Large Flange CNC Machining: Manufacturing and Quality Guide
Flange Types and Materials
Large flange manufacturing produces weld neck, slip-on, blind and lap joint flanges. Materials: carbon steel A105 for standard service, 316/316L for corrosive, alloy F11/F22 for high temperature. Sizes per ASME B16.5 (to 24) and B16.47 (larger).
Pressure classes: 150# to 2,500#. Facing: raised face, flat face, ring joint according to service.
| Type | Material | Standard | Pressure Class |
|---|---|---|---|
| Weld Neck | A105 steel | ASME B16.5 | 150-2500# |
| Slip-On | A105 steel | ASME B16.5 | 150-600# |
| Blind | A105 steel | ASME B16.5 | 150-2500# |
| Lap Joint | 316L SS | ASME B16.5 | 150-600# |
CNC Machining
Vertical lathe for facing, boring and OD turning. Heavy-duty horizontal boring mill for bolt holes. Gasket surface finish Ra 1.6-3.2. Bolt hole PCD tolerance ±0.5mm. Bore tolerance H7 for weld neck preparation.
Large machines with 2-4m capacity. In-process probing for critical dimensions. Temperature compensation for accuracy.
| Operation | Machine | Tolerance |
|---|---|---|
| Face Seal Surface | VTL | IT8 |
| Bore ID | VTL/Boring | IT7 |
| Bolt Holes | Radial drill | ±0.5mm PCD |
| OD Turn | VTL | IT9 |
Quality and Testing
Hydrostatic test: 1.5x rated pressure, 30 min hold. MPI for weld neck. Hardness, chemistry and tensile per material spec. Dimensional inspection per ANSI standards. Marking per MSS SP-25.
Surface finish inspection with comparator. Thread inspection for stud bolt holes. Material cert traceability.
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