China Suppliers Factory for Carbon Steel and Stainless Steel Flanges for Pipe Connections
Common Flange Types
| Flange Type | Description | Typical Applications |
| WNWeld Neck Flange | Features a long tapered hub that provides reinforcement; butt-welded to pipe | High-pressure, high-temperature services; critical applications requiring high integrity |
| SOSlip-On Flange | Slides over pipe and welded both inside and outside; lower installation cost | Low to medium pressure applications; general piping systems |
| BLBlind Flange | Solid flange with no bore; used to close pipe ends, valves, or pressure vessel openings | Pipeline termination; pressure testing; future expansion points |
| THDFThreaded Flange | Bore with threads; screws onto threaded pipe without welding | Low-pressure utility services; areas where welding is hazardous |
| SWSocket Weld Flange | Bore with socket counterbore; pipe inserted and fillet welded | Small diameter, high-pressure lines; typically ½" to 4" NPS |
| LJLap 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
⬜
Flat Face (FF)
Flush with bolt circle
⭕
Ring-Type Joint (RTJ)
Metal ring gasket groove
| Face Type | Description | Typical Gasket |
| RFRaised Face | Sealing surface raised above bolt circle; most common facing | Soft or semi-metallic gaskets |
| FFFlat Face | Sealing surface flush with bolt circle | Full-face non-metallic gaskets |
| RTJRing-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 most commonly used flange type in industrial piping systems?
The Weld Neck Flange (WN) and Slip-On Flange (SO) are among the most widely used. Weld Neck Flanges are preferred for high-pressure and high-temperature critical applications due to their reinforced tapered hub, while Slip-On Flanges are popular for general piping systems where cost efficiency is a priority.
Q
What is the difference between a Raised Face (RF) and a Flat Face (FF) flange?
A Raised Face (RF) flange has a sealing surface that is elevated above the bolt circle, concentrating the gasket load and making it the most common facing type. A Flat Face (FF) flange has its sealing surface flush with the bolt circle and typically uses a full-face non-metallic gasket, which is often required when connecting to cast iron or other brittle material flanges.
Q
Which ASTM standard applies to stainless steel flanges?
Stainless steel flanges are manufactured in accordance with ASTM A182. This standard covers forged or rolled alloy and stainless steel pipe flanges, with common grades including F304, F304L, F316, and F316L, suitable for a wide range of corrosive and high-temperature service conditions.
Q
When should a Blind Flange be used instead of other flange types?
A Blind Flange (BL) is used when a pipe end, valve, or pressure vessel opening needs to be completely sealed. It is commonly applied for pipeline termination, pressure testing of piping systems, and at locations planned for future expansion. Since it has no bore, it provides a solid, pressure-tight closure.
Q
What are the advantages of a Lap Joint Flange in corrosive service applications?
Lap Joint Flanges consist of two parts — a stub end and a backing flange — where the backing flange rotates freely around the stub end. This design is highly advantageous in corrosive service because only the stub end (which contacts the fluid) needs to be made from expensive corrosion-resistant alloys, while the backing flange can be made from lower-cost carbon steel. It also facilitates easy alignment and frequent dismantling.
Q
What type of gasket is used with a Ring-Type Joint (RTJ) flange facing?
Ring-Type Joint (RTJ) flange facings use metal ring gaskets, either oval or octagonal in cross-section. These gaskets seat into a precisely machined groove on the flange face and provide an extremely reliable metal-to-metal seal, making RTJ flanges ideal for high-pressure and high-temperature applications such as those found in oil and gas production and refining.