5 Different Types of ANSI Flanges

In case this is the first time you’re hearing the phrase, ANSI flanges simply refers to flanges whose construction meets ANSI (American National Standards Institute) specifications.

Large diameter flanges

These may be either smaller or large diameter flanges and as you would expect, there are a variety of different styles of ANSI flanges used by process engineers across a wide range of industries. Keep reading for brief descriptions of the most common types of ANSI-compliant flanges.

Threaded Flanges

Threaded flanges are a very popular choice, since they can be easily integrated into an assembly without requiring welding. Their threaded design also allows for flanges to be salvaged and reused when an assembly is dismantled, provided the flange is otherwise in good condition.

Standards, Dimensions & Weight of Threaded flanges

Threaded Flanges can be used in very high pressure services and their major advantage is that they can be assembled without welding.

• ASME/ANSI B16.5 Class 150 TH
• ASME/ANSI B16.5 Class 300 TH
• ASME/ANSI B16.5 Class 600 TH
• ASME/ANSI B16.5 Class 900 TH
• DIN 2565 PN6
• DIN 2566 PN10

Slip On Flanges

These flanges are often chosen for applications where no disassembly is anticipated, since these ANSI flanges are welded into place. Despite the fact that welding is required, they are considered to be one of the easier types of flanges to properly fit and align.



Standards, Dimensions & Weight of Slip on flanges

The Slip-on flange has a low hub because the pipe slips into the flange prior to welding.

• ASME/ANSI B16.5 Class 150 SO
• ASME/ANSI B16.5 Class 300 SO
• ASME/ANSI B16.5 Class 600 SO
• ASME/ANSI B16.5 Class 900 SO
• BS 3293 Class 150 SO
• BS 3293 Class 300 SO
• BS 3293 Class 600 SO
• DIN 86029 PN 10

Blind Flanges

A blind flange is most often used in applications, which require stopping up the end of a flanged pipe, pressure vessel or valve. As the name implies, these ANSI flanges do not feature an outlet.



Standards, Dimensions & Weight of Blind flanges

• ASME/ANSI B16.5 Class 150 BL
• ASME/ANSI B16.5 Class 300 BL
• ASME/ANSI B16.5 Class 600 BL
• ASME/ANSI B16.5 Class 900 BL

• ASME/ANSI B16.5 Class 1500 BL
• ASME/ANSI B16.5 Class 2500 BL
• DIN 2527 PN10
• DIN 2527 PN16

• ASME B16.47 Series A/MSS SP-44 Class 150 BL
• ASME B16.47 Series A/MSS SP-44 Class 300 BL
• ASME B16.47 Series A/MSS SP-44 Class 600 BL
• ASME B16.47 Series A/MSS SP-44 Class 900 BL
• ASME B16.47 Series B/API 605 Class 75 BL
• ASME B16.47 Series B/API 605 Class 150 BL
• ASME B16.47 Series B/API 605 Class 300 BL
• ASME B16.47 Series B/API 605 Class 600 BL
• ASME B16.47 Series B/API 605 Class 900 BL

Lap Joint Flanges

These ANSI flanges differ from other styles in that their use requires an end connector; the pipe, valve or other product to be connected with the flange does not come into physical contact with it. However, this type of flange assembly allows for the rotation of the flange and makes it well suited for applications where the assembly may need to be dismantled relatively frequently for cleaning and maintenance.



Standards, Dimensions & Weight of Lap joint flange

Lap joint flange is having two components, a stub end, and a loose backing flange. 

• ASME/ANSI B16.5 Class 150 LJ
• ASME/ANSI B16.5 Class 300 LJ
• ASME/ANSI B16.5 Class 600 LJ
• ASME/ANSI B16.5 Class 900 LJ
• ASME/ANSI B16.5 Class 1500 LJ
• ASME/ANSI B16.5 Class 2500 LJ

TYPES OF ASME/ANSI FLANGES

Forged Flanges are perfectly finished with precision using the latest machinery. Forged flange is the best mechanical properties of a flange product, its raw materials are generally tube, and then after cutting and then continue to beat, to eliminate the ingot in the segregation, loose and other defects.

ASME/ANSI Flange types differ in shape, size range and connection method.

The main types of standard flanges are listed below:

WELD NECK FLANGE

A weld neck flange ("WN") has a long tapered hub that can be welded with a pipe or a fitting and is normally used in high pressure and low or high temperatures applications.

• LONG WELD NECK FLANGE

BLIND FLANGE

Blind flanges do not have a center hole, differently from all other types of flanges seen above, and are used to seal a pipeline, or a valve / pressure vessel and prevent flow. Blind flanges have to withstand remarkable mechanical stress due to system pressure and bolting.

SLIP ON FLANGE

A slip on flange is connected with pipes or fittings by two fillet welds, inside and outside the flange. The diameter of a slip on flange is larger than the diameter of the connected pipe so it can slide on the pipe to fit it smoothly.

THREADED FLANGE

Threaded flanges are joined to pipes by screwed connections, generally without welding activities (in certain cases, though, small welds are applied to increase the strenght of the connection).

SOCKET WELD FLANGE

Socket weld flanges are connected to pipes using a fillet weld which is executed on the outer of the flange. Socket Weld Flanges are used for small-size and high-pressure piping. Their static strength is equal to slip on flanges, but their fatigue strength is stronger than double-welded slip on flanges.

LAP JOINT FLANGE

Lap joint flanges do not have a raised face and are used in conjunction with stub ends . Lap joint flanges are similar to slip on flanges except for the radius at the crossing of the flange face and the bore to accommodate the flanged portion of the stub end.

Price and mechanical properties are higher than ordinary casting flange a grade. The flange is a part that connects the pipe with the pipe and the valve, is connected to the pipe end. It is also used for the flange on the equipment inlet and outlet.