China Factory Suppliers of Carbon Steel and Stainless Steel Flanges for Leak-Proof Pipe Connections
Common Flange Types
| Flange Type | Description | Typical Applications |
| Weld Neck Flange WN | Features a long tapered hub that provides reinforcement; butt-welded to pipe | High-pressure, high-temperature services; critical applications requiring high integrity |
| Slip-On Flange SO | Slides over pipe and welded both inside and outside; lower installation cost | Low to medium pressure applications; general piping systems |
| Blind Flange BL | Solid flange with no bore; used to close pipe ends, valves, or pressure vessel openings | Pipeline termination; pressure testing; future expansion points |
| Threaded Flange THDF | Bore with threads; screws onto threaded pipe without welding | Low-pressure utility services; areas where welding is hazardous |
| Socket Weld Flange SW | Bore with socket counterbore; pipe inserted and fillet welded | Small diameter, high-pressure lines; typically ½" to 4" NPS |
| Lap Joint Flange LJ | 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 |
| Raised Face RF | Sealing surface raised above bolt circle; most common facing | Soft or semi-metallic gaskets |
| Flat Face FF | Sealing surface flush with bolt circle | Full-face non-metallic gaskets |
| Ring-Type Joint RTJ | 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 applications where joint integrity is critical. A Slip-On Flange (SO) slides over the pipe and is welded both inside and outside, offering a simpler, lower-cost installation suited for low to medium pressure systems.
Q
Which flange facing type is most commonly used in industrial piping?
The Raised Face (RF) is the most widely used flange facing type in industrial piping. Its sealing surface is raised above the bolt circle, concentrating bolt load pressure on a smaller gasket area, which improves sealing efficiency. It is compatible with both soft and semi-metallic gaskets.
Q
What material standard should I choose for high-temperature flange applications?
For high-temperature service, Alloy Steel flanges conforming to ASTM A182 are recommended. Chrome-moly grades such as F11 and F22 provide excellent strength and oxidation resistance at elevated temperatures. For standard carbon steel applications, ASTM A105 is the typical choice.
Q
When should a Blind Flange be used?
A Blind Flange (BL) is used to seal or close the end of a pipe, valve, or pressure vessel opening. It is commonly used for pipeline termination, pressure testing of systems, and designating future expansion connection points. Since it has no bore, it creates a complete seal at the pipe end.
Q
What type of gasket is required for a Ring-Type Joint (RTJ) flange face?
Ring-Type Joint (RTJ) flanges require metal ring gaskets, either oval or octagonal in cross-section, which seat into a precision-machined groove in the flange face. This design provides an extremely tight metal-to-metal seal, making RTJ flanges well-suited for high-pressure and high-temperature applications.
Q
What are the advantages of a Lap Joint Flange in corrosive service environments?
The Lap Joint Flange (LJ) uses a two-part assembly consisting of a stub end and a backing flange that rotates freely. This design allows the use of expensive corrosion-resistant alloys only for the stub end (which contacts the fluid), while the backing flange can be made from lower-cost carbon steel. It also simplifies alignment during assembly and is ideal for systems that require frequent dismantling for inspection or maintenance.