Knowledge

18Dec, 2025

38. What is acid embrittlement (or hydrogen embrittlement)? How does it occur?
The term "acid embrittlement" in steel pipes refers to the reduction in mechanical strength and increased brittleness that occurs after acid washing. This defect arises w
17Dec, 2025

37. What quality defects are likely to occur during pickling, and how can the...
(1) Under-acidizing: After acid pickling of steel pipes, residual iron oxide scale on the surface is referred to as under-acidizing defect. To prevent this, first reduce the pickli
17Dec, 2025

36. Why is it necessary to soak steel pipes in hot water for a period before ...
Prior to acid washing, steel pipes should be preheated in hot water (25-50°C) for 1-3 minutes before the process begins. This practice offers multiple benefits: (1) It removes
15Dec, 2025

35. The internal and external factors affecting the pickling of steel pipes c...
1) The composition, structure, processing process, and surface condition of the steel pipe itself, as well as the composition, structure, thickness, and uniformity of the oxide sca
15Dec, 2025

34. What is the effect of ferric chloride (and ferrous chloride) content in h...
When performing acid pickling on steel pipes, industrial-grade hydrochloric acid is typically used directly to achieve faster pickling rates. During the process, the iron matrix in
15Dec, 2025

33.What are the advantages and disadvantages of steel pipe pickling in hydroc...
Advantages: 1) The pickling speed is fast; 2) The corrosion of the base metal of the steel pipe is less, thus saving steel consumption; 3) The diffusion of hydrogen into the base m
15Dec, 2025

32. What are the optimal temperature and concentration for pickling?
When the concentration of hydrochloric acid solution increases from 2% to 25%, the acid washing speed increases tenfold. When using hydrochloric acid solution for steel pipe acid w
09Dec, 2025

31. Why is acid pickling necessary for steel pipe billets?
The acid pickling of steel pipe blanks serves to remove iron oxide scale formed during pipe production and welding. Although some scale may flake off during shaping, the exposed st
09Dec, 2025

30. What are the factors affecting the service life of hot-dip galvanized zin...
(1) Thickness Considerations: The thickness of hot-dip galvanized coatings directly impacts their service life. Generally, maintaining a zinc layer thickness between 7-10 mm ensure
05Dec, 2025

29. What is the principle of zinc coating anti-corrosion?
The corrosion rate of zinc coatings varies depending on the properties of zinc salts (corrosion products) formed on the surface under different conditions. When zinc salts like zin
04Dec, 2025

28. What are the main factors that determine the corrosion rate of zinc coating?
The corrosion rate of zinc coatings varies depending on the properties of zinc salts (corrosion products) formed on the surface under different conditions. When zinc salts like zin
04Dec, 2025

27. Why does the zinc coating corrode faster at the beginning than later?
The newly hot-dip galvanized zinc layer has no protective layer covering its surface, so its corrosion rate is relatively fast. However, once a layer of corrosion products appears,

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