M16 Hex Bolt (GB/T 5783 / ISO 4017) are specified by thread size, length and head dimensions. The M16 row from the standard is reproduced below, followed by the drill sizes, spanner size and torque values used when installing this size.
M16 Dimensional Row (GB/T 5783 / ISO 4017)
| Size | Pitch (mm) | Nominal diameter d (mm) | Length L (mm) | Width across flats s (mm) | Width across corners e (mm) | Head height k (mm) |
|---|---|---|---|---|---|---|
| M16 | 2.0 | 16 | 100 | 24.0 | 26.75 | 10.0 |
Spanner & Drive for M16 Hex Bolt — GB/T 5783 / ISO 4017 (Series 010)
M16 Hex Bolt — GB/T 5783 / ISO 4017 (Series 010) have a width across flats of 24.0 mm — fit a 24.0 mm open-ended spanner or socket. Use a 6-point socket for tight clearances and to reduce rounding; for repeated assembly choose a torque wrench so the joint preload is repeatable.
Hole Sizes for M16
| Coarse-thread pitch (ISO 724) | 2 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 17.5 mm |
| Tapping drill, coarse thread | 14 mm |
Tightening Torque for M16
| Class 8.8 (dry, ~µ 0.125) | ≈ 210 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 295 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 355 Nm |
Indicative dry-joint values. Lubrication can lower the required torque by 15–25%. Always confirm against the joint design, especially when going up a strength class.
Proof Load & Strength for M16
| Tensile stress area As (ISO 898-1) | 157 mm² |
|---|---|
| Proof load, class 8.8 | 91 kN |
| Proof load, class 10.9 | 130 kN |
| Proof load, class 12.9 | 152 kN |
| Min. ultimate tensile, class 8.8 | 126 kN |
Proof load = stress area × proof stress per ISO 898-1. Design joints so the working preload stays below the proof load of the selected class.
M16 Hex Bolt — GB/T 5783 / ISO 4017 (Series 010) Weight
A steel M16 hex bolt at the listed 100 mm length weighs approximately 197 g each — about 197 kg per 1,000 pieces. Stainless A2/A4 weighs roughly the same (density 7.9–8.0 g/cm³). Actual weight varies slightly with head form, thread and finish; use this figure for freight estimation only.
Common Applications for M16 Hex Bolt — GB/T 5783 / ISO 4017 (Series 010)
M16 Hex Bolt — GB/T 5783 / ISO 4017 (Series 010) are commonly specified for medium-duty structural connections, automotive sub-frames and equipment chassis.
Mating Parts for M16
For M16, pair with a M16 hex nut (ISO 4032 / DIN 934) and, where used, a M16 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.
When to Step Up or Down from M16
When the joint preload approaches the proof load of M16 class 8.8, step up to M20 class 8.8 (or move to M16 class 10.9). When the joint is over-specified, M12 often saves weight and cost without losing the safety margin.