| (d1) | d2 | d3 | m | s | t |
|---|---|---|---|---|---|
| M12 | 21 | 14.5 | 12 | 22 | 2 |
| M16 | 26 | 18.5 | 16 | 27 | 2 |
| M20 | 31 | 22.5 | 20 | 32 | 2 |
| M24 | 35 | 26.5 | 24 | 36 | 3 |
| M27 | 40 | 30.5 | 27 | 41 | 3 |
| M30 | 45 | 33.5 | 30 | 46 | 3 |
| M33 | 49 | 36.5 | 33 | 50 | 3 |
| M36 | 53.5 | 39.5 | 36 | 55 | 3 |
| M39 | 58.5 | 42.5 | 39 | 60 | 3 |
| M42 | 63.5 | 45.5 | 42 | 65 | 3 |
| M45 | 68.5 | 49.5 | 45 | 70 | 3 |
| M48 | 73.5 | 53.5 | 48 | 75 | 4 |
| M52 | 78.5 | 57.5 | 52 | 80 | 4 |
| M56 | 83.5 | 63 | 56 | 85 | 4 |
A reliable enquiry defines the finished component, not only the material grade. State the governing dimensional standard, nominal diameter, thread form and pitch, length convention, quantity, surface finish and required delivery condition. Include a drawing when a standard leaves more than one configuration open or when ends, points, drilled features, reduced shanks or non-standard thread lengths are involved.
Confirm the specified B7 material grade, the design temperature and pressure context, and any project material specification. Identify the compatible nut and washer grades. If sour, low-temperature or other special service applies, the responsible engineer should approve the material and supplementary requirements.
Name the dimensional standard and revision, thread class or tolerance, and whether dimensions are checked before or after coating. A coating can affect thread fit and friction, so specify the complete coating system, lubricant condition and mating parts together.
State the certificate type, heat and manufacturing-lot traceability, marking, mechanical tests, chemical analysis and any dimensional or nondestructive examination reports. Additional testing must be invoked before production with its method, sampling and acceptance criteria.
For related decisions, review the material specification, mechanical properties, coating guide, thread guide and testing and certification guide. Technical values should always be verified against the current governing standard and approved project documents.
