Weld Neck Alloy Steel Flange 48 Inch Sch10S To Sch160 ASTM A350 JIS B2220

ASTM A350 LF3 ANSI B16.5/B16.47 Alloy Steel Weld Neck Flanges

Product Information

Standards & Materials: ASTM A1350 Grade LF3

Pipe flanges made from ASTM A350 Grade LF3 are generally used in low temperature services with notch toughness testing requirements. The ASTM A350 Grade LF3 refers to a low-alloy steel designated as “3.5% nickel steel” or “3.5-Ni steel”. The deliberately controlled addition of nickel content can reduce the brittle-ductile transition temperature, whereupon improve its low temperature notch toughness significantly. The flanges may be manufactured in accordance with ASME B16.5 or ASME B16.47, or custom-designed.

Chemical Composition of ASTM A182 F11 Alloy Flanges

Mechanical Properties of ASTM A182 F11 Alloy Flanges

Charpy V-Notch Impact Test

Flanges made from ASTM A350 LF3 Class 1 or Class 2 shall take the Charpy V-notch impact test at a standard testing temperature of -150°F [-101°C]. The specimens shall be prepared in three pieces in size of 10 by 10 mm with the same heat number of the flange. The minimum impact energy required for average of each set of three specimens shall be 15 ft*lbf [20 J] for Class 1 and 20 ft*lbf [27 J] for Class 2; The minimum impact energy required for each one specimen only is 12 ft*lbf [16J] for Class 1 and 15 ft*lbf [20 J] for Class 2.

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.

Long Weld Neck Flanges (LWN)

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.

Manufacturing Process