The EN 353-1:2014 standard for vertical fall arrest systems
Considering the changes to this important standard.
In 2004, the UK’s Health and Safety Executive (HSE) issued a safety warning regarding EN 353-1:2002 which relates to guided-type fall arresters including a rigid anchor line commonly found on fixed ladders and other vertical structures. Information received by the HSE from various committees, manufacturers and end users raised concerns on the use of such products following reported cases of serious injuries and some fatalities. These resulted from the user falling backwards, thus not engaging the locking device due to a force perpendicular to the line.
Since then, EN 353-1:2002 has been withdrawn on safety grounds and replaced by EN 353-1:2014. This introduces various locking tests, including a fall-back test as well as other function tests to take into account any foreseeable similar occurrences. SATRA has a dedicated test facility to carry out testing in accordance to EN 353-1:2014 to help manufacturers to improve their products and check that they meet the requirement of EN 353-2:2014.
Materials and construction
Guided-type fall arresters (referred to as ‘fall arresters’ in this article) consist of a travelling device which moves along a fixed rail or a wire made of steel or galvanised steel, with a minimum diameter of 8 mm, anchored between two points with a line tension of 0.25 kN or greater. An energy-dissipating element is normally included, either on the top anchor or the connecting element between the travelling device and the user. The energy-dissipating element is designed to absorb the force of the fall and keep the force on the user below 6 kN.
The fall arrester, including the rigid anchor line, shall be equipped with the ability to prevent incorrect orientation of the fall arrester when being attached or fitted to the rigid anchor line, as these devices are designed to lock in only one direction.
Connecting elements between the user and the fall arrester must be permanently attached to the fall arrester to prevent the user from changing it. In addition, no other connecting elements must be used or added, as such a change will directly affect the fall characteristics by increasing the free fall distance and the amount of force put through the system, causing it to possibly fail to arrest the fall in accordance with EN 353-1:2014.
The fall arrester must travel freely in both directions without manual intervention so as not to hinder any activities the user may be carrying out and his or her ability to climb freely.
U-bolt clamps – including those conforming to EN 13411-5 – shall not be used to form a top termination in the rigid anchor line made from wire rope (that is, above the working length of the anchor line). U-bolts may be used on the lower terminations of the wire rope, as these will not be load bearing during a fall on the system.
Static forces are used to measure the strength of the system and apply a safety factor, and these forces will not be put through the system or the user in normal use. The force is applied much slower than the dynamic test (mentioned later in this article) and at a controlled rate as not to shock-load the system.
Non-metallic materials intended to remain permanently installed are now required to have a static strength of 22 kN to cover possible degradation in service due to abrasion and weathering. This is not necessary for non-metallic components that are removed after use, as these will be stored safely according to the manufacturer’s instructions.
Pre-loading of the energy-dissipating element has been introduced to check that it does not deploy prematurely under loads that can be expected in normal service, by the user applying their body weight to the rigid anchor line by any means.
The fall arrester and rigid anchor line is subjected to a force of 15 kN for the static strength test. This is based on safety factor of 2.5x on a maximum arrest force of 6 kN during a fall.
The load on the user must be below 6 kN. However, the load on the anchorage may exceed this. Should the load at the anchorage point exceed that of 6 kN during the dynamic performance test, the rigid anchor line will be tested statically to 2.5x the maximum recorded force during the dynamic performance test.
If the device cannot rotate freely around the rigid anchor line, a lateral 1 kN load is applied statically. This requirement is to check that the fall arrester does not become detached from the rigid anchor line with a lateral movement by the user. This is not normally an issue for wire rope systems, but is more for systems incorporating a rail anchor line system, as these do not allow any lateral movement.
Dynamic testing simulates a fall using the worst-case scenario, with maximum user weight and free fall putting all the available energy into the fall. These tests apply a shock load to the system as the mass accelerates and decelerates rapidly. Such forces may be seen in a real-life situation should a user fall.
In general terms, the human physique can be classified by type, size and composition and can be defined as i) ‘endomorph’ – characterised by a preponderance of body fat, ii) ‘mesomorph’ – marked by a well-developed musculature and iii) ‘ectomorph’ – distinguished by a lack of much fat or muscle tissue. Under dynamic conditions, these different physiques can generate different results.
For consistency and reproducibility of testing, performance tests are conducted with a rigid steel mass of 100 kg representing a single user.
The objective of the performance tests is to confirm that the arrest of a fall is made in line with the test requirements, thus keeping the arrest force and distance to a minimum to prevent harm to the user.
During the dynamic performance test, the load on the user and the anchorage system is measured. The force on the user must not exceed 6 kN. However, the anchorage force can exceed this but must still have a 2.5x safety factor in strength. The fall arrester must engage within 0.5 m and the maximum arrest distance for the user cannot exceed 1 m.
The objective of the function tests is to confirm correct operation of the fall arrester locking feature under foreseeable conditions of use using minimum- and/or maximum-rated loads as specified by the manufacturer. There are no force requirements for the function tests, as these are measured in the dynamic performance test. However, the same requirements still apply for dynamic performance – the fall arrester should engage within 0.5 m and the arrest distance of the user should remain below 1 m.
These function tests have now replaced the locking tests from the previous version of this standard. This is because the old locking tests only tested that the device locked using a minimum of 5 kg and did not measure how long it took for the device to lock or the arrest distance of the user. The test mass for these tests has also been increased to be most representative of the end user.
Cold function: The purpose of this test is to check the locking function of the fall arrester at low temperature (that is, not warmer than -30°C). This test is carried out using a 100 kg rigid steel test mass. Depending on engineering tolerances, the cold temperature may affect the fall arrester’s ability to engage due to contraction of metallic components.
In the 2014 (pre-amendment) version of the standard, the guided-type fall arrester sample is immersed in water at 10-30ºC for five minutes, and then it is hung to dry on an anchor line for 15 minutes. After being removed from the rigid anchor line, the arrester is subjected to the lowest temperature claimed by the manufacturer (at least -30ºC) for a minimum of four hours.
In an A1:2017 amendment, the requirement for the sample to be immersed in water prior to being subjected to the low temperature has been removed.
Minimum distance minimum/ maximum user weights: This test is used to check the locking function of the fall arrester when a user is positioned as close as possible to the rigid anchor line, and in contact with the fall arrester. As guided-type fall arresters work mainly on a lever that compresses against the rigid anchor line to increase friction and acts as the braking mechanism during the fall, the reduced distance between the user and the fall arrester may have adverse effects on the lever being able to engage.
Fall-back minimum/maximum user weights: There is a risk of a user falling backwards during use, and this has been addressed in a fall-back function test. A load is applied to the fall arrester in an unlocked condition, to represent a typical backwards load that could be expected in service. Similar to the minimum distance, the force applied away from the system may once again affect the fall arrester’s ability to lock.
On a guiding bracket: Guiding brackets are used on wire systems to reduce the deflection of the wire away from the climbing surface when the user leans away from it. The guided-type system is primarily a fall arrester, although it limits the user’s movement to the set climbing path.
The function test for the guiding bracket has been introduced to check the locking function of the fall arrester. It also assesses the integrity of the guiding bracket on a rigid anchor line made of wire rope in the event of a fall occurring when the fall arrester is positioned directly on the guiding bracket. The guiding bracket should not hinder the fall arrester’s ability to arrest a fall.
Sideways fall: When working at height, the area of work may be to the user’s side. If a user falls while leaning to one side, he or she will swing back to the centre as they fall, creating a pendulum motion which may not engage the fall arrester or could cause it to disengage during the fall.
The potential of loading the guided-type fall arrester in a sideways direction has been addressed in the new function test. The sideways test is conducted using the maximum rate load only, as this will apply higher stresses on the fall arrester and rigid anchor line. This test only applies if the fall arrester cannot freely rotate around the rigid anchor line due to guiding or intermediate brackets or for systems incorporating a rail, as none of these allow any lateral movement.
Sideways-leaning anchor (if the line can be used at a maximum angle of 15 degree from vertical): This test was included to cover foreseeable conditions of use. As these systems are installed mainly on ladders, to be consistent with all parts of EN ISO 14122 – ‘Safety of machinery – Permanent means of access to machinery’ standard and ISO standards concerning the allowed inclination for ladders, this function test covers the angle of 15 degrees from the vertical.
Corrosion resistance: When metallic components are exposed to the elements, they will corrode over time – unless they are treated to slow down the effects. Rusting of key components may affect the fall arrester’s ability to function correctly or lead to complete structural failure of the device.
The corrosion testing of the metallic components is now assessed by a 48-hour exposure time, compared to the previous 24-hour corrosion test. The extra exposure to neutral salt spray can lead to failures of metallic components that are already used on products which required only 24-hour exposure. This longer test may highlight the need for a change of coating on the metallic components in order to meet the new requirements.
Marking: The only change between EN 353-1:2002 and EN 353-1:2014 with regards to marking is that the minimum and maximum rated loads must now be marked on the fall arrest device.