| Electrode Type and Application | Confirm whether the product is RP, HP, or UHP grade and whether it is suitable for the customer's electric arc furnace operating conditions. | Technical datasheet, product drawing, furnace current range, and written grade recommendation from the supplier. | High | A lower-priced RP electrode may be unsuitable for high-current or high-power furnace operation. |
| Nominal Dimensions and Tolerance | Nominal diameter: 200 mm; nominal length: 1,800 mm. Verify diameter, length, ovality, end-face flatness, and machining tolerances against the approved drawing. | Dimensional inspection report, calibrated measuring equipment records, approved drawing, and pre-shipment inspection photographs. | High | Excessive dimensional variation can create poor nipple fit, unstable electrical contact, or installation delays. |
| Bulk Density | Typical minimum values depend on grade; approximately 1.60 g/cm³ for RP, 1.66 g/cm³ for HP, and 1.68 g/cm³ or higher for many UHP specifications. | Batch test report, laboratory method, sampling plan, and comparison with the agreed technical specification. | High | Low density may indicate excessive porosity and can contribute to oxidation, higher consumption, and breakage. |
| Electrical Resistivity | Grade-dependent reference ranges commonly used in purchasing specifications are about 8.5–10.5 μΩ·m for RP, 5.5–7.5 μΩ·m for HP, and 4.5–6.5 μΩ·m for UHP. | Batch-specific resistivity report, test temperature, test method, and laboratory traceability. | High | Higher resistivity increases voltage loss and heat generation under the same operating conditions. |
| Flexural Strength | Typical minimum requirements vary by grade and specification; approximately 6.0 MPa for RP, 10.0 MPa for HP, and 10.5 MPa or higher for UHP are commonly referenced levels. | Mechanical test report, test direction, sample preparation details, and batch number. | High | Insufficient strength can result in electrode cracking or breakage during charging, vibration, or connection. |
| Coefficient of Thermal Expansion | Select a low and stable coefficient suitable for the furnace cycle; typical graphite electrode specifications are often below 2.5 × 10⁻⁶/°C, depending on grade and test range. | Thermal expansion test report, test temperature range, and applicable standard or internal method. | High | High or inconsistent thermal expansion can increase thermal stress and joint failure risk. |
| Ash Content | A controlled low ash level is preferred; many industrial graphite electrode specifications set ash at approximately 0.5% maximum, subject to grade and raw-material design. | Chemical analysis report, raw-material declaration, and batch traceability record. | Medium | Elevated ash can introduce impurities into the melt and may indicate inconsistent raw-material control. |
| Nipple and Thread Quality | Confirm nipple compatibility, thread profile, pitch, taper, thread accuracy, contact-surface finish, and tightening requirements. The nipple should be supplied or approved as a matched system. | Thread inspection report, thread gauges, nipple drawing, joint torque guidance, and compatibility statement. | High | Poor thread machining or mismatched nipples may cause hot spots, arcing, looseness, and joint breakage. |
| Raw-Material and Manufacturing Control | Evaluate needle coke or petroleum coke selection, forming, baking, impregnation where applicable, graphitization, machining, and final inspection controls. | Process flow chart, quality-control plan, furnace records, incoming-material inspection, and corrective-action procedure. | High | Inconsistent graphitization or baking can produce internal defects that are not visible during routine visual inspection. |
| Quality Management and Testing Capacity | Prefer a supplier with a documented quality management system, calibrated laboratory equipment, batch traceability, and independent or customer-witnessed inspection capability. | Quality certificate, calibration records, test laboratory list, inspection plan, and sample retention procedure. | High | A certificate alone does not prove product consistency unless it is supported by batch-level data and traceability. |
| Production Capacity and Lead Time | Assess confirmed monthly capacity, reserved production slots, normal lead time, peak-season lead time, and the ability to meet the required quantity of 200 × 1,800 mm electrodes. | Production schedule, capacity statement, recent delivery records, and agreed shipment milestone plan. | High | Quoted capacity may combine several factories or product sizes and may not represent available capacity for the requested specification. |
| Packaging and Export Handling | Use dry, impact-resistant export packaging with protection for machined ends and nipples. Packaging should support container loading, lifting, and moisture control. | Packaging specification, loading photographs, packing list, pallet details, and damage-claim procedure. | Medium | Inadequate end protection or moisture exposure can cause mechanical damage and handling problems before installation. |
| Inspection and Acceptance Terms | Define inspection points before production, during machining, and before shipment. Establish measurable limits for dimensions, physical properties, appearance, and packing condition. | Purchase specification, inspection and test plan, agreed sampling level, nonconformance process, and independent inspection option. | High | Vague acceptance terms make it difficult to reject nonconforming electrodes or resolve performance disputes. |
| Total Cost of Ownership | Compare not only unit price but also electrode consumption, breakage rate, joint performance, freight, packaging, inspection, replacement cost, and furnace downtime. | Full quotation, freight basis, warranty terms, consumption records from comparable furnaces, and trial-order results. | High | The lowest purchase price may lead to higher operating cost if consumption or breakage is excessive. |
| After-Sales Technical Support | Confirm response time, installation guidance, storage instructions, operating recommendations, failure analysis, and availability of replacement units. | Service-level agreement, technical support contacts, troubleshooting guide, and documented corrective-action examples. | Medium | Delayed technical support can extend downtime when breakage or abnormal consumption occurs. |