Stainless Steel Pipe Fittings

Spectacle Blind Flanges By

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Spectacle Blind Flanges By

Separating one part of a line from another requires a spectacle blind Flange, able to switch from closed to open and back again. Bleed rings provide a means to release pressure from the pipe through a controlled opening.

Spectacle Blind Flanges Of Materials used:
Carbon Steel:
ASTM A105, A350 LF1,LF2 CL1/CL2 LF3 CL1/CL2, ASTM A694 F42,F46,F48,F50,F52,F56,F60,F65,F70

Stainless Steel:
ASTM A182 F304/304L, F316/316L, F316H,F316Ti,F321,F44(UNS S31254)

Alloy Steel:
ASTM A182 F1,F5/a,F9,F11,F12,F22,F91

Duplex&Super Duplex Steel:
ASTM A182 F51/UNS S31803,F53/UNS S32750 F55/UNS S3260

Special Alloy Steel:
Monel400,Inconel 600, Inconel 625, Inconel 800, Inconel 825, chrome-moly.

Key Features:

Can be attached to the pipe without welding (sometimes an additional seal weld is used as well) Ideal for higher pressure and temperature applications for small pipe sizes.
Not recommended for larger loads, especially when subjected to higher torque.

Uses of threaded flanges:

•   Threaded flanges can be fitted to pipes of various sizes without welding and this is one chief benefit for which these flanges are highly demanded. 
•   They can be used in extremely high pressure applications, particularly at or near atmospheric temperature, where the necessary post weld heat treatment is not possible. 
•   They are ideal for small diameter piping applications. 
•   They are economical and time saving devices. 
•   These threaded flanges are normally designed for non-cyclic applications. 
•   The flanges are suitable to be used in applications where welding is hazardous.
•   They can be used in highly explosive areas.

These types of flanges are made from plate, and come in 3 different types.

The first and most widely used type are spec blinds – short for spectacle: these are flanges with two equal outside diameter (OD) parts welded together by way of a ‘bridge’. One of the parts also contains an inside diameter (ID), while the other is a blank, or blind. A whole is put at the halfway mark of the bridge. These are also called spectacles, figure 8’s, and figure 8 blanks, because of their resemblance to reading glasses (spectacles) and figure 8’s. These are referred to as ‘Line Blanks’ in the ASME/ANSI standards. 

The second and third types are quite similar: both have longer bridges, referred to as ‘paddles’, which resemble longer handles. One type has only an OD, and so is a blind plate – similar in appearance to a large pizza oven peel. These are referred to as paddle blinds. The other type is exactly the same but comes with an ID as well, enabling flow-through when installed in a piping system. These pieces have holes in the paddle which enables field personnel to determine by sight which piece is installed in a system. These are referred to as paddle spacers, and are often supplied in sets together with the paddle blinds.

All 3 types of these flanges are used in piping systems or pressure vessels where the flow needs to be interrupted from time to time. They are installed between two pipe flanges (as specified above), and by way of a screw inserted into the hole in the bridge or paddle, they are able to rotate or ‘swing’ into and out of position to interrupt or allow the flow, as the user sees fit.

Our spec blind flanges are available with raised, flat, or RTJ faces.

Materials : Nickel Alloy Spectacle Blind Flanges

• ASTM / ASME SB 564 / 160 / 472 
• UNS 10276 (HASTELLOY C 276 Spectacle Blind Flanges)
• UNS 2200 (NICKEL 200 Spectacle Blind Flanges)
• UNS 2201 (NICKEL 201 Spectacle Blind Flanges)
• UNS 4400 (MONEL 400 Spectacle Blind Flanges)
• UNS 8020 (ALLOY 20 Spectacle Blind Flanges)
• UNS 8825 INCONEL 825 Spectacle Blind Flanges)
• UNS 6600 (INCONEL 600 Spectacle Blind Flanges)
• UNS 6601 (INCONEL 601 Spectacle Blind Flanges)
• UNS 6625 (INCONEL 625 Spectacle Blind Flanges)

Copper Alloy Spectacle Blind Flanges
ASTM / ASME SB 61 / 62 / 151 / 152.
C 70600 (CU -NI- 90/10) – Cupro Nickel Spectacle Blind Flanges
C 71500 (CU -NI- 70/30) – Copper Nickel Spectacle Blind Flanges
UNS NO. C 92200, UNS NO. C 83600, UNS NO. UNS NO C 10100,
C 10200, C 10300, C 10800, C 12000, C 12200

Duplex Stainless Steel Spectacle Blind Flanges
ASTM / ASME A/SA 182 UNS F 44, F 45, F51, F 53, F 55, F 60, F 61.

Alloy Steel Spectacle Blind Flanges – AS Spectacle Blind Flanges
ASTM SA 182 F1/F5/F9/F11/F22/F91

Carbon Steel Spectacle Blind Flanges – CS Spectacle Blind Flanges
ASTMA 105 Gr. F42/46/52/56/60/65/70

Low Temperature Carbon Steel Spectacle Blind Flanges – LTCS Spectacle Blind Flanges
A350 LF2/A350 LF3

Value Added Services
• Hot Dip Galvanizing • Electro polish

Test Certificate
Mill Test Certificate as per EN 10204 / 3.1B

Duplex Stainless Steel : Duplex Stainless Steel Spectacle Blind Flanges
– Duplex SS Spectacle Blind Flanges

ASTM A 182 – Spectacle Blind Flanges
F 51 UNS S31803 Spectacle Blind Flanges
S32750 Spectacle Blind Flanges
S31500 Spectacle Blind Flanges
ASTM / ASME A/SA 182 UNS Spectacle Blind Flanges
F 44 Spectacle Blind Flanges
F 45 Spectacle Blind Flanges
F51 Spectacle Blind Flanges
F 53 Spectacle Blind Flanges
F 55 Spectacle Blind Flanges
F 60 Spectacle Blind Flanges
F 61 Spectacle Blind Flanges

Copper Nickel Spectacle Blind Flanges – Cu-Ni Spectacle Blind Flanges

Source: Zhejiang Yaang Pipe Industry Co., Limited (

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