Din - 71550

Let’s decode the most important tolerance classes defined or recommended by DIN 71550.

is a withdrawn German technical standard titled "Bead for union joint for hoses in pipes" (German: Sicken für Schlauchverbindungen in Rohrleitungen ). Published in July 1979, it specified the dimensions and design of beads (or raised ridges) on metal pipes used to secure hose connections, primarily within vehicle cooling systems. Overview of DIN 71550

It is more conservative and precise for high-reliability German and European engineering (e.g., automotive, machine tools, wind turbines). Din 71550

For more information on the DIN 71550 standard, please refer to the following resources:

Required torque = 500 Nm × SF 2.0 = 1000 Nm. 570 < 1000 → Not sufficient. Need heavier fit. Let’s decode the most important tolerance classes defined

Try per DIN 71550.

It is frequently cited alongside other active standards like for cooling system dimensions and materials. Overview of DIN 71550 It is more conservative

Reference copies and summaries are available on platforms like GlobalSpec for a particular pipe diameter? DIN 71550 - 1979-07

It specifically addresses —also known as interference fits—where the internal dimension of a hole (e.g., a hub) is deliberately smaller than the external dimension of a shaft (e.g., an axle). This interference creates a permanent, non-detachable joint that relies on elastic deformation to secure components without additional fasteners like keys or splines.

Defines the profile and dimensions of a raised ridge (bead) on a metal pipe to prevent a rubber hose from sliding off once a clamp is applied.

The standard assumes a typically between 0.08 and 0.12 for steel-on-steel, dry, machined surfaces. For assemblies with lubricant during pressing (common to reduce galling), μ may drop to 0.05–0.08.