China Suppliers and Factory for Carbon Steel and Stainless Steel Flanges for Reliable Pipe Connections
Common Flange Types
| Flange Type | Description | Typical Applications |
|---|---|---|
| WN Weld Neck Flange | Features a long tapered hub that provides reinforcement; butt-welded to pipe | High-pressure, high-temperature services; critical applications requiring high integrity |
| SO Slip-On Flange | Slides over pipe and welded both inside and outside; lower installation cost | Low to medium pressure applications; general piping systems |
| BL Blind Flange | Solid flange with no bore; used to close pipe ends, valves, or pressure vessel openings | Pipeline termination; pressure testing; future expansion points |
| THDF Threaded Flange | Bore with threads; screws onto threaded pipe without welding | Low-pressure utility services; areas where welding is hazardous |
| SW Socket Weld Flange | Bore with socket counterbore; pipe inserted and fillet welded | Small diameter, high-pressure lines; typically ½" to 4" NPS |
| LJ Lap Joint Flange | Two-part assembly with stub end and backing flange; flange rotates freely | Systems requiring frequent dismantling; corrosive services with expensive materials |
Flange Facing Types
| Face Type | Description | Typical Gasket |
|---|---|---|
| RF Raised Face | Sealing surface raised above bolt circle; most common facing | Soft or semi-metallic gaskets |
| FF Flat Face | Sealing surface flush with bolt circle | Full-face non-metallic gaskets |
| RTJ Ring-Type Joint | Groove machined into face for metal ring gasket | Oval or octagonal metal ring gaskets |
Standard
| Material Type | Standard | Common Grades |
|---|---|---|
| Carbon Steel | ASTM A105 | Standard specification for forged carbon steel piping components |
| Carbon Steel (Low Temp) | ASTM A350 | For low-temperature service; common grade LF2 |
| Stainless Steel | ASTM A182 | Forged stainless steel; common grades F304, F304L, F316, F316L |
| Alloy Steel | ASTM A182 | Chrome-moly grades for high-temperature; F11, F22 |
Wall Thickness Schedules
Frequently Asked Questions
Q
What is the difference between a Weld Neck Flange and a Slip-On Flange?
A Weld Neck Flange (WN) features a long tapered hub and is butt-welded to the pipe, making it ideal for high-pressure and high-temperature critical applications. A Slip-On Flange (SO) slides over the pipe and is welded both inside and outside, offering lower installation costs and suiting low to medium pressure general piping systems.
Q
When should a Blind Flange be used?
A Blind Flange (BL) is a solid flange with no bore, used to close off the ends of pipes, valves, or pressure vessel openings. It is commonly used for pipeline termination, pressure testing, and at future expansion points where additional connections may be needed later.
Q
What are the main flange facing types and how do they differ?
The three main facing types are Raised Face (RF), Flat Face (FF), and Ring-Type Joint (RTJ). RF is the most common, with the sealing surface raised above the bolt circle and using soft or semi-metallic gaskets. FF has the sealing surface flush with the bolt circle and uses full-face non-metallic gaskets. RTJ has a groove machined into the face for oval or octagonal metal ring gaskets, offering superior sealing for high-pressure applications.
Q
What material standards are commonly used for flanges?
Common flange material standards include ASTM A105 for forged carbon steel, ASTM A350 for low-temperature carbon steel (grade LF2), and ASTM A182 for both stainless steel (grades F304, F304L, F316, F316L) and alloy steel (chrome-moly grades F11, F22 for high-temperature service).
Q
What is a Lap Joint Flange and when is it preferred?
A Lap Joint Flange (LJ) is a two-part assembly consisting of a stub end and a backing flange that rotates freely around the stub end. It is preferred in systems that require frequent dismantling for inspection or maintenance, and in corrosive services where expensive alloy materials are needed, as only the stub end needs to be made from the costly material.
Q
In what situations is a Threaded Flange the best choice?
A Threaded Flange (THDF) is best suited for low-pressure utility services and environments where welding is hazardous or not feasible, such as in explosive atmospheres. Since it screws directly onto a threaded pipe without welding, it provides a practical and safe connection method in those specific conditions.