For a DIN 2391 or EN 10305 honed-bore enquiry, copy the approved standard, grade, manufacturing route, delivery condition, OD, ID, wall, bore tolerance, roughness, straightness, length, and inspection-document type. The written Kanpur quotation must confirm the exact offered size and condition; this page provides no stock band.
When should procurement ask for DIN 2391 ST52 honed-bore tubes?
Use DIN 2391, ST52, a seamless or welded route, honing, or another finish only where the approved cylinder and material design names it. The barrel application alone does not select or exclude a standard, grade, manufacturing route, delivery condition, or bore finish.
The phrase “DIN 2391 ST52 honed bore” is still incomplete unless the RFQ names the invoked edition, product scope, delivery condition, dimensions, finished-bore requirements, and documents. Treat any E355 offer as a proposed substitution requiring a line-by-line technical comparison and approval.
A hydraulic cylinder barrel is not just a pressure tube. It is also the bearing surface for the piston seal. The inside diameter must be controlled tightly enough for seal squeeze, must be round enough to avoid local bypass, and must be smooth enough to protect the seal lip without becoming so polished that oil retention is poor. DIN 2391 and EN 10305 provide the manufacturing basis; ISO 286 explains the H8/H9 tolerance language; ISO 4287 defines the roughness parameters that should appear on the inspection report.
For an RFQ, state OD x ID or OD x wall, approved grade and standard, delivery condition, finished-ID tolerance and finish, length, quantity, inspection-document requirement, and any cutting or machining allowance. Attach the controlled cylinder and seal information so the tube is not selected only from a catalogue size.
How do H8 and H9 bore tolerances change cylinder performance?
H8 and H9 are size-dependent ISO tolerance zones, not pressure, leakage, duty, price, or availability classes. Use only the nominal bore and tolerance approved by the cylinder and seal design, with the specified finish and inspection method.
An ISO tolerance-zone designation must be paired with the nominal size to obtain numerical limits. It does not by itself specify roundness, straightness, surface texture, material, pressure capacity, or seal compatibility.
The cylinder designer should evaluate the complete tolerance stack with the piston, guide rings, seals, pressure, temperature, fluid, speed, lubrication, and manufacturing route. Procurement should not change H8 to H9, or the reverse, for a cost or lead-time assumption.
The inspection report should state actual bore size, tolerance class, and measurement method. A single nominal ID is not enough. For long barrels, ask for straightness and ovality checks because a locally good bore can still create assembly issues if the tube bows over the stroke length.
What does BK+S mean for ST52 hydraulic cylinder tubes?
Treat BK+S as the delivery-condition callout defined by the invoked standard edition. It does not by itself establish grade, strength, machining stability, weldability, bore finish, or suitability for a cylinder operation.
Cold drawing and subsequent heat-treatment conditions affect material properties and residual stress. The responsible design and process plan must select the approved grade and condition for machining, welding, finishing, and service; a hydraulic-barrel label is not enough.
The approved drawing must select the grade and delivery condition from the design, fabrication, and service requirements. Verify chemistry and mechanical values in the inspection document required by the purchase order, together with heat identity and any specified hardness.
If the cylinder barrel will be welded, use a qualified procedure for the approved material and delivered condition. Follow the drawing and procedure for preparation, filler, preheat, post-weld treatment, and inspection; this page does not designate BK+S E355 as a standard port-welding choice.
Which surface-finish value should appear on a honed-bore tube RFQ?
Copy the required surface-texture parameters, limits, measurement method, sampling, lay or cross-hatch requirements, cleanliness, and protection from the approved cylinder and seal design. Do not use a universal Ra band.
Phrases such as “mirror finish” or “honed finish” are not measurable enough for inspection. Copy the approved Ra, Rz, Rmax, bearing-ratio, lay, or other surface-texture requirements exactly, including the evaluation and sampling method, rather than substituting a generic value.
Honing leaves a controlled cross-hatch pattern that helps retain oil. A bore that is too rough cuts seals; a bore that is too smooth can starve the contact of lubricant. Cleanliness also matters. Abrasive residue from finishing must be removed because it can score the piston seal during first commissioning.
For dispatch, request oiled bore protection, capped ends where practical, and handling that avoids dents on the ID mouth. A tube can meet DIN 2391 and still become scrap if the honed surface is rusted, dented, or contaminated before machining.
How is theoretical weight calculated for DIN 2391 ST52 honed tubes?
Use the nominal OD and wall thickness in the site's steel-tube density calculation to estimate mass before honing. Keep the result as a theoretical purchasing figure, then compare the dispatch weight and measured dimensions with the PO and MTC.
For a worked Kanpur procurement example, take an 89.0 mm OD tube with a 5.0 mm wall, giving a 79.0 mm nominal ID before the finished-bore allowance is considered. The unrounded site formula is (89.0 − 5.0) × 5.0 × 0.02466 = 10.3572 kg per metre, displayed as 10.36 kg/m. At that displayed rate, one 6-metre length is 62.16 kg. Keep the quotation, comparison sheet, and bundle estimate on the displayed kg/m value so the figures agree.
The matching 89.0 mm OD row in the indicative precision-tube price list is ₹95 to ₹118 per kg. That band is a budgeting reference for the listed size, not a family-wide promise for every DIN 2391 dimension or finish. A firm quote still depends on quantity, grade, mill source, delivery location, and current market conditions.
Treat a large difference between theoretical and scale weight as a reason to inspect, not as proof of a defect. Check actual OD, wall, length, quantity, and any machining allowance against the PO. The site's DIN 2391 St52 product page describes typical hydraulic working pressures of 100 to 350 bar, but pressure suitability still comes from the cylinder design and minimum finished wall, not from the weight estimate.
Procuring ST52 honed-bore tubes in Kanpur and North India
For a Kanpur-basis RFQ, state the exact DIN 2391 or EN 10305 requirement, offered material location, destination, freight basis, inspection scope, and required date. Treat stock, inspection access, and delivery timing as unknown until the written quotation confirms them.
The business address is 83/124, Steel Market, Bartan Bazar, Afim Kothi, Basanti Nagar, Juhi, Kanpur 208014. An RFQ may use an ex-warehouse Kanpur basis for comparison, but the written quotation must confirm where the offered material is physically located and whether pickup, inspection, or onward freight is available for that lot.
Tender and industrial buyers should request EN 10204 3.1 MTC when the PO requires certified steel. The certificate should identify the heat and report chemical and mechanical results. For E355, the cited EN 10305-1 chemistry limits are Carbon 0.22% maximum, Silicon 0.55% maximum, and Manganese 1.60% maximum. Read those values with the grade, delivery condition, and dimensional report rather than accepting a certificate for a different heat.
Commercial documents should show the quoted basis, the legally applicable GST rate on the current quotation, transport charge, consignee, and certificate requirement separately. Ask the written quotation to confirm stock status, material location, freight, timing, and whether any requested TPI or dimensional check can occur before issuing the PO.
How to specify DIN 2391 ST52 honed-bore tubes on an RFQ
Write the tube standard, grade, delivery condition, finished bore class, roughness, length, inspection documents, and Kanpur delivery basis as separate lines. Treat availability as unknown until the written quotation confirms the exact offered dimensions, condition, quantity, and date.
A honed-bore RFQ should not collapse into a single size string. State the approved standard, grade, delivery condition, OD x ID or OD x wall, finished bore class, roughness target, cut length, quantity, and required inspection-document type. If honing is included, say who finishes the bore and who issues the dimensional and roughness report.
Ask the written quotation to state the material location and whether pre-dispatch inspection is available; this page does not promise yard inspection. Show the ex-warehouse Kanpur basis, the legally applicable GST rate on the current quotation, packing, bore oiling, end protection, and destination freight as separate commercial lines.
If the drawing allows H9 instead of H8, or skived and roller-burnished finish instead of honing, write that substitution rule on the RFQ. Do not leave the supplier to choose a finish after pricing. Attach the piston-seal or cylinder drawing when leakage, stroke, or typical 100 to 350 bar duty is part of the design.
- State OD, ID or wall, and which of those dimensions is the finished honed bore.
- Name ST52 / E355 and BK+S separately from the H8 or H9 bore class.
- Give an ISO 4287 roughness limit such as Ra, plus straightness if the barrel is long-stroke.
- Require the inspection-document type and bore report named by the purchase order when the supplier also hones the tube.
- Quote ex-warehouse Kanpur, then add destination, quantity, and required date for freight confirmation.