{"id":6753,"date":"2021-04-22T12:36:05","date_gmt":"2021-04-22T04:36:05","guid":{"rendered":"https:\/\/xzfastener.com\/?p=6753"},"modified":"2026-06-22T12:37:55","modified_gmt":"2026-06-22T04:37:55","slug":"what-does-8-8-mean-on-a-bolt-buyers-guide","status":"publish","type":"post","link":"https:\/\/xzfastener.com\/ru\/what-does-8-8-mean-on-a-bolt-buyers-guide\/","title":{"rendered":"What Does 8.8 Mean on a Bolt? Buyer\u2019s Guide"},"content":{"rendered":"<p>When buyers see \u201c8.8\u201d on a bolt head, it is easy to think it is just a factory mark. It is not. For metric bolts, <strong>8.8 is a mechanical property class<\/strong>. It tells you the bolt\u2019s strength level under the relevant metric fastener standard.<\/p>\n\n\n\n<p>This marking is common on industrial bolts used in machinery, steel frames, brackets, equipment bases, and construction assemblies.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">What 8.8 Means<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">The Two Numbers Explained<\/h3>\n\n\n\n<p>In simple terms, the first number shows the nominal tensile strength. The second number shows the yield ratio.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u041c\u0430\u0440\u043a\u0438\u0440\u043e\u0432\u043a\u0430<\/th><th>Meaning<\/th><th>Practical Value<\/th><\/tr><\/thead><tbody><tr><td>8<\/td><td>Approx. 800 MPa nominal tensile strength<\/td><td>Indicates the bolt\u2019s strength level<\/td><\/tr><tr><td>.8<\/td><td>Yield ratio of about 0.8<\/td><td>Approx. 640 MPa yield strength<\/td><\/tr><tr><td>8.8<\/td><td>Metric property class<\/td><td>Used for carbon steel or alloy steel bolts<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>So, a class 8.8 bolt is stronger than low-grade general fasteners, but it is not the same as 10.9 or 12.9. It is also <strong>not the same as SAE Grade 8<\/strong>, which belongs to the inch fastener system.<\/p>\n\n\n\n<p>Buyers can review common <a href=\"https:\/\/xzfastener.com\/ru\/fastener-type\/bolts\/\">bolt products<\/a> and <a href=\"https:\/\/xzfastener.com\/ru\/products-category\/high-strength-fasteners\/\">high-strength fasteners<\/a> when comparing strength grades.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Where 8.8 Bolts Are Used<\/h2>\n\n\n\n<p>Class 8.8 bolts are widely used because they offer a strong balance of strength, availability, and cost.<\/p>\n\n\n\n<p>Common applications include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Machinery frames<\/li>\n\n\n\n<li>Steel brackets<\/li>\n\n\n\n<li>Equipment bases<\/li>\n\n\n\n<li>\u0421\u0442\u0440\u043e\u0438\u0442\u0435\u043b\u044c\u043d\u044b\u0435 \u043a\u0440\u0435\u043f\u043b\u0435\u043d\u0438\u044f<\/li>\n\n\n\n<li>Agricultural machinery<\/li>\n\n\n\n<li>General industrial assemblies<\/li>\n\n\n\n<li>Medium-load structural connections<\/li>\n<\/ul>\n\n\n\n<p>For many standard industrial jobs, 8.8 is enough. For higher-load or compact assemblies, buyers may need 10.9 or 12.9 instead.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">What Buyers Should Not Assume<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">8.8 Does Not Define Everything<\/h3>\n\n\n\n<p>A bolt marked 8.8 only tells part of the story. It does not define the full product specification.<\/p>\n\n\n\n<p>You still need to confirm:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>RFQ Item<\/th><th>Why It Matters<\/th><\/tr><\/thead><tbody><tr><td>\u0421\u0442\u0430\u043d\u0434\u0430\u0440\u0442<\/td><td>DIN, ISO, EN, or drawing controls dimensions<\/td><\/tr><tr><td>Size<\/td><td>Diameter, length, pitch, and thread length<\/td><\/tr><tr><td>Finish<\/td><td>Zinc, black, HDG, zinc flake, or plain<\/td><\/tr><tr><td>Nut grade<\/td><td>Weak nuts can strip before the bolt performs<\/td><\/tr><tr><td>Washer type<\/td><td>Soft washers may reduce preload<\/td><\/tr><tr><td>\u041f\u0440\u0438\u043b\u043e\u0436\u0435\u043d\u0438\u0435<\/td><td>Load, vibration, corrosion, and temperature matter<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>For common items, buyers can start from <a href=\"https:\/\/xzfastener.com\/ru\/products-category\/standard-fasteners\/\">standard fasteners<\/a>. For coating choices, review <a href=\"https:\/\/xzfastener.com\/ru\/products-category\/various-coated-fasteners\/\">various coated fasteners<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Common Buyer Mistakes<\/h2>\n\n\n\n<p>Avoid these problems:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Ordering \u201c8.8 bolt\u201d without standard or size details.<\/li>\n\n\n\n<li>Matching 8.8 bolts with low-grade nuts.<\/li>\n\n\n\n<li>Assuming zinc plating improves strength.<\/li>\n\n\n\n<li>Using 8.8 in severe corrosion without coating review.<\/li>\n\n\n\n<li>Replacing 10.9 with 8.8 to reduce cost without engineering approval.<\/li>\n\n\n\n<li>Mixing metric 8.8 with inch Grade 8 specifications.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">RFQ Checklist for 8.8 Bolts<\/h2>\n\n\n\n<p>A clear RFQ should include:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Product standard<\/li>\n\n\n\n<li>Diameter, length, and thread pitch<\/li>\n\n\n\n<li>Full thread or partial thread<\/li>\n\n\n\n<li>Class 8.8 requirement<\/li>\n\n\n\n<li>Surface finish<\/li>\n\n\n\n<li>Matching nuts and washers<\/li>\n\n\n\n<li>Quantity and packaging<\/li>\n\n\n\n<li>Required inspection reports<\/li>\n<\/ol>\n\n\n\n<p>For special lengths, head styles, or thread requirements, use <a href=\"https:\/\/xzfastener.com\/ru\/products-category\/custom-non-standard-fasteners\/\">custom non-standard fasteners<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Final Advice<\/h2>\n\n\n\n<p>The \u201c8.8\u201d mark means the bolt has a defined metric strength class. It is useful, but it is not a complete specification.<\/p>\n\n\n\n<p>For safe purchasing, confirm the grade, standard, size, thread, finish, nut, washer, and working condition before production.<\/p>\n\n\n\n<p><\/p>","protected":false},"excerpt":{"rendered":"<p>When buyers see \u201c8.8\u201d on a bolt head, it is easy to think it is just a factory mark. It is not. For metric bolts, 8.8 is a mechanical property class. It tells you the bolt\u2019s strength level under the relevant metric fastener standard. This marking is common on industrial bolts used in machinery, steel [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[479],"tags":[504],"class_list":["post-6753","post","type-post","status-publish","format-standard","hentry","category-fastener-knowledge-library","tag-strength-grades-mechanical-properties"],"acf":[],"_links":{"self":[{"href":"https:\/\/xzfastener.com\/ru\/wp-json\/wp\/v2\/posts\/6753","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/xzfastener.com\/ru\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/xzfastener.com\/ru\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/xzfastener.com\/ru\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/xzfastener.com\/ru\/wp-json\/wp\/v2\/comments?post=6753"}],"version-history":[{"count":1,"href":"https:\/\/xzfastener.com\/ru\/wp-json\/wp\/v2\/posts\/6753\/revisions"}],"predecessor-version":[{"id":6754,"href":"https:\/\/xzfastener.com\/ru\/wp-json\/wp\/v2\/posts\/6753\/revisions\/6754"}],"wp:attachment":[{"href":"https:\/\/xzfastener.com\/ru\/wp-json\/wp\/v2\/media?parent=6753"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/xzfastener.com\/ru\/wp-json\/wp\/v2\/categories?post=6753"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/xzfastener.com\/ru\/wp-json\/wp\/v2\/tags?post=6753"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}