The correct selection, installation and testing of Scaffold Anchor Ties is critical to the overall safety and stability of scaffold structures of all types.
In this article, we will cover the process of correctly testing scaffold anchors for strength and stability for for the normal use of scaffold structures. In all scenarios an adequate margin of safety with respect to the working load should always be implemented.
The main factors of effective scaffold anchor testing include
The capacity of anchor points can vary greatly depending on the load direction. There are essentially two different types of loads, horizontal and vertical.
This is the major load a typical tie assembly must cope with, it usually originates from wind loads which are transferred to the anchors as either Compression or Tension loads.
Vertical loads are referred to as Shear loads and Bending loads.
In most cases, vertical loads are transferred down the scaffold, through standards to the ground, however, in scenarios where the scaffold is supported by a building structure, or where it supports a temporary roof which are typically affected by wind uplift, vertical shear loads may arise. Where this is the case a specially designed anchor may be required.
The bending capacity for standard anchors is generally very low, so efforts to minimize loading of this nature is critical to the overall stability and strength of the scaffold. This will be considered by the Engineer during the design production.
Whenever there is any doubt as to the adequacy of the base material in which the anchors will be installed, preliminary tests should be carried out to ensure the type of anchor being used is suitable for the building substrate. The NASC publication, TG4:11, ‘Anchorage Systems for Scaffolding’ recommends that five sample anchors should be tested in an area that is ideally located away from where the works will be carried out.
The test load applied should be two times that of the required working load for all anchors, expect nylon inserts which should be tested to three times the working load.
Proof Testing Anchors
Proof testing should be carried on at least 3 or 5% (1 in 20) of all installed anchors once they have been installed to ensure their strength and stability.
This number applies to the following separate areas:
- Different fixings that may have been used
- Where the base material is different
- Where the condition of the base material has been affected by weather conditions on a different elevation
- Where a different team of installers has worked
Anchors should be tested to a load of 1.25 times the working load. It is good practice for all tested anchors to be be clearly identified with a tag outlining the date of the test and the load applied. The testing should be performed by a trained and competent individual who should preferable be independent of the installer/installation team.
Should anchors be installed into mortar joints then the testing regime should be doubled from 1 in 20 (5%) to 1 in 10 (10%).
Should one anchor fail a test, then the test frequency should be doubled to at least 10% of all anchors and a minimum of six. Should two anchors fail then the test frequency should be doubled again to 1 in 5 and a minimum of twelve. More than two failures should be treated as a serious issue, with a thorough review of the fixing and installation methods being carried out, prior to continuing.
Fixed Anchors should be re-examined at regular intervals and it is normal to do so during statutory scaffold inspections. Additional checks may be required following events that may have affected the structure, such as high winds or accidental vehicle contact. For more information on scaffold inspections please do review our article on How Often Should Scaffold be Inspected
Scaffold Anchor Testing Equipment
The quality and reliability of the testing equipment is of critical importance. At leaches we supply the BIG BEN ANCHOR TEST KIT FOR SCAFFOLD ANCHOR TIES which is used to test the adequacy of anchors in most construction materials, either for the purpose of establishing safe workloads or to validate the correct installation of existing fixings.
Corrosion of Scaffold Anchors
Although scaffold tie anchors are regarded as temporary fixings (up to two years being regarded as the definition of temporary) rust and corrosion will take place if let unprotected in the structure. It is therefore recommended that re-testing for structures that remain for more 12 months is performed.
The purpose of this article is to cover the basics for effective Scaffold anchor testing. For more detailed information on Anchor testing please click the links below. Alternatively, if you have a requirement for equipment advice or have any further questions please contact us on firstname.lastname@example.org or 01432 246 800
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