High-Quality Carbon Steel and Stainless Steel Flanges for Pipe Connections - China Suppliers & Factory
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 most commonly used flange type in industrial piping systems?
The Weld Neck Flange (WN) is widely regarded as the most reliable choice for critical industrial applications due to its long tapered hub and butt-weld connection, which provides excellent reinforcement under high-pressure and high-temperature conditions.
Q What is the difference between a Raised Face (RF) and a Flat Face (FF) flange?
A Raised Face (RF) flange has its sealing surface elevated above the bolt circle, concentrating bolt load on a smaller gasket area for a tighter seal. A Flat Face (FF) flange has its sealing surface flush with the bolt circle and typically uses a full-face non-metallic gasket, commonly specified when mating with cast iron or non-metallic equipment.
Q When should a Blind Flange be used instead of other flange types?
A Blind Flange is used when you need to completely seal off the end of a pipeline, valve, or pressure vessel opening. It is ideal for pipeline termination, pressure testing operations, and locations designated for future system expansion.
Q What material standard is used for stainless steel flanges?
Stainless steel flanges are manufactured in accordance with ASTM A182, which covers forged or rolled alloy and stainless steel pipe flanges. Common grades include F304, F304L, F316, and F316L, each offering varying levels of corrosion resistance and mechanical performance.
Q What is a Ring-Type Joint (RTJ) flange facing and when is it used?
A Ring-Type Joint (RTJ) facing features a precision-machined groove in the flange face that accepts a solid metal ring gasket (oval or octagonal). This facing type is used in high-pressure and high-temperature applications such as oil and gas wellheads, refineries, and critical process systems where a superior metal-to-metal seal is required.
Q Why would a Lap Joint Flange be chosen for a piping system?
A Lap Joint Flange is ideal for systems that require frequent dismantling for inspection or maintenance, as the backing flange rotates freely around the stub end, making bolt-hole alignment easy. It is also cost-effective in corrosive service environments where expensive alloy materials are needed, since only the stub end—not the backing flange—needs to be made from the costly material.