D EUTSCHE NORM June 2001

Compression couplings (LL series) with {

tapered stud end
3900

ICS 23.040.60 Supersedes April 1984 edition.

Lötlose Rohrverschraubungen mit Schneidring – Einschraubstutzen

der Reihe LL mit kegeligem Einschraubgewinde

In keeping with current practice in standards published by the International Organization for Standardization
(ISO), a comma has been used throughout as the decimal marker.

Foreword
This standard has been prepared by the Normenausschuss Rohrleitungen und Dampfkesselanlagen
(Pipelines and Pressure Vessels Standards Committee).

Amendments
This standard differs from the April 1984 edition as follows:
a) The standard now only covers couplings rated for nominal pressures up to 100 bar.
b) The specifications for surface roughness and finish have been amended.
c) The standard has been editorially revised.

Previous editions
DIN 3900: 1957-06, 1966-10, 1984-04.
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All dimensions are in millimetres.

1 Scope
This standard specifies the design and dimensions of extra-light duty series (LL) compression couplings with
tapered stud end and with type W port as in DIN 3861, rated for nominal pressures up to 100 bar, for use in
compression coupling assemblies.
In combination with type X tapped holes as in DIN 3852-1 or DIN 3852-2, tapered stud ends as specified here
are interchangeable with series LL, type A stud ends as in DIN 3901.
NOTE: Tightness of the assembly cannot be guaranteed since this is a function of the medium conveyed,
the working pressure and temperature, and the combination of materials used. Therefore, when designing
compression couplings as specified in this standard, use of a seal is recommended.

Continued on pages 2 and 3.

Translation by DIN-Sprachendienst.
In case of doubt, the German-language original should be consulted as the authoritative text.

© No part of this translation may be reproduced without the prior permission of Ref. No. DIN 3900 : 2001-06
DIN Deutsches Institut für Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany, English price group 05 Sales No. 0105
has the exclusive right of sale for German Standards (DIN-Normen).
05.02
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DIN 3900 : 2001-06

2 Normative references
This standard incorporates, by dated or undated reference, provisions from other publications. These normative
references are cited at the appropriate places in the text, and the titles of the publications are listed below. For
dated references, subsequent amendments to or revisions of any of these publications apply to this standard
only when incorporated in it by amendment or revision. For undated references, the latest edition of the
publication referred to applies.
DIN 158-1 Metric taper external and mating parallel internal screw threads – Dimensions, tolerances
and inspection
DIN 3852-1 Stud ends and tapped holes with metric fine pitch thread, for use with compression
couplings, valves and screw plugs – Dimensions
DIN 3852-2 Stud ends and tapped holes with pipe thread, for use with compression couplings, valves and
screw plugs – Dimensions
DIN 3853 Compression couplings – Compression ends for coupling nuts
DIN 3858 Pipe threads for compression couplings – Parallel internal threads and metric taper external
threads – Thread dimensions
DIN 3859-1 Compression fittings and couplings – Technical delivery conditions
DIN 3861 Compression rings (ferrules) for use with compression couplings – Design and type W
compression ends (ports)
DIN 3901 Stud fittings with type A stud end as in DIN 3852
DIN 24312 Fluid power – Pressure: concepts and characteristic values
DIN EN ISO 4042 Fasteners – Electroplated coatings (ISO 4042 : 1999)

3 Dimensions and designation

Design details left unspecified in figure 1 shall be selected as appropriate.
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1 2

Key to figure
1 Stud end as in DIN 3852-1 or DIN 3852-2
2 Compression end as in DIN 3853
3 Type W port as in DIN 3861

Figure 1: Dimensions of coupling with tapered stud end (notation)

Designation of a compression coupling with stud end with metric thread (M), extra-light duty series (LL), made
of steel (St), for an 8 mm pipe outside diameter (8):
Coupling DIN 3900 – LL 8 M – St
Designation of a compression coupling with stud end with pipe thread (R), extra-light duty series (LL), made of
steel (St), for an 8 mm pipe outside diameter (8):
Coupling DIN 3900 – LL 8 R – St
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DIN 3900 : 2001-06

Table 1: Dimensions of couplings with tapered stud end

Type C stud end

Approx.
Nominal (as in DIN 3852-1 or
Pipe Compression end details Width mass,
pressure DIN 3852-2)
Series outside (type W port as in across in kg,
diameter (as in with metric with pipe DIN 3861) flats, s per
DIN 24312)1) thread (as in thread (as in 100 units
DIN 158-1) DIN 3858)
d2 i2 d2 i2 d7 i3 d9 d10 l
LL 4 M8 ´ 1 keg 8 R1/8 8 M8 ´ 1 8 4 3 20 102 ) 0,8
(extra- 5 M8 ´ 1 keg 8 R1/8 8 M10 ´ 1 8 5 3,5 20 11 0,9
100
light 6 M10 ´ 1 keg 8 R1/8 8 M10 ´ 1 8 6 4,5 20 11 0,8
duty) 8 M10 ´ 1 keg 8 R1/8 8 M12 ´ 1 9 8 6 22 12 0,9
1) Applies only to steel couplings (cf. DIN 3859-1 for technical delivery conditions)
2) Width across flats of 11 mm for pipe threads.

4 Materials
The standard material of couplings with tapered stud end shall be steel as specified in DIN 3859-1. Other
materials specified in DIN 3859-1 shall be the subject of agreement, with the relevant symbol being included in
the designation.

5 Finish
The standard finish shall be Fe/Zn 8c2C as in DIN EN ISO 4042. Other types of finish (cf. DIN 3859-1) shall be
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the subject of agreement, with the relevant symbol being included in the designation.

6 Technical delivery conditions

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