GB / DIN / ANSI Befestigungsnormen: Exportleitfaden

Overview of Major Fastener Standards Systems

Fastener standards vary significantly between regions. DIN (Deutsches Institut für Normung) is the European standard system widely adopted globally—DIN 933 for full thread hex bolts and DIN 931 for partial thread are the most referenced standards in Africa and Asia. GB (Guobiao, Chinese national standard, prefixed GB/T or GB) has become increasingly important as Chinese manufacturers dominate global fastener supply. ANSI/ASME standards (American National Standards Institute) use inch-based measurements—ANSI B18.2.1 for hex bolts and B18.6 for machine screws are the primary references for North American and some Gulf markets. UNC (Unified National Coarse) thread is the standard coarse thread in inch-system fasteners, while UNF (Unified National Fine) is used when finer thread control is needed. For export fastener procurement, always specify the exact standard number, not just the type, to avoid dimensional mismatches.

GB Standard Stainless Steel Bolts: Specifications and Export

GB standard stainless steel hex bolts (GB/T 5782/5783 for hex bolts, GB/T 6170 for nuts) are the Chinese equivalent of DIN standards. GB/T 5782 corresponds to DIN 931 (partial thread) and GB/T 5783 corresponds to DIN 933 (full thread). The dimensional tolerances and mechanical properties are essentially harmonized with ISO standards. For export to Africa, GB standard fasteners are commonly accepted, particularly in markets where Chinese infrastructure projects have established the standard. Our factory stocks both GB and DIN marked bolts for flexible fulfillment. For SABS-regulated markets (South Africa, SADC), ensure the fastener is certified to the relevant SABS standard, which may reference ISO or DIN as the base standard.

DIN Standard Bolts: Global Reference Standard

DIN standard stainless steel bolts remain the de facto global reference for fastener specifications. Key DIN standards: DIN 933 (full thread hex bolt, ISO 4017 equivalent), DIN 931 (partial thread hex bolt, ISO 4014 equivalent), DIN 934 (hex nut, ISO 4032 equivalent), DIN 125 (flat washer, ISO 7089 equivalent). While DIN standards are now technically superseded by ISO equivalents under the Vienna Agreement, the DIN designation persists in commercial usage because engineers and buyers recognize it. For fastener export, specifying DIN 933 Grade A4-70 provides universal clarity—A4 indicates 316 stainless (A2 is 304), and 70 indicates 700 MPa minimum tensile. The metric thread pitch must also be specified: coarse (default) or fine.

UNC Thread and Imperial Standard Fasteners

UNC (Unified National Coarse) thread stainless steel bolts and imperial standard hex nuts remain common in markets influenced by American equipment and specifications. The UNC thread profile (60-degree angle, rounded root) provides faster assembly and better resistance to cross-threading compared to metric coarse threads. UNC bolts are sized in inches—1/4" through 1-1/2" diameter are common stock items. UNF (Unified National Fine) offers more thread engagement in thin materials and better fatigue resistance. Our imperial standard export line includes UNC 304/316 stainless bolts and nuts with American Society of Mechanical Engineers (ASME) dimensional compliance. For projects specifying ANSI B18.2.1 bolts, we can supply to those exact dimensions with appropriate certifications.

Standard Comparison: DIN vs GB vs ANSI

Frequently Asked Questions