ຄວາມຄືບໜ້າ
ຄວາມຄືບໜ້າ | GALVANIZED TUBE SERIES
Pre-Galvanized Flat Rectangular Steel Tube
A broad fixing face. A compact section depth. Zinc protection for practical metal fabrication.
QIDAMT galvanized flat rectangular steel tube is roll-formed and welded from galvanized carbon steel strip. Its shallow rectangular profile is suited to furniture components, display frames, partitions and fabricated metal assemblies where space, appearance and assembly dimensions matter.
Product Advantages at a Glance
Compact Flat Profile
The unequal sides provide a broad attachment face while keeping the section depth small. This helps designers fit panels, furniture frames and infill components within a limited assembly space.
Zinc-Coated Surface
Zinc provides corrosion protection to the steel surface. Coating route, coverage and thickness can be specified to match the intended service environment and finishing requirements.
Practical Section Geometry
The hollow section provides a compact profile for fabricated assemblies. Flat faces make alignment, joining and mounting easier to plan during fabrication.
Galvanized Tube Range
QIDAMT supplies flat rectangular tube for compact fabricated assemblies alongside pre-galvanized square and rectangular steel tube ແລະ hot-dip galvanized round steel tube. The range provides different section shapes for panel frames, furniture components, partitions and general metalwork.
Shandong Qida Metal Technology Co., ຈຳກັດ. is based in Liaocheng, ຊານຕົງ, ຈີນ. Product selection covers section dimensions, steel grade, zinc coating and delivery requirements, with each combination defined in the agreed order specification.
National Standard Technical Parameters
Manufacturing route: continuously galvanized steel strip, roll-formed and longitudinally welded into a rectangular hollow section. The following tables list national-standard requirements by material, thickness and coating designation. They contain standard values only.
Carbon Steel Base Materials — GB/T 700-2006
| Base steel grade | Thickness range for listed yield value (ມມ) | ຄວາມເຂັ້ມແຂງຂອງຜົນຜະລິດ (MPa) | ຄວາມແຮງ tensile (MPa) |
|---|---|---|---|
| Q195 | t ≤ 16 | 195* | 315–430 |
| Q215A / Q215B | t ≤ 16 | ≥ 215 | 335–450 |
| Q235A / Q235B | t ≤ 16 | ≥ 235 | 370–500 |
*GB/T 700-2006 specifies the Q195 yield value as a reference, not a delivery acceptance criterion. These are base-steel values, not finished-tube tensile-test requirements.
Galvanized Strip Grades — GB/T 2518-2019
| Strip designation | ຄວາມເຂັ້ມແຂງຂອງຜົນຜະລິດ (MPa) | ຄວາມແຮງ tensile (MPa) | Elongation A80, minimum (%) |
|---|---|---|---|
| DX51D+Z | No numerical limit specified in the standard | 270–500 | 22 |
| DX52D+Z | 140–300* | 270–420 | 26 |
| DX53D+Z | 140–260 | 270–380 | 30 |
| S220GD+Z | ≥ 220 | ≥ 300 | 20 |
| S250GD+Z | ≥ 250 | ≥ 330 | 19 |
| S280GD+Z | ≥ 280 | ≥ 360 | 18 |
| S300GD+Z | ≥ 300 | ≥ 370 | 18 |
| S320GD+Z | ≥ 320 | ≥ 390 | 17 |
| S350GD+Z | ≥ 350 | ≥ 420 | 16 |
A80 values above apply at t > 0.70 ມມ. *For DX52D+Z, the yield limits apply to FB and FC surface quality. These are coated-strip requirements before tube forming.
Thickness Bands and Elongation Requirements — GB/T 2518-2019
| Nominal coated-strip thickness t (ມມ) | DX51D+Z A80 minimum (%) | DX52D+Z A80 minimum (%) | DX53D+Z A80 minimum (%) |
|---|---|---|---|
| 0.20 ≤ t ≤ 0.35 | 15 | 19 | 23 |
| 0.35 < t ≤ 0.50 | 18 | 22 | 26 |
| 0.50 < t ≤ 0.70 | 20 | 24 | 28 |
| 0.70 < t ≤ 6.00 | 22 | 26 | 30 |
Recommended Nominal Strip Thicknesses — GB/T 25052-2024
| Thickness band | Standard size increment | Selected nominal thicknesses (ມມ) |
|---|---|---|
| t < 1.00 ມມ | 0.05 ມມ | 0.20 / 0.25 / 0.30 / 0.35 / 0.40 / 0.45 / 0.50 / 0.55 / 0.60 / 0.65 / 0.70 / 0.75 / 0.80 / 0.85 / 0.90 / 0.95 |
| 1.00 ≤ t ≤ 6.00 ມມ | 0.10 ມມ | 1.00 / 1.10 / 1.20 / 1.30 / 1.40 / 1.50 / 1.60 / 1.70 / 1.80 / 1.90 / 2.00 / 2.20 / 2.50 / 3.00 / 3.50 / 4.00 / 4.50 / 5.00 / 6.00 |
Nominal strip thickness includes the coating. GB/T 2518-2019 covers 0.20–6.00 mm; GB/T 25052-2024 defines 0.05 mm increments below 1.00 mm and 0.10 mm increments from 1.00 mm upward. Strip thickness is distinct from tube outside dimensions.
Pure-Zinc Coating Designations — GB/T 2518-2019
| Coating designation | Three-point average minimum, both sides combined (g/m²) | Single-point minimum, both sides combined (g/m²) |
|---|---|---|
| Z60 | 60 | 51 |
| Z80 | 80 | 68 |
| Z100 | 100 | 85 |
| Z120 | 120 | 102 |
| Z150 | 150 | 127.5 |
| Z180 | 180 | 153 |
| Z200 | 200 | 170 |
| Z220 | 220 | 187 |
| Z250 | 250 | 212.5 |
| Z275 | 275 | 233.75 |
| Z350 | 350 | 297.5 |
| Z450 | 450 | 382.5 |
| Z600 | 600 | 510 |
Equal coating on both sides: the single-point minimum is 85% of the specified nominal coating mass. The designation gives combined coating mass, not a per-side thickness in micrometres.
Finished-Section Workmanship and Packing — GB/T 6725-2017
| ລາຍການ | National-standard requirement |
|---|---|
| External weld reinforcement after burr removal | Normally ≤ 0.5 ມມ |
| Bundle straps for L ≤ 7 ມ | 3 positions |
| Bundle straps for 7 ມ < L ≤ 10 ມ | 4 positions |
| Bundle straps for L > 10 ມ | 5 positions |
| End strap distance from the tube end | ≤ 1 ມ |
| Maximum weight per packing case | 4 t |
| Maximum inspection batch, outside perimeter ≤ 400 ມມ | 60 t |
| Maximum inspection batch, outside perimeter > 400 ມມ | 100 t |
The material and coating tables define national-standard grades and classes, not a stock guarantee for every combination. Finished pre-galvanized tube outside dimensions, piece length and their tolerances require a product specification: GB/T 2518 governs the strip, and GB/T 6728-2025 excludes sections formed and welded from galvanized strip.
Flat Rectangular Section Details
The wide face provides a flat interface for panels and fittings. The narrow side keeps the assembly depth compact, and the hollow centre provides internal clearance for the designed assembly.
Pre-Galvanized Surface and Fabrication
The zinc coating is applied to the strip before tube forming. The broad galvanized faces provide a practical finish for panel frames, furniture components and partitions. The longitudinal weld area and cut ends are separate finishing locations: strip coating designations describe the coated strip, not the thickness of a repaired weld or cut edge.
ການເຊື່ອມໂລຫະ, drilling and cutting should follow the fabrication procedure for the assembly. Protect processed areas with the specified coating repair system. Dry, ventilated storage and separation from standing water help preserve the zinc surface before fabrication.
Application Guide
| ຄໍາຮ້ອງສະຫມັກ | Useful product characteristic | Design consideration |
|---|---|---|
| Furniture and display frames | Compact depth and flat attachment surfaces | Connection design, appearance and dimensional fit |
| Partitions and panel frames | Broad fixing face for panel interfaces | Fastener position, panel spacing and deflection |
| Gate and fence infill | Regular rectangular appearance and zinc protection | Exposure, drainage and protection after fabrication |
| General fabricated assemblies | Hollow section with unequal sides | Bending orientation, wall thickness and joint access |
Load-bearing and safety-critical assemblies require approved engineering design and the appropriate certified material. This page describes fabrication tube and does not designate it as pressure pipe.
Quality Inspection and Packing Details
Inspection covers the tube dimensions, weld area, coating surface, bundle identification and packing condition.
- ຂະໜາດ: verify both outside sides, steel wall thickness and piece length using the agreed measurement locations and tolerances.
- ຮູບຮ່າງ: inspect straightness, twist, corner profile, end squareness and any processing features that affect assembly.
- Surface and weld area: evaluate coating condition, handling marks, weld-area finish and cut-edge treatment against the specified acceptance criteria.
- Identification: match section size, piece count, bundle marks and agreed material or inspection records.
- ການຫຸ້ມຫໍ່: define bundle weight, size separation, strapping, handling protection and label information for the transport method.
Keep galvanized tube dry and ventilated during storage. Support bundles off the ground, prevent trapped water between close surfaces and inspect wet deliveries promptly. Good handling protects both the visible finish and the condition of the material before fabrication.
Product Questions
How is pre-galvanized rectangular tube formed?
Galvanized steel strip passes through forming rolls and is longitudinally welded into a closed rectangular section. The zinc coating is applied to the strip before tube forming.
Does a larger zinc coating value mean stronger tube?
ບໍ່. Zinc coating specifications describe surface protection. Steel strength depends on the material grade, section geometry and applicable test requirements.
Are all rectangular tube sizes covered by the same thickness range?
ບໍ່. Size and thickness combinations depend on the production route and product specification. The national-standard tables above identify material grades, nominal strip thicknesses and coating classes separately.
Which information determines whether a section fits my assembly?
Outside dimensions, ຄວາມຫນາຂອງຝາ, corner geometry, ຄວາມທົນທານ, piece length, hole positions and joint design all affect fit. Where the shallow side is particularly small, check the internal clearance and fastener arrangement on the drawing.
