Q700 / Q355 / 510L high-strength Punched-hole customization 80,000 t/yr bus tubes Company-reported

Bus-Frame High-Strength Square & Rectangular Tubes

Bus-frame high-strength square and rectangular steel tubes in Q700, Q355 and 510L — punched-hole face and cut length customized per vehicle model, with on-site consignment stock service for Yutong, King Long and other bus builders (per company records). Eight high-frequency welding lines.

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Punched bus-frame square tube bundles — end-face view in the production hall

PRODUCT PHOTOGRAPHY

Punched-Hole Customization — Close-Up

Punched faces and hole patterns are programmed per the bus builder's drawing — every face of the tube can be punched to spec.

Punched-face square tube stack, close-up view — Punched-face tube stackPunched-face close-up · bundled for dispatch

SPECIFICATIONS

Bus-Frame Tube SKUs — Q700 / Q355 / 510L

Every SKU below is in current production, grouped by grade. Complex special-shaped sections are made to drawing.

"+" marks faces punchable in combination; "*" marks a fixed length for the current production batch (unmarked lengths are the 6,000 mm standard). Both length and punched face are customized per vehicle model.

Q700 high-strength — 24 SKUs

Size H×B×t (mm)	Unit weight (kg/m)	Std. length (mm)	Punchable faces	Bundle (pcs)
30×30×1.5	1.342	6,000	30	169
30×30×2	1.758	6,000	30	169
40×30×2	2.072	6,000	30 + 40	130
40×40×1.5	1.813	6,000	40	100
40×40×2	2.386	6,000	40	100
50×20×1.5	1.53	6,000	All 4 faces	160
50×30×1.5	1.813	6,000	30 + 50	104
50×40×2	2.7	6,000	40 + 50	80
50×40×3	3.956	6,000	40 + 50	80
50×50×1.5	2.35	6,000	50	64
50×50×2	3.014	6,000	50	64
60×40×2	3.014	6,000	40 + 60	70
60×50×2	3.328	5,200*	50 + 60	56
60×50×2.5	4.121	6,000	50 + 60	56
60×50×3	4.898	6,000	50 + 60	56
60×60×3	5.369	5,200*	60	49
60×60×4	7.034	5,200*	60	49
70×50×2	3.562	6,000	50 + 70	48
80×40×2	3.642	6,000 / 5,000*	40 + 80	50
100×40×2	4.19	6,000	40 + 100	40
100×40×3	6.13	6,000	40 + 100	40
100×50×4	8.918	5,600*	50 + 100	24
120×50×4	10.68	6,000	50 + 120	24
120×60×3	8.195	5,200*	60 + 120	21

Complex special-shaped / oval sections are produced to drawing (current running oval tubes: 36×96 and 56×156, wall 3–6 mm, Q235/Q355 — see the table below and the Vehicle-Grade Steel Sections page).

Q355 — 12 SKUs

Size H×B×t (mm)	Unit weight (kg/m)	Std. length (mm)	Punchable faces	Bundle (pcs)
20×20×1.5	0.871	6,000	20	169
30×10×1.5	0.871	6,000	30	240
30×20×1.5	1.107	6,000	20 + 30	156
30×30×3	2.36	6,000	30	169
40×20×1.5	1.342	6,000	20 + 40	200
40×30×1.5	1.578	6,000	30 + 40	130
50×30×2	2.386	5,800*	30 + 50	104
50×30×3	3.485	5,800*	30 + 50	104
50×40×3	3.78	6,000	40 + 50	80
P50×50×2	3.015	6,000	All 4 faces	64
50×50×2	3.014	5,800*	50	64
60×40×4	5.778	6,000	40 + 60	70

510L main section + oval tubes (Q235/Q355)

Size H×B×t (mm)	Unit weight (kg/m)	Std. length (mm)	Punchable faces	Bundle (pcs)
120×60×6	15.826	5,100*	60 + 120	21
36×96×3–6 (oval)	—	6,000–12,000	None (oval)	—
56×156×3–6 (oval)	—	6,000–12,000	None (oval)	—

Standard lengths of 5,000–6,000 mm are kept in stock; both length and punched-hole face are customized per vehicle model, covering 8.5 m / 10.5 m / 12 m coach platforms. Unit weight is calculated per the GB/T 6728-2025 (superseding GB/T 6728-2017) appendix formula. High-strength grades (Q700 / Q355 skeleton tube) have no national standard grade system and are supplied to a technical agreement between buyer and mill; the 510L parent coil is produced to GB/T 3273.

GENERAL RANGE

General Square & Rectangular Tube Range

Beyond the bus-frame SKUs above, the line also runs a general cold-formed square/rectangular tube range for structural and industrial use.

Type	Size range (mm)	Wall thickness (mm)	Material grades	Standard
Square tube	20×20 – 120×120	1.5 – 6	Q195 / Q235B / Q355B (high-strength per supply agreement)	GB/T 6728-2025
Rectangular tube	20×30 – 160×80	1.5 – 6	Q195 / Q235B / Q355B (high-strength per supply agreement)	GB/T 6728-2025

Indicative stock range — larger sections are on the Large-Size Square Tubes page. Export orders can be produced to EN 10219 / ASTM A500 Gr.B/C on request.

PRODUCTION PROCESS

From Coil to Bundled Tube

Eight high-frequency welding lines run the sequence below (per company profile).

STEP 01

Coil Uncoiling & Slitting

Hot-rolled coil is uncoiled and slit to the strip width for each SKU.

STEP 02

High-Frequency Welding Forming

The strip is roll-formed and high-frequency welded into the tube section.

STEP 03

Sizing & Cut-to-Length

The welded tube is sized to final section and cut to length.

STEP 04

Sawing

Tubes are sawn to the exact length called out on the vehicle drawing.

STEP 05

Punching (Per Drawing)

Punched-hole faces and patterns are programmed per the bus builder's drawing.

STEP 06

Painting & Drying

Tubes are painted and oven-dried for corrosion protection.

STEP 07

Bundling & Warehousing

Finished tubes are bundled, tagged and moved to warehouse stock.

BUS & COACH BUILDERS

Supplied To

Consignment and direct-supply relationships with the following bus & coach builders (per company catalogue):

Zhengzhou Yutong Xiamen King Long Beiqi Foton Hefei JAC Zhengzhou Shaolin Chongqing Hengtong Guilin Daewoo North Benz Shaanxi Tongli Company-reported

GALLERY

Stock & Workshop Photography

Production hall and finished-goods stock on the bus-frame tube line.

Punched tube bundle, close view of the hole pattern — Punched tube bundle, close viewBundled square tube, hole pattern visible

Wrapped tube bundles staged in the production hall — Consignment-ready tube bundlesWrapped bundles staged in the production hall

Finished square and rectangular tube stacks in the production hall — Finished tube stock in the production hallMixed square/rectangular tube stacks

Mixed square and rectangular tube stock, bundled for shipment — Mixed square & rectangular tube stockStacked bundles staged for shipment