{"id":6433,"date":"2025-09-15T14:48:55","date_gmt":"2025-09-15T12:48:55","guid":{"rendered":"https:\/\/www.gns-nederland.nl\/?p=6433"},"modified":"2026-09-09T15:25:22","modified_gmt":"2026-09-09T13:25:22","slug":"thread-on-fittings-how-about-it","status":"publish","type":"post","link":"https:\/\/www.gns-nederland.nl\/en\/thread-on-fittings-how-about-it\/","title":{"rendered":"Thread on fittings: what you need to know."},"content":{"rendered":"<p class=\"isSelectedEnd\">We regularly receive questions about the threads used on different types of fittings. Is the internal or external thread tapered or parallel? Can different thread types be used together?<\/p>\n<p class=\"isSelectedEnd\">Although there are, of course, exceptions to the rule, the following applies to the most commonly used thread types, <strong>BSPT<\/strong> <em>(British Standard Pipe Taper)<\/em> and <strong>NPT<\/strong> <em>(National Pipe Taper)<\/em>:<\/p>\n<ul data-spread=\"false\">\n<li>The different thread types are <strong>not interchangeable<\/strong>. An exception is a combination of internal BSPP or BSPG (parallel) thread with external BSPT R (tapered) thread. You might expect BSPT with parallel Rp and Rs threads (which can be confusing when dealing with BSPT threads) to also fit BSPP\/G (parallel) threads. However, this is not the case due to differences in nominal diameter.<\/li>\n<li><strong>BSPT fittings<\/strong> have a <strong>parallel internal thread (Rp) and a tapered external thread (R)<\/strong> as standard. <strong>NPT fittings<\/strong> have <strong>tapered internal and external threads<\/strong> as standard.<\/li>\n<li>Although the internal and external threads of BSPT and NPT fittings engage with each other and may therefore appear to seal on the thread, the use of a <strong>sealant or thread-sealing tape is essential<\/strong> to achieve a leak-tight connection.<\/li>\n<\/ul>\n<h2><span style=\"color: #de5307;\"><strong>BSP or NPT?<\/strong><\/span><\/h2>\n<p class=\"isSelectedEnd\">Both BSP (&#8220;Gas thread&#8221;) and NPT are thread standards used on pipes and pipe fittings to connect them together. Neither is inherently better than the other. The choice between BSP and NPT is primarily determined by geographical location. Roughly speaking:<\/p>\n<ul data-spread=\"false\">\n<li><strong>BSP<\/strong> is mainly used in the UK, Europe, Asia, Australia, New Zealand and South Africa \u2014 and in most other countries worldwide.<\/li>\n<li><strong>NPT<\/strong> is mainly used in the <strong>USA and Canada<\/strong>.<\/li>\n<\/ul>\n<h2><span style=\"color: #de5307;\"><strong>BSPT vs. NPT<\/strong><\/span><\/h2>\n<p class=\"isSelectedEnd\">Both BSPT and NPT use tapered threads, but they differ in the number of threads per inch. The <strong>1\/2&#8243; and 3\/4&#8243; sizes<\/strong> are an exception, as they have the same number of threads per inch.<\/p>\n<p class=\"isSelectedEnd\">However, the threads differ in two other fundamental respects. With <strong>NPT<\/strong>, the thread crests and roots are flat, whereas <strong>BSP<\/strong> threads have rounded crests and roots. Secondly, the thread angle is <strong>60\u00b0 for NPT<\/strong> and <strong>55\u00b0 for BSP<\/strong>.<\/p>\n<h2><span style=\"color: #de5307;\"><strong>BSPT on NPT and vice versa?<\/strong><\/span><\/h2>\n<p class=\"isSelectedEnd\">Although an NPT fitting may appear to fit into a BSPT fitting in some cases (or vice versa), such connections <strong>will NOT provide a reliable seal<\/strong> due to the differences described above.<\/p>\n<p class=\"isSelectedEnd\"><strong>GNS supplies thread adapters that make it possible to connect two otherwise incompatible thread types.<\/strong><\/p>\n<p class=\"isSelectedEnd\">Click <span style=\"color: #de5307;\"><a style=\"color: #de5307;\" href=\"https:\/\/www.gns-nederland.nl\/wp-content\/uploads\/2020\/02\/Schroefdraden-soorten-en-kenmerken-Screw-threads-types-and-characteristics.pdf\"><strong><span class=\"text-token-text-primary cursor-text rounded-sm\" data-placeholder-token=\"true\">here<\/span><\/strong><\/a> <\/span>for an overview of the most common thread types, including their abbreviations, meanings and characteristics, or <span style=\"color: #de5307;\"><a style=\"color: #de5307;\" href=\"mailto:info@gns-nederland.nl\"><strong><span class=\"text-token-text-primary cursor-text rounded-sm\" data-placeholder-token=\"true\">here<\/span><\/strong><\/a>\u00a0<\/span>to email us with your question.<\/p>\n<p>* <strong>Taper:<\/strong> gradually narrowing; conical.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>We regularly receive questions about the threads used on different types of fittings. Is the internal or external thread tapered or parallel? Can different thread types be used together? Although there are, of course, exceptions to the rule, the following applies to the most commonly used thread types, BSPT (British Standard Pipe Taper) and NPT [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":2225,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_relevanssi_hide_post":"","_relevanssi_pin_for_all":"","_relevanssi_pin_keywords":"","_relevanssi_unpin_keywords":"","_relevanssi_related_keywords":"","_relevanssi_related_include_ids":"","_relevanssi_related_exclude_ids":"","_relevanssi_related_no_append":"","_relevanssi_related_not_related":"","_relevanssi_related_posts":"","_relevanssi_noindex_reason":"","footnotes":""},"categories":[14],"tags":[],"class_list":["post-6433","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.0 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Thread on fittings: what you need to know. - GNS Nederland<\/title>\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.gns-nederland.nl\/en\/thread-on-fittings-how-about-it\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Thread on fittings: what you need to know. - GNS Nederland\" \/>\n<meta property=\"og:description\" content=\"We regularly receive questions about the threads used on different types of fittings. 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