AISI 4130 Ring Type Joint Flanges

Pipe flanges that are made to standards called out by ASME B16.5 or ASME B16.47, and MSS SP-44. They are typically made from forged materials and have machined surfaces. 

ASME B16.5 refers to nominal pipe sizes (NPS) from ½" to 24". B16.47 covers NPSs from 26" to 60". Each specification further delineates flanges into pressure classes: 150, 300, 400, 600, 900, 1500 and 2500 for B16.5, and B16.47 delineates its flanges into pressure classes 75, 150, 300, 400, 600, 900. 

However these classes do not correspond to maximum pressures in psi. Instead, the maximum pressure depends on the material of the flange and the temperature. For example, the maximum pressure for a Class 150 flange is 285 psi, and for a Class 300 Flange it is 740 psi (both are for ASTM A105 Carbon Steel and temperatures below 100F).
Flange dimensions are determined by the pipe size and the pressure class required for the application. Flanges are standardized according publications from organizations like ASME, MSS, API and others.

ASME/ANSI B16.5flange provides
Flange Type :
Thread Flange
Blind Flange
Slip On Flange
Weld Neck Flange
Spectacle Blind Flange
Spacer & Spade
LWN Flange
Orifice Flange
flange dimensions for pipes ranging 1/2" to 24" - in classes ranging 150 to 2500.
Steel Pipe Dimensons - Schedule 40
Steel Pipe Dimensions - Schedule 80

We have good stock for flange below :

Spectacle Blind Flange

Thread Flange

Blind Flange

Slip On Flange

Wn Flange

Asme B16.5 flange

Spectacle Blind Flange
Stainless Steel Lap Joint Flange
Stainless Steel Plate Flanges
Stainless Steel Threaded Flange
Raised Face Threaded Flange
Stainless Steel Blind Flange
Raised Face Blind Flange
Slip On Pipe Flange