Specification summary of GB as applied to square channel-steel washer: the dimensions the standard controls, the tolerance and product grades it defines, the full specified size range, and the equivalent DIN/ISO/ASME designations.
GB — Scope
GB specifies the dimensions and tolerances of square channel-steel washer — gb/t 852 (series 083). Material, property class, surface finish and packaging are governed by separate documents in the same standards family (for example ISO 898-1 for the mechanical property classes of bolts and screws).
Tolerance & Product Grades
GB, alongside the related GB/T 852 entries on this site, specifies product grades (typically A or B for fine work and C for general engineering) and tolerance classes for the controlling dimensions. Choose the grade against the precision your application requires.
Dimensions Specified by GB
| For bolt size | Inner diameter d1 (mm) | Outer diameter d2 (mm) | Thickness t (mm) | Reference standard |
|---|---|---|---|---|
| M3 | 3.2 | 7.0 | 0.5 | ISO 7089 / GB/T 97.1 |
| M4 | 4.3 | 9.0 | 0.8 | ISO 7089 / GB/T 97.1 |
| M5 | 5.3 | 10.0 | 1.0 | ISO 7089 / GB/T 97.1 |
| M6 | 6.4 | 12.0 | 1.6 | ISO 7089 / GB/T 97.1 |
| M8 | 8.4 | 16.0 | 1.6 | ISO 7089 / GB/T 97.1 |
| M10 | 10.5 | 20.0 | 2.0 | ISO 7089 / GB/T 97.1 |
| M12 | 13.0 | 24.0 | 2.5 | ISO 7089 / GB/T 97.1 |
| M14 | 15.0 | 28.0 | 2.5 | ISO 7089 / GB/T 97.1 |
| M16 | 17.0 | 30.0 | 3.0 | ISO 7089 / GB/T 97.1 |
| M18 | 19.0 | 34.0 | 3.0 | ISO 7089 / GB/T 97.1 |
| M20 | 21.0 | 37.0 | 3.0 | ISO 7089 / GB/T 97.1 |
| M24 | 25.0 | 44.0 | 4.0 | ISO 7089 / GB/T 97.1 |
| M30 | 31.0 | 56.0 | 4.0 | ISO 7089 / GB/T 97.1 |
| M36 | 37.0 | 66.0 | 5.0 | ISO 7089 / GB/T 97.1 |
Equivalent Standards
Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Square Channel-Steel Washer — GB/T 852 (Series 083) page. Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.
Companion Standards
GB controls only the geometry of square channel-steel washer — gb/t 852 (series 083). The mechanical strength is set by ISO 898-1 (bolts and screws) or ISO 898-2 (nuts); the surface finish is governed by separate finish standards (e.g. ISO 4042 for electroplating). For corrosion testing, the relevant document is ISO 9227 (neutral salt spray).