Painted Structural Hollow Section

Tianjin Brisk Metalwork Co., Ltd. is one of the leading manufacturers and suppliers of painted structural hollow section in China. We have world-leading production equipment and strong manufacturing capabilities. Please feel free to buy bulk durable painted structural hollow section from our factory.

Our Product

Tianjin Brisk Steel focus on produce and supply hollow section and steel pipe

Black tube is cheaper per tonne, but the cost shifts to your workshop. Blasting, priming, drying and handling a second time take floor space and days. We see three reasons buyers move to painted supply:

• Floor space and schedule. The coating step is already done, so incoming tube goes straight to cutting and welding.
• Rust control during storage. Bare tube can flash-rust in a damp yard within days. A cured primer film protects it while it waits.
• One consistent coating. A film applied in a controlled line is more even than a brush-and-spray job done between other tasks.

Painted supply is not the right call for every project. Where members will be hot-dip galvanized later, or where the specification demands a full blast-and-multi-coat system applied after fabrication, black or oiled tube is the sensible choice. We say so at the quotation stage rather than sell you a coating you will remove.

Silicon and phosphorus in the steel change how zinc reacts with it. In reactive steels the coating grows thick, rough and dark grey, and in some cases it becomes brittle and can chip at edges and corners.

• We can supply heats with silicon and phosphorus controlled to the range your galvanizer recommends.
• The heat number on the certificate lets you and the galvanizer match chemistry to the coating result.
• For projects where appearance matters, such as visible canopies and architectural frames, a bright, even finish is far easier to achieve with a suitable base steel.

The coating is only as good as the surface under it. Our sequence is simple and recorded:

1. Surface cleaning. Mill scale, oil and loose rust are removed by blasting or mechanical cleaning before any paint goes on.
2. Inspection before coating. Surface condition is checked against the cleanliness grade agreed in the order.
3. Coating application. Primer (and an intermediate coat where specified) is applied to the outside of the section.
4. Curing. The film is fully cured before tubes are bundled, so stacking does not mark or stick the coating.
5. Film thickness check. Dry film thickness is measured on sampled tubes and noted in the coating record.

The details that decide whether a painted tube performs are the edges and corners. Paint thins out over sharp edges first. On rectangular and square sections, the rounded outer corner of cold-formed tube helps the film wrap evenly, and we check film thickness at the corners as well as on the flat faces.

We match the coating to where the tube will go, not to what is easiest for us to apply.

Colour is agreed at order. Common choices are grey and red-oxide primer; other colours are available for exposed members. Tell us which topcoat you will use, so we can select a primer that bonds to it and does not lift or wrinkle when you overcoat.

Painted tube is fabrication-friendly, but there are practical points we tell every customer:

• Weld zones: Primer films are generally thin, but fumes from heated paint are unpleasant and can affect weld quality. Local grinding back to bright metal at the joint area is standard practice.
• Cut ends: Cutting exposes bare steel. Ends and cut faces need touch-up with a compatible primer after fabrication.
• Inside surface: The coating is applied to the outer surface. Interiors are left as supplied unless a closed-section or sealed-end specification applies.
• Handling: Use soft slings or padded supports to avoid scuffing the cured film.

Planning for touch-up is not a weakness of painted supply. It is how every coated structural member is handled, and it is better to know in advance.

• Steel-frame buildings: columns, beams and bracing that are primed before erection
• Canopies, carports and walkway structures
• Trusses and roof frames with exposed members
• Mezzanines and platforms
• Machine frames and equipment skids
• Handrails, guardrails and secondary framing
• Signage and display structures

A structural fabricator we supply was producing 84 portal frame members from 150 x 100 x 5 mm S355J0H RHS. They had been buying black tube and priming it in their own yard. Over one wet fortnight, about 15 of the 84 tubes showed surface rust before the primer was applied, and each needed re-blasting. That added roughly 3 working days to the programme.

For the next order we supplied the same section blasted and primed at our factory, with a coating record per bundle. Re-blasting dropped to 2 tubes out of 84, both damaged by on-site scuffing. The fabricator moved the freed floor space to a second welding bay and shortened the cycle. The result came from controlling the coating at source, not from a different steel.

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