About Precision Tubes
Cold-drawn precision-tube options referenced to DIN 2391 terminology and the EN 10305 series. Specify manufacturing route, grade, delivery condition, dimensions, tolerance class, surface, and tests from the component drawing.
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 150mm |
|---|---|
| Wall Thickness (WT) | 1mm to 15mm |
| Grades | DIN 2391 / EN 10305: ST35, ST45, ST52 |
| Lengths | Random lengths (4m-7m) or exact cut-to-length |
| Delivery Condition | BK (Cold Finished), BKW, BKS, GBK, NBK |
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.
- Hydraulics & Pneumatics: Cylinder barrels and fluid lines.
- Automotive: Shock absorbers, steering columns, and axles.
- Heavy Machinery: Earthmoving equipment arms and actuators.
- Bicycles & Two-Wheelers: Frame fabrication and front forks.
Potential source references
The quotation must identify the proposed manufacturer, current availability, inspection documents, and delivery basis for the specific RFQ.
- TI Machining
- ISMT Limited
- Heavy Metal & Tubes
- Mahalaxmi Seamless
Applicable standards and specifications
Precision tube definition and product boundary
A precision tube is a dimension-controlled tube intended for machining, forming, fluid lines, or cylinder work. Cold drawing reduces the tube to the ordered dimensions and changes the surface and mechanical condition. The product may begin as seamless tube or welded tube, so the RFQ must identify CDS or CDW when the manufacturing route matters.
DIN 2391 and EN 10305 are the standard families already used throughout this catalogue. EN 10305-1 covers seamless cold-drawn precision tubes, while EN 10305-4 addresses seamless cold-drawn tubes for hydraulic and pneumatic power systems. Legacy drawings often use ST52 language, while current enquiries may use E355. The MTC and approved equivalence note should settle acceptance.
A standard cold-drawn tube is not automatically a finished hydraulic barrel. Honing or skiving and roller burnishing may still be required to achieve the specified bore class and roughness. A tube described only as smooth bore remains incomplete for procurement unless the drawing defines the measurable finish.
Suitable users and duties that need another product
Hydraulic-cylinder shops use precision tubes for barrels and machined components. Pneumatic equipment makers, automotive suppliers, heavy-machinery repairers, and two-wheeler fabricators use the same family for parts that need controlled OD, ID, wall, or straightness. Printing-cylinder shops may use selected seamless precision shells when machining allowance and balance requirements suit the drawing.
A buyer should not use this catalogue description as a pressure rating. Design pressure, temperature, end closures, fatigue duty, weld details, and the selected standard control service suitability. Boiler pressure parts need the specified boiler material and IBR documentation, not a generic ST52 or E355 substitution.
Ordinary structural hollow sections also belong in a different purchase line. They can be suitable for frames or supports, but their dimensional and surface requirements differ from a seal-running cylinder bore. Buying a structural section and planning to remove large machining allowance can erase an apparent rate advantage.
How Kanpur cylinder shops write the RFQ
Begin with the drawing reference, standard, manufacturing route, and grade. Then state OD x ID or OD x wall, dimensional tolerances, straightness, cut length, and quantity. If ST52 or E355 equivalence is allowed, write the acceptance condition and require the MTC to identify the supplied grade and delivery condition.
Delivery condition matters because it affects subsequent bending, welding, and machining. The catalogue uses BK, BKW, BKS, GBK, and NBK descriptions. Copy the drawing terminology rather than choosing a condition from stock availability. Ask the designer to approve substitutions before the supplier cuts material.
For a finished bore, state H8 or H9 only when the drawing requires it, and add the maximum Ra value, measurement method, inspection points, and report format. Include chamfer, squareness, machining allowance, rust protection, end plugs, wrapping, and bundle support. These details protect the bore during movement from Kanpur to the machine shop.
Request the EN 10204 inspection-document type named by the project, heat traceability, dimensional report, and roughness report for a finished bore. Add TPI when the PO or end customer requires independent witnessing. IBR Form III-C is for boiler mountings and fittings and should not be copied into a normal hydraulic barrel RFQ.
- Identify CDS or CDW, standard, ST52 or E355 grade, and the required delivery condition.
- State OD, ID, wall, each tolerance, straightness, cut length, and machining allowance.
- Define unfinished, honed, or skived and roller-burnished bore condition in measurable terms.
- List MTC 3.1, dimensional readings, bore report, roughness report, and TPI hold points.
- Ask for ex-warehouse Kanpur price, applicable taxes, freight, packing, and delivery basis separately.
Precision tube comparison for Kanpur procurement
The manufacturing route and finish should match the operation that follows receipt. The table keeps parent-tube selection separate from final bore finishing, which makes competing quotations easier to compare.
| Supply description | OD range | Wall range | Typical next operation | Acceptance evidence |
|---|---|---|---|---|
| CDS precision tube | 6-150 mm | 1-15 mm | Machining, honing, or forming | MTC, dimensions, condition, and surface check |
| CDW precision tube | 6-150 mm | 1-15 mm | Machining or formed component work | MTC, weld-route declaration, dimensions, and condition |
| Honed bore tube | 6-150 mm | 1-15 mm | Cylinder barrel preparation | MTC, finished ID readings, H8 or H9 result, and Ra report |
| As-drawn tube | 6-150 mm | 1-15 mm | Further drawing, machining, or finishing | MTC, dimensions, straightness, and surface condition |
The drawing, ordered standard, delivery condition, inspection plan, and inspection documents control final acceptance.
Worked weight example for a cut-length order
A Kanpur machine shop can estimate parent-tube mass before asking for cutting. For a 50 mm OD tube with 4 mm wall, calculate weight = (50 - 4) x 4 x 0.02466 = 4.54 kg/m.
Using the displayed 4.54 kg/m value, a 6 m parent length has a theoretical mass of 27.24 kg before coating, end preparation, or permitted manufacturing variation. Use the cut plan to total required metres, then include machining allowance and expected remnants as separate planning items rather than changing the tube weight formula.
Theoretical mass supports BOQ checks, freight planning, and quote normalization. It does not prove bore tolerance, straightness, or surface roughness. Those acceptance points need measurements and reports. Compare the delivered quantity with the packing list and agreed invoicing basis after the dimensional inspection is complete.
Inspection points before machining starts
In practice, a tube can carry the correct grade description and still be unsuitable for the planned machining sequence. Match heat numbers and delivery condition on the MTC first. Then measure OD, ID, wall, straightness, length, and cut-end condition against the PO before removing identification marks.
Inspect the bore under clean light. Look for corrosion, scoring, embedded debris, end bruising, and damage from lifting tools. A finished bore needs the specified dimensional and roughness record. A visual statement such as mirror finish cannot replace an Ra limit or the bore class written on the drawing.
Keep honed surfaces plugged and protected. Supports should prevent long tubes from bending under their own handling arrangement, while separators prevent one tube from marking another. Photograph condition at unloading if the consignment will wait before machining.
Common PO failures include mixing OD x wall with OD x ID, omitting tolerance direction, accepting ST52 without a standard, and leaving honing responsibility unclear. Another frequent mismatch is ordering BK when the next operation needs a condition suitable for forming. Resolve those conflicts during quotation review.
Kanpur supply basis and delivery planning
Precision-tube buyers in Panki, Dada Nagar, Fazalganj, Chakeri, and the wider Kanpur industrial belt should require the formal quotation to identify proposed mill source, dimensions, grade, condition, finish, current availability, and cutting scope for the specific RFQ.
Use an ex-warehouse Kanpur comparison with applicable taxes and freight shown separately. Add the delivery PIN code, unloading method, bundle-length limit, and requirement for covered or protected transport. Regional service and timing must be confirmed in the offer rather than inferred from a site-wide claim.
Buyers sending material to Lucknow, Agra, Prayagraj, Varanasi, Gorakhpur, Jhansi, Bareilly, or Patna can use the matching city page for delivery context. The accepted PO should still control the actual dispatch date and vehicle plan. A city-page indication is not a commitment for a non-stock size.
Key points for hydraulic tube buyers
- Name the manufacturing route, standard, grade, and delivery condition together.
- Treat a cold-drawn parent tube and a finished hydraulic bore as different supply states.
- Put OD, ID, wall, tolerance direction, straightness, length, and finish on the PO.
- Verify MTC, dimensions, bore report, and surface condition before machining.
- Separate ex-warehouse Kanpur price, GST, freight, cutting, finishing, and inspection.
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.