Can the mobile scaffold be used in bad weather (such as strong wind and rainstorm)?
Mobile scaffold is strictly prohibited to be used in severe weather (such as strong wind and rainstorm), which is determined by its structural characteristics and safety risks. The following will explain the impact of different types of severe weather and specific reasons for taboos:
1、 Taboos and risks of use in windy weather
The stability of mobile scaffolding is extremely sensitive to wind force. According to the "Technical Code for Safety of High Altitude Operations in Construction" (JGJ80) and industry practice, when the wind force reaches level 4 or above, the use of mobile scaffolding is prohibited (level 4 wind speed is 5.5-7.9m/s, equivalent to blowing up ground dust and paper). The specific reasons are as follows:
Sudden drop in anti overturning ability
The bottom support area of mobile scaffolding is relatively small (especially for wheeled frames), and wind can generate lateral thrust, causing the center of gravity of the frame to shift. For every 1 level increase in wind force, the lateral thrust increases by about 1.5 times: for example, a 6-meter-high mobile scaffold can withstand a horizontal thrust of about 120N at level 4 wind, which increases to 180N at level 5 wind, exceeding the critical value of the scaffold's anti overturning ability (usually ≤ 150N), and is prone to overall overturning.
Structural shaking causes component failure
Strong winds can cause severe shaking of the frame, and the connection nodes between the uprights, crossbars, and fasteners may experience repeated changes in stress, which may result in loosening of fastener bolts and bending of the uprights (more pronounced when the aspect ratio is too large). If the wind speed reaches level 6 or above (wind speed 10.8-13.8m/s), the shaking amplitude of the frame can reach more than 30cm, and the operators cannot maintain balance, resulting in a significant increase in the risk of falling.
Increased risk of falling objects from high altitude
Tools and materials (such as wrenches and steel pipes) on scaffolding may be blown off by the wind. The higher the wind speed, the farther the horizontal projection distance of the falling object, which significantly increases the threat to ground personnel and equipment.
2、 Taboos and risks in rainstorm
In rainstorm weather (including moderate to heavy rain, hourly rainfall ≥ 10mm), mobile scaffolding is also prohibited. The core risks focus on ground stability and structural corrosion:
Ground subsidence or slippage
Rainstorm will cause a sudden increase in the ground soil moisture content. If the foundation is soft soil (such as soil, sandy soil), local settlement may occur, resulting in uneven support of the frame, unbalanced force on the pole and tilt. Even if the ground hardens, rainwater will reduce the friction between the bottom of the frame (especially the wheeled frame) and the ground, making it easy for personnel to fall due to the sliding of the frame when moving on the working level.
Corrosion of metal components and decrease in strength
The upright and cross bars of the mobile scaffold are mostly steel, which will accelerate the corrosion in rainstorm, especially the bolts and nuts of fasteners. The thread may be stuck or corroded and broken after the rainwater infiltrates, reducing the joint connection strength. If they continue to be used without thorough inspection after rainstorm, structural collapse may be caused by hidden damage of components.
Electrical safety hazards
If the operation involves the temporary use of electricity (such as electric tools), rainstorm will increase the risk of electric shock: the rain may cause damage to the insulation layer of the wire, conduct the metal parts of the scaffold, and cause electric shock accidents for operators.
3、 Emergency response in adverse weather conditions
In case of strong wind and rainstorm during use, the following measures shall be taken immediately:
Emergency evacuation: Operators should immediately stop their work and evacuate in an orderly manner from a safe passage (such as a ladder) to the ground. It is prohibited to stay on the frame or climb in panic.
Fixed frame: Push the mobile scaffold to a sheltered and elevated location, and use windproof cables (diameter ≥ 12mm) to rigidly connect the frame to the building (with one cable set every 2m height). The wheeled frame needs to lock the wheel brakes and place triangular wooden blocks on both sides of the wheels to prevent slipping.
Inspection after rain: after the rainstorm, it is necessary to check whether the bottom of the pole is settled, whether the fasteners are rusted and loose, and whether the wheels are stuck. After confirming that all parts are normal and the ground is dry, they can be reused.
summarize
The design of mobile scaffold is not strengthened for severe weather (such as no wind proof cable fixing point, no waterproof and anti-corrosion treatment), and its stability and safety will decline sharply in strong wind and rainstorm. Therefore, it is necessary to strictly follow the principle of "no use in adverse weather", pay attention to weather forecasts in advance, complete frame reinforcement and personnel evacuation before adverse weather arrives, and avoid safety accidents from the source.
