Steel Pipe Flange


Octal offers steel pipe flange (pipeline flange) material in carbon (ASTM A105), Alloy (ASTM A182), and stainless (304L, 316L) flange. In different dimensions and pressure class.

What is steel pipe flange (pipeline flange)

Pipeline flange, also called flange plate. A flange is a parts that connecting pipes in pipeline systems.

Meanwhile, it also applied for connecting between two devices (pipe with valves or with equipment).

Why and how steel flange working for pipeline system

The connection between two pipes can be directly welded together, but it is difficult to connect together without welding. When the connection part have problems, it will be hard to repair. The same problem also happened between pipe and valve connection.

Flange is usually used for connecting pipes or valves, so it can solve the above problems easily.

The flange connection type usually comes with double units, with a gasket and some bolts & nuts to connect each other. (Firstly pipes are welded on the flanges, then valves and other equipment could be installed on flanges.)

When connecting these parts, put gasket in the middle of two flanges, then tightening the flange screws, so the two will be connected together tightly.

As a word,

The flange connection way is convenient, flexible and labor saving.

In case pipeline maintenance, we can remove screws on the flange, take away corresponding pipes or valves. Meanwhile to replace new pipes and valves.

Flange Performances

Flange connection has good strength and sealing, simple structure and low cost. It can be repeatedly disassembled.

Failure mode

The flange connection mainly have leakage problem, and the leakage quantity should be controlled within the allowable range of process and environment.

Flange types

According to the connection way between the pipe and flange, the flange can be divided into the following five basic types:

Slip on SO Flange
Weld Neck WN Flange
Socket Welding Flange
Thread Flange
Blind Flange
DN Flange

According to different pipeline pressure and seal gasket type, there are different sealing surface types for steel pipe flange.

Flat face (FF) pipe flange

It is suitable for less pressure occasion.( PN≤1.6MPa).

Raised face (RF) pipe flange

Sealing surface structure is simple and smooth, and easy for machining. Meanwhile it’s easy to carry out anti-corrosion lining.
However, the contact area is larger, the gasket will become squeeze on both sides easily as pre-loading. Then it will not easy to press.

Male-female (M/F) face flange

It is composed of a convex and concave surface, placing the gasket on the concave. It can prevent the gasket from being extruded. So Male-female face flanges can be applied to the higher pressure occasions.

Tongue-groove (T/G) face steel flange

The touch surface is made of tongue and groove. The gasket is placed in the slot, and it cannot be squeezed.
Comparing RF and MFM, T/G face flange can obtain good sealing effect. The structure and manufacturing of flange are more complex.
It is difficult to replace the gasket in the slot. Tongue and groove seal face is suitable for flammable, explosive, toxic medium and high pressure occasions.

Pipeline Flange material specification

Pipeline Flange are commonly used for carbon steel, alloy steel and stainless steel.
Frequently used material as below:
Carbon steel: STM A105
Alloy steel: ASTM A182 F11, F22, LF2
Stainless steel: 304/L, 316/316L

We supply carbon, alloy, stainless steel pipe flange in different dimensions and pressures

Octal Supply flanges in below ranges:

Range of Sizes: 1/2” to 40”, DN10 to DN3000 of steel flanges
Range of Thickness: SCH5 to SCH160 of steel flanges
Pressure range: Class 150, Class 300, Class 600, Class 900, Class 1500, Class 2500, from PN 0.6Mpa to PN 42Mpa
Type of Ends: Rased Face – RTJ – Flat Face

Steel Flange Material Standards and Grades

Carbon steel flange standards: ASTM A105, ASME A/SA 105, 350LF 2
Stainless steel flanges standards: F304, 304L, 309S, 309H, 310S, 316, 316L, 317, 317L, 321, 321H, 347, and 904L
Alloy steel flange standards: ASTM A182, ASME A182, ASME SA182, ASTM A182 F1, F11, F12, F22, F5, F9, F91
ASME B16.5, ASME B16.47, ASME B16.48, AWWA C207, MSS SP-44,
More standards available in: DIN2573, DIN2577, DIN2630, DIN2631, DIN2632, DIN2533, DIN2634, DIN2635, DIN2636
BS4054, BS3293, EN1092-1, ISO 7005
JIS B2220
HG/T20592, HG/T21516-21518

Steel Flange Applications

Steel Pipe Flange is a kind of pipe fitting to connect two pipes, or pipes and valves, or the equipment. The holes on the flange connected by the steel studs, then use the gasket in the middle for sealing between two flanges. So by the different application and style, there are slip on flange, blind flange, socket weld flange, threaded flange, weld neck flange and reducing flange.

Octal offers steel pipe flange with various kinds and applicable to different industrial areas, Oil & Gas transportaion, Chemical Plant, Power Station, Water Treatment, Refining etc.

ASTM A105, ASTM A182

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