Corrosion Resistant Flat Face Weld Neck Flange ANSI B16.5/B16.47 Alloy Steel

ASTM A182 F11 ANSI B16.5/B16.47 Alloy Steel Weld Neck Flanges

Product Information

Standards & Materials: ASTM A182 F11

The ASME B16.5 and ASME B16.47 flanges can be made from ASTM A182 Gr.F11 Class 2 steels by a forging process. They may be furnished in various flange types covering welding neck, slip on, and blind, etc. Both ASME B16.5 and ASME B16.47 have endorsed the use of ASTM A182 Gr. F11 Class 2 in Material Group 1.9, which has the nominal chemical composition of 1.25Cr-0.5Mo-Si. Flanges made from this steel are generally used with maximum working temperature limit of 590°C [1100°F]. It is permissible but not recommended for prolonged use above 590°C [1100°F].

Chemical Composition of ASTM A182 F11 Alloy Flanges

Mechanical Properties of ASTM A182 F11 Alloy Flanges

Flange Type: Weld Neck (WN)

A weld neck flange, also called a tapered hub flange or high-hub flange, is a kind of flange that can relocate stress to the pipes, ensuring a decrease in high-stress concentration at the bottom of the flange. There are two welding neck flanges designs – the first type is used with pipes while the second, longer type cannot be used with pipes but with a process plant. The weld neck flange comprises of a round fitting that extends beyond the rim of the circumference. These flanges, typically manufactured from forging, are actually welded to pipes.

This flange type is regarded as high-hub flanges, which were created so stress could be transferred to the pipe and decreasing the stress concentration at the bottom of the flange.

The long welding neck flange is mainly applied to the construction of pressure vessel functioning as a nozzle (such as a thermowell nozzle). To attach a common welding neck flange to a pressure vessel, a piece of pipe is required with additional welding. A LWN flange on the other hand attaches directly to the vessel, hence, it can be viewed as an integrally reinforced nozzle. It avoids making a weld seam at pipe to flange and provides self-reinforcement.

Reducing Weld Neck Flange

It is also called reducing welding neck flange, because the flange neck has a reducing diameter that to weld to a smaller diameter pipe.

The reducing weld neck flange is used to make a reduction in the diameter of the pipe. A reducing flanged joint consists of a reducing flange and a standard flange, functioning like a reducer fitting. As illustrated in Figure-1, the larger end of reducing flange A, which is in contact with the standard flange B, is known as “the size from which the reduction is being made”; the smaller end of the reducing flange A, which will be welded to a pipe, is known as “the size to which the reduction is being made”. The flow should travel from the smaller size to the larger. If the flow direction were reversed, severe turbulence could develop.

In order to make a reduction in the pipe line with two standard welding neck flanges, an additional reducer shall be used as illustrated in Figure-2. The overall length of this configuration is 2L+H, which is much longer than L+M of a reducing flanged joint as illustrated in Figure-1. It means that the use of reducing flanges can effectively save space in crowed situation. In fact, the reducing flange is most frequently used in installations with limited space.

Pressure-Temperature Ratings

Both ASME B16.5 and ASME B16.47 has stipulated pressure-temperature ratings for ASTM A182 F5 steel, which are maximum allowable working gauge pressures in psi units at the temperature in degrees Fahrenheit. The data sheet is divided by Classes: ASME B16.5 flanges are available in Class 150, 300, 400, 600, 900, 1500, 2500; ASME B16.47 Series A are available in Classes 150, 300, 400, 600, 900; and ASME B16.47 Series B are available in Classes 75, 150, 300, 400, 600, 900.

Manufacturing Process