Specification summary of GB/T 6172.1 as applied to thin hex nut: the dimensions the standard controls, the full specified size range, and the equivalent DIN/ISO/ASME designations.
GB/T 6172.1 — Scope
GB/T 6172.1 is "Fasteners — Hexagon thin nuts (chamfered) — Product grades A and B". GB/T 6172 1 is the Chinese national adoption of the same document.
Material, property class, surface finish and packaging are governed by separate documents — ISO 898-1 and ISO 898-2 for mechanical property classes, ISO 4042 for electroplated finishes.
Tolerance & Product Grades
GB/T 6172.1 defines product grades A and B. The grade sets how closely the finished part has to follow the nominal dimensions; it is not a strength rating.
Dimensions Specified by GB/T 6172.1
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e (mm) | Nut height m (mm) | Reference standard |
|---|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 6.01 | 1.8 | ISO 4035 / GB/T 6172 |
| M4 | 0.7 | 7.0 | 7.66 | 2.2 | ISO 4035 / GB/T 6172 |
| M5 | 0.8 | 8.0 | 8.79 | 2.7 | ISO 4035 / GB/T 6172 |
| M6 | 1.0 | 10.0 | 11.05 | 3.2 | ISO 4035 / GB/T 6172 |
| M8 | 1.25 | 13.0 | 14.38 | 4.0 | ISO 4035 / GB/T 6172 |
| M10 | 1.5 | 16.0 | 17.77 | 5.0 | ISO 4035 / GB/T 6172 |
| M12 | 1.75 | 18.0 | 20.03 | 6.0 | ISO 4035 / GB/T 6172 |
| M14 | 2.0 | 21.0 | 23.36 | 7.0 | ISO 4035 / GB/T 6172 |
| M16 | 2.0 | 24.0 | 26.75 | 8.0 | ISO 4035 / GB/T 6172 |
| M18 | 2.5 | 27.0 | 30.14 | 9.0 | ISO 4035 / GB/T 6172 |
| M20 | 2.5 | 30.0 | 33.53 | 10.0 | ISO 4035 / GB/T 6172 |
| M24 | 3.0 | 36.0 | 39.98 | 12.0 | ISO 4035 / GB/T 6172 |
| M30 | 3.5 | 46.0 | 50.85 | 15.0 | ISO 4035 / GB/T 6172 |
| M36 | 4.0 | 55.0 | 60.79 | 18.0 | ISO 4035 / GB/T 6172 |
Companion Standards
GB/T 6172.1 controls only the geometry of thin hex nut — gb/t 6172.1 / iso 4035 (series 055). The mechanical strength is set by ISO 898-1 (bolts, screws and studs) or ISO 898-2 (nuts); the surface finish is governed by separate finish standards such as ISO 4042 for electroplating. For corrosion testing, the relevant document is ISO 9227 (neutral salt spray).
When to Specify GB/T 6172.1
Choose GB/T 6172.1 for international engineering work and OEM supply where ISO standards are the contractual reference. It is the default modern specification for thin hex nut — gb/t 6172.1 / iso 4035 (series 055).
Custom manufacturing · Made to drawing
Need a nut to this standard in a non-standard size?
Parts built to GB T 6172 1 are already in the catalog, so a special is usually a variation on existing tooling rather than a new design — which is what keeps the cost down. Made by cold heading or tapping.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
