Thread grade and size of the threads of hose fittings

Author:admin Date:2022-11-03

1. Grades: The threads of hose fittings specify six different grades, namely 1A, 2A, 3A (external thread) and 1B, 2B, 3B (internal thread). The suffix A and B refer to the external thread and the internal thread respectively.

2. Threads of grades 1A and 1B are specified for weapons and equipment and some special use requirements, that is, they can be used in situations that require easy and rapid assembly or where the thread can be assembled with slight damage and stains.

3. Grades 2A and 2B threads are the most commonly used standard threads on general-purpose bolts, screws, nuts and similar threaded fasteners.

4. Grade 3A and 3B threads are used in applications where the tightness of the thread fit, the lead and the accuracy of the half angle are high. Class 3A and 3B threads can only be obtained with high-precision equipment and effective measurement and inspection methods.

5. Marking example:

1-12 UNF-A (1 inch 12 teeth, A means external thread, B means internal thread).

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