How to ensure the safe use of rectangular tubes in decoration and renovation?

How to ensure the safe use of rectangular tubes in decoration and renovation?
The key to ensuring the safe use of rectangular tubes in decoration and renovation lies in comprehensive control of the entire process, from source selection, standardized construction, and post-maintenance. This focus is on preventing risks such as structural collapse, detachment, and corrosion, while also balancing environmental protection and daily safety.
1. Source Control: Choosing the right rectangular tube is the foundation of safety.
Incorrect selection can directly lead to safety hazards. It is important to clearly identify three key indicators based on the intended use scenario to avoid substandard products or mismatched specifications.
Choosing the right material and surface treatment
For outdoor applications (such as doorways, awnings, and landscaping): Select hot-dip galvanized rectangular tubes with a zinc layer thickness of at least 85μm (this can be confirmed through professional testing or by reviewing the manufacturer's report) to prevent rust caused by rain and humidity, thereby reducing structural strength.
For indoor applications (such as suspended ceilings, partitions, and furniture): For dry environments (such as living rooms and bedrooms), select ordinary cold-rolled steel rectangular tubes (with a painted surface). For humid environments (such as bathrooms and kitchens), galvanized tubes are still recommended to prevent moisture-induced rust on the inner wall. Avoid using "non-standard tubes": Some rectangular tubes produced by small factories have problems such as "false wall thickness" (e.g., 1.5mm marked but only 1.2mm in reality) and high material impurities. Choose products that comply with the national standard (GB/T 6728-2020) and ask the manufacturer to provide a material list. Matching Specifications with Load-Bearing Requirements
For load-bearing applications (such as ceiling joists, furniture frames, and balcony railings): Calculate wall thickness and cross-sectional dimensions based on the actual load. For example:
Indoor ceiling main joists: If only supporting gypsum board and lighting fixtures, select rectangular tubes with a cross-section of 20mm x 40mm and a wall thickness of 1.2-1.5mm.
Balcony railing posts: To support human support, select rectangular tubes with a cross-section of 30mm x 50mm and a wall thickness of 1.5mm or greater.
Outdoor canopy main frames: For larger coverage areas (e.g., 3m x 2m), select rectangular tubes with a cross-section of 40mm x 60mm and a wall thickness of 2.0mm or greater to avoid bending and deformation due to insufficient load-bearing capacity.
For non-load-bearing applications (such as wall moldings and light box frames), select thin-walled tubes (0.8-1.2mm thick). However, ensure the overall structural stability and avoid excessive thinness that could easily break. Check the appearance and quality.
Visual inspection: The surface should be free of obvious dents, scratches, or zinc layer loss (for galvanized pipes). The pipe ends should be free of burrs or deformation. The cross-sectional dimensions should be uniform (length and width can be measured with a tape measure, with an error of no more than 0.5mm).
Simple test: Tap the pipe wall with your hand. A crisp sound, no muffled sound, may indicate hollowness or impurities. For thin-walled pipes, apply light pressure. If there is no noticeable deformation, the pipe is considered acceptable.
II. Standardized Construction: The construction process is critical to safety.
Even if the correct pipe material is selected, improper construction (such as loose welding or unstable fixing) can still lead to safety accidents. Four key construction points should be carefully considered.
Welding Quality: Avoid "cold welds" and "missing welds."
For load-bearing structures (such as guardrail posts and main ceiling purlins): Full welds must be used. The weld height must be no less than the pipe wall thickness (e.g., for a wall thickness of 1.5mm, the weld height must be ≥1.5mm). The weld surface must be free of pores and slag inclusions. After welding, remove the weld slag and apply an anti-rust treatment (such as anti-rust paint). Non-load-bearing structures (such as decorative partitions and light box frames): A combination of spot welding and full welding can be used, but critical connection points (such as frame corners) must be fully welded to prevent breakage under load.
Inspection method: After welding, manually shake the connection to ensure there is no noticeable looseness. If necessary, perform a simple load-bearing test (e.g., place a 5kg weight on the ceiling keel and observe for 12 hours to ensure no deformation).
Securing method: Ensure "firmness without displacement"
Connection to wall/floor: Use expansion bolts or chemical anchors, not simple nails. For example:
Connection between ceiling keel and top floor slab: Install expansion bolts (≥M8) every 600mm to prevent the keel from falling off.
Connection between guardrail posts and ground: The bottom of the post should be pre-buried or secured with M10 expansion bolts, with the bolts inserted ≥50mm into the ground/wall to prevent tipping. Fixing of suspended structures: For example, outdoor awnings and high-altitude billboards, in addition to fixing at both ends, additional support points are required in the middle (such as a hanging point or support column every 1.5m) to prevent collapse caused by excessive force at a single point.