What are the standards for flange bolts?

Flange bolt standards form two main families: piping flange bolting (which connects pipe flanges) and hex flange bolts (which have an integrated washer-like head). The correct standard for your project depends entirely on your application and location.

📍 Piping Flange Bolting Standards

These standards specify the bolts used to assemble a flanged connection between pipes, valves, or pressure vessels.

· Common Standards:
  · ASME B16.5: The primary US standard for pipe flanges, fittings, and bolting.
  · EN 1515-4: The European standard for selecting bolting for equipment under the Pressure Equipment Directive.
  · AS 2129: The Australian standard covering flanges and bolting for pressure-retaining equipment.
  · 46 CFR § 56.25-20: US Coast Guard maritime regulation requiring ASME B16.5 compliance.
· What They Cover: Dimensions (diameter, length), number of bolts, material properties (e.g., ASTM grades), and selection criteria based on pressure, temperature, and service conditions.

🔩 Hex Flange Bolt (Structural) Standards

These apply to bolts with a built-in circular flange under the head, often used in automotive and structural applications.

· Common Standards:
  · DIN 6921: A widely recognized German standard for hexagon flange bolts.
  · EN 1662: European standard for small series hexagon bolts with a flange (M5 to M16).
  · JIS B1189: Japanese industrial standard.
  · IFI 111: US Industrial Fasteners Institute standard.
· What They Cover: Dimensions of the bolt and integrated flange, thread pitch, and mechanical property classes (e.g., 8.8, 10.9).

🛠️ How to Select the Right Standard

1. Determine the Application: Is it for a pressurized piping system or a structural/mechanical assembly?
2. Identify Your Governing Region/Industry: For piping, follow the regional code (e.g., ASME in the US, EN in Europe). For machinery, check the equipment manufacturer's specifications.
3. Consult the Specific Standard: The full standard documents contain critical data tables on dimensions, material grades, temperature limits, and installation requirements.

To give more targeted advice, could you share whether you're working with piping systems or mechanical assemblies (like automotive or machinery)? Knowing your region (e.g., North America, EU, Asia-Pacific) would also help narrow down the most relevant standards.