Pipe Rejection Criteria — buyer's pre-acceptance checklist

What a rejection note is, and what it is not

A rejection note records a non-conformance against the PO. It is not a price complaint, not a preference about mill brand, and not a way to reopen a specification the drawing already accepted.

The glossary defines a rejection note as the buyer document that identifies non-conforming material, cites the heat number, and states return, replacement, or scrap. Use that paper at the Kanpur yard or at site receiving. Verbal “this looks thin” is not a record.

Reject against written limits: product standard, class or schedule, grade, end finish, coating, and certificate type. Do not reject because a cheaper class exists, or because another mill’s brochure shows a different wall.

This checklist is for industrial procurement, PWD and JJM contractors, sugar-mill stores, fire-system installers, borewell contractors, and hydraulic shops taking pipe from Kanpur. It is not a laboratory method standard and not a substitute for TPI witness at the mill.

• Reject against the PO and the named product standard
• Cite heat number, size, and failed check
• Do not use a remembered wall percentage from another product
• Hold the load before cutting or painting

What surface and visual defects lead to pipe rejection?

Excessive pitting, seams, or laminations usually lead to rejection. A simple "wash" or paint coat often hides surface defects that only appear after blasting.

Check for: Seams (spiral), Laminations (internal), Pits.

Use the NDE method named by the inspection plan, such as dye penetrant, magnetic-particle, or ultrasonic testing.

Paint, oil, or a light mill wash can hide pits until blasting or galvanizing prep. For fire-hydrant and GI lots, inspect after any coating claim, not only on black pipe. Laminations in the wall are a body defect; do not repair them by grinding into minimum wall.

Seam issues on ERW pipe are weld-line defects, not a reason to apply a seamless tolerance table. If the PO requires NDE, the method and acceptance belong on the ITP. Visual-only receipt cannot prove an internal lamination is absent.

• Lamination: Internal rust/seam
• Pitting: Rust spots
• Seam: Weld line imperfection

Which dimensional tolerance violations cause rejection?

Reject wall thickness, OD, ovality, or length only against the limit stated by the PO and its applicable product standard. Critical line pipe may require additional dimensional checks in the inspection plan.

IS 1239 Light, Medium, and Heavy class walls are tabulated by NB. IS 3589 uses OD and stated wall. ASTM A53 uses NPS and schedule. DIN 2391 and EN 10305 use named dimensional classes. None supplies a universal wall percentage for every pipe.

Trade offers sometimes print a mill tolerance without identifying the product standard or class. Do not turn that offer into a receiving rule. Read the PO, then the dimensional table in its cited edition. If the PO is silent, record the missing requirement and obtain a written disposition.

Ovality and length checks follow the same principle. Random length is acceptable only when the PO says random length. Fixed-length acceptance needs the limit stated by the order or governing standard. Keep short pieces identified and separate rather than hiding them inside a full-length bundle.

Measure a representative set chosen under the inspection plan. Record the instrument, calibration status, location, and result against the exact limit. A weighbridge difference can trigger measurement, but it cannot establish wall thickness by itself.

• Wall: compare with the ordered class, schedule, or millimetre value
• OD and ovality: use the applicable product-standard limits
• Length: use random or fixed-length terms on the PO
• Missing limit: obtain a written disposition before release

Where to read wall and OD limits by product

Each product family points to a different standard page. The receiving inspector opens that page and the PO, not a single percentage remembered from seamless pipe.

Use the table as a map. It does not reprint wall millimetres. Class thickness for IS 1239 lives on the class chart. Schedule walls live on the pipe schedule chart. Precision classes live on the DIN 2391 cluster.

If two documents disagree, the purchase order wins for commercial receipt, and the design specification wins for whether the PO was correctly written. Fix the next PO; do not silently accept thin wall because the truck is waiting in Kanpur.

• Open the product standard named on the PO
• Measure OD, wall, and length on sample lengths
• Never copy one row onto another product
• If the PO is silent, do not invent a gate limit

Worked example: under-wall mass on 50 NB Medium

Theoretical mass is a useful screening check for billed quantity. It can trigger wall measurement, but acceptance still follows the ordered class or wall and its applicable tolerance.

Take 50 NB Medium from the site weight chart: OD 60.3 mm, wall 3.6 mm. W = (60.3 − 3.6) × 3.6 × 0.02466 = 5.03 kg/m. A 6 m length is 30.2 kg theoretical plain-end mass.

If a bundle measures 3.3 mm wall, compare that result with the ordered class and its applicable limit. Do not classify it from the mass example. Mass is a commercial sanity check when pipe is billed by kilogram.

One hundred lengths of 6 m at 5.03 kg/m are 3.018 t theoretical. A systematic shortfall against that figure, after coating and coupling allowances, is a reason to measure wall with a calibrated ultrasonic thickness gauge before unloading acceptance.

Do not reuse this calculation in later sections or in the FAQ. Other sizes use the same site formula on the weight calculator and the pipe weight chart.

• Use one theoretical-mass calculation as a screening check
• 50 NB Medium: 5.03 kg/m, 30.2 kg per 6 m
• Mass shortfall triggers wall measurement
• Acceptance still follows PO wall or class

RFQ checklist so receiving has a limit to use

If the PO omits class, wall, grade, end finish, or certificate type, the gate cannot reject fairly. Write those fields before dispatch.

Size: NB or OD. Wall: class, schedule, or millimetres. Grade: YST, Fe, ASTM, or DIN as applicable. Length: random or fixed. End finish: plain, bevel, thread and couple. Coating: black or GI to the coating standard on the order.

Certificate: name Type 3.1, Type 3.2, or another required inspection document on the PO. For IBR, use III-A steam pipe, III-B tube, or III-C mounting and fitting as applicable. Inspection, packing, delivery, freight, taxes, and date must follow the current written order.

PWD, JJM, fire, and borewell jobs should paste the tender clause into the RFQ. Hydraulic cylinder tube should state OD class and bore class, not “MS pipe heavy”.

• NB or OD, wall or class, grade
• Length, end finish, coating
• MTC 3.1 / 3.2 / applicable IBR form
• TPI if named, packing, Kanpur delivery basis

Receiving steel pipe at the Kanpur yard

Do the paper match, the heat match, and a sample OD/wall check before the truck is released onto NH routes out of Kanpur.

For a Kanpur-origin order, confirm the actual material location, packing, collection or destination, carrier, freight, taxes, availability, and promised date in the accepted quotation. A route list is not a stock or delivery guarantee.

In practice, mixed-class bundles and remarking are the failures that show up at a stockyard. Check stencil, tag, packing list, and MTC together. A wrong grade is a critical mix-up; do not sort it after cutting.

Local buyer types use different acceptance documents. PWD and JJM lots follow the ISI and MTC requirements named by their tenders. Sugar-mill boiler tubes follow the applicable IBR document path. Fire-system, borewell, and hydraulic orders each need their ordered class, thread, dimensions, and condition checked.

Use steel pipes Kanpur, GI pipes Kanpur, MS ERW Kanpur, borewell Kanpur, and the Kanpur steel market pages for local supply context. File the rejection note and send the next order through the RFQ form.

• Match heat on tag, stencil, list, and MTC
• Sample OD and wall against the PO standard
• Do not accept invoice-only in place of MTC
• Hold mixed-class or mixed-grade bundles

Key points before you sign the receiving copy

Five receiving rules. No new limits.

Use this box at the gate. It does not add chemistry or pressure figures beyond the pages already cited.

Photograph the marking, instrument display, and affected area before unloading. Attach those records to the heat-specific rejection note so the purchaser can review the same evidence.

• Wall, OD, and length limits come from the PO and the named product standard or class
• Do not apply one seamless percentage to IS 1239, IS 3589, A53, and precision tube
• Visual pits, laminations, and wrong end finish are rejectable when they breach the order
• Wrong grade or heat mismatch is a critical fail
• Mass from the site formula is a sanity check, not a substitute for measured wall