What are the standards for aluminum alloy lean tube connectors？

The standards for aluminum alloy precision tube connectors primarily focus on dimensional compatibility, material performance, modular design, and industry application specifications. According to authoritative public data up to May 2026, the core standards are as follows:

1. Core Dimension Standards
- Pipe outer diameter: ∅28mm (actual 27.8mm ±0.2mm), the universal standard diameter for third-generation aluminum alloy precision tubes.
- Wall thickness: The commonly used wall thickness for aluminum alloy lean tubes ranges from 0.8–2.0mm, and connectors must be compatible with this range.
- Internal diameter of the connecting piece: Compatible with ∅28mm pipes, typically featuring a cross-type bidirectional positioning structure, with four grooves on the outer side for fastener fixation.

II. Material and Craftsmanship Standards
- Pipe material: Made of 6061-T6 or equivalent-grade aluminum alloy, anodized with tensile strength ≥185 N/mm² and oxide film thickness ≥11μm.
- Connection material:
- Commonly used for electrophoretic coating of carbon structural steel (e.g., GB/T 3091-2015) or SUS304 stainless steel (for high cleanliness/anti-static applications).
- Surface treatment requirements: Salt spray test ≥720 hours (for carbon steel parts) or surface resistance ≤10⁶Ω (for anti-static stainless steel parts).
Load-bearing capacity: High-quality connectors can support ≥300kg (aluminum alloy parts) to ≥500kg (heavy-duty steel parts).

III. Functional and Compatibility Standards
Modular compatibility: Supports combination use with various types of pipes, including steel-plastic composite pipes, stainless steel pipes, and aluminum alloy pipes.
- Connection method:
- External clamping type (e.g., 90° external clamp, L-shaped external clamp): Tightened with an Allen wrench for external right-angle or angled connections.
- Internal expansion type (e.g., 90° internal expansion parts, L-shaped internal expansion parts): Used for internal connections to enhance aesthetics and structural stability.
- Quick disassembly/Manual assembly: Some high-end products support rapid manual connection, suitable for high-frequency reconfiguration production lines.
Standardized accessory types: include 90°/45°/cross/Universal/parallel/straight connectors, as well as auxiliary components such as casters, plugs, and adapter blocks.

IV. Reference to Industry and National Standards
Although there is no national mandatory standard specifically for "lean tube connectors," their design adheres to the following specifications:
- GB/T 3091-2015 (Welded Steel Pipes for Low-Pressure Fluid Transport)
- GB 5237-2008 (Aluminum Alloy Building Profiles)
- ISO 14644-1 (Cleanrooms and Associated Controlled Environments)
- ISO 9001 (Quality Management System)