U-channel base bracket

Specifications

Product Specification Sheet
Product Name	Welded U-Channel Post Base Bracket for Solar Mounting Structures
Part No.	SMB-U01
Category	Solar mounting brackets
Overview	Welded two-piece post base bracket for PV mounting structures: a rectangular base plate with two slotted holes carries a press-brake formed U-channel that receives and locks a square post or C-profile strut. Fillet-welded and hot-dip galvanized for long-term outdoor service.
Version	V1.0 \| 2026-09-15
Material
Main material	Q235B carbon steel, hot-dip galvanized
Grade and standard	Q235B per GB/T 700-2006 （S235JR equivalent per EN 10025-2）
Alternative material	SUS 304 stainless steel per GB/T 3280; S355JR for heavy-load bases; Q355B for cold-region projects
Raw material form and thickness	Flat plate 6.0 mm （0.236 in） nominal for both base plate and U-channel
Material certificate	EN 10204 3.1 mill certificate per heat number, traceable to base plate and U-channel batch
Process
Cutting / blanking	Base plate and U-channel blank cut by CNC laser or plasma cutting; blank size tolerance +/- 0.5 mm
Forming	U-channel formed by two 90° press-brake bends from a single strip （inner radius approx. 1.0 x t = 6 mm / 0.236 in）; base plate stays flat
Joining	Continuous fillet welding （MIG） along the two external contact lines where U-channel side walls meet the base plate; weld leg 4-5 mm
Secondary operations	Slotted holes 14 x 28 mm （0.551 x 1.102 in） on base plate; round holes Ø13 mm （0.512 in） on U-channel sides and rear face; deburring
Surface pretreatment	Weld slag and spatter removal, grinding of weld toes, alkaline degreasing, acid pickling, fluxing
Key process control points	U-channel perpendicularity to base plate, weld leg size and penetration, weld distortion control, slot position relative to channel centerline
Surface treatment
Treatment method	Hot-dip galvanizing after welding and forming; whole assembly dipped as one unit
Coating thickness	Average zinc layer >= 70 µm （0.0028 in）, local minimum >= 55 µm （0.0022 in）
Color and appearance	Matte silver-grey with normal zinc spangle; uniform coverage on welds; no zinc dross, no flaking, no uncoated area
Standard and salt-spray requirement	HDG per GB/T 13912-2020 （ISO 1461 equivalent）; NSS per GB/T 10125 / ISO 9227 >= 480 h without red rust
Surface roughness	Ra <= 12.5 µm on galvanized surfaces; weld beads dressed to Ra <= 25 µm where exposed
Pretreatment	Degreasing - pickling - rinsing - fluxing; welds must be slag-free before dipping
Tolerance
Overall profile tolerance	Base plate length / width +/- 1.0 mm （+/- 0.039 in）; U-channel width +/- 0.8 mm
Hole diameter and position tolerance	Round holes Ø13 mm （0.512 in） +0.3/0 mm; slots 14 x 28 mm +0.5/0 mm; hole position +/- 0.5 mm
Bend angle and bend radius tolerance	U-channel bend angle 90° +/- 1.5°; inner bend radius 6 mm （0.236 in） +/- 0.5 mm
Weld position tolerance	Weld position +/- 2.0 mm; angular distortion of U-channel to base plate <= 1.0° （perpendicularity 0.5 mm over 100 mm）
Flatness and straightness	Base plate flatness <= 1.5 mm / 100 mm; U-channel side wall straightness <= 1.0 mm over full length
Assembly fit tolerance	U-channel inner opening designed for square post / strut with 1.0-1.5 mm total clearance （M12 / 1/2 in hardware）
Dimension basis	Customer drawing / 3D model prevails; unspecified tolerances per GB/T 1804-m and GB/T 19804
Packaging
Surface protection	VCI anti-rust paper between layers; no direct contact with black （uncoated） steel
Unit inner packaging	Kraft paper or PE film wrapping, 10 pcs bundled with PP strap
Outer packaging	Wooden pallet with carton or crate, stretch film wrapped, corner protectors fitted
Quantity, carton size and gross weight	120 pcs per pallet; pallet 1100 x 1100 x 700 mm （43.3 x 43.3 x 27.6 in）; gross weight approx. 320 kg
Marking and shipping marks	Part no. SMB-U01, batch no., heat no., quantity, net/gross weight, carton no.; marks per customer requirement
Container loading and stacking	Max stacking 3 pallets high; 20GP approx. 18 pallets / 40HQ approx. 40 pallets
Storage and transport	Dry ventilated warehouse, palletized off the ground, kept dry and strapped during transport
Quality control
Incoming inspection	Mill certificate verification, plate thickness measurement, welding consumable （wire/gas） certificate check
First article approval	First article with weld cross-section macro check, full dimensions and perpendicularity report before mass run
In-process inspection frequency	Welding station checked every 2 hours （weld leg, spatter, distortion）; dimensional patrol every 200 pcs
Final and pre-shipment inspection	100% visual of welds and coating; AQL 1.0 for critical dimensions; coating thickness on each pallet; fit test with a gauge post
Inspection equipment	CMM, digital caliper, height gauge, weld gauge, square / protractor, coating thickness gauge, salt-spray chamber
Records and reports	Weld inspection records, dimensional report, coating report, mill certificate and COC issued per shipment; records kept 3 years
Nonconforming product handling	Segregated and red-tagged; weld defects （undercut, porosity, insufficient leg） repaired per approved WPS then re-inspected; coating defects re-galvanized
Quality system and certification	ISO 9001:2015 certified factory; WPS / PQR and welder qualification available; PPAP / 8D support on request
Notes	The parameters listed in the table are standard values based on product photographs and our factory's standard manufacturing processes. For items marked as "Recommended Values," as well as all dimensions, materials, and tolerances, the final specifications shall be determined by the customer's drawings (2D/3D), technical agreements, and the results of the first-article inspection.
Drawing Format	3D: .step / .stp / .igs 2D: .dxf / .dwg / .pdf
For Quotation	Drawing + material + surface treatment + quantity + tolerance requirement