DIN 3870 Union Nut Dimensions

Views: 310     Author: Site Editor     Publish Time: 2022-07-14      Origin: Site


The DIN 3870 specifications for S and L series coupling nuts and for type A nuts for use with cutting rings as in DIN 3861 and 24° cone metric couplings as in DIN 3865 (excluding series LL 3 and LL 1 6 fittings) are now given in DIN EN ISO 8434-1 .

1. Scope

This standard specifies the design and dimensions of extra-light duty series (LL) coupling nuts for use with compression couplings.

2. Dimensions and designation

Design details left unspecified in figure 1 shall be selected as appropriate.

Type A (cf. DIN EN ISO 8434-1 ).

Type B, for use with DIN 3863 spherical liners.

DIN 3870 tube nut Dimensions and designation

Thread countersunk to major diameter.

1 ) Thread run-out or thread undercut (optional).

2 ) For cold-pressed coupling nuts, a maximum overspill of 1 mm is permitted.

3 ) Thread minor diameter.

Designation of a type B coupling nut with thread run-out or thread undercut (B), extra-light duty series (LL), made of steel (St), for a 1 2 mm pipe outside diameter (1 2):

Nut DIN 3870 – B LL 1 2

If a specific thread design is required, this shall be incidated in the designation by including the relevant type number.


Designation of a type B coupling nut with thread run-out (B 2), extra-light duty series (LL), made of copper zinc alloy (MS), for a 1 2 mm pipe outside diameter (1 2):

Nut DIN 3870 – B 2 LL 1 2 – MS

Table 1: Nut dimensions

DIN 3870 Nut dimensions

3. Materials

The standard material of coupling nuts shall be steel, as specified in DIN 3859-1 . Other materials specified in DIN 3859-1 shall be the subject of agreement, and the relevant symbol added to the designation. In cases where a given manufacturing process (e.g. brazing) requires the use of other materials, these shall be selected with regard to the stress involved.

4. Screw thread and finish

Coupling nuts shall be provided with an ISO metric screw thread as specified in DIN 1 3-5 to DIN 1 3-7, medium tolerance quality as in DIN ISO 965-2. The standard finish shall be Fe/Zn 8c2C as in DIN EN ISO 4042. Other types of finish (cf. DIN 3859-1 ) shall be the subject of agreement, with the relevant symbol being included in the designation.

5. Technical delivery conditions

The technical delivery conditions specified in DIN 3859-1 shall apply.

6. Fitsch is Professional Manufactuer of DIN 3870 Tube Nuts.

We can provide you compression nut, uniont nut and DIN tube nut for 24 degree cone tube connectors, assembled withcutting ring, our quality is the same to Voss, Parker, Eaton, EMB etc brands. 

Forging of Nut DIN 3870


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