Understanding Types of Flanges & ASME Codes

Common Types of Flanges in Piping Systems

• Weld Neck Flange (WN): Designed for high-pressure applications. The tapered hub provides excellent stress distribution, especially for elevated temperature systems.
• Slip-On Flange (SO): Easy to install and weld, commonly used in low-pressure pipelines. Ideal for industrial piping systems in HVAC and water lines.
• Socket Weld Flange (SW): Typically used for small bore piping. Offers strong leakage resistance in high-pressure lines like oil & gas refineries.
• Blind Flange: Used to seal the end of a piping system or vessel. Helps in maintenance and pressure testing operations.
• Threaded Flange (TH): Used where welding is not feasible. Suitable for hazardous zones in petrochemical or chemical industries.
• Lap Joint Flange (LJ): Ideal for systems that require frequent dismantling. Used with stub ends, mainly in systems requiring high corrosion resistance.
• Orifice Flange: Special flange used with flow meters to measure flow rates. Designed as per ASME B16.36 standards.
• Spectacle Blind Flange: A safety device used to isolate a section of the pipeline. Common in shutdown and maintenance procedures.

Referenced ASME Codes for Flanges

• ASME B16.5: Covers pipe flanges and flanged fittings for sizes NPS ½” to 24”. It is the core standard for flange dimensions.
• ASME B16.47: Extends the flange standards for sizes NPS 26” to 60”. Divided into Series A and Series B flanges.
• ASME B31.1: Power Piping Code – used in steam, water, oil, gas systems found in electric power generating stations.
• ASME B31.3: Process Piping Code – governs design of chemical and petroleum plants, essential for industrial applications.
• ASME B16.36: Specifies dimensions for orifice flanges used in metering applications.
• ASME B16.48: Covers the standards for line blanks such as spectacle blinds and figure-8 blanks.
• ASME Section VIII Div. 1: A critical code for pressure vessel design, ensuring structural integrity under pressure conditions.

Importance of Flange Selection in Oil & Gas Engineering

• Improves system integrity under extreme pressure and temperature
• Facilitates maintenance and inspection access points
• Ensures compatibility with international piping codes
• Boosts safety and minimizes leakage in hazardous operations

Common Industries Using ASME Flanges

• Oil & Gas Refineries
• Petrochemical Plants
• Power Generation Units
• Marine & Offshore Engineering
• Pharmaceutical Piping Systems

This detailed guide is designed for both field engineers and fresh graduates looking to enhance their foundational knowledge in industrial piping systems. Understanding the types of flanges and their respective ASME codes is vital for the safe, reliable, and efficient operation of high-pressure systems in oil & gas, petrochemical, and power industries.