TS 7940 EN 20225

TS 7940 EN 20225 is a standard for the abbreviated presentation of dimensions and the associated symbols used for fasteners such as bolts, screws, studs and nuts. In technical drawings and cataloguing, it provides a common notation for expressing dimensions clearly and consistently.

What the dimensioning notation is used for

This is not just a drafting convention; it is a notation system for showing key fastener dimensions such as length, diameter, thread and related basic size information in a controlled way. Although bolts, screws, studs and nuts are different product families, the short designations and symbols used for each help reduce ambiguity in design, procurement, manufacturing and technical documentation. Standardised notation supports consistent identification and prevents confusion between similar fastener types.

How the scope is bounded

The stated scope covers the method of dimensioning recommended for use unless otherwise specified in the appropriate product standards. In other words, this document is not a product standard defining every geometric property or performance requirement of fasteners; it focuses on how dimensions and symbols are presented. In practical use, the final dimensional and product details are often governed by the relevant bolt, screw, stud or nut standard.

• Common short-form notation for bolts, screws, studs and nuts
• Symbols used in technical drawings and product descriptions
• A recommended dimensioning method unless an applicable product standard says otherwise
• A notation standard separate from the fastener’s own performance or manufacturing requirements