# DIN 977 — DIN / ISO / BS fastener equivalents and the sizes where they are not interchangeable

For DIN 977, iso standard is ISO 21670; part is Hex Weld Nut with Flange; interchangeability verdict is Check spec, verified against its source on 2026-08-05.

- **DIN standard:** DIN 977 _(verified: appears in the quote below)_
- **ISO standard:** ISO 21670 _(verified: appears in the quote below)_
- **Part:** Hex Weld Nut with Flange _(verified: appears in the quote below)_
- **Interchangeability verdict:** Check spec _(verified: appears in the quote below)_

## What the source says

> Hex Weld Nut with Flange | DIN 977 | ISO 21670 | Check spec | Weld bosses/OD differ by series.

## Sources disagree

More than one authority states this, and they do not state the same
thing. Both are reproduced with the source each came from.

### Part

monsterbolts.com says part is **Hex Weld Nut with Flange**, as of 2026-08-05.

> Hex Weld Nut with Flange | DIN 977 | ISO 21670 | Check spec | Weld bosses/OD differ by series.

Source: https://monsterbolts.com/pages/common-din-numbers-for-metric-fasteners

trfastenings.com says part is **Hexagon Weld Nuts with flange**, as of 2026-08-05.

> DIN 977 | ISO 21670 | | Hexagon Weld Nuts with flange |

Source: https://www.trfastenings.com/knowledge-base/engineering-data/fastener-standards


## Source

- https://monsterbolts.com/pages/common-din-numbers-for-metric-fasteners
- https://www.trfastenings.com/knowledge-base/engineering-data/fastener-standards

Last verified: 2026-08-05. Review by: 2029-08-04.
Part of [DIN / ISO / BS fastener equivalents and the sizes where they are not interchangeable](https://referencesource.org/fastener-standard-interchangeability-exceptions/).