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Hot Dipped Galvanized Hex Head Bolt from China Suppliers - Quality Factory Manufacturing
Production parameter
| Thread size d |
M12 | M16 | M20 | M22 | M24 | M30 | |||
| P | pitch | 1.75 | 2 | 2.5 | 2.5 | 3 | 3.5 | ||
| ds | Max | 12.7 | 16.7 | 20.84 | 22.84 | 24.84 | 30.84 | ||
| Min | 11.3 | 15.3 | 19.16 | 21.16 | 23.16 | 29.16 | |||
| s | Max | 18 | 24 | 30 | 34 | 36 | 46 | ||
| Min | 17.57 | 23.16 | 29.16 | 33 | 35 | 45 | |||
| e | Max | 20.7 | 27.7 | 34.6 | 39.3 | 41.6 | 53.1 | ||
| Min | 19.85 | 26.17 | 32.95 | 37.29 | 39.55 | 50.85 | |||
| dw | Min | 16.5 | 22 | 27.7 | 31.35 | 33.2 | 42.7 | ||
| c | Max | 0.6 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | ||
| Min | 0.15 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | |||
| da | Max | 14.7 | 18.7 | 24.4 | 26.4 | 28.4 | 35.4 | ||
| r | Min | 0.6 | 0.6 | 0.8 | 0.8 | 0.8 | 1 | ||
| k | Max | 7.95 | 10.75 | 13.4 | 14.9 | 15.9 | 19.75 | ||
| Min | 7.05 | 9.25 | 11.6 | 13.1 | 14.1 | 17.65 | |||
| b | Single nut bolt | according to | d + 9 | d + 9 | d + 8 | d + 9 | d + 7 | d + 6 | |
| nominal | 21 | 25 | 28 | 31 | 31 | 36 | |||
| Double nut bolt | according to | 1.8d + 9 | 1.8d + 10 | 1.8d + 10 | 1.8d + 13 | 1.8d + 11 | 1.8d + 8 | ||
| nominal | 30.6 | 38.8 | 46 | 52.6 | 54.2 | 62 | |||
Production description
HDG generally refers to hot-dip galvanizing. Hot-dip galvanizing is to make the molten metal react with the iron matrix to produce an alloy layer, so that the matrix and the coating are combined. Hot-dip galvanizing is to pickle the iron and steel parts first, in order to remove the iron oxide on the surface of the iron and steel parts, after pickling, it is cleaned in a tank of ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride, and then sent to the hot dip coating tank. Hot-dip galvanizing has the advantages of uniform coating, strong adhesion and long service life.
The countersunk head of hot dip galvanized bolts is usually used where the connection is required. It is a non-standard part in the shape of a U and is therefore also known as a U-bolt. Hot-dip galvanized bolts with threads at both ends can be used in combination with nuts. The utility model is mainly used for fixing tubular or flaky objects.
The corrosion resistance is mainly determined by the thickness of the galvanized layer, so the thickness measurement is often the main basis for judging the quality of the galvanized layer. The angle and speed of the solution also have a great influence. Therefore, it is practically impossible to obtain a completely uniform coating thickness.
Frequently Asked Questions (FAQ)
What does HDG mean in the context of fasteners?
HDG stands for Hot-Dip Galvanizing. It is a process where iron or steel parts are pickled to remove iron oxide, cleaned in chemical solutions, and then dipped in molten zinc to form an alloy layer, providing excellent corrosion protection and durability.
What are the benefits of Hot-Dip Galvanized (HDG) bolts?
HDG bolts offer key advantages such as a highly uniform protective coating, exceptionally strong adhesion to the metal substrate, and a long service life even in harsh outdoor environments.
How is the quality of the galvanized layer evaluated?
The quality of the galvanized layer is primarily judged by its thickness. A thicker zinc layer generally correlates to stronger corrosion resistance.
Why is the coating thickness on HDG bolts sometimes uneven?
During the galvanizing process, factors such as the angle at which the bolts are removed from the solution and the speed of processing affect how the molten zinc flows, making a completely uniform thickness difficult to achieve in practice.
What are U-bolts and how are they used?
U-bolts are non-standard hot-dip galvanized fasteners shaped like the letter U. They feature threads on both ends, allowing them to be used with nuts to secure and fix tubular or flat objects.