China Carbon Steel and Stainless Steel Flanges for Pipe Connections - Top Suppliers and Factory Quality
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
🔵
Raised Face (RF)
Most common facing type
Most common facing type
⬜
Flat Face (FF)
Flush with bolt circle
Flush with bolt circle
⭕
Ring-Type Joint (RTJ)
Metal ring gasket groove
Metal ring gasket groove
| 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 a lower installation cost and suited for low to medium pressure general piping systems.
Q
When should a Blind Flange be used?
A Blind Flange is a solid flange with no bore, used to seal off the end of a pipe, valve, or pressure vessel opening. It is commonly used for pipeline termination, pressure testing, and at future expansion points where a pipeline may be extended later.
Q
What is the most common flange facing type and what gasket does it use?
The Raised Face (RF) is the most common flange facing type. Its sealing surface is raised above the bolt circle, and it typically uses soft or semi-metallic gaskets to achieve an effective seal.
Q
What material standard is used for stainless steel flanges?
Stainless steel flanges are manufactured to ASTM A182, which covers forged stainless steel piping components. Common grades include F304, F304L, F316, and F316L, each offering different levels of corrosion resistance and temperature performance.
Q
What is a Lap Joint Flange and when is it preferred?
A Lap Joint Flange 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 service applications where expensive alloy materials are used, since only the stub end needs to be made from the costly material.
Q
What is a Ring-Type Joint (RTJ) flange facing and where is it used?
A Ring-Type Joint (RTJ) flange facing has a groove machined into the face that accepts an oval or octagonal metal ring gasket. This design provides an extremely reliable and leak-proof seal, making it suitable for high-pressure and high-temperature applications such as oil and gas processing equipment and wellhead assemblies.