When we buy threaded joints, we will find that there are several specifications. The more common ones are the inch, metric and American. Some people don’t know how to distinguish between these three. This article will explain to you about an inch, metric, and The difference between American-made threaded joints so that everyone can buy.
The difference between the three is that the units used and marked, the tooth profile angle, and the tolerance zone are different. Among them, the unit of the metric threaded joint uses the metric unit, and the unit of measurement for the imperial and American threaded joints uses the imperial unit.
Inch threaded joints:
Unit: inch
Standard: BS 84-2007 etc.
Tolerance zone: 1B, 2B, 3B...
Tooth angle: 55 degrees
Tolerance zone: 1B, 2B, 3B...
Marking: 3/8-16 BSW-2B
Thread code: BSW, BSF, etc., the code is different, the thread pitch of the threaded joint produced is different
Metric ordinary threaded joints:
Unit: mm
Standard number: GB/T196-2003, etc.
Tolerance zone: 7H, 6H, 5H, 4h, 6h, 6g...
Tooth angle: 60 degrees
Marking: M20*1.5-6H (M nominal diameter * pitch-precision)
Thread code: M, coarse and fine teeth can be marked by the pitch
American-made ordinary threaded joint (unified thread)
Unit: inch
Standard number: ANSI B1.1
Tolerance zone: 1B, 2B, 3B...
Tooth shape angle: 60 degrees
Marking: 3/8-16 UNC-2B (nominal diameter-number of teeth per inch thread code-precision)
Thread code: UNC, UNF, UNEF, UN, etc., we can distinguish the size of the thread pitch by the code
The main difference between metric threaded joints and British and American threaded joints
The thread of the metric joint is expressed by the pitch, while the thread of the US-English joint is expressed by the number of threads per inch.
The metric thread uses a 60-degree equilateral profile, while the British thread uses an isosceles 55-degree profile, and the American thread also uses an isosceles 60-degree profile.
The thread unit of the metric connector uses the metric unit (such as mm), while the unit of the thread of the American-imperial connector is the inch unit (such as inch).
Nowadays, many people in the industry generally use "points" to refer to the thread size, where one inch is equivalent to 8 points, then 1/4 inch is 2 points, and so on.
In addition, ISO is the metric thread standard of 60 degrees, UN is the thread standard of 60 degrees, API is the American petroleum pipe thread standard of 60 degrees, and W is the British Wyeth thread standard of 55 degrees;
NPT BSP thread technology, there are differences between NPT, PT, G thread, NPT, PT, G thread difference, as for NPT, PT, G are all pipe threads.
Among them, NPT is the abbreviation of National (American) Pipe Thread, which is the 60-degree tapered pipe thread in the American standard. This standard is mainly used in North America. As for its national standard, you can refer to GB/T12716-2011.
PT is the abbreviation of Pipe Thread, which belongs to the 55-degree sealed tapered pipe thread. It is also a member of the Wyeth thread family. It is mostly used in Europe and Commonwealth countries. The taper is 1:16. Customers can refer to the national standard GB/T7306-2000 learn.
