{"id":15378,"date":"2020-08-21T11:26:35","date_gmt":"2020-08-21T09:26:35","guid":{"rendered":"https:\/\/www.rct-online.de\/magazin\/?p=15378"},"modified":"2025-12-11T09:26:43","modified_gmt":"2025-12-11T08:26:43","slug":"threads-and-thread-types","status":"publish","type":"post","link":"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/","title":{"rendered":"A Guide to Screws and Thread Types"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_73 ez-toc-wrap-center counter-hierarchy ez-toc-counter ez-toc-white ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/#Screws_Nuts_and_Threads_%E2%80%93_a_Brief_Overview\" title=\"Screws, Nuts, and Threads \u2013 a Brief Overview\">Screws, Nuts, and Threads \u2013 a Brief Overview<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/#But_What_Is_a_Thread_and_How_Does_It_Work\" title=\"But What Is a Thread and How Does It Work?\">But What Is a Thread and How Does It Work?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/#Thread_Manufacturing\" title=\"Thread Manufacturing\">Thread Manufacturing<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/#Are_All_Threads_the_Same\" title=\"Are All Threads the Same?\">Are All Threads the Same?<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/#Metric_ISO_Thread_M\" title=\"Metric ISO Thread (M)\">Metric ISO Thread (M)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/#Metric_ISO_Trapezoidal_Thread_Tr\" title=\"Metric ISO Trapezoidal Thread (Tr)\">Metric ISO Trapezoidal Thread (Tr)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/#Round_Thread_Rd\" title=\"Round Thread (Rd)\">Round Thread (Rd)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/#Whitworth_Pipe_Thread_W\" title=\"Whitworth Pipe Thread (W)\">Whitworth Pipe Thread (W)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/#Saw_Thread_S\" title=\"Saw Thread (S)\">Saw Thread (S)<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/#Right-Hand_and_Left-Hand_Threads\" title=\"Right-Hand and Left-Hand Threads\">Right-Hand and Left-Hand Threads<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/#Is_Everything_Spinning_Now_%E2%80%93_Standards_Provide_Clarity\" title=\"Is Everything Spinning Now? \u2013 Standards Provide Clarity!\">Is Everything Spinning Now? \u2013 Standards Provide Clarity!<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/#Different_Countries_Different_Threads\" title=\"Different Countries, Different Threads\">Different Countries, Different Threads<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/#The_Thread_Types_at_a_Glance\" title=\"The Thread Types at a Glance\">The Thread Types at a Glance<\/a><\/li><\/ul><\/nav><\/div>\n<h2><span class=\"ez-toc-section\" id=\"Screws_Nuts_and_Threads_%E2%80%93_a_Brief_Overview\"><\/span>Screws, Nuts, and Threads \u2013 a Brief Overview<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\"><strong>What do a toothpaste tube, a jar of jam, a water bottle, and a light bulb have in common? A screw connection. The basic principle behind such a connection is interlocking threads. In this article, you will learn what this feature is, how it is manufactured, which types exist, and how they are distinguished.<\/strong><\/p>\n<p style=\"text-align: justify;\">When thinking of screws and their counterparts, nuts, most people imagine hardware stores and assembling furniture or other objects. However, screw connections and their threads are not always made of metal and can also be found in many everyday items.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"But_What_Is_a_Thread_and_How_Does_It_Work\"><\/span>But What Is a Thread and How Does It Work?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">To manufacture a thread, spiral-shaped grooves are cut into the circumference of a cylindrical workpiece. The resulting grooves form the characteristic profile. They can be incorporated on the outside of a bolt or on the inside of a nut.<\/p>\n<p><center><a href=\"https:\/\/www.rct-online.de\/en\/fasteners\/nuts\/30398\/hex-nut-din-934-made-of-pc\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-5428 size-full\" title=\"Hex Nut (DIN 934) made of PC\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/sechskantmutter-din-934-aus-pc.jpg\" alt=\"Hex Nut (DIN 934) made of PC\" width=\"300\" height=\"270\" \/><\/a> <a href=\"https:\/\/www.rct-online.de\/en\/fasteners\/screws\/crossed-pan-head\/30499\/slotted-countersunk-head-screw-din-963-made-of-pp\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-5429 size-full\" title=\"Slotted Countersunk Head Screw (DIN 963) made of PP\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/senkkopfschraube-din-963-aus-pp-mit-schlitz.jpg\" alt=\"Slotted Countersunk Head Screw (DIN 963) made of PP\" width=\"300\" height=\"270\" \/><\/a><\/center><\/p>\n<p style=\"text-align: justify;\">When an external thread that matches in size and shape engages with an internal thread, a screw connection is created. It allows parts to be joined securely yet remain detachable. To ensure proper function and interchangeability of internal and external counterparts, their geometry and dimensions are specified in standards.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Thread_Manufacturing\"><\/span>Thread Manufacturing<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">Typically, the helical grooves of this profile are cut using a chip-removing process, regardless of thread type. For cost reasons, larger quantities are produced by machine. For this purpose, machine taps and thread-cutting heads have been developed. In mechanical engineering, techniques such as turning, milling, grinding, and thread whirling are also used to produce higher volumes.<\/p>\n<figure id=\"attachment_5419\" aria-describedby=\"caption-attachment-5419\" style=\"width: 600px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-5419 size-full\" title=\"Tool for cutting internal and external threads\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/Werkzeug-zum-Schneiden-von-Innen-und-Aussengewinden.jpg\" alt=\"Werkzeug zum Schneiden von Innen- und Aussengewinden gewinde-und-gewindearten\" width=\"600\" height=\"400\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/Werkzeug-zum-Schneiden-von-Innen-und-Aussengewinden.jpg 600w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/Werkzeug-zum-Schneiden-von-Innen-und-Aussengewinden-300x200.jpg 300w\" sizes=\"(max-width: 600px) 100vw, 600px\" \/><figcaption id=\"caption-attachment-5419\" class=\"wp-caption-text\"><center>Tool for cutting internal and external threads<\/center><\/figcaption><\/figure>\n<h2><span class=\"ez-toc-section\" id=\"Are_All_Threads_the_Same\"><\/span>Are All Threads the Same?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">As the earlier everyday examples suggest, threads have countless applications. However, a jar of jam must meet different requirements than a water or gas pipe. Accordingly, various thread types exist, depending on their specific requirements and uses. They can be distinguished by the following key characteristics:<\/p>\n<ul style=\"text-align: justify;\">\n<li>Use: fastening and motion threads<\/li>\n<li>Position: external and internal threads<\/li>\n<li>Direction of rotation: right-hand and left-hand threads<\/li>\n<li>Number of starts: single-start and multi-start threads<\/li>\n<li>Thread profiles: flank angles<\/li>\n<\/ul>\n<p style=\"text-align: justify;\">The most common thread types are presented below.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Metric_ISO_Thread_M\"><\/span>Metric ISO Thread (M)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">The metric ISO thread has a flank angle of 60\u00b0. The flank angle describes the inclination of the thread flanks and determines the shape of the thread profile. This metric ISO variant comes in two versions: coarse and fine. The coarse version is the most frequently used and is found in all types of screw connections.<\/p>\n<blockquote>\n<p style=\"text-align: justify;\">The fine version differs from the coarse type by having a smaller pitch. The pitch is the distance a threaded bolt moves during one full rotation.<\/p>\n<\/blockquote>\n<p style=\"text-align: justify;\">Due to the smaller pitch, the fine thread has a larger core diameter. The core diameter is the undamaged part of the thread, measured perpendicular to the axis between the lowest points of the thread grooves. With its larger undamaged cross-section, the fine thread is more stable, safer in fastening applications, and allows finer adjustments in motion applications. It is used for standard screw connections and additionally in micrometer screws and interchangeable photographic lenses.<\/p>\n<p><center><a href=\"https:\/\/www.rct-online.de\/en\/tube-hose-connectors\/connectors-made-of-plastic\/threaded-adapter\/29110\/double-nipple-made-of-pp-pvdf-or-pfa-detachable\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-5433 size-full\" title=\"Double Nipple made of PP, PVDF or PFA - detachable\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/doppelnippel-aus-pp-pvdf-oder-pfa-loesbar.jpg\" alt=\"Double Nipple made of PP, PVDF or PFA - detachable\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/doppelnippel-aus-pp-pvdf-oder-pfa-loesbar.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/doppelnippel-aus-pp-pvdf-oder-pfa-loesbar-150x150.jpg 150w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a> <a href=\"https:\/\/www.rct-online.de\/en\/tube-hose-connectors\/connectors-made-of-plastic\/barb-connectors\/28903\/mini-screw-in-connector-with-male-thread-npt-1\/8-quot\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-5434 size-full\" title=\"Mini Screw-in Connector with male thread NPT 1\/8&quot;\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/mini-schlauchtuelle-mit-aussengewinde-npt-1-8-quot.jpg\" alt=\"Mini Screw-in Connector with male thread NPT 1\/8&quot;\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/mini-schlauchtuelle-mit-aussengewinde-npt-1-8-quot.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/mini-schlauchtuelle-mit-aussengewinde-npt-1-8-quot-150x150.jpg 150w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/center><\/p>\n<h3><span class=\"ez-toc-section\" id=\"Metric_ISO_Trapezoidal_Thread_Tr\"><\/span>Metric ISO Trapezoidal Thread (Tr)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">As the name suggests, the metric ISO trapezoidal thread has a trapezoidal profile with a flank angle of 30\u00b0. It is used for motion spindles subject to high loads in two axial directions, such as in bevel-gear valves.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Round_Thread_Rd\"><\/span>Round Thread (Rd)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">The round thread has a profile that resembles a wave because the crest and transitions are rounded. Like the metric ISO trapezoidal design, it has a flank angle of 30\u00b0. Round threads are more resistant to dirt, heat, and shock loads. They are therefore used in load hooks, rail vehicle couplings, and as screw bases for light bulbs.<\/p>\n<figure id=\"attachment_5423\" aria-describedby=\"caption-attachment-5423\" style=\"width: 200px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-5423 size-full\" title=\"Thread of a light bulb\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/Schraubgewinde-einer-Gluehlampe.jpg\" alt=\"Thread of a light bulb\" width=\"200\" height=\"181\" \/><figcaption id=\"caption-attachment-5423\" class=\"wp-caption-text\"><center>Thread of a light bulb<\/center><\/figcaption><\/figure>\n<p style=\"text-align: justify;\">Round threads are also used for glass threads, designated as GL. However, the flank angle of the bolt thread differs from the standard round profile and is 60\u00b0 instead of 30\u00b0.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Whitworth_Pipe_Thread_W\"><\/span>Whitworth Pipe Thread (W)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">The pipe thread, invented by British engineer Sir Joseph Whitworth (1803\u20131887) and named after him, was introduced in 1841, making it the first standardized fastener design in the world. In the Whitworth pipe thread, the nut and bolt threads have different shapes, but the flank angle of both is 55\u00b0. The bolt thread has a conical shape, while the nut thread is cylindrical. This geometry allows for pressure-tight connections of water and gas pipes and related fittings. Due to its origin, the Whitworth form is specified in inches rather than millimeters and is therefore also called inch thread.<\/p>\n<figure id=\"attachment_5425\" aria-describedby=\"caption-attachment-5425\" style=\"width: 350px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-5425 size-full\" title=\"British engineer Sir Joseph Whitworth\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/Sir-Joseph-Whitworth.jpg\" alt=\"Sir Joseph Whitworth\" width=\"350\" height=\"474\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/Sir-Joseph-Whitworth.jpg 350w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/Sir-Joseph-Whitworth-222x300.jpg 222w\" sizes=\"(max-width: 350px) 100vw, 350px\" \/><figcaption id=\"caption-attachment-5425\" class=\"wp-caption-text\"><center>British engineer Sir Joseph Whitworth (engraving after a photograph, c. 1882)<\/center><\/figcaption><\/figure>\n<p style=\"text-align: justify;\">Together with the metric ISO variant, the Whitworth pipe thread is classified as a \u201csharp thread.\u201d Both have triangular thread profiles with flattened or rounded transitions.<\/p>\n<h3><span class=\"ez-toc-section\" id=\"Saw_Thread_S\"><\/span>Saw Thread (S)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">As the name indicates, both nut and bolt threads resemble the shape of saw teeth in profile view. With a flank angle of 30\u00b0, this motion profile can absorb larger forces in one axial direction. Saw threads are used in lifting and pressure spindles in presses.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"Right-Hand_and_Left-Hand_Threads\"><\/span>Right-Hand and Left-Hand Threads<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">Threads that tighten clockwise (to the right) are called right-hand threads. Left-hand versions tighten counterclockwise. The direction of rotation is important in fastening applications when rotational loads could loosen a screw connection. A common everyday example is the pedals on a bicycle.<\/p>\n<p style=\"text-align: justify;\">Here, different thread directions are used; otherwise, the pedals would loosen while riding. Additionally, different thread directions in gas welding equipment ensure that gas and oxygen connections cannot be mixed up. The gas connection always has a left-hand version, and the oxygen connection always has a right-hand version.<\/p>\n<p><center><a href=\"https:\/\/www.rct-online.de\/en\/tube-hose-connectors\/connectors-made-of-plastic\/screw-joints-for-tubings\/28968\/straight-connector-with-male-thread-made-of-pp-or-pvdf-short\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-5440 size-full\" title=\"Straight Connector with Male Thread made of PP or PVDF - short\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/gerader-verbinder-mit-aussengewinde-aus-pp-oder-pvdf-kurz.jpg\" alt=\"Straight Connector with Male Thread made of PP or PVDF - short\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/gerader-verbinder-mit-aussengewinde-aus-pp-oder-pvdf-kurz.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/gerader-verbinder-mit-aussengewinde-aus-pp-oder-pvdf-kurz-150x150.jpg 150w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a> <a href=\"https:\/\/www.rct-online.de\/en\/tube-hose-connectors\/connectors-made-of-plastic\/glass-thread-adapter\/31228\/thread-adapter-made-of-pp-pvdf-or-pfa-loose-gl-nut\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-5441 size-full\" title=\"Thread adapter made of PP, PVDF or PFA - loose GL-nut\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/gewindeadapter-aus-pp-pvdf-oder-pfa-lose-gl-ueberwurfmutter.jpg\" alt=\"Thread adapter made of PP, PVDF or PFA - loose GL-nut\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/gewindeadapter-aus-pp-pvdf-oder-pfa-lose-gl-ueberwurfmutter.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/gewindeadapter-aus-pp-pvdf-oder-pfa-lose-gl-ueberwurfmutter-150x150.jpg 150w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/center><\/p>\n<h2><span class=\"ez-toc-section\" id=\"Is_Everything_Spinning_Now_%E2%80%93_Standards_Provide_Clarity\"><\/span>Is Everything Spinning Now? \u2013 Standards Provide Clarity!<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">To distinguish threads from one another, not only size and shape but also thread designation are defined in Europe by the European Committee for Standardization (CEN). The designations contain at least one abbreviation for the profile and one for the thread size. Thread size refers to the external diameter of the fastener, also called the nominal diameter. For example, <em>M12<\/em> is a metric ISO thread with a nominal diameter of 12 mm. If necessary, additional properties such as pitch may be included in the short designation. Thus, <em>Tr50 x 24<\/em> is a metric ISO trapezoidal thread with a nominal diameter of 50 mm and a pitch of 24 mm.<\/p>\n<p style=\"text-align: justify;\">Fine-thread designations are an exception, as specifying the pitch is mandatory.<\/p>\n<p><center><a href=\"https:\/\/www.rct-online.de\/en\/closure-elements\/caps\/caps-made-of-elastomers\/30590\/high-therm-stud-protection-cap-made-of-tpe\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-5445 size-full\" title=\"High-Therm Stud Protection Cap made of TPE\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/bolzenschutzkappe-aus-tpg.jpg\" alt=\"High-Therm Stud Protection Cap made of TPE\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/bolzenschutzkappe-aus-tpg.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/bolzenschutzkappe-aus-tpg-150x150.jpg 150w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a> <a href=\"https:\/\/www.rct-online.de\/en\/closure-elements\/plugs\/plugs-made-of-plastics\/30625\/threaded-protection-plug-made-of-ldpe\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-5446 size-full\" title=\"Threaded Protection Plug made of LDPE\" src=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/gewindeschutzstopfen-aus-ldpe.jpg\" alt=\"Threaded Protection Plug made of LDPE\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/gewindeschutzstopfen-aus-ldpe.jpg 300w, https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/gewindeschutzstopfen-aus-ldpe-150x150.jpg 150w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/a><\/center><\/p>\n<h2><span class=\"ez-toc-section\" id=\"Different_Countries_Different_Threads\"><\/span>Different Countries, Different Threads<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p style=\"text-align: justify;\">Things become more complex when thread designations from other countries are considered. In the United States, for example, such connections are designated in a different order. First comes the nominal diameter in inches, followed by the pitch in threads per inch, and finally the thread type. Thus, <em>NPT 1\/16&quot; \u2013 27<\/em> refers to a pipe thread for self-sealing connections with an external diameter of 1\/16 inch, equivalent to 7.895 mm, and a pitch of 27 threads per inch. In addition to NPT (National Pipe Taper), UNF (Unified National Fine Thread Series) is another major American thread type. It is a fine series and, like the NPT thread, has a flank angle of 60\u00b0.<\/p>\n<p style=\"text-align: justify;\">Like the European metric ISO form, the UNF series is used for standard screw connections.<\/p>\n<h2><span class=\"ez-toc-section\" id=\"The_Thread_Types_at_a_Glance\"><\/span>The Thread Types at a Glance<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<table data-tablestyle=\"MsoTableGrid\" data-tablelook=\"1184\">\n<tbody>\n<tr>\n<td><b>Short designation<\/b><\/td>\n<td><b>Flank angle<\/b><\/td>\n<td><b>Description<\/b><\/td>\n<\/tr>\n<tr>\n<td>G<\/td>\n<td>55\u00b0<\/td>\n<td>Cylindrical pipe thread for non-sealing connections in the thread<\/td>\n<\/tr>\n<tr>\n<td>GL<\/td>\n<td>30\u00b0<\/td>\n<td>Cylindrical round thread for glass threads<\/td>\n<\/tr>\n<tr>\n<td>M<\/td>\n<td>60\u00b0<\/td>\n<td>Metric ISO thread (single- and multi-start)<\/td>\n<\/tr>\n<tr>\n<td>NPT<\/td>\n<td>60\u00b0<\/td>\n<td>American: National Pipe Taper \u2013 pipe thread for self-sealing connections<\/td>\n<\/tr>\n<tr>\n<td>Pg<\/td>\n<td>80\u00b0<\/td>\n<td>Steel conduit thread<\/td>\n<\/tr>\n<tr>\n<td>R<\/td>\n<td>55\u00b0<\/td>\n<td>Tapered pipe thread for sealing connections in the thread<\/td>\n<\/tr>\n<tr>\n<td>Rd<\/td>\n<td>30\u00b0<\/td>\n<td>Cylindrical round thread (single- and multi-start)<\/td>\n<\/tr>\n<tr>\n<td>S<\/td>\n<td>30\u00b0<\/td>\n<td>Metric saw thread (single- and multi-start)<\/td>\n<\/tr>\n<tr>\n<td>SQ<\/td>\n<td>0\u00b0<\/td>\n<td>Square thread<\/td>\n<\/tr>\n<tr>\n<td>Tr<\/td>\n<td>30\u00b0<\/td>\n<td>Metric ISO trapezoidal thread (single- and multi-start)<\/td>\n<\/tr>\n<tr>\n<td>UNF<\/td>\n<td>60\u00b0<\/td>\n<td>American: Unified National Fine Thread Series<\/td>\n<\/tr>\n<tr>\n<td>W<\/td>\n<td>55\u00b0<\/td>\n<td>Tapered and cylindrical Whitworth thread<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr \/>\n<pre><strong>Image sources:<\/strong>\r\nHeader image | \u00a9 M. Schuppich \u2013 stock.adobe.com\r\nTool for cutting internal and external threads | \u00a9 Arthur Palmer \u2013 stock.adobe.com\r\nThread of a light bulb | \u00a9 Radiojon \u2013 de.wiktionary.org<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Screws, Nuts, and Threads \u2013 a Brief Overview What do a toothpaste tube, a jar of jam, a water bottle, and a light bulb have in common? A screw connection. The basic principle behind such a connection is interlocking threads. In this article, you will learn what this feature is, how it is manufactured, which &hellip;<\/p>\n","protected":false},"author":7,"featured_media":12305,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1,3028,2744],"tags":[3115,3645,3636,3644,3642,3646,3641,3635,3047,3643,3637,3638,3640,3639],"class_list":["post-15378","post","type-post","status-publish","format-standard","has-post-thumbnail","","category-all-articles","category-alle-beitraege-en","category-chemical-technology-in-action","tag-connector","tag-countersunk-screw","tag-double-nipple","tag-hexagon-nut","tag-hose-nozzle","tag-mini-en","tag-nuts","tag-olt-protection-cap","tag-schlauchtuelle-en","tag-screws","tag-thread","tag-thread-adapter","tag-thread-protection-plug","tag-thread-types"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v23.1 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>A Guide to Screws and Thread Types - Reichelt Chemietechnik Magazine<\/title>\n<meta name=\"description\" content=\"What types of threads are there and how do they differ? \u2192 Metric &amp; inch \u2705 Cylindrical &amp; tapered \u2705 G, GL, M, NPT, Rd, UNF &amp; more \u2705\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"A Guide to Screws and Thread Types - Reichelt Chemietechnik Magazine\" \/>\n<meta property=\"og:description\" content=\"What types of threads are there and how do they differ? \u2192 Metric &amp; inch \u2705 Cylindrical &amp; tapered \u2705 G, GL, M, NPT, Rd, UNF &amp; more \u2705\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/\" \/>\n<meta property=\"og:site_name\" content=\"Reichelt Chemietechnik Magazine\" \/>\n<meta property=\"article:published_time\" content=\"2020-08-21T09:26:35+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2025-12-11T08:26:43+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/verdreht-und-zugeschraubt.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"800\" \/>\n\t<meta property=\"og:image:height\" content=\"533\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"Dr. Karl-Heinz Heise\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Dr. Karl-Heinz Heise\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"10 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/\",\"url\":\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/\",\"name\":\"A Guide to Screws and Thread Types - Reichelt Chemietechnik Magazine\",\"isPartOf\":{\"@id\":\"https:\/\/www.rct-online.de\/magazin\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/#primaryimage\"},\"image\":{\"@id\":\"https:\/\/www.rct-online.de\/magazin\/en\/threads-and-thread-types\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/www.rct-online.de\/magazin\/wp-content\/uploads\/2020\/09\/verdreht-und-zugeschraubt.jpg\",\"datePublished\":\"2020-08-21T09:26:35+00:00\",\"dateModified\":\"2025-12-11T08:26:43+00:00\",\"author\":{\"@id\":\"https:\/\/www.rct-online.de\/magazin\/#\/schema\/person\/de5369aedc25d1f064871d823629e056\"},\"description\":\"What types of threads are there and how do they differ? 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