacture mechanical structures or hydraulic equipment. It has the characteristics of high dimensional accuracy and good surface finish, which can save machining time and improve material utilization and product quality.

The inspection standards for small-diameter seamless steel pipes involve appearance quality, dimensional deviation, mechanical properties and chemical composition. Ensure that the steel pipe is defect-free, meets design requirements, withstands external forces and has corrosion resistance. The inspection standards for small-diameter seamless steel pipes are an important basis for ensuring the quality and safety of steel pipes. Strict inspection is required during purchase and use to ensure quality and safety.

Appearance quality inspection

The appearance quality of small-diameter seamless steel pipes is the primary inspection standard. The surface of the steel pipe should be smooth, free of defects such as cracks, folds, and tooth marks, and should be free of oxide scale and irritating odor. The ends of the steel pipe should be cut straight, and there should be no defects such as cracks, scars and ovals on the surface, nor should there be defects that cause pitting during use. These appearance quality inspections are to ensure that the steel pipe can withstand pressure, resist corrosion, and have a long service life during use.

Dimensional deviation inspection

The dimensional deviation of small-diameter seamless steel pipes is also one of the important inspection standards. The outer diameter, inner diameter and wall thickness of the steel pipe should meet the design requirements, and the deviation value should be within the specified range. Generally speaking, the outer diameter deviation is generally not more than plus or minus 0.2mm, the inner diameter deviation is generally not more than plus or minus 0.1mm, and the allowable deviation of the wall thickness is generally not more than plus or minus 12.5%. These dimensional deviation inspections are to ensure that the steel pipe can meet the engineering requirements during use and ensure the normal operation of the pipeline system.

Mechanical property inspection

The mechanical properties of small-diameter seamless steel pipes are a key part of the inspection standards. Mechanical properties include indicators such as tensile strength, yield strength, and elongation. The tensile strength should meet the design requirements, the yield strength should not be less than a certain proportion of the tensile strength, and the elongation should not be less than a certain percentage. The inspection of these mechanical properties is to ensure that the steel pipe can withstand and resist damage when subjected to external forces, and to ensure the safety and stability of the pipeline system.

Chemical composition analysis

The chemical composition of small-diameter seamless steel pipes is also an important part of the inspection standards. The chemical composition of the steel pipe should meet the design requirements, including the content of elements such as carbon (C), silicon (Si), manganese (Mn), sulfur (S), phosphorus (P), chromium (Cr), nickel (Ni), and copper (Cu). The analysis of chemical composition is to ensure that the material of the steel pipe meets the engineering requirements and has sufficient corrosion resistance and mechanical properties. The specific methods can be chemical analysis and instrumental analysis (such as infrared C-S instrument, direct reading spectrometer, N-O instrument, etc.).

Nondestructive testing inspection

Ultrasonic testing, eddy current testing, magnetic particle testing, electromagnetic ultrasonic testing, and penetrant testing are used to detect crack defects on the surface and inside of steel pipes.

Summary

In summary, the inspection standards for small-diameter seamless steel pipes cover multiple aspects such as appearance quality, dimensional deviation, mechanical properties, and chemical composition. The implementation of these inspection standards is to ensure the quality and safety of steel pipes and to ensure the normal operation and service life of the pipeline system. Therefore, when purchasing and using small-diameter seamless steel pipes, inspection and acceptance should be carried out in strict accordance with relevant standards and specifications to ensure the quality and safety of steel pipes.

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