Fasteners may seem universal, but differences in standard systems can significantly impact head dimensions, thread length, tolerances, mechanical properties, and acceptance requirements during cross-border procurement, drawing conversions, and alternative selection. This article summarizes common fasteners used in engineering. ISO, DIN, GB/T and ASME (often referred to as ANSI American Standard) Fastener StandardsThe corresponding relationships are provided for quick reference when communicating with designers, procurement staff, and suppliers.
Update Notice:As of May 2026,GB/T 5782-2025(Hex head bolts) and GB/T 5783-2025(Hex head bolts with full thread) have been available. February 1, 2026Implementation will involve revising to adopt ISO 4014:2022 and ISO 4017:2022 respectively. The current version should be checked first during procurement and drafting.
I. Comparison Table of International Standards for Common Fasteners
| Fastener Types | ISO International Standard (Current Version) | DIN Common Old Numbering/Common Names | GB/T Chinese Standard (Current Version) | ASME/ANSI American Standard Reference (Imperial System Series) |
|---|---|---|---|---|
| Hex head bolts, partially threaded | ISO 4014:2022 | DIN 931 | GB/T 5782-2025 | ASME B18.2.1 (Imperial Units) |
| Hex head bolts, fully threaded | ISO 4017:2022 | DIN 933 | GB/T 5783-2025 | ASME B18.2.1 (Imperial Units) |
| Type 1 hexagonal nut | ISO 4032:2023 | DIN 934 | GB/T 6170-2015 | ASME B18.2.2 (Imperial Units) |
| Thin hexagonal nuts | ISO 4035:2023 | DIN 439 | GB/T 6172.1-2016 | ASME B18.2.2 (Imperial Units) |
| Hex socket head cap screws | ISO 4762:2004 | DIN 912 | GB/T 70.1-2008 | ASME B18.3 (Imperial Units) |
| Reduced load capacity countersunk hex socket screws | ISO 10642:2026 | DIN 7991 | GB/T 70.3-2023 | ASME B18.3 (Imperial Units) |
| Flat washers, Class A | ISO 7089:2000 | DIN 125-A | GB/T 97.1-2002 | ASME B18.21.1 (Imperial Units) |
| Spring Washer | Confirmation required by application | DIN 127 | GB/T 93-2025 | ASME B18.21.1 (Imperial Units) |
| Hex socket set screw | ISO 4026:2026 | DIN 913 | GB/T 77-2007 | ASME B18.3 (Imperial Units) |
| Hex socket set screw | ISO 4027:2026 | DIN 914 | GB/T 78-2007 | ASME B18.3 (Imperial Units) |
| Hex socket head cap set screw | ISO 4028:2026 | DIN 915 | GB/T 79-2007 | ASME B18.3 (Imperial Units) |
| Hex socket set screw | ISO 4029:2026 | DIN 916 | GB/T 80-2007 | ASME B18.3 (Imperial Units) |
illustrate:The table shows common industry-standard correspondences for initial selection and price inquiry communication. The DIN column contains older designations or conventional names commonly used in the market; the ASME/ANSI columns listing B18.2.1, B18.2.2, B18.3, and B18.21.1 are imperial series references and are not equivalent to ISO, DIN, or GB/T metric products. Different standards and versions may differ in dimensional series, tolerances, performance grades, surface conditions, or inspection rules; they cannot be directly interchanged based solely on "corresponding standards." Formal procurement should be based on drawings, current standard texts, and technical requirements confirmed by both parties.
II. What are the differences between ISO, DIN, GB/T and American standards?
- ISO:Standards published by the International Organization for Standardization (ISO) are widely used in international trade for metric fasteners, facilitating cross-regional technical communication.
- DIN:German standards, with many classic designations such as DIN 933 and DIN 912, are still commonly used in purchasing practices, and some products have gradually adopted the corresponding EN ISO/ISO standards.
- GB/T:For Chinese national recommended standards, the current GB/T version should generally be given priority in domestic design, manufacturing, and acceptance.
- ASME/ANSI:The common dimensional standard system in North American projects is usually used with imperial UNC/UNF threads and inch dimensions, and cannot be directly mixed with metric ISO/DIN/GB/T products.
III. Key items that must be confirmed simultaneously during the selection process
| Confirm Project | Key points to check |
|---|---|
| Threaded system | Metric coarse/fine thread, or imperial UNC/UNF; diameter and pitch must match. |
| Size and tooth length | Nominal diameter, length, partial or full thread, head size, countersunk angle. |
| Materials and performance | Carbon steel strength grade, or stainless steel A2/A4 and performance grade (e.g., A2-70, A4-70). |
| Surface and environment | Requirements include natural color, passivation, and galvanization; suitable for indoor, coastal, chemical, or high-temperature environments. |
| Inspection documents | Dimensional reports, material certificates, mechanical properties, salt spray or batch traceability requirements. |
IV. Stainless Steel Fastener Material Selection Recommendations
For general indoor equipment, railings, and mechanical connections, load-bearing capacity and corrosion resistance requirements should be considered. A2 (common 304 series)Stainless steel fasteners are generally a better choice for coastal, humid, chlorine-containing, or more corrosive environments. A4 (common 316 series)Material. The actual project should also consider load, temperature, electrochemical corrosion risk, and maintenance cycle to determine the appropriate material.
5. How to clearly state your requirements when inquiring about prices or placing an order?
It is recommended to specify the following in the inquiry information:Standard number + Specifications + Pitch + Material/Performance grade + Surface requirements + Quantity + Inspection or packaging requirementsFor example: "ISO 4017, M10×30, A4-70, natural color, quantity 5,000 pieces, material certificate required." Clear technical information helps to quickly match inventory, reduce substitution errors, and improve delivery accuracy.
Conclusion
Fastener standard reference tables are suitable for quick-locating product lines, but reliable connections ultimately depend on the correct standard version, material properties, and application conditions. Haijin Stainless Steel can provide fasteners according to drawings or standard requirements.Stainless steel boltsWe offer selection and processing support for nuts, washers, and non-standard fasteners. Please feel free to provide specifications and application scenarios for consultation.
