M30 is one of the standard coarse-thread sizes for stud bolt, double-end under GB/T 901 / DIN 939. The sections below reproduce the dimensional row, list the matching tools and hole sizes, and summarize where this size is normally specified.
M30 Dimensional Row (GB/T 901 / DIN 939)
| Thread size | Pitch (mm) | Length L (mm) | Engagement depth bm (mm) | Material | Reference standard |
|---|---|---|---|---|---|
| M30 | 3.5 | 240 | 45 | Cl. 8.8 alloy steel | DIN 939 / GB/T 901 |
Hole Sizes for M30
| Coarse-thread pitch (ISO 724) | 3.5 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 33 mm |
| Tapping drill, coarse thread | 26.5 mm |
Tightening Torque for M30
| Class 8.8 (dry, ~µ 0.125) | ≈ 1400 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 2000 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 2400 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 M30
| Tensile stress area As (ISO 898-1) | 561 mm² |
|---|---|
| Proof load, class 8.8 | 337 kN |
| Proof load, class 10.9 | 466 kN |
| Proof load, class 12.9 | 544 kN |
| Min. ultimate tensile, class 8.8 | 449 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.
Common Applications for M30 Stud Bolt, Double-End — GB/T 901 / DIN 939 (Series 091)
M30 Stud Bolt, Double-End — GB/T 901 / DIN 939 (Series 091) are commonly specified for structural steelwork, heavy machinery foundations and large flange joints.
Mating Parts for M30
For M30, pair with a M30 hex nut (ISO 4032 / DIN 934) and, where used, a M30 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.
