Purchase specifications for heat-resistant and wear-resistant castings for boiler burners

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Purchase Specifications for Heat- and Wear-Resistant Castings for Boiler Burners (Trial) 1 Scope These purchase specifications establish the technical requirements for the procurement and acceptance of heat- and wear-resistant castings used in boiler burners. 2 Referenced standards: GB/T6414‑1999 – Tolerances for dimensions of castings; GB/T6060.1‑1997 – Comparison specimens for surface roughness·Cast surfaces; GB8492‑1987 – Heat-resistant cast steel parts. 3 Selection of suppliers: 3.1 Manufacturers of heat-resistant and wear-resistant castings must be qualified suppliers approved by our company’s quality management department, and they must possess the necessary production capabilities (see clause 4.2.1 of these specifications). 3.2 The personnel in our company responsible for signing contracts must specify the number of this procurement specification and/or the standards for manufacturing heat-resistant or wear-resistant castings, as well as any additional technical requirements, in the contract. If necessary, the manufacturer shall provide a copy of its corporate standards, which shall be distributed to all relevant departments of our company by the personnel responsible for signing contracts at our company. 4 Technical Requirements 4.1 Chemical Composition 4.1.1 Heat-resistant castings: The chemical composition of heat-resistant castings shall comply with the specifications in Table 1; or, with the approval of our company’s material specialist, the components may be supplied in accordance with the standards set by the manufacturer, and the standard numbers and corresponding grades shall be specified in the contract and technical agreement. 4.1.2 Wear-resistant castings: The chemical composition of wear-resistant castings shall comply with the requirements specified in Table 2; or, with the approval of our company’s material responsibility engineer, it is permissible to supply them in accordance with the chemical composition specifications set by the manufacturer’s own standards, and the standard number and corresponding grade shall be indicated in the contract and technical agreement. 4.2 Mechanical Properties 4.2.1 Heat-resistant Castings Qualified suppliers with the necessary production capacity should be selected based on the temperature requirements specified in the design drawings. The type of casting chosen must have undergone high-temperature performance tests (either high-temperature hardness tests or high-temperature tensile tests), and such tests must be repeated after any adjustments are made to the production equipment or processes. The supplier shall provide the corresponding test data in the quality certificate, and shall meet one of the requirements specified in Table 3. 4.2.2 Wear-resistant castings: Wear-resistant castings for blades with HRc ≥ 50 ； Welded elbows and other components require wear-resistant castings with an HRc value of ≥38; if there are special requirements, these shall be specified separately in the technical agreement. 4.3 Surface Quality and Dimensional Tolerances 4.3.1 The geometric dimensions and dimensional tolerances of heat-resistant and wear-resistant castings must meet the requirements of CT1 grade as specified in GB/T6414-1999, unless otherwise indicated in the drawings. 4.3.2 The inner and outer surfaces of the casting shall be cleaned thoroughly to achieve a smooth surface; the depth of any local depressions shall not exceed 10% of the nominal wall thickness, otherwise welding repairs shall be carried out to level them out. The height of sand swelling on the surface of the casting shall not exceed 2 mm; otherwise, it should be polished. Table 1 Chemical composition (% ) of heat-resistant castings
Material code: C(1) Si(1) Mn(1) P S Cr(2) Ni(2) Mo(1) Re (addition amount) N(1)
NR1: 0.60–1.00 ≤ 1.60 ≤ 2.00 ≤ 0.060 ≤ 0.040; 30.0–36.0, 7.0–10.0… ≤ 0.50, 0.20–0.33
NR2: 0.35–0.55, 1.40–2.50, 11.4… 4.3
3.3 The surface of the castings must be free from cracks, honeycombed pores, and other defects that could affect their usability; if such defects are present, they must be repaired by welding, provided that the area of each welded repair does not exceed 30×30 mm2. 4.3.4 The inner surface of the casting shall be free from defects such as honeycombed pores, sand holes, and inclusions; otherwise, it shall be repaired by welding, provided that the area of each welded repair section does not exceed 30×30 mm2. 4.3.5 The surface roughness of the castings shall comply with the provisions of GB/T6060.1-1997. 3 Inspection and Re-inspection 3.1 The inspection of heat-resistant and wear-resistant castings is generally carried out by the supplier, under the supervision of the purchaser. The supplier may entrust a third party to conduct the inspection. If the supplier entrusts the purchaser’s inspection department to conduct the inspection, then that inspection report can be used as the purchaser’s re-inspection result, and no further re-inspection of that item is required. 3.2 The manufacturer is responsible for providing the samples for re-inspection; these samples should be delivered to our company in a timely manner before the products arrive at the company. The dimensions and cutting locations of the samples shall comply with GB8492-1987. 3.3 Our company conducts re-inspection in accordance with clauses 4.1, 4.2.2, and 4.3. 4 Packaging, marking and quality certificates The packaging, marking and quality certificates shall comply with the provisions of GB8492.