High-Quality Circular Flange Suppliers & Manufacturer

A circular flange provides perfectly axisymmetric stress distribution under hydraulic working pressure and axial thrust. When high hydraulic pressures (such as 35 MPa or higher) are applied, rectangular flanges generate severe bending stress concentrations at the corners and along the narrower edges, which often causes fatigue micro-fractures over extended duty cycles. Circular flanges distribute tensile loads equally across all bolt locations along the Pitch Circle Diameter (PCD), maximizing sealing contact uniformity and preventing uneven O-ring extrusion.

To generate an accurate technical quote within 24 hours, our engineering department requires: Outer Diameter (OD), Bolt Circle Diameter (PCD), number and diameter of through-holes or tapped threads, pilot spigot diameter and depth (with fit tolerances), seal groove geometry (width, depth, and surface roughness), base steel grade (e.g., 42CrMo4, C45, or 316L), and continuous/peak working pressure. Providing 2D drawings (DWG/PDF) or 3D CAD files (STEP/IGES) significantly expedites production planning.

We employ two proven engineering approaches: First, wherever possible for high-stress applications, we supply one-piece integrated forged barrels where the circular flange and cylinder tube are CNC-machined from a single forging, eliminating weld joints entirely. Second, for welded assemblies, we perform strict pre-heating, multi-pass robotic submerged arc or narrow-gap TIG welding with matching low-hydrogen consumables, followed by post-weld stress-relief heat treatment (PWHT) and 100% ultrasonic non-destructive testing (NDT).

Our CNC machining centers are calibrated to produce parts according to ISO, DIN, ANSI/ASME, SAE, and JIS engineering standards. This includes ISO 6H internal and external thread tolerances for cylinder nuts and retaining rings, SAE J518 Code 61/62 four-bolt flange connections, DIN 69872 and JIS B6339 pull studs/retention knobs, and standard ER DIN 6499 collet chuck specifications for precision CNC machining tooling.

Export goods undergo a rigorous multi-tier preservation protocol: All machined sealing faces, bolt circles, and polished rod surfaces are degreased and coated with heavy-duty VCI (Vapor Corrosion Inhibitor) rust-preventative oil, protected with dedicated high-density polyethylene flange protectors, shrink-wrapped in vacuum-sealed anti-static plastic, and secured inside custom-built fumigated solid wooden crates lined with waterproof foam sheets to prevent maritime moisture penetration and shifting during intermodal transit.