What is Cold-rolled (DKP) box sections?
Cold-rolled box section — DKP tube in Turkish — is square or rectangular tube roll-formed and HF-welded from DC01 cold-rolled strip (EN 10130) instead of hot-rolled strip. The difference is entirely in the surface and the gauge: cold-rolled strip is scale-free, smooth (Ra ≈ 1 µm), lightly oiled and held to ±0.05 mm, so the tube comes out bright, uniform and thin — walls from 0.7 mm, where hot-rolled tube starts at 1.2–1.5 mm. That is what furniture, shop-fitting, lighting and appliance makers need: a tube that can be chrome-plated to a mirror, powder-coated without texture showing through, bent on a mandrel into a chair frame and welded with almost no spatter. It is not a structural product — there is no guaranteed yield and EN 10219 does not cover it — and it rusts quickly if left bare outdoors. Our Dilovası mill rolls 190 size/wall combinations from 10×10×0.7 to 90×90×2; the weld bead is removed outside as standard and inside on request for tubes that are bent or plated.
Cold-rolled box section sizes and weight per metre
Our DKP mill list — 190 size/wall combinations with kg/m and kg per 6 m bar.
| Size (mm) | Wall (mm) | kg/m | kg per 6 m bar |
|---|---|---|---|
| 10 × 10 | 0.7 | 0.2 | 1.22 |
| 10 × 10 | 0.8 | 0.23 | 1.39 |
| 10 × 10 | 0.9 | 0.26 | 1.54 |
| 10 × 10 | 1 | 0.28 | 1.7 |
| 10 × 10 | 1.2 | 0.33 | 1.99 |
| 10 × 20 | 0.7 | 0.31 | 1.88 |
| 10 × 20 | 0.8 | 0.36 | 2.14 |
| 10 × 20 | 0.9 | 0.4 | 2.39 |
| 10 × 20 | 1 | 0.44 | 2.64 |
| 10 × 20 | 1.2 | 0.52 | 3.12 |
| 10 × 20 | 1.5 | 0.64 | 3.82 |
| 10 × 20 | 2 | 0.82 | 4.9 |
| 10 × 30 | 0.7 | 0.42 | 2.54 |
| 10 × 30 | 0.8 | 0.48 | 2.89 |
| 10 × 30 | 0.9 | 0.54 | 3.24 |
| 10 × 30 | 1 | 0.6 | 3.58 |
| 10 × 30 | 1.2 | 0.71 | 4.25 |
| 10 × 30 | 1.5 | 0.87 | 5.23 |
| 10 × 30 | 2 | 1.13 | 6.78 |
| 10 × 40 | 1 | 0.75 | 4.52 |
| 10 × 40 | 1.2 | 0.9 | 5.38 |
| 10 × 40 | 1.5 | 1.11 | 6.64 |
| 10 × 40 | 2 | 1.44 | 8.66 |
| 10 × 50 | 1.2 | 1.09 | 6.51 |
| 10 × 50 | 1.5 | 1.34 | 8.05 |
| 10 × 50 | 2 | 1.76 | 10.55 |
| 15 × 15 | 0.7 | 0.31 | 1.88 |
| 15 × 15 | 0.8 | 0.36 | 2.14 |
| 15 × 15 | 0.9 | 0.4 | 2.39 |
| 15 × 15 | 1 | 0.44 | 2.64 |
| 15 × 15 | 1.2 | 0.52 | 3.12 |
| 15 × 15 | 1.5 | 0.64 | 3.82 |
| 15 × 15 | 2 | 0.82 | 4.9 |
| 15 × 20 | 0.8 | 0.42 | 2.52 |
| 15 × 20 | 0.9 | 0.47 | 2.81 |
| 15 × 20 | 1 | 0.52 | 3.11 |
| 15 × 20 | 1.2 | 0.61 | 3.68 |
| 15 × 20 | 1.5 | 0.75 | 4.52 |
| 15 × 25 | 0.7 | 0.42 | 2.54 |
| 15 × 25 | 0.8 | 0.48 | 2.89 |
| 15 × 25 | 0.9 | 0.54 | 3.24 |
| 15 × 25 | 1 | 0.6 | 3.58 |
| 15 × 25 | 1.2 | 0.71 | 4.25 |
| 15 × 25 | 1.5 | 0.87 | 5.23 |
| 15 × 25 | 2 | 1.13 | 6.78 |
| 15 × 30 | 1 | 0.68 | 4.05 |
| 15 × 30 | 1.2 | 0.8 | 4.82 |
| 15 × 30 | 1.5 | 0.99 | 5.93 |
| 15 × 30 | 2 | 1.29 | 7.72 |
| 15 × 40 | 0.9 | 0.75 | 4.51 |
| 15 × 40 | 1 | 0.83 | 4.99 |
| 15 × 40 | 1.2 | 0.99 | 5.95 |
| 15 × 40 | 1.5 | 1.23 | 7.35 |
| 15 × 40 | 2 | 1.6 | 9.61 |
| 20 × 20 | 0.7 | 0.42 | 2.54 |
| 20 × 20 | 0.8 | 0.48 | 2.89 |
| 20 × 20 | 0.9 | 0.54 | 3.24 |
| 20 × 20 | 1 | 0.6 | 3.58 |
| 20 × 20 | 1.2 | 0.71 | 4.25 |
| 20 × 20 | 1.5 | 0.87 | 5.23 |
| 20 × 20 | 2 | 1.13 | 6.78 |
| 20 × 30 | 0.7 | 0.53 | 3.2 |
| 20 × 30 | 0.8 | 0.61 | 3.65 |
| 20 × 30 | 0.9 | 0.68 | 4.09 |
| 20 × 30 | 1 | 0.75 | 4.52 |
| 20 × 30 | 1.2 | 0.9 | 5.38 |
| 20 × 30 | 1.5 | 1.11 | 6.64 |
| 20 × 30 | 2 | 1.44 | 8.66 |
| 20 × 35 | 0.9 | 0.75 | 4.51 |
| 20 × 35 | 1 | 0.83 | 4.99 |
| 20 × 35 | 1.2 | 0.99 | 5.95 |
| 20 × 35 | 1.5 | 1.23 | 7.35 |
| 20 × 35 | 2 | 1.6 | 9.61 |
| 20 × 40 | 0.7 | 0.64 | 3.86 |
| 20 × 40 | 0.8 | 0.73 | 4.4 |
| 20 × 40 | 0.9 | 0.82 | 4.93 |
| 20 × 40 | 1 | 0.91 | 5.47 |
| 20 × 40 | 1.2 | 1.09 | 6.51 |
| 20 × 40 | 1.5 | 1.34 | 8.05 |
| 20 × 40 | 2 | 1.76 | 10.55 |
| 20 × 50 | 0.9 | 0.96 | 5.78 |
| 20 × 50 | 1 | 1.07 | 6.41 |
| 20 × 50 | 1.2 | 1.27 | 7.64 |
| 20 × 50 | 1.5 | 1.58 | 9.47 |
| 20 × 50 | 2 | 2.07 | 12.43 |
| 20 × 60 | 0.9 | 1.11 | 6.63 |
| 20 × 60 | 1 | 1.23 | 7.35 |
| 20 × 60 | 1.2 | 1.46 | 8.77 |
| 20 × 60 | 1.5 | 1.81 | 10.88 |
| 20 × 60 | 2 | 2.39 | 14.32 |
| 20 × 80 | 1.2 | 1.84 | 11.03 |
| 20 × 80 | 1.5 | 2.28 | 13.7 |
| 20 × 80 | 2 | 3.01 | 18.08 |
| 20 × 100 | 2 | 3.64 | 21.85 |
| 25 × 25 | 0.7 | 0.53 | 3.2 |
| 25 × 25 | 0.8 | 0.61 | 3.65 |
| 25 × 25 | 0.9 | 0.68 | 4.09 |
| 25 × 25 | 1 | 0.75 | 4.52 |
| 25 × 25 | 1.2 | 0.9 | 5.38 |
| 25 × 25 | 1.5 | 1.11 | 6.64 |
| 25 × 25 | 2 | 1.44 | 8.66 |
| 25 × 40 | 0.7 | 0.7 | 4.19 |
| 25 × 40 | 0.8 | 0.8 | 4.78 |
| 25 × 40 | 0.9 | 0.89 | 5.36 |
| 25 × 40 | 1 | 0.99 | 5.93 |
| 25 × 40 | 1.2 | 1.18 | 7.07 |
| 25 × 40 | 1.5 | 1.46 | 8.76 |
| 25 × 40 | 2 | 1.92 | 11.49 |
| 25 × 50 | 0.9 | 1.03 | 6.2 |
| 25 × 50 | 1 | 1.15 | 6.88 |
| 25 × 50 | 1.2 | 1.37 | 8.21 |
| 25 × 50 | 1.5 | 1.7 | 10.18 |
| 25 × 50 | 2 | 2.23 | 13.37 |
| 25 × 55 | 0.9 | 1.11 | 6.63 |
| 25 × 55 | 1 | 1.23 | 7.35 |
| 25 × 55 | 1.2 | 1.46 | 8.77 |
| 25 × 55 | 1.5 | 1.81 | 10.88 |
| 25 × 55 | 2 | 2.39 | 14.32 |
| 30 × 30 | 0.7 | 0.64 | 3.86 |
| 30 × 30 | 0.8 | 0.73 | 4.4 |
| 30 × 30 | 0.9 | 0.82 | 4.93 |
| 30 × 30 | 1 | 0.91 | 5.47 |
| 30 × 30 | 1.2 | 1.09 | 6.51 |
| 30 × 30 | 1.5 | 1.34 | 8.05 |
| 30 × 30 | 2 | 1.76 | 10.55 |
| 30 × 40 | 0.8 | 0.86 | 5.15 |
| 30 × 40 | 0.9 | 0.96 | 5.78 |
| 30 × 40 | 1 | 1.07 | 6.41 |
| 30 × 40 | 1.2 | 1.27 | 7.64 |
| 30 × 40 | 1.5 | 1.58 | 9.47 |
| 30 × 40 | 2 | 2.07 | 12.43 |
| 30 × 50 | 0.8 | 0.99 | 5.91 |
| 30 × 50 | 0.9 | 1.11 | 6.63 |
| 30 × 50 | 1 | 1.23 | 7.35 |
| 30 × 50 | 1.2 | 1.46 | 8.77 |
| 30 × 50 | 1.5 | 1.81 | 10.88 |
| 30 × 50 | 2 | 2.39 | 14.32 |
| 30 × 60 | 1 | 1.38 | 8.29 |
| 30 × 60 | 1.2 | 1.65 | 9.9 |
| 30 × 60 | 1.5 | 2.05 | 12.29 |
| 30 × 60 | 2 | 2.7 | 16.2 |
| 30 × 70 | 1 | 1.54 | 9.23 |
| 30 × 70 | 1.2 | 1.84 | 11.03 |
| 30 × 70 | 1.5 | 2.28 | 13.7 |
| 30 × 70 | 2 | 3.01 | 18.08 |
| 30 × 100 | 2 | 3.96 | 23.74 |
| 35 × 35 | 0.9 | 0.96 | 5.78 |
| 35 × 35 | 1 | 1.07 | 6.41 |
| 35 × 35 | 1.2 | 1.27 | 7.64 |
| 35 × 35 | 1.5 | 1.58 | 9.47 |
| 35 × 35 | 2 | 2.07 | 12.43 |
| 40 × 40 | 0.8 | 0.99 | 5.91 |
| 40 × 40 | 0.9 | 1.11 | 6.63 |
| 40 × 40 | 1 | 1.23 | 7.35 |
| 40 × 40 | 1.2 | 1.46 | 8.77 |
| 40 × 40 | 1.5 | 1.81 | 10.88 |
| 40 × 40 | 2 | 2.39 | 14.32 |
| 40 × 50 | 1 | 1.38 | 8.29 |
| 40 × 50 | 1.2 | 1.65 | 9.9 |
| 40 × 50 | 1.5 | 2.05 | 12.29 |
| 40 × 50 | 2 | 2.7 | 16.2 |
| 40 × 60 | 1.2 | 1.84 | 11.03 |
| 40 × 60 | 1.5 | 2.28 | 13.7 |
| 40 × 60 | 2 | 3.01 | 18.08 |
| 40 × 80 | 1.2 | 2.22 | 13.3 |
| 40 × 80 | 1.5 | 2.76 | 16.53 |
| 40 × 80 | 2 | 3.64 | 21.85 |
| 40 × 100 | 1.5 | 3.23 | 19.36 |
| 40 × 100 | 2 | 4.27 | 25.62 |
| 40 × 120 | 2 | 4.9 | 29.39 |
| 45 × 45 | 1 | 1.38 | 8.29 |
| 45 × 45 | 1.2 | 1.65 | 9.9 |
| 45 × 45 | 1.5 | 2.05 | 12.29 |
| 45 × 45 | 2 | 2.7 | 16.2 |
| 50 × 50 | 1.2 | 1.84 | 11.03 |
| 50 × 50 | 1.5 | 2.28 | 13.7 |
| 50 × 50 | 2 | 3.01 | 18.08 |
| 50 × 90 | 1.5 | 3.23 | 19.36 |
| 50 × 90 | 2 | 4.27 | 25.62 |
| 50 × 100 | 2 | 4.58 | 27.5 |
| 60 × 60 | 1.2 | 2.22 | 13.3 |
| 60 × 60 | 1.5 | 2.76 | 16.53 |
| 60 × 60 | 2 | 3.64 | 21.85 |
| 60 × 80 | 1.5 | 3.23 | 19.36 |
| 60 × 80 | 2 | 4.27 | 25.62 |
| 60 × 100 | 2 | 4.9 | 29.39 |
| 60 × 120 | 2 | 5.53 | 33.16 |
| 70 × 70 | 1.5 | 3.23 | 19.36 |
| 70 × 70 | 2 | 4.27 | 25.62 |
| 80 × 80 | 2 | 4.9 | 29.39 |
| 80 × 100 | 2 | 5.53 | 33.16 |
| 90 × 90 | 2 | 5.53 | 33.16 |
Roll-formed from DC01 cold-rolled strip; smooth oiled surface; 6 m lengths.
Grades, standards and tolerances
| Grade / standard | Yield (MPa) | Note |
|---|---|---|
| DC01 (EN 10130) | ≤ 280 (typ. 200–240) | the standard — smooth, formable, weldable |
| DC03 / DC04 | ≤ 240 / 210 | for tube that is bent or swaged after welding |
| S235JRH (hot-rolled black) | ≥ 235 | the structural alternative — see square hollow section |
Dimensions follow EN 10219 for size and squareness; wall tolerance ±0.08–0.12 mm (tighter than hot-rolled tube); surface smooth, lightly oiled; weld seam scarfed on request.
Surface and finishing
| Finish | Preparation | Result |
|---|---|---|
| Powder coating | degrease (alkaline), optional phosphate | smooth, uniform — no scale texture |
| Chrome / nickel plating | degrease, polish (bright strip on request) | mirror finish on 0.7–1.2 mm tube |
| Wet paint | degrease, primer | furniture-grade finish |
| Bare, oiled | — | indoor use within 3–6 months |
Cold-rolled tube is uncoated: it rusts outdoors within weeks if left bare. For outdoor frames use pre-galvanized tube.
Lengths and stock
Length 6 m (+30/−0), cut lengths ±2 mm on the mill saw. Stock at Dilovası: 15×15, 20×20, 25×25, 30×30, 40×40, 50×50 and 20×40, 25×50, 30×60 in 1.0–1.5 mm; other sizes and walls rolled within a week. Squareness and straightness to EN 10219-2; wall ±0.08–0.12 mm; weld bead removed outside, inside scarfing on request.
Cutting, bending, welding and finishing
Cold saw and laser tube cutting with clean, burr-free ends; mandrel or roll bending for chair and rack frames; swaging, flattening and hole-punching in-line; MIG / TIG / spot welding with minimal spatter on the clean surface; polishing for plating; powder coating and plating by the customer or through our partners.
Where it is used
- Office, school and hospital furniture frames
- Shop fittings, display stands and racks
- Lighting poles, lamp bodies and stands
- Bicycle, fitness and playground equipment
- White-goods and appliance frames
- Decorative railings and interior partitions
Cold-rolled vs hot-rolled box section
Hot-rolled square hollow section is stronger per ton, cheaper and structural, but scaled and available only from 1.2–1.5 mm. Cold-rolled box section is thinner (0.7 mm), smoother, tighter in tolerance and finish-ready, at about 150 USD/t more — the choice wherever the tube is seen. For a coloured tube without painting see pre-painted box section; for outdoor use galvanized square tube.
Price
DKP tube is priced per ton on our cold-rolled tube list — above black tube for the strip and the light gauges. The bands below separate the volume range and the very small sizes (highest per ton). Cutting and bending per piece.
Bands from our weekly export list (September 2026), FOB Istanbul, full-container quantities, excluding freight and certificates. Firm price per project on RFQ within one working day.
Export and packing
We ship Cold-rolled (DKP) box sections in strapped bundles of 0.8–2 t per size and length, tagged and — for coated sections — paper-wrapped; 24–25 t of 6 m bars per 40' HC, 20 t per 20', 12 m by flat-rack. HS code 7306.61.
| Term | Detail |
|---|---|
| MOQ | 3 t (mixed sizes accepted) |
| Incoterms | FOB Istanbul · CIF / CFR Gulf, Africa · DAP EU, Balkans, Iraq, Caucasus · DAP Aktau |
| Lead time | Stock 15×15–50×50: 2–5 working days; others 5–10 days |
| Packing | Bundles 0.5–1 t, paper-wrapped, strapped, tagged |
| Container / truck | 40' HC ≈ 22–24 t of 6 m (light bundles) |
| Documents | Invoice, packing list, EN 10204 3.1, CE DoP (EN 10219-1), certificate of origin; SASO / SONCAP / PVoC on request |
| Payment | 30% advance, balance against B/L copy; L/C at sight above 100 t |
Certificates
Documentation for Cold-rolled (DKP) box sections: strip mill certificate EN 10204 3.1, our production record (size, wall, straightness, weld test), CE DoP under EN 10219-1; third-party 3.2 certificates on request.
How to order
Send size × wall × length, quantity, finish intended (powder coat / plating — bright strip for plating), any cutting, bending or hole pattern; furniture-maker cut lists are welcome.
Standards
- EN 10305-5 — welded cold-sized square/rectangular precision tubes (reference)
- EN 10130 — DC01 strip
- EN 10219 — dimensions where applicable
- EN 10204 3.1
Grades
Grade data sheets (chemistry, mechanicals, equivalents) are on our reference site: DC01 · DC03 · S235JRH
Frequently asked questions
What is DKP tube?
The Turkish name for box section rolled from cold-rolled (DC01) strip — thin-wall (0.7–2 mm), smooth and scale-free, used for furniture, fittings and plated or powder-coated frames.
What is the difference between cold-rolled and hot-rolled square tube?
Cold-rolled tube is made from DC01 cold-rolled strip: thinner walls, smoother surface, tighter tolerance, finish-ready, dearer and non-structural; hot-rolled tube (S235JRH) is thicker, scaled, cheaper and structural.
Can cold-rolled box section be chrome plated?
Yes — it is the standard tube for chrome furniture; order bright strip and outside seam scarfing for a mirror finish.
Is DKP tube suitable for outdoor use?
Only when powder-coated or painted; bare it rusts within weeks. For outdoor frames use pre-galvanized tube.
What is the thinnest wall you roll?
0.7 mm in 10×10 to 30×30 mm; 1.0 mm up to 50×50; 1.2–2 mm in the larger sizes.