Document verification is performed before any physical inspection of the delivered material begins. If the documentation package is incomplete or inconsistent, the material must be quarantined until the correct documents are received — no matter how urgently production needs the material. Accepting material without complete documentation creates untraceable pressure parts, which is an unconditional code violation under ASME Section VIII, ASME B31.3, and ISO 3834-2.

• Purchase Order (PO) Checking: Verify that the delivered material matches the PO in every respect — material grade, standard, size, schedule or class, quantity, and heat treatment condition. Any deviation from the PO is a non-conformance.
• Drawing and Specification Verification: Cross-check the material against the applicable engineering drawing, piping material specification (PMS), or vessel data sheet. Confirm that the delivered product form (plate, pipe, fitting, flange) and dimensions match the drawing requirement.
• Material Test Certificate (MTC) Review: Confirm the MTC (mill certificate) is present, covers the delivered heat number, meets the applicable ASTM / ASME material specification, and shows actual measured values (not just “meets specification” without values) for chemistry and mechanical properties.
• Heat Number Verification: Every delivered item must have the heat number physically stamped, painted, or tagged on it. Verify the heat number on the material exactly matches the heat number on the MTC. A mismatch is a mandatory rejection condition.
• Delivery Challan and Invoice Checking: Confirm quantities, item descriptions, and order references on the delivery note match the PO. Document any shortages or damaged packaging before signing the delivery receipt.
• Approved Vendor Verification: Confirm the manufacturer and supplier are on the project’s Approved Vendor List (AVL) for this material category. Material from non-approved sources must not enter the production system without formal concession approval.

Material identification bridges the gap between the paper document and the physical material. Colour coding, stamped markings, and proper labelling systems exist precisely to prevent the most dangerous type of material error: a correctly documented heat delivered alongside incorrectly identified individual pieces that have been mixed or re-marked. Positive identification must be maintained throughout the material’s entire journey from goods receiving to the weld joint.

• Material Grade Verification: Confirm the material grade marking (e.g., “A106-B” for carbon steel pipe, or “316L” for stainless pipe) matches the PO and MTC. For pressure pipe, check both the ASTM designation and the grade suffix.
• Size, Thickness, and Schedule Checking: Physically measure or verify the nominal pipe size (NPS), outside diameter (OD), and wall thickness (schedule or nominal mm) match the PO and drawing. Do not rely on supplier stencilling alone — verify with calipers or tape measure.
• Schedule / Class Checking: For pipe, verify the schedule (e.g., Sch 40, Sch 80, Sch XXS) or for fittings and flanges confirm the pressure class (150#, 300#, 600# etc.) per ASME B16.5 or B16.9.
• Colour Coding Verification: Many projects specify colour-coded end caps or paint bands for specific materials (e.g., yellow = P91, blue = 316L). Verify colour codes against the project material colour coding specification.
• Proper Marking Availability: ASME B31.3 and ASME Section VIII require material markings to be present on all pressure parts. Verify that heat number, material grade, standard, size, and manufacturer’s name or mark are legible and will be preserved through the first cut operation.
• Traceability Maintenance: Establish and record the traceability chain at receiving — item number on material register linked to MTC heat number. This chain must be maintained when material is cut: transfer heat numbers to cut pieces before the original marking area is removed.

Visual inspection of incoming material is a systematic examination of the entire delivered quantity — not a sample. Every pipe length, every plate, every fitting must be examined for the conditions listed below. Visual defects found at receiving must be formally recorded on the inspection receiving report. Borderline conditions (e.g., light surface pitting) must be assessed against the applicable product standard tolerance and the design corrosion allowance before a disposition decision is made.

Dimensional inspection at receiving confirms that the material as-delivered will fit into the piping system or pressure vessel as designed. Piping and fittings that are outside dimensional tolerance create fit-up problems — incorrect root gaps, high-low misalignment beyond code limits, and interfering geometries — that either produce weld defects or require costly rework. All dimensional measurements must be recorded on the receiving inspection report with actual measured values, not simply “passed”.

• Length Verification: For cut-to-length pipe or plate, verify the delivered length against the PO tolerance. For standard mill-length pipe, confirm all lengths are within the applicable ASTM standard length tolerance.
• OD and ID Checking: Measure the outside diameter at a minimum of two perpendicular axes at each pipe end and at mid-length. For ASME B31.3 pressure pipe, verify OD is within the ASTM tolerance for the nominal size. Ovality (difference between max and min OD at any cross-section) must be within tolerance for the applicable product standard.
• Thickness Measurement: Measure wall thickness using ultrasonic wall thickness gauge at multiple circumferential locations on each pipe length, and at multiple locations across plate surface. Minimum measured thickness must not be less than the minimum ordered thickness per the applicable ASTM tolerance (typically nominal minus 12.5% for seamless pipe per ASTM A106).
• Flange Dimension Checking: For flanges, verify bore diameter, raised face diameter, bolt hole circle diameter (PCD), bolt hole diameter, quantity of bolt holes, flange face finish (RF, FF, RTJ), and overall flange dimensions against ASME B16.5 or B16.47 as applicable.
• Bolt Hole and PCD Verification: Use a bolt hole PCD gauge or vernier caliper to verify that bolt holes are correctly positioned on the bolt circle. Even a single bolt hole out of position will prevent the flange from bolting up correctly in the field — a problem that may not be discovered until erection.
• Straightness and Roundness Checking: For pipe, check straightness by rolling on a flat surface or using a straight edge. For plate and structural, check for camber and bow. Out-of-straight material requires correction before use or must be rejected if correction is not feasible within tolerance.

The Material Test Certificate (MTC) is not just a piece of paper — it is the legally and technically binding document that proves the material meets its specification. Verifying the MTC requires checking not just that the document exists, but that every individual test result is within the specification limits, and that the test methods used comply with the applicable ASTM or ASME material standard. A fabricator who accepts a material solely on the basis of a supplier’s statement of compliance without verifying the MTC values has not performed proper incoming inspection.

• Chemical Composition Checking: Verify all reported element percentages against the ASTM/ASME specification maximum and minimum limits. Pay particular attention to carbon content (affects weldability and PWHT requirements), sulphur and phosphorus (embrittlement risk), and chromium/molybdenum content in alloy steels.
• Mechanical Properties Verification: Check that tensile strength, yield strength, elongation, and reduction-in-area values all meet specified minimums. For low-temperature service, verify Charpy impact test results at the specified test temperature and that they meet the code minimum absorbed energy requirement.
• Hardness Testing: Where hardness is specified (e.g., for sour service per NACE MR0175 — max 22 HRC / 248 HV), confirm the MTC reports hardness values and they are within limits. For P91, verify the hardness falls within the tempered martensite range (typically 187–248 HBW).
• Code Compliance Verification: Confirm the material standard and grade listed on the MTC are permitted materials under the applicable design code (ASME Section VIII, B31.3, B31.1). Verify the product specification level (PSL) where required (e.g., API 5L for line pipe in Category M fluid service under B31.3).
• Heat Treatment Condition: Verify the heat treatment condition stated on the MTC matches what the specification requires — normalised, quenched and tempered, solution annealed, etc. For P91 (SA-335 P91), confirm the MTC states normalising and tempering were performed and that the final Cr and Mo content is within the enhanced B31.3 range if required.

Alloy material substitution — a wrong alloy delivered in place of a specified alloy — is one of the most dangerous failure modes in process plant construction. In many cases, carbon steel and low-alloy steel pipe look identical to the eye: the only way to distinguish SA-106 Gr.B carbon steel from SA-335 P22 or P91 Cr-Mo alloy steel is by composition analysis. The consequence of using the wrong alloy in a high-temperature service application includes accelerated creep damage, hydrogen attack, and rupture during service. PMI is not optional for these materials.

• PMI Testing: Perform XRF or OES PMI on a minimum of 10% of pipe lengths, 100% of fittings and flanges for alloy materials (or as specified by the project PMI plan per API RP 578). Record PMI results against the heat number on the material register.
• Hardness Testing: Verify bulk hardness of received alloy materials — particularly P91 — is within the expected as-received range. P91 incorrectly heat treated (not normalised and tempered) may arrive at incorrect hardness and must be rejected.
• PWHT Verification (for pre-treated components): For alloy components supplied in the post-weld heat treated condition (e.g., pre-welded sub-assemblies), verify that PWHT was performed and that the PWHT chart and temperature records are included in the documentation package.
• NDT Verification: For critical alloy pressure parts, confirm that any NDT (RT, UT, MT, PT) required by the product specification or purchase order has been performed and that the test reports are included with the MTC package.

Welding consumables — SMAW electrodes, TIG filler wire, MIG wire, SAW wire and flux, FCAW wire — are materials that become part of the permanent weld metal in the pressure boundary. They require the same level of incoming traceability, certification review, and physical condition inspection as base materials, yet are frequently treated as general consumable items. This is a significant quality risk: the wrong electrode grade, a damp low-hydrogen electrode, or an expired batch can introduce weld metal chemistry non-compliance, hydrogen cracking, or porosity into welds that cannot be detected until expensive NDE is performed.

• Electrode Grade Verification: Confirm the AWS electrode classification (e.g., E7018-H4, E8018-B2, E316L-16) matches the WPS requirement for the base material and service. Check the electrode packaging and data sheet — do not rely on the box label alone as restamped or counterfeit electrodes are a known industry problem.
• Filler Wire Checking: For TIG (GTAW) filler wire and MIG (GMAW) wire, verify the AWS classification (e.g., ER70S-6, ER316L, ER90S-B3) against the applicable WPS. Verify diameter matches WPS specification.
• Batch Number Verification: Each delivered batch of consumables must have a batch or lot certificate from the manufacturer showing the chemical composition of the deposited weld metal and the mechanical properties of test welds made with that batch. File batch certificates with the welding documentation for the project.
• Oven Temperature Checking: Low-hydrogen electrodes must be placed in a rod oven at 120–150°C immediately on receipt. Verify that the rod oven is functioning and at the correct temperature using a calibrated thermometer. Log the receipt date and oven entry date for every batch.
• Proper Storage Condition: Verify storage facilities: rod ovens for low-hydrogen SMAW electrodes; dry sealed containers for TIG wire; humidity-controlled stores for flux; ambient storage for cellulosic electrodes (E6010/E6011). Reject any consumables that show moisture damage, rust on the wire, damaged flux coating, or expired shelf life.

Many material specifications and project quality plans require the material manufacturer to perform non-destructive testing on the finished product before dispatch. This is particularly common for seamless pressure pipe (UT for wall thickness and seam defects under ASTM E213/E309), pressure vessel plates (UT for laminations per ASTM A578), and fittings and flanges (UT, MT, or PT per product standard). At incoming inspection, the QC engineer must verify that all required NDT was actually performed, that the test reports are attached to the MTC package, and that all results are within the acceptance criteria of the applicable standard.

• RT Report Checking: For weld seams in ERW (Electric Resistance Welded) or EFW (Electric Fusion Welded) pipe, or for pressure vessel plate butt welds supplied as sub-assemblies, verify RT or digital radiography reports showing seam weld quality meets the acceptance criteria of the applicable standard.
• UT Report Checking: Verify UT reports for wall thickness and volumetric examination. For P91 pipe, confirm UT was performed per the ASME SA-335 specification supplementary requirements (S3, S5, S10) where specified in the purchase order.
• PT/MT Report Verification: For forgings (flanges, fittings) and castings, verify that PT or MT was performed as required by the product standard. Check that the examination covered the required surfaces and that the report references the applicable acceptance standard.
• Acceptance Criteria Confirmation: Verify that the acceptance criteria cited in each NDE report match the applicable code or specification. A report that simply states “accepted” without referencing a specific acceptance standard is not acceptable — the criterion must be traceable.
• Calibration Validity Checking: Confirm that the NDE equipment calibration records cited in the reports were valid at the time of examination. Calibration certificates for UT equipment, radiographic source activity, and reference blocks must all be within their stated calibration periods.

Material that passes incoming inspection can still be degraded before it reaches the welding station if it is not stored and handled correctly. Storage failures — particularly mixed material storage or unprotected outdoor storage — have caused catastrophic failures in completed equipment because contamination introduced during storage is invisible after fabrication. A robust material storage and preservation system is not an overhead: it is a quality investment that protects all the work done during receiving inspection.

• CS and SS Separate Storage: Carbon steel and stainless steel (and other corrosion-resistant alloys) must be physically separated — different storage bays, separate racks, dedicated lifting equipment for each material family. Iron contamination from carbon steel contact destroys the passive layer of stainless steel and is invisible until corrosion develops in service.
• Wooden or Rubber Support Usage: All pipe and plate must be stored off the ground on wooden dunnage (carbon steel) or rubber/nylon-covered supports (stainless steel and alloys). Direct ground contact causes localised corrosion and contamination, and may make heat number identification difficult.
• Rain and Moisture Protection: Alloy materials, stainless steel, and low-hydrogen welding consumables must be protected from precipitation and condensation. Cover stored material with tarpaulins or store under cover. Moisture-sensitive materials (P91 pipe, SS sheet) should be stored indoors.
• End Cap Protection: All pipe must be stored with factory end caps in place or replacement plastic end caps fitted. Open pipe ends allow moisture, dirt, insects, and debris to enter the bore — contamination that is extremely difficult to clean out before welding and creates porosity and inclusion defects.
• No Direct Ground Contact: This applies to all materials without exception. Even for temporary lay-down during receipt processing, use wooden sleepers or rubber mats. Ground contact introduces chloride contamination on stainless steel and creates crevice corrosion in anaerobic conditions on all alloys.

Material acceptance is a formal decision — not an informal understanding between site personnel. A completed Receiving Inspection Report (RIR) signed by the responsible Quality Control Inspector is required before any material can be tagged “ACCEPTED” and released to the material storage system. Material is accepted only when all of the following six conditions are satisfied without exception. The acceptance decision is binary: all six pass, or the material is placed in quarantine pending resolution.

Rejection is not a negative outcome — it is the system working correctly. The purpose of incoming inspection is to catch non-conforming material before it enters the production system, not after. A rejection at the gate costs a supplier conversation and a replacement delivery. The same non-conformance caught after fabrication costs rework, re-NDE, schedule delay, and potentially vessel rejection or plant shutdown. Material that meets any of the following seven rejection conditions must be immediately physically tagged with a red REJECTED label, segregated from all accepted and uninspected material, and formally dispositioned through a Non-Conformance Report (NCR).

• Wrong Material Grade: The delivered material is a different grade than specified — e.g., SA-106 Gr.A delivered instead of Gr.B, or carbon steel pipe instead of P22. Wrong grade material may have insufficient strength, wrong weldability, or unacceptable service properties. Unconditional rejection — no use-as-is concession is possible for a grade substitution on a pressure part without full engineering re-analysis and code compliance review.
• Missing MTC: The MTC is absent, covers a different heat number, or does not cover the required test values. Material without a valid MTC is untraceable and uncertified — it cannot legally be used as a pressure part under ASME, API, or ISO 3834 systems. No exceptions.
• Heat Number Mismatch: The heat number physically marked on the material does not match the heat number on the MTC. This may indicate a labelling error — or it may indicate material substitution. Either way, the material cannot be accepted until positive material identity is established by the manufacturer or through PMI and mechanical testing. If positive identity cannot be established, reject.
• Failed PMI/NDT: PMI results show the material composition is outside the specified range (e.g., XRF shows Cr content inconsistent with claimed alloy grade), or NDT reports show rejectable defects (laminations, cracks, excessive wall thinning). These are unconditional rejection conditions — material integrity or identity cannot be confirmed.
• Excessive Corrosion: Corrosion or pitting that, when measured, exceeds the maximum pitting depth or minimum remaining wall thickness permitted by the product standard or by the design minimum thickness plus corrosion allowance. Heavy rust that cannot be fully removed to expose a sound metal surface is also a rejection condition for materials to be welded.
• Dimension Out of Tolerance: Any measured dimension (OD, wall thickness, length, bolt hole PCD, flange bore, straightness) that falls outside the tolerance specified on the engineering drawing, PO, or applicable product standard. Dimensional non-conformances may be dispositioned as use-as-is by engineering concession in some cases — but this requires formal engineering review and written concession, not an informal field decision.
• Transport Damage Found: Significant mechanical damage caused during transport — severe dents, crushed or bent pipe ends, deformed flange faces, broken threads, or impact damage to coatings that may have caused underlying material cracking. Minor transport marks that do not affect dimensional or fitness-for-service requirements may be accepted by engineering concession; significant damage is a rejection condition.