{"id":14616,"date":"2026-10-29T14:56:13","date_gmt":"2026-10-29T06:56:13","guid":{"rendered":"https:\/\/sunhyings.com\/?p=14616"},"modified":"2026-10-29T14:56:13","modified_gmt":"2026-10-29T06:56:13","slug":"astm-a563-nuts-for-a325-and-a490-bolts-selection-and-verification-checklist","status":"publish","type":"post","link":"https:\/\/sunhyings.com\/fr\/blog\/astm-a563-nuts-for-a325-and-a490-bolts-selection-and-verification-checklist\/","title":{"rendered":"\u00c9crous ASTM A563 pour boulons A325 et A490 : liste de contr\u00f4le pour la s\u00e9lection et la v\u00e9rification"},"content":{"rendered":"\n<style>\n.sunhy-blog-article { min-width: 0; max-width: 100%; overflow-wrap: break-word; }\n.sunhy-blog-article .sunhy-table-wrap {\n  display: block;\n  box-sizing: border-box;\n  width: 100%;\n  min-width: 0;\n  max-width: 100%;\n  overflow-x: auto;\n  -webkit-overflow-scrolling: touch;\n}\n.sunhy-blog-article .sunhy-table-wrap:focus-visible {\n  outline: 2px solid #1763a5;\n  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22px;background:#eef4f8;border:1px solid #d6e3ec;border-radius:8px}\n.sunhy-blog-article .sunhy-editorial-figure{margin:30px 0}.sunhy-blog-article .sunhy-editorial-figure img{display:block;width:100%;height:auto;aspect-ratio:3\/2;object-fit:contain;background:#eaf0f4;border-radius:10px}.sunhy-blog-article .sunhy-editorial-figure figcaption{font-size:13px;line-height:1.65;color:#617685;padding:11px 3px}.sunhy-blog-article .sunhy-related-reading{background:#f4f8fb}.sunhy-blog-article .sunhy-related-reading ul{margin:0}.sunhy-blog-article .sunhy-reference-box{border-top:1px solid #dce5eb;background:#f8fafb;padding:22px;margin:32px 0;border-radius:8px;font-size:14px}.sunhy-blog-article .sunhy-reference-box h2{font-size:22px;background:none;border:0;padding:0;margin-top:0}\n@media(max-width:767px){.sunhy-blog-article{font-size:16px;line-height:1.75}.sunhy-blog-article h2{font-size:23px;margin-top:32px;padding:10px 13px}.sunhy-blog-article h3{font-size:19px}.sunhy-blog-article .sunhy-toc ol{columns:1}.sunhy-blog-article .sunhy-summary-box,.sunhy-blog-article .sunhy-warning-box,.sunhy-blog-article .sunhy-procurement-note,.sunhy-blog-article .sunhy-related-reading,.sunhy-blog-article .sunhy-cta,.sunhy-blog-article .sunhy-toc{padding:19px}.sunhy-blog-article .sunhy-table-wrap th,.sunhy-blog-article .sunhy-table-wrap td{padding:11px 13px}}\n\n.sunhy-blog-article .sunhy-faq details{border:1px solid #d4e1eb;border-radius:8px;background:#f7fafc;padding:17px 20px;margin:12px 0}.sunhy-blog-article .sunhy-faq summary{cursor:pointer;font-weight:700;color:#183f5c;line-height:1.5}.sunhy-blog-article .sunhy-faq details p{margin:14px 0 0}.sunhy-blog-article .sunhy-faq summary:focus-visible{outline:3px solid #bc842d;outline-offset:4px}\n<\/style>\n<article class=\"sunhy-blog-article\">\n<aside class=\"sunhy-summary-box sunhy-added\" aria-label=\"Quick answer\"><p class=\"sunhy-box-label\">Quick answer<\/p><p>ASTM A563 nuts for A325 and A490 structural bolts must be selected from the combinations permitted by the applicable structural bolting specification. <strong>Matching the thread size or choosing a higher-strength nut is not enough.<\/strong> The correct choice depends on the bolt grade, Type 1 or Type 3 designation, coating condition, and the requirements governing the complete bolting assembly.<\/p><\/aside><nav class=\"sunhy-toc sunhy-added\" aria-label=\"Article contents\"><p class=\"sunhy-toc-title\">In this guide<\/p><ol><li><a href=\"#identify-the-bolt-before-selecting-the-nut\">Identify the Bolt Before Selecting the Nut<\/a><\/li><li><a href=\"#which-astm-a563-nut-grades-are-permitted\">Which ASTM A563 Nut Grades Are Permitted?<\/a><\/li><li><a href=\"#why-coatings-change-nut-compatibility\">Why Coatings Change Nut Compatibility<\/a><\/li><li><a href=\"#verify-nut-markings-threads-and-inspection-records\">Verify Nut Markings, Threads and Inspection Records<\/a><\/li><li><a href=\"#specify-the-correct-nuts-and-assemblies-in-an-rfq\">Specify the Correct Nuts and Assemblies in an RFQ<\/a><\/li><li><a href=\"#sunhy-faq-14616\">Frequently asked questions<\/a><\/li><\/ol><\/nav>\n<p>Under the 2025 <em>RCSC Specification for Structural Joints Using High-Strength Bolts<\/em>, different nut grades are permitted for plain and coated assemblies. For example, a plain A325 Type 1 bolt has more permitted ASTM A563 nut-grade options than the corresponding coated assembly. An A490 Type 3 bolt has a different requirement again.<\/p>\n<p>For procurement and quality control, this creates two separate questions: <strong>Is the nut grade permitted for the specified bolt configuration? And does the delivered nut meet the applicable product and assembly requirements?<\/strong> Both need answers before acceptance.<\/p>\n<h2 id=\"identify-the-bolt-before-selecting-the-nut\">Identify the Bolt Before Selecting the Nut<\/h2>\n<p>A325 and A490 remain familiar designations, but the structural heavy-hex bolt grades are now covered by ASTM F3125\/F3125M. ASTM A563\/A563M addresses the nuts, while the RCSC specification addresses their use in structural bolted joints. These standards perform different functions and should not be treated as interchangeable acceptance documents.<\/p>\n<p>RCSC 2025 identifies ASTM F3125 Grade A325 heavy-hex bolts as Group 120 and Grade A490 heavy-hex bolts as Group 150. These groups distinguish structural bolting strength categories; they are not ASTM A563 nut-grade designations.<\/p>\n<p>Before consulting a nut compatibility reference, establish the actual bolt configuration:<\/p>\n<ul>\n<li><strong>Bolt grade and style:<\/strong> F3125 Grade A325 or A490, and whether the item is a conventional heavy-hex bolt or a different matched-assembly product.<\/li>\n<li><strong>Bolt type:<\/strong> Type 1 or Type 3. Type 3 is associated with weathering steel and has distinct permitted mating components.<\/li>\n<li><strong>Nominal diameter and thread designation:<\/strong> These determine the required mating dimensions and thread compatibility.<\/li>\n<li><strong>Surface condition:<\/strong> Plain, hot-dip galvanized, mechanically galvanized, or another coating specifically permitted for the assembly.<\/li>\n<li><strong>Governing specification and edition:<\/strong> The project or purchase order may reference a particular ASTM or RCSC edition rather than the newest publication.<\/li>\n<\/ul>\n<p>A bolt described only as &#8220;A325, 3\/4 inch&#8221; does not provide enough information to finish the nut selection. The Type and coating condition could change the permitted grade, even if the nominal diameter remains the same.<\/p>\n<p>The nut style also matters. RCSC 2025 generally specifies heavy-hex nuts meeting ASTM A563 for the relevant heavy-hex structural bolt assemblies, subject to its stated substitution provisions. A standard hex nut with a familiar grade designation should not be accepted merely because it threads onto the bolt. The required nut geometry and dimensional standard must also match the specified assembly.<\/p>\n<p>For general background on <a href=\"https:\/\/sunhyings.com\/blog\/hex-nut-grades-explained\/\">hex nut grades and bolt compatibility<\/a>, see the separate SUNHY technical overview.<\/p>\n<p>The distinction matters beyond the nut itself. RCSC 2025 also requires the washer Type, where applicable, to correspond to the bolt Type. Procurement should therefore identify the bolt, nut, and washer as a compatible system rather than three unrelated catalogue items.<\/p>\n<h2 id=\"which-astm-a563-nut-grades-are-permitted\">Which ASTM A563 Nut Grades Are Permitted?<\/h2>\n<p>The starting point for an RCSC 2025 structural connection is Table 2.2, which establishes permitted ASTM A563 nut grades according to bolt Group, Type, and coating condition. The following explanation summarizes the selection consequences rather than replacing the governing table.<\/p>\n<h3>A325 Type 1: Plain and coated assemblies differ<\/h3>\n<p>For a plain ASTM F3125 Grade A325 Type 1 bolt, RCSC 2025 permits ASTM A563 Grades C, C3, D, DH, and DH3.<\/p>\n<p>That range of options is sometimes condensed into a manufacturer&#8217;s preferred combination. Grade DH, for example, is a common choice, but it is not the only grade permitted for the plain configuration under this edition.<\/p>\n<p>The situation changes when the A325 Type 1 bolt is coated in compliance with RCSC Section 2.8. Here, Table 2.2 identifies <strong>ASTM A563 Grade DH<\/strong>.<\/p>\n<p>A purchaser should not carry over a previously approved Grade C nut specification simply because the bolt grade and diameter remain unchanged. Changing the coating specification can change the permitted nut grade and the required assembly verification.<\/p>\n<h3>A490 Type 1: A narrower selection<\/h3>\n<p>For plain ASTM F3125 Grade A490 Type 1 bolts, RCSC 2025 permits Grades DH and DH3. For Type 1 assemblies coated in accordance with Section 2.8, the permitted ASTM A563 grade is DH.<\/p>\n<p>This distinction prevents two common errors.<\/p>\n<p>First, an A563 Grade C nut should not be approved for an A490 assembly by reasoning that it is acceptable for some A325 applications. The permitted combinations are different.<\/p>\n<aside class=\"sunhy-warning-box sunhy-added\" aria-label=\"Important specification check\"><p class=\"sunhy-box-label\">Important specification check<\/p><p>Second, a Grade DH3 nut permitted for a plain A490 Type 1 configuration should not automatically be assumed permissible for the corresponding coated configuration. Coated assemblies must be checked against their own specification conditions.<\/p><\/aside>\n<h3>Type 3 weathering bolts require their own matching decision<\/h3>\n<p>For plain Type 3 configurations, RCSC 2025 permits C3 or DH3 nuts with Group 120 (A325) bolts, and DH3 nuts with Group 150 (A490) bolts.<\/p>\n<p>The &#8220;3&#8221; designation is significant because weathering material selection is not solely a question of mechanical strength. A connection designed around weathering steel requires appropriate consideration of the mating components and their exposure conditions.<\/p>\n<p>The RCSC table does not provide a general coated Type 3 combination in these rows. Therefore, a purchaser should not extend the plain Type 3 permissions to a coated weathering assembly without an applicable specification basis and the required engineering approval.<\/p>\n<h3>Can ASTM A194 Grade 2H replace an A563 nut?<\/h3>\n<p>RCSC 2025 Section 2.3.2 permits ASTM A194 Grade 2H nuts as substitutes for ASTM A563 Grades C, D, and DH.<\/p>\n<p>This is a defined permission, not a blanket statement that any A194 nut can replace any A563 nut. In particular, it should not be extended automatically to C3 or DH3 weathering-grade requirements.<\/p>\n<p>Where Grade 2H is proposed, the buyer still needs to confirm the heavy-hex configuration, correct thread fit, applicable coating requirements, documentation, and complete assembly conditions. A permissible substitute grade does not eliminate the need to verify the delivered component.<\/p>\n<p>ASTM A563\/A563M also contains provisions concerning stronger-grade substitutions with notice to the purchaser. Those provisions must be read alongside any more specific structural-joint and purchase-order restrictions. A supplier&#8217;s proposed upgrade is not an automatic authorization to change a specified structural assembly.<\/p>\n<p>The practical selection rule is straightforward: <strong>identify a permitted grade first, then verify that the proposed nut has the required style, finish, and supporting evidence.<\/strong><\/p>\n<p class=\"sunhy-engineering-example sunhy-added\" data-example=\"1\">In an illustrative finish revision, an A325 Type 1 order changes from plain to a permitted coated assembly while the original nut line remains unchanged. A nut permitted for the plain configuration may not satisfy the coated row. Recheck the governing pairing, nut treatment and complete assembly evidence. The <a href=\"https:\/\/sunhyings.com\/blog\/hex-nut-grades-explained\/\">nut-grade guide<\/a> supplies background; the cited structural pairing table controls this decision.<\/p>\n\n<figure class=\"sunhy-editorial-figure sunhy-added\"><img loading=\"lazy\" src=\"https:\/\/sunhyings.com\/wp-content\/uploads\/2026\/10\/galvanized-a325-bolt-nut-fit-sunhy.webp\" alt=\"Galvanized heavy hex bolt, matching nut and washer inspection\" width=\"1536\" height=\"1024\" loading=\"lazy\" decoding=\"async\" class=\"wp-image-14639\" title=\"A563 nuts for a325 and a490 bolts \u2014 illustrative inspection view\" srcset=\"https:\/\/sunhyings.com\/wp-content\/uploads\/2026\/10\/galvanized-a325-bolt-nut-fit-sunhy.webp 1536w, https:\/\/sunhyings.com\/wp-content\/uploads\/2026\/10\/galvanized-a325-bolt-nut-fit-sunhy-800x533.webp 800w, https:\/\/sunhyings.com\/wp-content\/uploads\/2026\/10\/galvanized-a325-bolt-nut-fit-sunhy-1024x683.webp 1024w, https:\/\/sunhyings.com\/wp-content\/uploads\/2026\/10\/galvanized-a325-bolt-nut-fit-sunhy-768x512.webp 768w, https:\/\/sunhyings.com\/wp-content\/uploads\/2026\/10\/galvanized-a325-bolt-nut-fit-sunhy-18x12.webp 18w\" sizes=\"auto, (max-width: 1536px) 100vw, 1536px\" \/><figcaption>Galvanized heavy hex bolt, matching nut and washer inspection. Illustrative arrangement; appearance does not establish grade or product conformity.<\/figcaption><\/figure><h2 id=\"why-coatings-change-nut-compatibility\">Why Coatings Change Nut Compatibility<\/h2>\n<p>Coating selection can alter the mechanical behavior of a bolting assembly even when the bolt and nut have unchanged nominal sizes.<\/p>\n<p>For galvanized or certain zinc-flake-coated assemblies, the coating adds material to the mating thread surfaces. To accommodate that thickness, structural nuts are commonly manufactured with intentionally oversized internal threads, known as <em>overtapping<\/em>.<\/p>\n<p>Overtapping creates clearance for the coated bolt threads, but it also reduces the amount of thread engagement. This matters because the nut must resist thread stripping while the bolt is subjected to the tensile loading associated with installation and service.<\/p>\n<p>A nut that is adequate in a plain-thread configuration cannot automatically be treated as adequate after its internal threads have been enlarged. The relevant nut strength requirements, coating conditions, and assembly tests must be satisfied.<\/p>\n<h3>Hot-dip galvanizing and mechanical galvanizing are not interchangeable processes<\/h3>\n<p>RCSC 2025 Section 2.8 distinguishes hot-dip galvanizing from mechanical galvanizing. The two processes have separate specification requirements, and the threaded components of a galvanized assembly must use the same applicable process.<\/p>\n<p>For Group 120\/A325 heavy-hex bolting, permitted galvanized assemblies require careful control of the corresponding nut treatment and lubrication. Hot-dip galvanized nuts are overtapped according to ASTM A563 requirements, and mechanically galvanized nuts have their own applicable overtapping requirements.<\/p>\n<p>The assembly should not be created simply by purchasing galvanized bolts from one source and nuts from another without establishing responsibility for compatibility testing.<\/p>\n<p>RCSC commentary explains why galvanized structural bolting is treated as a matched assembly. Changes to coating thickness, thread engagement, and lubrication can affect the ability to achieve the required tightening behavior without thread damage or stripping.<\/p>\n<p>For a galvanized assembly governed by these requirements, the supplier must provide the applicable matched and tested components. If separately sourced components are proposed, the purchaser must establish how the necessary assembly verification and certification responsibilities will be fulfilled.<\/p>\n<h3>A490 coating restrictions need precise wording<\/h3>\n<p>A490\/Group 150 heavy-hex bolts are not permitted to be hot-dip galvanized or mechanically galvanized under RCSC 2025.<\/p>\n<p>That restriction should not be simplified into &#8220;A490 bolts cannot be coated.&#8221;<\/p>\n<p>Section 2.8 separately permits qualifying zinc-flake coating systems complying with the specified ASTM F3393 classification and other applicable conditions. This is a defined coating route, not a general permission to use any commercial zinc-flake, zinc-plated, or galvanized finish.<\/p>\n<p>For a proposed coated A490 assembly, the buyer should verify the coating standard and classification, the supplier&#8217;s assembly configuration, the required treatment of the nuts, and the relevant product and assembly evidence.<\/p>\n<p>Older technical literature may refer to different zinc-flake standards used in previous editions. A historic designation or a supplier&#8217;s informal coating description is not sufficient evidence that a delivered assembly conforms to the requirements of RCSC 2025.<\/p>\n<h3>Hypothetical example: Changing the finish changes the nut decision<\/h3>\n<p>Assume an EPC purchaser is preparing a request for 3\/4-inch ASTM F3125 Grade A325 Type 1 heavy-hex bolts.<\/p>\n<p>The original specification calls for plain bolts, and the supplier offers plain ASTM A563 Grade C heavy-hex nuts. Grade C is one of the permitted A563 grades for this plain combination under RCSC 2025, provided the other product and project requirements are satisfied.<\/p>\n<p>The design is then revised to require hot-dip galvanized bolting.<\/p>\n<p>The buyer cannot simply keep the original Grade C nut specification and add galvanizing. Under the coated Group 120 Type 1 conditions in RCSC Table 2.2, the specified A563 grade is DH.<\/p>\n<p>The revised procurement request must address the permitted Grade DH nut, correct galvanizing process, overtapped thread configuration, lubrication, matching components, and applicable rotational-capacity evidence.<\/p>\n<p>The bolt diameter has not changed. The required selection and verification work has.<\/p>\n<p>This assumed case illustrates a specification decision; it is not a recorded project, a tested product result, or proof of any supplier&#8217;s manufacturing capability.<\/p>\n<h2 id=\"verify-nut-markings-threads-and-inspection-records\">Verify Nut Markings, Threads and Inspection Records<\/h2>\n<p>A permitted grade on a purchase order establishes what should be supplied. Receiving inspection establishes whether the actual shipment matches the specified requirements.<\/p>\n<p>These are related but different decisions, and neither can be completed by checking the nut grade marking alone.<\/p>\n<h3>Confirm the nut&#8217;s identity<\/h3>\n<p>Inspect the nut for the applicable grade identification and manufacturer&#8217;s identification, using the marking requirements of the governing standard and the permitted marking arrangements.<\/p>\n<p>The markings help identify whether the supplied item is represented as Grade C, C3, D, DH, DH3, or another permitted specification grade. A194 Grade 2H has its own designation and should not be silently relabelled as A563 DH.<\/p>\n<p>The inspector must also confirm the required heavy-hex style and nominal size. The grade marking is useful evidence of identification, but it does not independently establish that the nut passed every chemical, hardness, proof-load, or dimensional acceptance requirement.<\/p>\n<p>If the marking is missing, inconsistent with the purchase order, or not traceable to the supplier&#8217;s documentation, the discrepancy should be resolved before the component is accepted for the specified structural assembly.<\/p>\n<h3>Verify thread fit against the actual finish<\/h3>\n<p>Thread compatibility is more than matching the nominal diameter and pitch.<\/p>\n<p>A plain nut and an overtapped coated nut can have different finished internal-thread conditions. That difference may be intentional and necessary for the specified assembly.<\/p>\n<p>Receiving inspection should confirm the relevant thread designation, applicable dimensional requirements, coating condition, and whether overtapping is required. Where gauging or dimensional records are supplied, their acceptance basis should correspond to the specified finished nut condition rather than an assumed uncoated configuration.<\/p>\n<p>An assembler should not attempt to correct a questionable fit by uncontrolled thread chasing, removal of the coating, or applying an unapproved lubricant. Such actions could change the supplied assembly condition and invalidate the basis of its verification.<\/p>\n<p>A bolt and nut turning freely by hand does not demonstrate that the assembled fastener system meets the specified load, coating, or installation requirements.<\/p>\n<h3>Distinguish product testing from assembly verification<\/h3>\n<p>Three forms of evidence are especially important, but they establish different things.<\/p>\n<div class=\"sunhy-table-wrap\" role=\"region\" aria-label=\"Comparison of structural nut product and assembly verification evidence\" tabindex=\"0\">\n<table>\n<thead>\n<tr><th scope=\"col\">Evidence<\/th><th scope=\"col\">What it helps establish<\/th><th scope=\"col\">What it does not establish alone<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td>Nut product conformity and test report<\/td><td>Compliance with applicable ASTM A563 or A194 material, mechanical, and dimensional requirements, within the reported scope<\/td><td>That the nut was tested as part of the actual supplied bolt\u2013nut\u2013washer assembly<\/td><\/tr>\n<tr><td>Rotational-capacity evidence, where required<\/td><td>Compatibility of the applicable coated assembly, including its lubricant and capacity to undergo the specified rotation without unacceptable failure<\/td><td>That the completed structural joint was installed and inspected correctly<\/td><\/tr>\n<tr><td>Pre-installation verification records, where required by the installation method<\/td><td>That the specified assembly and installation procedure demonstrate the required pretensioning behavior before installation<\/td><td>That every nut lot independently satisfies all product specification requirements<\/td><\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>ASTM F606\/F606M provides mechanical testing methods for threaded fastener products, including applicable nut proof-load and hardness testing. The product standard and governing purchase requirements determine the actual acceptance criteria.<\/p>\n<p>A proof-load test evaluates the nut&#8217;s response to a defined axial test load under specified conditions. It is not the same as the pretension achieved in a completed structural joint. Similarly, a hardness result cannot automatically be substituted for the required proof-load evidence.<\/p>\n<p>The exact numerical test limits, sampling arrangements, and acceptance conditions must be checked against the contractual ASTM A563\/A563M edition and the particular product configuration. Published data from an older edition should not be presented as current ASTM A563\/A563M-26 acceptance requirements without verification.<\/p>\n<p>RCSC 2025 Section 2.9 addresses the availability of applicable product and assembly test reports to the Engineer of Record and Inspector. Pre-installation verification is separately associated with the relevant installation procedure. These responsibilities should remain distinct in the project&#8217;s inspection plan.<\/p>\n<h3>Use receiving inspection to close actual discrepancies<\/h3>\n<p>Consider a shipment labelled &#8220;A563 DH heavy hex nuts&#8221; for coated A325 Type 1 bolts.<\/p>\n<p>The receiving decision should not stop at the DH identification. The inspector should determine whether the specified coating was applied, whether the threads were processed for that coating, whether the required lubrication and matched-assembly conditions were maintained, and whether the required records are available.<\/p>\n<p>The documentation should identify the actual supplied product and the applicable lot or other traceability identifiers required by the purchase order. Traceability statements must be consistent with the records; a generic catalogue certificate is not proof of testing for a particular delivered lot.<\/p>\n<p>If a record refers to a different grade, finish, or assembly configuration, the buyer should request clarification or hold the affected material rather than infer compliance from visual similarity.<\/p>\n<p class=\"sunhy-engineering-example sunhy-added\" data-example=\"2\">A hypothetical delivery contains DH-marked nuts with no clear finished-thread or lubricant basis for the ordered coated assembly. The grade mark does not resolve those conditions. Reconcile the product records, coating, overtapping and matched components, retaining the <a href=\"https:\/\/sunhyings.com\/blog\/traceability-for-automotive-fasteners\/\">lot-specific evidence relationship<\/a>. Do not correct an unexplained tight fit by uncontrolled thread chasing.<\/p>\n\n<h2 id=\"specify-the-correct-nuts-and-assemblies-in-an-rfq\">Specify the Correct Nuts and Assemblies in an RFQ<\/h2>\n<p>A useful RFQ does more than state &#8220;ASTM A563 nuts for A325 bolts.&#8221; It defines enough information for a supplier to propose the correct items and for the purchaser to verify the delivered assembly without making assumptions.<\/p>\n<p>The following checklist separates selection information from verification evidence.<\/p>\n<div class=\"sunhy-table-wrap\" role=\"region\" aria-label=\"Structural bolt and nut RFQ and receiving inspection checklist\" tabindex=\"0\">\n<table>\n<thead>\n<tr><th scope=\"col\">RFQ or receiving item<\/th><th scope=\"col\">What to specify or confirm<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td>Governing documents<\/td><td>Applicable ASTM F3125\/F3125M, ASTM A563\/A563M, RCSC, and project editions<\/td><\/tr>\n<tr><td>Bolt configuration<\/td><td>Grade A325 or A490, Type 1 or Type 3, style, nominal diameter, length, and thread designation<\/td><\/tr>\n<tr><td>Nut requirement<\/td><td>Permitted A563 grade or approved substitute, heavy-hex style, size, and marking requirements<\/td><\/tr>\n<tr><td>Washer configuration<\/td><td>Required washer specification, Type, finish, and special configuration where applicable<\/td><\/tr>\n<tr><td>Coating<\/td><td>Exact coating method, governing coating specification, classification, and finish condition<\/td><\/tr>\n<tr><td>Thread treatment<\/td><td>Whether overtapping is required and how finished-thread conformity will be verified<\/td><\/tr>\n<tr><td>Assembly condition<\/td><td>Matched component requirements, specified lubrication, packaging, and handling controls<\/td><\/tr>\n<tr><td>Acceptance evidence<\/td><td>Product conformity reports, applicable lot identification, and assembly test records required for the configuration<\/td><\/tr>\n<tr><td>Changes and substitutions<\/td><td>Written identification and approval of any departure from the specified nut grade, finish, or assembly<\/td><\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>Not every project requires an identical document package. The evidence requirement should follow the applicable standards, connection and installation conditions, and contract documents. A buyer can request additional traceability or inspection records, but those requests should not be represented as universal ASTM requirements.<\/p>\n<p>For coated assemblies, it is useful to ask the supplier to identify who is responsible for the complete assembly verification, rather than simply providing separate bolt, nut, and washer certificates.<\/p>\n<p>For a plain A490 Type 3 assembly, the focus changes to confirming the permitted weathering-grade nut and mating component configuration. Asking for an unrelated galvanizing record would not solve the relevant acceptance question.<\/p>\n<p><strong>The final procurement decision should follow a clear sequence:<\/strong> establish the bolt identity, confirm the permitted nut configuration, verify the coating and thread conditions, and review the actual product and assembly evidence. If a proposed substitution changes that basis, obtain the necessary specification and project approval before accepting it.<\/p>\n<p>SUNHY&#8217;s <a href=\"https:\/\/sunhyings.com\/fasteners\/bolts\/structural-bolts\/\">structural bolt product information<\/a> may serve as a starting point for a technical inquiry. Buyers should provide the bolt grade and Type, nut grade, dimensions, finish, quantity, and required documentation for a configuration-specific review. Availability, manufacturing capability, and conformity must be confirmed for the particular order rather than inferred from this guide.<\/p>\n<aside class=\"sunhy-procurement-note sunhy-added\"><p>To provide those details, buyers can <a href=\"https:\/\/sunhyings.com\/contact-us\/\">submit a technical inquiry<\/a>.<\/p><\/aside>\n<h3>Technical reference basis<\/h3>\n<ul>\n<li>Research Council on Structural Connections (RCSC). <a href=\"https:\/\/www.boltcouncil.org\/files\/2025RCSCSpecification.pdf\" target=\"_blank\" rel=\"noopener noreferrer nofollow\"><em>Specification for Structural Joints Using High-Strength Bolts<\/em><\/a>, June 5, 2025. Particularly the bolt Group definitions, permitted nut-grade requirements, coated assembly provisions, and test-report requirements.<\/li>\n<li>ASTM International. <a href=\"https:\/\/store.astm.org\/a0563_a0563m-26.html\" target=\"_blank\" rel=\"noopener noreferrer nofollow\"><em>ASTM A563\/A563M-26 \u2014 Standard Specification for Carbon and Alloy Steel Nuts (Inch and Metric)<\/em><\/a>.<\/li>\n<li>ASTM International. <a href=\"https:\/\/store.astm.org\/f3125_f3125m-26.html\" target=\"_blank\" rel=\"noopener noreferrer nofollow\"><em>ASTM F3125\/F3125M-26 \u2014 Standard Specification for High Strength Structural Bolts and Assemblies<\/em><\/a>.<\/li>\n<li>ASTM International. <a href=\"https:\/\/store.astm.org\/f0606_f0606m-26a.html\" target=\"_blank\" rel=\"noopener noreferrer nofollow\"><em>ASTM F606\/F606M-26a \u2014 Standard Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners, Washers, Direct Tension Indicators, and Rivets<\/em><\/a>.<\/li>\n<\/ul>\n<p>The 2025 RCSC document is the edition used for the pairing explanations in this guide. Actual acceptance requirements must follow the standards and editions governing the project; this article does not reproduce the complete ASTM product specifications.<\/p>\n<aside class=\"sunhy-related-reading sunhy-added\" aria-label=\"Related technical reading\"><p class=\"sunhy-box-label\">Related technical reading<\/p><ul><li><a href=\"https:\/\/sunhyings.com\/fasteners\/bolts\/structural-bolts\/\">Structural bolt specification and enquiry<\/a><\/li><li><a href=\"https:\/\/sunhyings.com\/blog\/hex-nut-grades-explained\/\">Hex nut grades and selection checks<\/a><\/li><li><a href=\"https:\/\/sunhyings.com\/blog\/hex-nut-dimensions-guide\/\">Nut dimensions and head-clearance checks<\/a><\/li><\/ul><\/aside>\n<section class=\"sunhy-faq sunhy-added\" aria-labelledby=\"sunhy-faq-14616\"><h2 id=\"sunhy-faq-14616\">Frequently asked questions<\/h2><details><summary>Which A563 nut should be used with A325?<\/summary><p>Identify bolt Type and finish first, then use the permitted grade in the governing table. Plain and coated combinations do not have identical options.<\/p><\/details><details><summary>Can A194 2H replace every A563 nut?<\/summary><p>No. The cited RCSC substitution permission is limited to specified A563 grades. Do not extend it automatically to weathering-grade requirements.<\/p><\/details><details><summary>Does a stronger nut automatically approve a substitution?<\/summary><p>No. Check the applicable grade permission, style, thread condition, coating, documentation and any required approval for the actual assembly.<\/p><\/details><\/section>\n<\/article>\n<script type=\"application\/ld+json\">{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"@id\": \"https:\/\/sunhyings.com\/blog\/astm-a563-nuts-for-a325-and-a490-bolts-selection-and-verification-checklist\/#faq\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"Which A563 nut should be used with A325?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Identify bolt Type and finish first, then use the permitted grade in the governing table. 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V\u00e9rifiez les grades autoris\u00e9s, le surtaraudage, le remplacement par A194 2H et les enregistrements d'inspection.<\/p>","protected":false},"author":1,"featured_media":14647,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[35],"tags":[],"class_list":["post-14616","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-selection-comparison"],"_links":{"self":[{"href":"https:\/\/sunhyings.com\/fr\/wp-json\/wp\/v2\/posts\/14616","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sunhyings.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sunhyings.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sunhyings.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/sunhyings.com\/fr\/wp-json\/wp\/v2\/comments?post=14616"}],"version-history":[{"count":3,"href":"https:\/\/sunhyings.com\/fr\/wp-json\/wp\/v2\/posts\/14616\/revisions"}],"predecessor-version":[{"id":14714,"href":"https:\/\/sunhyings.com\/fr\/wp-json\/wp\/v2\/posts\/14616\/revisions\/14714"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/sunhyings.com\/fr\/wp-json\/wp\/v2\/media\/14647"}],"wp:attachment":[{"href":"https:\/\/sunhyings.com\/fr\/wp-json\/wp\/v2\/media?parent=14616"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sunhyings.com\/fr\/wp-json\/wp\/v2\/categories?post=14616"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sunhyings.com\/fr\/wp-json\/wp\/v2\/tags?post=14616"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}