Plain Flanges  Manufacturers, Traders, Suppliers

A plate flange is a type of steel flange made from a flat, circular plate that has bolt holes around its perimeter and a central opening matching the pipe size. It is typically welded directly to the pipe (usually with a fillet weld) and used in low-pressure applications.
Key Characteristics:

• Flat structure, usually without a hub or neck
• Available as EN 1092-1 Type 01, DIN 2576, BS4504, or ANSI B16.5 equivalents
• Easy to manufacture and cost-effective
• Commonly used with gaskets for leak-tight sealing

Production Process of Plate Flanges
The manufacturing of plate flanges typically involves a series of mechanical and thermal steps to ensure they meet dimensional, material, and performance standards. Here's an overview of the standard production process:
Step-by-Step Plate Flange Manufacturing Process

• Material used: Carbon steel, stainless steel, or alloy steel plates (commonly S235JR, P250GH, A105, etc.)
• Steel plates are selected based on the required standard (EN, DIN, ANSI, etc.)

Cutting

• CNC flame cutting or plasma cutting is used to cut circular blanks (discs) from the steel plate.
• Outer and inner diameters are cut as per flange dimension specs.

Drilling Bolt Holes

• Bolt holes are drilled using a CNC drilling machine or radial drilling machine.
• Position and size are strictly controlled to match flange standards.

Machining

• Turning (lathe machining):

• Machining the sealing face (raised face or flat face)
• Ensuring parallelism and dimensional accuracy

Additional machining for surface finish, beveling, and facing.
Marking

• Stamping or laser engraving is done to add:

• Standard (e.g., EN1092-1, DIN2576)
• Pressure rating (e.g., PN10, PN16)
• Material grade
• Size
• Heat number and traceability data

Heat Treatment (if required)

• For certain materials or stress-relieving, heat treatment may be applied after machining.

Surface Treatment

• Anti-rust coating: Black paint, zinc plating, or oiling (e.g., with WD-40)
• Can also include electro-galvanizing or epoxy coating if specified

Inspection & Quality Control

• Dimensional check with gauges and calipers
• Visual inspection for defects
• Material test certificate (MTC) verification (EN 10204 3.1 or 3.2 if required)
• Optional: Ultrasonic test (UT) or Magnetic particle test (MT)

Packaging

• Typically bundled with steel straps or packed in wooden pallets/boxes
• Protected with plastic wrapping or rust-proof paper

Applications:

• Water pipelines
• Firefighting systems
• Ventilation ducts
• Low-pressure chemical pipelines
• Irrigation systems
• Common in fabrication, shipbuilding, and agriculture piping systems