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Taper threads, British Standard Pipe Taper thread (BSPT), whose diameter increases or decreases along the length of the thread; denoted by the letter R. BSPT threads [2] These can be combined into two types of joints: Jointing threads These are pipe threads where pressure-tightness is made through the mating of two threads together.
British Standard Whitworth (BSW) is an imperial-unit-based screw thread standard, devised and specified by Joseph Whitworth in 1841 and later adopted as a British Standard. It was the world's first national screw thread standard, and is the basis for many other standards, such as BSF , BSP , BSCon , and BSCopper .
Imperial Metric fastening size conversion charts; International Thread Standards; Conversion chart Whitworth/BSF/AF and metric Archived 2 May 2010 at the Wayback Machine; Spanner Jaw Sizes Additional information and spanner jaw size table. Unified Screw Threads Series; ASME B1.1-2003 Unified Inch Screw Threads, (UN and UNR Thread Form)
A screw thread is an inclined plane wrapped around a cylinder or cone in the form of a helix, with the former being called a straight thread and the latter called a tapered thread. More screw threads are produced each year than any other machine element. [1] Threads are generally produced according to one of the many standards of thread systems.
A metric ISO screw thread is designated by the letter M followed by the value of the nominal diameter D (the maximum thread diameter) and the pitch P, both expressed in millimetres and separated by a dash or sometimes the multiplication sign, × (e.g. M8-1.25 or M8×1.25).
The standard for Nominal Pipe Size (often abbreviated NPS, which should not be confused with the abbreviation NPS for the straight thread form standard) is loosely related to the inside diameter of Schedule 40 series of sizes. Because of the pipe wall thickness of Schedule pipe, the actual diameter of the NPT threads is larger than the Nominal ...
Many thread sizes have several possible tap drills, because they yield threads of varying thread depth between 50% and 100%. Usually thread depths of 60% to 75% are desired. People frequently use a chart such as this to determine the proper tap drill for a certain thread size or the proper tap for an existing hole.
My own view is that DN is preferable because this refers to the pipe size, and any given pipe size can only be threaded to the same thread size, whereas mm is an exact mm dimension but one which has no direct relationship to the thread size, eg, 1/2" is 12.7mm not 15mm, and 3/4" is 19.1mm not 20mm, etc. —Preceding unsigned comment added by ...