Research: What Are the Types of Flanges in Piping Systems?
Flanges are critical components in industrial piping systems, allowing for easy connection, disassembly, and maintenance of pipes, valves, pumps, and other equipment. Understanding the types of flanges, their suitable applications, and relevant standards is essential for engineers, buyers, and system designers in industries such as oil & gas, chemical processing, HVAC, power plants, and water treatment.
🔍 What Is a Pipe Flange?
A flange is a mechanical device used to join pipes, valves, pumps, and other equipment. It typically consists of a disc or ring that provides a method for bolting components together in a secure and leak-proof manner.
🔧 Common Types of Flanges and Their Applications
| Flange Type | Description | Applications | Keywords |
|---|---|---|---|
| Weld Neck Flange (WN) | Long tapered hub, butt-welded to pipe for high-pressure service | High-pressure, high-temp pipelines | weld neck flange pressure rating |
| Slip-On Flange (SO) | Slides over pipe, fillet welded on both sides | Low-pressure, low-cost systems | slip on flange vs weld neck |
| Socket Weld Flange | Pipe is inserted into socket and fillet welded | Small diameter, high-integrity systems | socket weld flange usage |
| Lap Joint Flange (LJ) | Used with a stub end; allows easy alignment and rotation | Systems requiring frequent dismantling | lap joint flange for stainless pipe |
| Threaded Flange (TH) | Screwed onto pipe with external threads | Non-welded systems, small-diameter piping | threaded flange vs socket weld |
| Blind Flange (BL) | No bore; used to close the end of a pipe | Line isolation, pressure testing | blind flange pressure rating |
| Orifice Flange | Used with flow measurement instruments (e.g., orifice plates) | Flow monitoring in oil & gas | orifice flange assembly |
| Long Weld Neck Flange | Similar to WN but with an extended neck | Vessels, tanks, heat exchangers | long weld neck flange dimensions |
🌡️ Flange Selection Based on Working Conditions
| Condition | Recommended Flange Type |
|---|---|
| High pressure / High temperature | Weld Neck, Long Weld Neck |
| Frequent disassembly required | Lap Joint, Slip-On |
| Corrosive media | Use stainless steel or alloy flanges with proper lining (e.g., PTFE) |
| Compact space / Threaded lines | Threaded flange |
| Dead-end piping or pressure testing | Blind flange |
📏 Common Flange Standards
To ensure compatibility and pressure integrity, flange dimensions follow international standards:
| Standard | Region / Organization | Typical Pressure Classes | Search Keywords |
|---|---|---|---|
| ASME B16.5 | USA / ANSI | Class 150, 300, 600, 900, 1500, 2500 | ASME flange chart, ANSI flange dimensions |
| EN 1092-1 | Europe | PN6, PN10, PN16, PN25, PN40 | EN flange type 01, 05, 11, 21 |
| JIS B2220 | Japan | 5K, 10K, 16K, 20K | JIS flange standards |
| GOST / DIN | Russia / Germany | PN10, PN16, PN25, PN40 | DIN flange dimensions chart |
| API 605 / 6A | Oil & gas pipelines | High-pressure equipment | API flange for oil and gas |
When sourcing flanged valves — such as flanged butterfly valves, flanged gate valves, or flanged ball valves — always ensure:
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Flange face type matches (e.g., raised face, flat face, RTJ)
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Bolt circle (BC), pressure class, and material grade are compatible
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Flange standard aligns with piping system design
🏷️ Seallon Tip: Precision-Matched Flanged Valves
Seallon’s butterfly valve Universal Series (e.g., SB71) are available with standardized flanges compatible with:
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ASME Class 150
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EN PN10 / PN16
JIS 5K / 10K
BS TABLE D / TABLE E
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Options for RF, FF, or RTJ flange faces
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High-precision machining ensures leak-tight connections
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Custom flange drilling or coatings available on request
Perfect for: Steam lines, boiler systems, seawater pipelines, fire protection loops, chemical tanks.
