Schedule 40 vs Schedule 80 Steel Pipe: How to Choose the Right Wall Thickness
Explore galvanized steel pipe sizes, OD, wall thickness, and schedule 40 charts. Learn how to measure galvanized pipe size and astm a53 specifications.
By Luyuan Steel Technical Team | Updated August 24, 2026
Hot rolled sheet steel is a practical choice when a project needs structural strength, economical thickness and fabrication flexibility rather than a bright cosmetic surface. The purchasing decision should connect grade, thickness, tolerance, surface condition, processing route and inspection documents to the finished part. This guide uses Luyuan’s published hot rolled sheet range and project references; exact availability must be confirmed against the current mill schedule.
Information basis: Luyuan’s product data lists hot rolled sheet thickness from 2 to 10 mm and a listed tolerance of +/-1% for coil and sheet products. Published grade references include Q235B, Q345B, A36, S235JR and S355JR depending on application. No SKU-specific certificate number is disclosed in the source library, so the governing standard and certificate scope should be written into the purchase order.

Hot rolled sheet is formed at elevated temperature, which allows the mill to process thicker material efficiently. The surface may retain mill scale or receive pickling and oiling, depending on the ordered finish. Compared with cold rolled sheet, hot rolled material normally offers wider dimensional tolerances and a less uniform surface, but it is often better suited to welded frames, brackets, machinery parts and general structural work.
Do not treat “hot rolled” as a complete specification. Two sheets with the same nominal thickness can differ in grade, yield-strength requirement, flatness, edge condition, surface treatment and inspection plan. Those differences can change cutting yield, weld preparation and downstream rework.
| Field | Luyuan published reference | What the buyer should confirm |
|---|---|---|
| Hot rolled sheet thickness | 2–10 mm | Nominal thickness, permitted deviation and measurement method |
| Listed tolerance | +/-1% for listed coil/sheet products | Whether the project needs a tighter class or a different standard |
| Product forms | HR coil, HR sheet and HR rod | Coil, leveled sheet or cut-to-length plate and the required packing |
| Processing | Cutting, bending, punching, welding and decoiling depending on product | Which operations are included in the quote and which are performed locally |
| Surface | As-rolled or processed finish subject to order | Mill scale, pickled and oiled condition, dry delivery, rust protection and appearance limits |
The tolerance shown above is a published reference, not an automatic promise for every thickness. Put the applicable standard, thickness class and inspection frequency in the RFQ. If the part is cut on a CNC line, include the maximum camber, flatness and edge-trim variation that the machine can accept.
Q235B is commonly specified for general structural and fabricated components where the design calculations and governing standard support that grade. It can fit frames, supports and non-critical brackets, but the supplier must still state the standard edition, chemistry and mechanical-property requirements for the ordered thickness.
Q345B is referenced in Luyuan’s hot rolled project material for applications requiring a higher-strength structural option. The higher grade does not remove the need to check welding procedure, notch sensitivity, forming limits and the design code. Confirm that the required impact, elongation or test temperature requirements are included when applicable.
A36, S235JR and S355JR appear in the published project references for different application and market requirements. These designations are not interchangeable labels. Ask the supplier to quote one agreed standard, not a list of “equivalent” grades, and request the MTC fields that demonstrate compliance.

Mill scale can be acceptable for welded structural members that will be blasted and painted later. It is a poor fit for a visible panel or a process that needs a clean substrate immediately. Pickled and oiled sheet removes scale and adds temporary corrosion protection, but the oil must be compatible with the next operation. If the sheet will be laser-cut, formed or painted, state whether oil, flash rust, scratches and roll marks are acceptable.
A frequent mistake is approving a sample photograph as the surface standard. Photographs show appearance under one light; they do not define roughness, scale adhesion, flatness or allowable defects. Use a written surface class, reference sample and rejection procedure.
Luyuan lists cutting, bending, punching, welding and decoiling as available processing options depending on product. Make the processing boundary explicit so a quote does not silently assume that local fabrication will complete a step that was expected at the mill.
| Project need | Why hot rolled sheet may fit | Check before approval |
|---|---|---|
| Welded frames and supports | Useful thickness range and fabrication access | Grade, weld procedure, flatness and edge preparation |
| Machinery guards and brackets | Cutting, punching and bending can be combined with an economical substrate | Surface acceptance, bend radius and dimensional tolerance |
| Industrial platforms and structures | Structural grades and project-based sourcing support | Design code, traceability, MTC and coating or paint preparation |
| Visible appliance or automotive panel | Usually not the first choice when a smooth, tight-tolerance surface is critical | Compare cold rolled sheet and the required surface class |
Compared with common light-gauge cold rolled solutions, hot rolled sheet usually gives the fabricator more tolerance and surface preparation work to manage. Compared with thicker plate or section steel, it can simplify cutting and handling for medium-gauge components. The right boundary is set by the finished part, not by the product name alone.
Before shipment, align the bundle mark, heat or batch reference, MTC and packing list. A practical acceptance sequence is:

Luyuan’s resource library describes batch traceability, English Mill Test Certificates, pre-shipment inspection and third-party inspection support. These are process capabilities, not a substitute for naming the required documents and acceptance authority in the contract.
Write the request so a supplier can price the same material: “Hot rolled sheet steel, [grade and standard], [thickness] mm x [width] mm x [length] mm, [surface condition], [tolerance class], [edge condition], [processing], quantity [X] metric tons, MTC and pre-shipment inspection required, export packing for [destination], delivery by [date].” Add whether the sheet is for welding, bending, punching, painting or direct installation.
For Luyuan’s current manufacturing and processing scope, review the capability page. For a quotation, send the drawing, grade, dimensions, surface, processing and inspection requirements through the contact page.
Luyuan’s published hot rolled sheet reference is 2–10 mm. Confirm the exact thickness, width, tolerance and delivery form against the current production schedule.
It can be suitable for structural and fabricated parts when the grade, design code, weld procedure and inspection documents match the project. A product label alone is not design approval.
Use mill scale when later blasting or surface preparation is planned and acceptable. Choose pickled and oiled when a cleaner substrate and temporary corrosion protection are needed, after confirming compatibility with forming or painting.
Only when the finished part can accept the different surface, tolerance and forming behavior. Visible panels, tight bends and close-dimension components may require cold rolled material instead.
Next step: Send the design standard, grade, thickness, dimensions, surface condition, processing route, quantity, destination and inspection scope before requesting a hot rolled sheet steel quotation.
Luyuan Steel Technical Team supports steel manufacturing, processing, quality-control documentation, product specification and international project supply.
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