Precision Metric Stud Fasteners for High-Integrity Bolted Flange and Pressure Vessel Assemblies in Global Projects.
ASME B18.31.1M Metric Clamping Full Body Type Studs are metric-series unheaded threaded fasteners with threads at both ends and a full-diameter unthreaded body shank, expressed in SI dimensional units and engineered to provide consistent, uniform clamping load distribution across bolted flange joints, pressure vessel cover connections, heat exchanger bundles, and critical structural assemblies in global metric-standard engineering projects. The ASME B18.31.1M standard defines metric dimensional requirements for body diameter, overall stud length, thread length at each end, thread pitch, and body diameter tolerances , ensuring precise dimensional compliance for full-body clamping studs procured from multiple global suppliers for large-scale international industrial projects. When manufactured to ASTM A1082, the specification for high-strength stainless steel bolting material, these metric full-body clamping studs provide exceptional corrosion resistance paired with the controlled clamping performance required for offshore oil and gas flanges, desalination plant pressure equipment, LNG terminal piping, and chemical process heat exchangers operating in aggressive saline and chemical service environments. The full-body design ensures that the elastic stretch of the stud under bolt load is distributed uniformly along the full shank length, providing predictable bolt preload behavior and improved fatigue resistance in gasketed joints subject to pressure cycling and thermal expansion loads. ASTM A1082 metric full-body clamping studs are available with EN 10204 Type 3.1 documentation for full material traceability.
| Nominal Size Diameter, D |
Thread Length, B | UMax. = 2P |
Nominal Length, L | Body Diameter, DS | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| LT ≤ 250 | 250 < LT ≤ 400 | LT > 400 | Max. | Min. (by Length) | ||||||||
| Min. | Max. | Min. | Max. | Min. | Max. | Range | Incr. | LT ≤ 150 | LT > 150 | |||
| M1.6 | 9.2 | 9.9 | - | - | - | - | 0.7 | 25-50 | 5 | 1.60 | 1.29 | 1.29 |
| M2 | 10 | 10.8 | - | - | - | - | 0.8 | 25-50 | 5 | 2.00 | 1.65 | 1.65 |
| M2.5 | 11 | 11.9 | - | - | - | - | 0.9 | 30-50 | 5 | 2.50 | 2.12 | 2.12 |
| M3 | 12 | 13 | - | - | - | - | 1 | 30-50 | 5 | 3.00 | 2.58 | 2.58 |
| M4 | 14 | 15.4 | - | - | - | - | 1.4 | 35-90 | 5 | 4.00 | 3.43 | 3.43 |
| M5 | 16 | 17.6 | - | - | - | - | 1.6 | 40-90 | 5 | 5.00 | 4.36 | 4.36 |
| M6 | 18 | 20 | 24 | 26 | - | - | 2 | 50-90 100-160 |
5 10 |
6.00 | 5.82 | 5.70 |
| M8 | 18 | 20.5 | 26.5 | 24 | - | - | 2.5 | 50-90 ≥ 100 |
5 10 |
8.00 | 7.78 | 7.64 |
| M10 | 26 | 29 | 32 | 35 | 45 | 48 | 3 | 60-160 ≥ 180 |
10 20 |
10.00 | 9.78 | 9.64 |
| M12 | 30 | 33.5 | 36 | 39.5 | 49 | 52.5 | 3.5 | 60-160 ≥ 180 |
10 20 |
12.00 | 11.73 | 11.57 |
| M14 | 34 | 38 | 40 | 44 | 53 | 57 | 4 | 80-160 ≥ 180 |
10 20 |
14.00 | 13.73 | 13.57 |
| M16 | 38 | 42 | 44 | 48 | 57 | 61 | 4 | 90-160 ≥ 180 |
10 20 |
16.00 | 15.73 | 15.57 |
| M20 | 46 | 51 | 52 | 57 | 65 | 70 | 5 | 100-160 > 180 |
10 20 |
20.00 | 19.67 | 19.48 |
| M24 | 54 | 60 | 60 | 66 | 73 | 79 | 6 | 130-160 ≥ 180 |
10 20 |
24.00 | 23.67 | 23.48 |
| M30 | 66 | 73 | 72 | 79 | 85 | 92 | 7 | 150-160 ≥ 180 |
10 20 |
30.00 | - | 29.48 |
| M36 | 78 | 86 | 84 | 92 | 97 | 105 | 8 | ≥ 200 | 20 | 36.00 | - | 35.38 |
| M42 | 90 | 99 | 96 | 105 | 109 | 118 | 9 | ≥ 240 | 20 | 42.00 | - | 41.38 |
| M48 | - | - | 108 | 118 | 121 | 131 | 10 | ≥ 280 | 20 | 48.00 | - | 47.38 |
| M56 | - | - | 124 | 135 | 137 | 148 | 11 | ≥ 300 | 20 | 56.00 | - | 55.26 |
| M64 | - | - | 140 | 152 | 153 | 165 | 12 | ≥ 340 | 20 | 64.00 | - | 63.26 |
| M72 | - | - | 156 | 168 | 169 | 181 | 12 | ≥ 380 | 20 | 72.00 | - | 71.26 |
| M80 | - | - | 172 | 184 | 185 | 197 | 12 | ≥ 400 | 20 | 80.00 | - | 79.26 |
| M90 | - | - | - | - | 205 | 217 | 12 | ≥ 440 | 20 | 90.00 | - | 89.13 |
| M100 | - | - | - | - | 225 | 237 | 12 | ≥ 480 | 20 | 100.00 | - | 99.13 |
| Nominal Length | Tolerance | |
|---|---|---|
| Over | Through | |
| 6 | 10 | ± 0.29 |
| 10 | 18 | ± 0.35 |
| 18 | 30 | ± 0.42 |
| 30 | 50 | ± 0.50 |
| 50 | 80 | ± 0.95 |
| 80 | 120 | ± 1.10 |
| 120 | 180 | ± 1.25 |
| 180 | 250 | ± 1.45 |
| 250 | 315 | ± 1.60 |
| 315 | 400 | ± 1.80 |
| 400 | 500 | ± 2.00 |
| >500 | ... | ± 5.00 |
ASTM A1082/A1082M (2016) Table 1 lists 14 duplex (ferritic-austenitic) grades, S31100, S31260, S31803, S32101, S32202, S32205 (2205), S32304 (2304), S32506, S32550 (255), S32750 (2507), S32760, S32906, S32950 and S39277, and 5 precipitation-hardening grades, S15700 (Type 632), S17400 (Type 630), S17600 (Type 635), S17700 (Type 631) and S35500 (Type 634). Grade selection depends on design, service conditions and the mechanical properties required.
Dimensions follow ASME B18.31.1M, tabulated on this page. ASTM A1082/A1082M sets chemistry (Table 1), heat treatment and mechanical properties (Tables 2 to 4) and marking (Table 5). ASTM A962/A962M general requirements also apply, and A1082 prevails where the two conflict (clause 4.1). Inch-pound units apply unless the order specifies A1082M (clause 1.4).
ISO 15156-3 Table A.24 accepts wrought duplex stainless steel for any equipment when it is solution-annealed and liquid-quenched or rapidly cooled, has 35 % to 65 % ferrite and has had no ageing heat treatment. With 30 ≤ PREN ≤ 40 and Mo ≥ 1.5 % the limit is 232 °C (450 °F) and 10 kPa (1.5 psi) H2S partial pressure; with 40 < PREN ≤ 45 it is 232 °C (450 °F) and 20 kPa (3 psi). Table A.27 accepts wrought 17-4 PH (S17400) at 33 HRC max after a double age at 620 °C (1150 °F) or a modified double age, for named wellhead, valve and subsurface components, up to 3.4 kPa (0.5 psi) H2S and pH 4.5 or above.
The grade symbol comes from Table 5 (clause 11.1), for example 32750 for S32750 or 174H for S17400 in H1150D. With Supplementary Requirement S2 the marking goes on one end of each stud; if the area is too small, the grade symbol may go on one end and the manufacturer's identification on the other. Studs under 3/8 in. [10 mm], and 1/4 in. [6 mm] studs that need more than three symbols, are marked by agreement.
Table 4: solution annealed at 1880 to 2060 °F [1025 to 1125 °C], water quenched. Up to and including 2 in.: tensile 116 ksi [800 MPa] and yield 80 ksi [550 MPa] min. Over 2 in.: 110 ksi [760 MPa] and 75 ksi [515 MPa] min. Elongation 15 % min and hardness 33 HRC or 310 HB max for both. The marking grade symbol is 32750 (Table 5).
