SIST EN 74-1:2022

SLOVENSKI STANDARD
oSIST prEN 74-1:2020
01-december-2020
Spojke, vezne centične spojke in podnožne plošče za delovne in nosilne odre - 1.
del: Cevne spojke - Zahteve in preskusni postopki
Couplers, spigot pins and baseplates for use in falsework and scaffolds - Part 1:
Couplers for tubes - Requirements and test procedures
Kupplungen, Zentrierbolzen und Fußplatten für Arbeitsgerüste und Traggerüste - Teil 1:
Rohrkupplungen - Anforderungen und Prüfverfahren
Raccords, goujons d’assemblage et semelles pour étaiements et échafaudages - Partie
1 : Raccords de tubes - Exigences et modes opératoires d’essai
Ta slovenski standard je istoveten z: prEN 74-1
ICS:
91.220 Gradbena oprema Construction equipment
oSIST prEN 74-1:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 74-1:2020


DRAFT
EUROPEAN STANDARD
prEN 74-1
NORME EUROPÉENNE

EUROPÄISCHE NORM

October 2020
ICS 91.220 Will supersede EN 74-1:2005
English Version

Couplers, spigot pins and baseplates for use in falsework
and scaffolds - Part 1: Couplers for tubes - Requirements
and test procedures
Raccords, goujons d'assemblage et semelles pour Kupplungen, Zentrierbolzen und Fußplatten für
étaiements et échafaudages - Partie 1 : Raccords de Arbeitsgerüste und Traggerüste - Teil 1:
tubes - Exigences et modes opératoires d'essai Rohrkupplungen - Anforderungen und Prüfverfahren
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 53.

If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.


EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 74-1:2020 E
worldwide for CEN national Members.

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Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and symbols . 6
3.1 Terms and definitions . 7
3.2 Symbols and abbreviations . 8
4 Types and classes of couplers . 9
4.1 Types of couplers . 9
4.2 Classes of couplers . 9
4.2.1 General. 9
4.2.2 Transmissible internal forces, moments and related stiffnesses . 10
5 Reference tubes and bar for coupler tests . 13
6 General requirements . 13
6.1 Materials . 13
6.2 Design . 14
6.3 Manufacturer’s drawing . 18
6.4 Production . 18
7 Test methods and evaluation of results . 18
7.1 General. 18
7.2 Slipping and failure force . 22
7.2.1 Slipping force F (RA,SW,PA,SF) . 22
s
7.2.2 Failure force F (RA,SW,PA) . 26
f
7.3 Pull-apart force F (RA) . 29
p
7.3.1 Purpose of test . 29
7.3.2 Test arrangement . 29
7.3.3 Test procedure . 29
7.3.4 Evaluation of test results . 29
7.4 Stiffnesses and ultimate moments . 30
7.4.1 Cruciform bending stiffness c and c and ultimate bending moment M
φ1,MB φ2,MB ult
(RA) . 30
7.4.2 Rotational moment M and stiffness c (RA) . 34
T φ,MT
7.4.3 Bending moment resistance (SF) . 36
7.5 Indentation (RA,SW,PA) . 38
7.5.1 Purpose of test . 38
7.5.2 Test arrangement . 38
7.5.3 Test procedure . 39
7.5.4 Evaluation of tests results . 40
8 Designation . 40
9 Marking . 40
10 Test report . 41
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11 Evaluation of test results . 41
12 Assessment . 41
13 Product manual . 41
A.1 Nominal values . 42
A.2 Tolerances and limiting dimensions after coating . 43
Bibliography . 46

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European foreword
This document (prEN 74-1:2020) has been prepared by Technical Committee CEN/TC 53 “Temporary
works equipment”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 74-1:2005.
Compared to EN 74-1:2005 the following changes have been made:
1) reference tubes with the specified yield strengths are not procurable therefore these requirements
are changed;
2) new test conditions are specified;
3) the requirement for the bending moment of sleeve couplers are changed;
4) in addition, editorial changes are made.
The couplers specified in this European standard are intended for use in scaffolds erected in accordance
with EN 12811-1 and falsework erected in accordance with EN 12812.

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Introduction
This is the second of three parts of a standard for couplers.
This first part, EN 74-1, covers common types of friction couplers.
The second part, EN 74-2, deals with other less common types of couplers.
The third part, EN 74-3, deals with plain base plates and loose spigot pins.
EN 74-1 defines a set of steel and aluminium reference tubes for the required tests.
EN 74-1 is not intended to prevent the development of other types of couplers. For example couplers
may be manufactured in aluminium or other materials or be designed for use with steel or aluminium
tubes other than the normally used 48,3 mm nominal outside diameter. Whilst such couplers cannot
comply with this European standard, it is recommended that the principles of this European standard
are considered in their design and assessment.
The couplers in this European Standard are intended for use in scaffolds and falsework for connecting
48,3 mm outside diameter steel and aluminium tubes which fulfil in other respects (e.g. material grade,
thickness and tolerances) the requirements given in EN 12811-1, EN 12811-2 and EN 12810-1.
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1 Scope
This document specifies, for right angle couplers, swivel couplers, sleeve couplers and parallel couplers
working by friction:
— materials;
— design requirements;
— strength classes with different structural parameters including values for resistance and stiffness;
— test procedures;
— assessment;
and gives
— recommendations for ongoing production control.
For testing, screw couplers are tightened to a torque of 50 Nm and wedge couplers are tightened with a
500 g hammer until the jarring blow.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 12811-1:2003, Temporary works equipment — Part 1: Scaffolds — Performance requirements and
general design
EN 12811-2:2004, Temporary works equipment — Part 2: Information on materials
EN 12811-3:2002, Temporary works equipment — Part 3: Load testing
EN 6892-1, Metallic materials — Tensile testing — Part 1: Method of test at room temperature
(ISO 6892-1)
EN ISO 898-1, Mechanical properties of fasteners made of carbon steel and alloy steel — Part 1: Bolts,
screws and studs (ISO 898-1)
EN ISO 898-2, Mechanical properties of fasteners made of carbon steel and alloy steel — Part 2: Nuts with
specified property classes — Coarse thread and fine pitch thread (ISO 898-2)
EN 12812, Falsework — Performance requirements and general design
3 Terms, definitions and symbols
For the purposes of this document, the following terms and definitions apply / the terms and definitions
given in EN 12811-1:2003 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
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3.1 Terms and definitions
3.1.1
coupler
device used for connecting two tubes
EXAMPLE

Key
1 closing flap
2 base
3 centre rivet (for swivel couplers)
4 nut with integrated washer
5 T−Bolt
6 rivet
Figure 1 — Designation of components of right angle and swivel coupler
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3.1.2
wedge coupler
coupler in which the clamping force is obtained by tightening a closing flap around the tube by means of
hammering home a wedge
3.1.3
screw coupler
coupler in which the clamping force is obtained by tightening a closing flap around the tube by means of
a nut and a bolt
3.1.4
supplementary coupler
right angle coupler positioned touching an identical coupler in order to increase the slip resistance
3.1.5
assessment
checking process to establish compliance with the requirements specified in this document
3.2 Symbols and abbreviations
For the purpose of this document, the following symbols apply:
F slipping force in kN;
s
F failure force in kN;
f
F pull apart force in kN;
p
M bending or cruciform bending moment in kNm;
B
c cruciform bending stiffness in kNm/rad;
φ(i),

MB
M rotational moment in kNm;
T
c rotational stiffness in kNm/rad;
φ,MT
F specified value for slipping force in kN;
s,c
F specified value for failure force in kN;
f,c
F specified value for pull apart force in kN;
p,c
M specified value for bending moment in kNm;
B,c
c specified value for cruciform bending stiffness in kNm/rad;
φ(i),

MB,c
M specified value for rotational moment in kNm;
T,c
c specified value for rotational stiffness in kNm/rad;
φ,MT,

c
ν displacement in millimetres of the transverse tube under load relative to a tube or solid bar in
rotational tests;
Δ displacement in millimetres of a coupler under load relative to a tube or solid bar;
i
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Δ indentation in millimetres;
10
P test load in kN;
P test load for indentation in kN;
ind
φ specified angle of rotation of a coupler in degrees;
P load bearing capacity of a coupler at failure;
f,ult
P load bearing capacity of a coupler for pull apart;
p,ult
M capacity of a coupler of cruciform ultimate bending moment;
ult
R yield strength;
eH
R proof stress at elongation of 0,2 %;
p,0.2
R tensile strength.
m
4 Types and classes of couplers
4.1 Types of couplers
The types of couplers are listed in Table 1.
Table 1 — Types of couplers
Type of coupler Identification Arrangement of tubes
Right angle coupler RA Crossing at a right angle
Swivel coupler SW Crossing at any angle
Parallel coupler PA Parallel
Sleeve coupler SF End to end coaxially

4.2 Classes of couplers
4.2.1 General
The classes for each type of coupler are given in Table 2.
Table 2 — Classes of couplers
Class
Type of coupler
A B AA BB
■ ■ ■ ■
Right angle coupler
Swivel coupler ■ ■ – –
Parallel coupler ■ ■ – –
■ ■
Sleeve coupler friction type – –
■ Specified class

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Classes A and B differ in transmissible internal forces and moments and in values of load bearing
capacity and stiffness. Couplers of classes AA and BB, used as single couplers have the same
characteristics as couplers of classes A and B respectively, but they may also be used to increase
slipping capacity if two identical couplers AA+AA or BB+BB are positioned touching each other.
4.2.2 Transmissible internal forces, moments and related stiffnesses
In general a connection between two tubes is able to transmit three forces and three moments at right
angles to each other with related stiffness.
Tables 3 to 6 show which structural parameters apply. See Table 8 for values for testing purposes.
Longitudinal stiffness may be derived from load — displacement curves for slipping forces.
Table 3 — Structural parameters for right angle couplers (RA)
Class
Structural parameters
A and AA B and BB
Slipping force F
■ ■
s
Rotational moment M *
– ■
T
Force or moment
Pull apart force F
■ ■
p
(Figure 2)
Failure force F
■ ■
f
Cruciform bending moment M *
– ■
B
Rotational stiffness c *
– ■
φ,MT
Connection stiffness
Cruciform bending stiffness c *
■
–
φ,MB
■ Resistance or stiffness specified
* Only for screw couplers

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Figure 2 — Forces and moments for a right angle coupler
Table 4 — Structural parameters for swivel couplers (SW)
Class
 Structural parameter
A B
Slipping force F (Figure 3)
■ ■
1
s
Failure force F (Figure 3)
2 ■ ■
f
■ Resistance specified


Figure 3 — Forces for a swivel coupler
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Table 5 — Structural parameters for parallel couplers (PA)
Class
 Structural parameter
A B
Slipping force F (Figure 4)
1 ■ ■
s
Failure force F (Figure 4)
■ ■
2
f
■ Resistance specified


Figure 4 — Forces for a parallel coupler
Table 6 — Structural parameters for sleeve couplers (SF)
Class
 Structural parameters
A B
Slipping force F (Figure 5)
■ ■
1
s
Bending moment M (Figure 5)
2 – ■
B
■ Resistance specified

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Figure 5 — Forces and moments for a sleeve coupler
5 Reference tubes and bar for coupler tests
The specified outside diameter of all tubes and bars shall be 48,3 mm with a tolerance for tubes
of ± 0,5 mm and for bars of ± 0,2 mm.
Reference tubes shall be used that are selected from normal production whose properties lie within the
tolerance bands specified in Table 7.
The tubes shall be unused and steel tubes shall be hot dip galvanized in accordance with EN 12811-2
class C2 of corrosion protection.
Table 7 — Reference tubes and bar for coupler tests
Wall thickness
Structural Wall
tolerance
Reference Material Yield strength or hardness
form thickness
mm
+0,1 − 0,2 (including
2
RT
Tube Steel 235 N/mm ≤ R 3,2 mm
S1
eH
corrosion protection)
2
315 N/mm ≤ R ≤ 345 N/mm
+0,1 − 0,2 (including
eH
RT
Tube Steel 2,7 mm
S2
corrosion protection)
2

+0,1 − 0,2 (including
2
RT
Tube Steel 235 N/mm ≤ R 4,0 mm
S3
eH
corrosion protection)
Alluminium
2
RT
Tube 195 N/mm ≤ R 4,0 mm +0,1 − 0,2
A
eH
alloy
RB Bar Steel ≥ 250 Brinell  See Clause 5

6 General requirements
6.1 Materials
All elements of couplers shall be made of steel or cast iron and shall fulfil the requirements given in
European Standards where design data are provided. Some information about those most commonly
used is given in EN 12811-2. Elements shall be protected against atmospheric corrosion in general in
accordance with EN 12811-2.
Electrolytical zinc coating C with an average thickness of 15 µm conforms to EN 12811-2:2004, 8.1.
z
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For screw and nut connection, other corrosion protection which is specified in EN or ISO standards may
be applied. It shall be shown that they achieve at least equivalent protection.
When tested to EN ISO 6892-1, cast irons shall have a minimum elongation of 5 % on ultimate strength
where l = 3d.
o
6.2 Design
6.2.1 A coupler model of a defined type and class shall conform to all requirements specified in
Table 8. It means for any structural parameter that the evaluated test results shall be equal or exceed
the specified values in this document except for indentation.
The characteristic values and safety coefficients to be applied for use shall be as given in EN 12811-1
and in EN 12812.
6.2.2 The design of couplers shall be such that after tightening onto any steel or aluminium tube given
in Clause 5 and tightened in accordance with 7.1.7 and 7.1.8, there shall be significant effective travel on
the nut or wedge.
NOTE Experience shows that 2 mm of thread or wedge remaining and a minimum gap of 2 mm between the
closing flap and the body are suitable limits.
The design shall be such that the T-bolt can only sit at the base of the pocket, see Figure 6.

T-bolt head sits not at the base of the pocket: T-bolt head sits at the base of the pocket
danger of sudden loss of pretension
Figure 6 — Position of T-bolt head at the base of pocket
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The design shall ensure that the thread of the T-bolt will not be damaged by the closing flap when
tightened.
6.2.3 A coupler shall be manufactured so that the elements cannot be separated during normal
service condition, except for bolts, nuts and washers.
Only metric and Whitworth threads are covered by this document.
The nominal bolt diameter shall be at least M12. The bolt strength class shall be at least grade 5.6 in
accordance with EN ISO 898-1. The proof load on each bolt, R , , shall not be less than 32,2 kN and the
p 02
R /R ratio not greater than 0,8.
eH M
The recommended bolt is M14 × 2, with tolerances in accordance with ISO 965.
1/2″ Whitworth threads shall comply with Annex A.
The nut and bolt combination shall be in accordance with EN ISO 898-2. The nut shall be one of the
following:
— plain hexagonal nut with a separate loose washer; or
— special flanged hexagonal nut having an integral fixed washer flange; or
— special hexagonal nut incorporating an integral rotating washer.
The outside diameter of the washers or nut flanges shall be at least equal to the measurement across
the corners of the hexagonal nuts at specified dimensions +2 mm. The washer or nut flange thickness
shall not be less than 2,5 mm. A loose washer shall have a hardness of between 200 HV and 300 HV.
NOTE Research has shown that the slipping resistance is dependant on the bolt tension. For a given torque
this tension is considerably increased when the integral friction coefficient on the thread is low. This integral
friction coefficient is significantly influenced by the type of corrosion protection and by the lubrication of the bolt
and nut connection.
6.2.4 The correct installation of the tubes in the sleeve couplers shall preferably be achieved
automatically by the design of the coupler, e.g. by a self-centring device; otherwise it shall be very easy
to verify visually that it is correctly assembled.
6.2.5 An AA or BB coupler shall also fulfil the performance requirements of A and B couplers.
6.2.6 A coupler shall not cause an indentation greater than that specified in Table 8 when tested in
accordance with 7.5.
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Table 8 — Test parameters and specified values
COUPLER CLASS COUPLER CONFIGURATION
Type Property parameter Symbols Clause Test parameter A AA B BB AA/AA BB/BB
SPECIFIED VALUES
Δ ≤ 7 mm
7,0 kN 10,0 kN 10,0 kN 15,0 kN
1
F
Slipping force 7.2.1
s,c
1 ≤ Δ ≤ 2 mm
10,0 kN 15,0 kN 15,0 kN 25,0 kN
2
F P
Failure force 7.2.2 20,0 kN 30,0 kN 30,0 kN 45,0 kN – –
f,c f,ult
c M = ± 0,13 kNm
stiffness* – 7,5 kNm/rad – –
φ,MT,c T
Rotation 7.4.2
M
moment* 1° ≤ θ ≤ 2° – 0,13 kNm – –
T,c
F P
Pull apart force 7.3 20,0 kN 30,0 kN – –
p,c p,ult
Right
angle c M /1,65 = 0,48 kNm
– 15,0 kNm/rad – –
φ1,MB,c B
Cruciform bending stiffness
couplers
on steel tube*
c M = 0,8 kNm
(RA) – 6,0 kNm/rad – –
φ2,MB,c B
c M /1,65 = 0,48 kNm
– 13,0 kNm/rad – –
φ1,MB,c B
Cruciform bending stiffness 7.4.1
on aluminium tube*
c M = 0,8 kNm
– 5,0 kNm/rad – –
φ2,MB,c B
Cruciform ultimate bending
M 2M
– 1,6 kNm – –
ult,c B
moment*
P = 6,67 kN
≤ 1,5 mm – – –
ind
Δ
Indentation 7.5
10
P = 10,0 kN
– ≤ 1,5 mm – –
ind
Δ ≤ 7 mm
7,0 kN 10,0 kN – –
1
F
Slipping force 7.2.1
s,c
1 ≤ Δ ≤ 2 mm
Swivel
10,0 kN 15,0 kN – –
2
(couplers
F P
Failure force 7.2.2 14,0 kN 20,0 kN – –
(SW)
f,c ult
Δ P = 4,7 kN
Indentation 7.5 ≤ 1,5 mm – – –
10 ind
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COUPLER CLASS COUPLER CONFIGURATION
Type Property parameter Symbols Clause Test parameter A AA B BB AA/AA BB/BB
SPECIFIED VALUES
P = 6,67 kN
– ≤ 15 mm – –
ind
F Δ ≤ 7 mm
7,0 kN 10,0 kN – –
s,c 1
Slipping force 7.2.1
1 mm ≤ Δ ≤ 2 mm
 10,0 kN 15,0 kN – –
2
Parallel
F P
Coupler Failure force 7.2.2 20,0 kN 30,0 kN – –
f,c ult
(PA)
P = 6,67 kN
≤ 1,5 mm – – –
ind
Δ
Indentation 7.5
10
P = 10,0 kN
– ≤ 1,5 mm – –
ind
Sleeve F 1 ≤ Δ ≤ 2 mm
Slipping force 7.2.1 6,0 kN 9,0 kN – –
s,c 2
coupler
M M
Bending moment 7.4.3 – 1,4 kNm – –
(SF) B,c B
* Only for screw couplers.

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6.3 Manufacturer’s drawing
For each coupler model, the manufacturer shall record on the drawings sufficient information for
unambiguous identification and as a reference for subsequent inspection.
a) geometry;
b) dimensions and tolerances;
c) mass with tolerance;
d) material specification for each element of the coupler;
e) type of surface protection for each element of the coupler.
6.4 Production
6.4.1 An appropriate method of quality control during a production program shall ensure that
couplers satisfy the performance requirements of this document and that they comply with the
manufacturer’s drawings.
NOTE Annex B gives recommendations for ongoing production control.
When the ongoing production control follows one of the inspection methods set out in Annex B, it may
be assumed that the couplers produced under this regime satisfy the requirements of this clause.
6.4.2 When ongoing production control procedures differ from those recommended in Annex B, they
should be drawn up by a person competent to do so.
Although it is not a requirement of this document, it is recommended that manufacturers submit their
production control procedures periodically to third party inspections.
7 Test methods and evaluation of results
7.1 General
7.1.1 The minimum number of tests carried out on different types and classes of each coupler shall be
in accordance with Table 9.
7.1.2 The specimen required for testing shall be randomly selected (see ISO 2859) from a batch of at
least 500 couplers.
7.1.3 Unused couplers shall be used for all tests except that,
— for failure force tests, th
...