About CDW Tubes
CDW stands for Cold Drawn Welded: a welded hollow that receives cold drawing to control specified dimensions, surface condition, and properties. The component drawing must define the required grade, delivery condition, tolerance, finish, tests and permitted application.
Use this page as a product and specification reference. The quotation must state the exact material grade, dimensions, manufacturer, certification or document scope, inspection, quantity, price, current availability, freight, and proposed delivery timing for the specific RFQ.
Specification reference
| Outer Diameter (OD) | 6mm to 120mm (round); custom sizes for square/rectangular |
|---|---|
| Wall Thickness (WT) | 0.8mm to 10mm |
| Grades | IS 3074, DIN 2393 (St 37/St 52), EN 10305-2, ASTM A513, SAE 1020 |
| Tolerances | State the ordered standard, tolerance class and project-specific OD, ID, wall and straightness limits |
| Lengths | Random (4-7m), fixed cut lengths, or exact cut-to-length |
Confirm the exact grade, dimensions, tolerance, test certificate, and current availability for your requirement before ordering.
Common applications
These are enquiry contexts, not universal approvals. The project design and governing specification must approve the exact product, grade, dimensions, and service conditions.
- Automotive: Steering columns, propeller shafts, axle tubes, shock absorber cylinders.
- Furniture: Office chairs, tables, shelving, gym equipment, display racks.
- Hydraulic & Pneumatic: Cylinder barrels, piston rods, pneumatic lines, actuator housings.
- Bicycle & Two-Wheeler: Frame tubes, handlebar tubes, seat posts, fork legs.
Who should use CDW tube, and who should choose another route
CDW tube fits components whose drawing needs better dimensional control, surface condition, or mechanical consistency than ordinary ERW tube provides. Typical buyers machine, bend, swage, plate, weld, or assemble the tube into steering parts, furniture, equipment, hydraulic housings, and general engineering components. The finished component drawing should control the RFQ rather than a broad application label.
CDW is not a default replacement for a seamless pressure tube, boiler tube, honed cylinder barrel, or pipe ordered by NB and schedule. A cold-drawn surface does not remove the original welded route. If weld-seam-free integrity, a certified pressure design, or a finished hydraulic bore is required, state that requirement and let engineering choose the correct product family.
- Hydraulic shops should distinguish a rough barrel blank from a honed or skived ready-to-assemble bore.
- Printing-cylinder shops should state machining allowance, straightness, concentricity, and final shell dimensions from the drawing.
- Automotive buyers should include the approved grade, delivery condition, process route, and control plan.
- Furniture fabricators should compare ordinary ERW when the drawing does not need CDW tolerances.
- PWD, JJM, borewell, and fire-system buyers should use their project pipe standard rather than a precision-component tube.
Potential source references
The quotation must identify the proposed manufacturer, current availability, inspection documents, and delivery basis for the specific RFQ.
- Tube Investments of India (TII)
- Goodluck India Ltd
- Hi-Tech Pipes Ltd
Applicable standards and specifications
CDW tube selection table for Kanpur buyers
This RFQ comparison uses the catalogue range only for enquiry planning. Final dimensions and tolerances must come from the controlled component drawing and quotation.
| Component need | Order dimension | Process note | Receipt check |
|---|---|---|---|
| Machined round component | OD, ID or wall, cut length | Leave stated machining allowance | Dimension report and surface condition |
| Bent automotive part | OD, wall, bend input length | State delivery condition | Ovality, cracks, and bend trial plan |
| Furniture section | Outside section, wall, length | Compare ERW alternative | Squareness, straightness, surface |
| Hydraulic housing blank | OD, ID, wall, length | State later honing or machining | Bore allowance and traceability |
| Special profile | Controlled drawing dimensions | Custom die or forming route | Approved sample and inspection method |
The table organizes RFQ inputs. It does not assign a tolerance or certify a component for pressure service.
How Kanpur engineering shops specify CDW tube
Issue the drawing with controlled characteristics marked. State round, square, rectangular, or special profile; OD or outside dimensions; wall or ID; grade; delivery condition; length; cut tolerance; surface condition; and quantity. If later machining controls the purchase, include the finished dimension and required stock allowance. Avoid placing only a nominal trade size on the PO.
Add straightness, ovality, corner radius, twist, decarburization, weld position, hardness, and surface requirements only when the drawing or process needs them. Define the inspection method and sampling plan. A supplier cannot price an open phrase such as close tolerance consistently because each bidder can assume a different limit.
- Attach a revision-controlled drawing and write the revision on the quotation and PO.
- Identify dimensions as maximum, minimum, bilateral, or reference values.
- State BK, BKW, BKS, GBK, NBK, or another approved delivery condition where applicable.
- Name pickled and oiled, bright, black, plated, or other required surface condition.
- Separate development samples, production quantity, and inspection records.
Worked weight example for a CDW tube order
A theoretical weight helps convert a piece schedule into kilograms. For a round carbon steel tube with 50 mm OD and 4 mm wall, weight = (OD - t) x t x 0.02466 kg/m. The unrounded result is 4.53744 kg/m, displayed as 4.54 kg/m. Using the unrounded value, one 6 m length is about 27.22 kg before coating and permitted dimensional variation.
If the PO requires exact cut pieces, multiply the weight per metre by the net cut length and piece count. Add an agreed allowance for sample pieces and process setup instead of hiding it in the finished quantity. Use actual weighment or the agreed theoretical basis for billing. This calculation does not assign a tolerance or pressure rating.
Common CDW procurement and inspection mistakes
The largest mistake is buying to the finished component size without machining or forming allowance. The second is naming one tolerance while leaving the mating dimension uncontrolled. Review OD, ID, wall, ovality, straightness, and cut length together. A tube can pass one diameter check and still fail assembly because the wall or shape is unsuitable.
Surface acceptance also needs a written comparator. Bright does not define roughness, pits, scratches, scale, or plating readiness. State the protected surface, defect limits, and packing method. For first supply, agree a sample or inspection plan before the production lot is cut. Keep accepted samples and measuring methods aligned between Kanpur and the receiving shop.
- Do not assume cold drawn means honed or ready for hydraulic seals.
- Do not mix outside-dimension and inside-dimension tolerances without checking wall feasibility.
- Do not approve a delivery-condition change through a rate-only comparison.
- Do not bundle precision faces against unprotected steel edges.
- Do not discard bundle tags before material is linked to the incoming inspection record.
IS 3074 and other CDW specification routes
The catalogue identifies IS 3074, DIN 2393, EN 10305-2, and ASTM A513 as common CDW specification routes. These standards are not interchangeable labels. Use the one named by the drawing or approved customer specification, then add the grade, delivery condition, dimensions, tolerances, surface, testing, and documentation required for the component.
An MTC supports material identity and reported test results. A dimensional report records the measurements requested by the inspection plan. Neither document proves that an unspecified finished component will fit. For automotive or repeat OEM work, agree the control plan, sample approval, traceability, and change-notification expectations before serial dispatch.
CDW tube dispatch from Kanpur to industrial buyers
CDW buyers in Panki, Dada Nagar, Fazalganj, Jajmau, Chakeri, Kanpur Dehat, Unnao and elsewhere should require the quotation to identify proposed size, grade, delivery condition, length, mill source, inspection scope, packing and current availability against the drawing and RFQ.
For enquiries outside Kanpur, provide the destination PIN code and state whether long lengths or exact cut pieces are required. Cut parts need protected ends, clear bundle labels, and a piece schedule that matches the invoice and inspection record. Availability, freight, and timing must be confirmed in the quotation.
What to include in the RFQ
- Specify the relevant standard or grade where known.
- Provide OD or NB, wall thickness or schedule, required length, and quantity.
- State the delivery city or PIN code and any unloading constraints.
- List MTC, IBR, TPI, marking, inspection, or other documentation requirements.
- Attach the controlled drawing and state its revision, product route, standard, and grade.
- Give profile, OD or outside size, ID or wall, straightness, ovality, and controlled tolerances.
- State delivery condition, surface finish, machining allowance, cut length, and end condition.
- List MTC, dimensional report, sample approval, TPI, and incoming inspection requirements.
- Define piece count, development allowance, packing, rust protection, and bundle identification.
- Separate ex-warehouse Kanpur price, freight, unloading, transit risk, and applicable taxes.
Key points for Kanpur buyers
- The component drawing, not a trade-size name, should control a CDW tube enquiry.
- Cold drawing improves dimensional control but does not make welded tube seamless.
- Delivery condition, tolerance, surface, and later processing must appear on the PO.
- A dimensional report and MTC answer different acceptance questions.
- Confirm Kanpur availability, sample plan, packing, freight, and dispatch for each RFQ.