EN 1092-1 12B DN20 PN10 Carbon Steel EN 10025-2 Necked Flat Welding Flange

Design Features

(1) Optimized Neck Structure
Conical Transition Design: A 7° neck taper (±1° tolerance) enables smooth stress transfer between the pipeline and the flange, reducing the fatigue risk at the weld joint.
Double-sided Welding Groove:
Inner Groove: 45°×2mm (ensuring full penetration).
Outer Groove: R3mm fillet (reducing the stress concentration factor to less than 1.2).
(2) Precision Machining of the Sealing Surface
Geometric Control of the Raised Face (RF):
The height of the raised boss is 2.0mm (+0.5/-0mm), and the diameter is φ42±0.5mm.
The surface roughness Ra≤3.2μm (polishing is required after turning).
The flatness is ≤0.05mm/100mm (superior to the 0.1mm standard of conventional flanges).
(3) Back Machining Features
Exclusive Treatment for Type 12B:
The back turning amount is 0.8mm less than that of Type 11, maintaining higher structural strength.
The back of the bolt hole is chamfered 1×45° (to avoid scratching the gasket during installation).