EN 74-1-2005 pdf download.Couplers, spigot pins and baseplates for use in falsework and scaffolds – Part 1: Couplers for tubes – Requirements and test procedures.
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 1281 1-2.
Electrolytical zinc coating C7 with an average thickness of 15 .im conforms to 8.1 of 12811-2:2004.
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 10002-1. cast irons shall have a minimum elongation of 5 % on ultimate strength where = 3d.
6.2 Design
6.2.1 A coupler model of a defined type and dass 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 European Standard 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 Expenence shows that 2 mm of thread or wedge remaining and a minimum gap of 2 mm between the dosing flap and the body are suitable limits,
6.2.3 A coupler shall be manufactured so that the elements cannot be separated during normal service condition.
The bolt class 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, R02, shall not be less than 32,2 kN and the ReHIRU ratio not greater than 0,8.
The recommended bolt Is M14x2, with tolerances in accordance with ISO 965.
% Whitworth threads shall comply with Annex A.
The nut and bolt combination shall be in accordance with EN 20898-2. 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.
d) material specification for each element of the coupler;
e) type of surface p4-otection fo4 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 European Standard and that they comply with the manufacturers drawings.
NOTE Annex B gives recommendations for ongorng 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.
NOTE Although it is not a requirement of this European Standard, it is recommended that manufacturers submt their production control procedures periodically to third party inspechons.
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 ultimate load tests, those used for slip tests may be reused.
7.1.4 Where the performance of a coupler depends on the load direction, the more unfavourable load direction shall be tested.
7.1.5 All test equipment shall have an accuracy ≤ 1 %. With exception, a torque wrench may have an accuracy of at least ± 5 %.
7.1.6 When testing screw couplers the conditioning for thread and bolt and nut connection shall be in accordance with the statement regarding lubrication given in the product manual (see Clause 13 e)).
7.1.7 Screw couplers shall be tightened with a torque of 50 Nm applied with a torque wrench conforming to
7.1.5.EN 74-1-2005 pdf download.