Safety nets have become one of the indispensable parts of the construction business, especially to prevent the risk of falling materials and people from heights.
Security networks, which were visible in centrally located projects in big cities until a few years ago, are becoming more common day by day.
ropes
In TS 1263-1, depending on the purpose of use of ropes; It is divided into three classes: edge rope, binding rope and joining rope. “Edge ropes” nets all around
They are the components that homogeneously distribute the impact of the safety net when it is exposed to the load and meet the final load. While "tying ropes" provide the connection between the nets and the hook points, "joining ropes" are used to combine more than one network. While the standards only mention ropes for the connections of the nets to the support structure or between each other, in the industry, hooks etc. mostly made of alloy or steel are used for these operations. materials are used.
networks
The term network is defined in TS 1263-1 as "the connection (combination) of small meshes".
Networks are examined in four classes according to the maximum mesh size (IRmR) and the minimum energy that the network must have (ER AR and ER BR). The necessity of using edge thread generally determines which of the Q and D eye pattern nets will be preferred in the market. In S and V type safety nets, where the use of edge rope is mandatory in the standard, D eye pattern nets are generally used.
SECURITY NET CLASSIFICATION
In TS EN 1263-1 Standard, security networks consist of 4 classes:
Classes A and B; It defines the minimum energy absorption capacity of the network, that is, how much energy it can absorb. This capacity is expressed in kJ.
For example; Class A is 2.3 kJ while class B is 4.4 kJ.
Classes 1 and 2 define the maximum mesh sizes.
For example; While it is 60 mm for class 1 size, it is 100 mm for class 2 size.
NETWORK ROPE
The mesh rope must be made of at least 3 separate threads knitted together so that they do not unravel and must be tested in accordance with TS EN 1263-1 Standard article 7.3.
EDGE (BORDER) ROPE
The boundary rope is the continuous rope passing through each mesh around the system S and V security network. The minimum tensile strength it must have varies depending on the type of rope.
For example; Type K rope must have a tensile strength of 30 kN. Edge ropes must be tested according to TS EN 1263-1 Standard Article 7.5.
BINDING ROPE
Mooring ropes connect the safety net to anchor points and/or structural elements on the netted structure. The minimum tensile strength the rope must have
varies depending on type. For example; While the tensile strength of L type or M type rope is 30 kN, this value is 15 kN for R type rope. If type F rope is used, the minimum tensile strength must be 20 kN. (Regarding ropes, TS EN 1263-1 Article 4.3 can be used for the types of ropes, their minimum tensile strength and the safety net systems in which they are used.)
Mooring ropes must be tested according to TS EN 1263-1 Standard Article 7.5.
JOINING ROPE
The bonding rope brings together multiple safety nets when more than one safety net is required for the area that needs to be protected. The minimum tensile strength of this rope must be 7.5 kN and TS
It must be tested according to EN 1263-1 Standard Article 7.5.
SAFETY NET LABEL
Safety nets must have a label indicating the following:
- Name or trademark of the manufacturer or importer
- Brief display information according to TS EN 1263-1 Standard article 5
(For example; Safety net EN 1263-1 – S – A 2 – Q 90 – 10 x 20 – M)
- Number showing that the test mesh and mesh are identical, given according to TS EN 1263-1 Standard article 6.1.5
- Month and year the net was manufactured
- Minimum energy absorption capacity of the test sample
- Manufacturer's code
- If Annex B is to be applied, only the approval of the authorized and independent organization for M level inspection (inspection)
The tag must be permanently attached to the network and must last for the life of the network.
USER INSTRUCTION BOOK
For the use and application of security networks, a (guide) instruction book according to TS EN 1263-1 Article 9 must be supplied with each delivery of the network. This instruction manual must be in the user's native language. The instructions for use must contain information on at least the following topics:
- Required anchoring forces
- Maximum drop height
- Minimum capture width
- Security network connections
- Minimum clearance distance below the safety net
- Storage
- Examination
- Renewal
In addition to these instructions, special installation instructions depending on the specific applications of the network must also be taken into account. Article 9 of TS EN 1263-1 Standard states that the instruction book must be delivered with the safety net, including the following information:
- Installation, use and dismantling of the network
- Storage, maintenance and inspection
- Dates for testing of test meshes
- Deprecation conditions
- Hazards that need to be warned (e.g. excessive temperature, chemical effects)
- Disclosure of conformity specified in Article 10 of TS EN 1263-1.
DETACHABLE TEST MESH
Safety nets should be tested at least every 12 months to prevent deterioration due to UV rays. All safety nets must have at least 3 loosely woven meshes for removal during testing. Each test mesh must have the same number, be made of the same material, and be in the same production batch as the mesh to which it is attached.
All safety nets that are more than 12 months old must have a current test label indicating that the net has been tested within the previous 12 months and meets the manufacturer's minimum tested energy absorption capacity. Test tags are valid for 12 months and must not expire when the network is set up. The network owner must retain the network test results.
DIMENSIONS OF SAFETY NETS
TS EN 1263-2 Standard is applied to system S security networks, system T, system U and system V security networks, whose area is only over 35 m2 and the shortest side of the network is at least 5 m long.
Considering the scope of TS EN 1263-2 Standard, system S security networks must meet the following criteria:
- Must have an area larger than 35 m2,
- The length of the shortest side must be at least 5 meters and
- The maximum fixing distance (distance between anchor points) should be 2.5 meters.
If the load falls on a network of less than 35 m2; Compared to networks with larger areas, there will be less stretching and more limited energy absorption due to the smaller network area. When the network area is less than 35 m2, the use of class B network with an energy absorption capacity of 4.4 kJ can be preferred.
FALL HEIGHT
Fall height is the distance a person falls from the work platform onto the safety net. The greater the height of the fall, the greater the impact of the fall.
The height of the fall should be kept at the minimum possible distance, with the safety net installed as close to the work platform as possible. if possible
Safety nets should not exceed a distance of 2 meters from the bottom of the working platform. The maximum fall height allowed in the TS EN 1263-2 standard is 6 meters. (This constitutes a nominal fall height of 7 meters, considering the employee's center of gravity.)
Within a distance of 2 meters from the outer edge of the net, the drop height (Hr) between the working platform and the net should not be more than 3 meters. The reason for this situation is; Safety nets do not stretch too much at corners and edges. (TS EN 1263-2)
If the slope of the working platform is more than 20 degrees,
The distance between the edge of the work platform and the lowest point of the outer edge of the safety net should not exceed 3 meters.
He: Height of fall
b : Capture width
c : The lowest point of the outer edge of the safety net
t: Distance between the edge of the work platform and the lowest point of the outer edge of the safety net
CAPTURE WIDTH
If the employee trips while moving, he or she will fall forward/forward in addition to falling downwards. Distance of falling forward
is affected by height. In other words, the higher the drop, the greater the forward motion. Safety nets providing protection at the edge of the work platform must be wide enough to cover the forward movement of the falling person. It refers to the width of catching the clear width between the edge of the working platform and the outer edge of the safety net.
Minimum catch widths for maximum fall heights specified in TS EN 1263-2 Standard are shown in the table below (Table 3).
CLEARANCE DISTANCE
There must be sufficient clearance under the safety net so that it can stretch (deform) when the employee falls. The amount of stretch depends on the drop height and the width of the web.
NETWORK SAG
Web sag or initial sag is the amount of deformation (stretching) caused by the web's own weight. The web sag should be between 5% and 10% of the shortest side of the web.
To ensure sufficient initial sag, the safety net must be at least 10% larger than the area it will cover (along both edges). Excess mesh should be rolled under the tying rope or tying system to distribute the load evenly and avoid too much stress on the mesh eyes.
OVER STRESS AND UNDER STRESS
Safety nets should not be overstretched so that they can flex and absorb the energy generated by the impact of a fall. An over-tensioned mesh or too many fixings
A mesh with one point may not stretch enough. In both cases, while the impact on the person falling on the net increases, the load applied to the net and structure also increases.
A low-tension net can stretch too much, and if there is not enough clearance under the net, the falling person may hit an obstacle or the ground.
APPLICATIONS
Security networks should be installed taking into account the criteria specified in the TS EN 1263-2 Standard:
Safety nets are manufactured to absorb the energy of falls up to 6 meters, but they should be installed as close to the work surface as possible. The scope of the gaps protected by safety nets should be clearly stated and employees at the top should be warned not to go beyond the scope of the safety net.
If safety nets constitute the first step of protection against falls, that is, if the fall cannot be prevented by other methods, the safety net should be installed below the working level, preferably at a distance not exceeding 2 meters.
When safety nets are used within system T, they are normally used only as a second step of fall protection, i.e. in addition to the use of guardrails, for example.
should be considered as a precaution. System T safety nets should be installed horizontally or with a slight slope backwards.
If the safety nets in class A and used within system S are used against a fall of more than 2 meters, the area of the nets should not be less than 35 m2 and the shortest side should be at least 5 meters. If any of these two criteria cannot be met, a class B security network should be used. Low area safety nets should be installed after consulting the manufacturer.
When the safety net is installed to protect employees who fall from the edge of the work area, care should be taken to ensure that the safety net has a sufficient catch width to take into account the possible horizontal movement of the employee who falls from the edge.
In the selection of the network to be used in the application (work to be done); Since the energy absorption capacity of the network decreases with age, its lifespan must be taken into account. If networks are to be in use for a year or more, checks should be made to verify that aging over the period of use has not reduced the energy absorption capacity of the network below the level for which it is classified.
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