One. What is a construction safety netting?
Construction safety netting is a personal protective equipment used to prevent falls, with a wide range of applications, primarily used in various high-altitude operations. Fall hazards in high-altitude work commonly occur on scaffolding, roofs, windows, hanging structures, deep pits, and deep trenches. The severity of fall injuries varies depending on the distance of the fall, ranging from minor injuries to severe injuries or death.
Types of safety nets: Safety nets are classified based on their hanging method, which can be either vertical or horizontal.
Safety netting function: The flat netting prevents falling objects and people, minimizing or reducing the impact and injury caused by falling. The vertical netting prevents people or objects from falling. The netting must withstand the weight and impact force of falling people and objects carrying tools, as well as the longitudinal pull and impact strength.
II. Construction Safety Net Standards
1、Vertical installation
Vertical scaffolding is commonly used in high-rise construction. The exterior side is typically fully enclosed with safety netting, usually made of fine nylon mesh. The safety netting should be securely fastened and completely enclose the scaffolding.
2、Horizontal safety net
Horizontal safety nets are commonly used on scaffolding for multi-story building construction. They are made of woven hemp, jute, or nylon ropes with a diameter of 9mm, typically with dimensions of 3m wide and 6m long, with mesh openings of approximately 5cm. Each properly installed safety net should be able to withstand an impact load of not less than 1600N. Safety nets should be installed on the second floor and every 3-4 floors above, with additional nets installed as the construction height increases. The ropes must be intact, firmly anchored, taut, and securely woven, and the support rods should be made of scaffolding steel tubes. The net width should not be less than 3m, and the minimum width of the first layer should be 6m.
3、Method for installing horizontal safety net supports
(1) Utilizing window sill support structure for exterior wall construction.
Bar 1 is fixed to the inner side of the upper window frame and secured to the inner support of the safety net. Bar 2 is fixed to the outer side of the lower window frame and secured to the diagonal support of the safety net. Bar 3 is fixed to the inner side of the wall and secured to Bar 2. The spacing between the diagonal supports of the safety net should not exceed 4m.
(2) Utilize steel support frames to install safety nets.
For walls without windows, a steel support frame can be installed with a safety net. Openings are pre-cut in the wall, and anchor plates are inserted. The anchor plates have a Ф 14 hole to accommodate the support frame's safety net. The steel support frame consists of Ф 12 steel bars, approximately 1.56m in length, with a curved hook at the top. The back of the hook is welded to a hook for hanging the safety net. The bottom is welded with a mounting bracket for an inclined support and a wall-mounted support foot. Additionally, a hook for attaching a nylon rope and a wall plate are welded near the top hook. The wall plate ensures that the support frame does not shift under load. The spacing between the support frames is typically 3 to 4 meters.
(3) First layer of large-span safety net
First-layer large-span safety net, can be constructed usingDiagonal bracing (Diagonal bracing), or can be installed on one side. Building protection net: In buildings, to prevent high-rise construction materials and personnel from falling, the building is surrounded with protective vertical nets to prevent casualties.
III. Requirements for the installation of safety nets
1. Safety nets must be installed below areas where high-altitude work is performed. When the building height exceeds 4m, a safety net that gradually rises with the wall must be installed, followed by a fixed safety net every 4m. Safety nets must also be installed at the top and bottom of cantilevered structures and bridge-type scaffolds.
2. The safety net should be installed with the bottom lower and the top higher, with a height difference of approximately 50cm for the protruding part. The support components should not have cracks or deformation; the inner edge of the net should be less than 15cm away from the wall; and the lowest point of the net should be more than 3m away from the surface of any object below.
3. Before use, check the safety net for signs of corrosion and damage.
4. During construction, ensure that the safety net is complete and effective, with appropriate support and even load distribution. The net should not contain any debris. The overlapped sections must be tightly and securely fastened, with no gaps. The safety protection net must not be removed or damaged during construction and can only be removed when working at ground level.
5、The support structure used for the safety netting must meet the following requirements: the diameter of the small end of wooden poles must not be less than 7cm, the diameter of the small end of bamboo poles must not be less than 8cm, and the spacing between support poles must not exceed 4m.
6. When the safety netting has been installed and needs to be temporarily removed for construction purposes, the contractor must notify and obtain the consent of the erecting party before removing it. Upon completion of the construction, the contractor must immediately restore the safety netting according to the specified requirements, and after the erecting party has inspected and approved it, it can be used.
7. Regularly clean the mesh of any debris; when welding operations are performed above the mesh, effective measures must be taken to prevent welding sparks from falling onto the mesh. The area around the mesh should not be exposed to prolonged, severe acid or alkaline fumes.
8. Regular inspection and tracking of usage records are required during use. Any safety nets that do not meet the required standards should be promptly removed.
9、Steel mesh and wire mesh must be strictly separated. Steel mesh must never be used in conjunction with wire mesh. When setting up steel mesh, the bottom must be securely tied.
10. When the safety netting is not in use, it must be stored and maintained properly to prevent moisture and mold growth.
11、When using new nets, it is mandatory to check the product label: ① whether it is a flat net or a standing net; ② the manufacturer's production license; ③ the product's factory release certificate. Old nets must be tested before use, and a test report must be available. The safety net must pass a dynamic load test using two 120kg weights, 1.5m apart, and free fall from a height of 4-5m. The net must remain intact for the test to pass.