ASME B16.5 Class 150 Threaded Flange

ASME B16.5 is the American standard for pipe flanges and flange fittings and is highly recognized worldwide. 

       The flange is the part that connects the pipe to the pipe and is connected to the end of the pipe. It is also used in the equipment inlet and outlet flange, for the two equipment before the connection. Flange connection refers to the flange, gasket and bolt connected as a group of detachable sealing structure. Pipe flange refers to the pipe in the pipe flange, it is used in the import and export flange of the equipment. There are holes on the flange, the bolt makes the two flanges tightly connected, and the flange is sealed with a gasket. Because the flange has good comprehensive performance, so it is widely used in chemical industry, construction, water supply, drainage, petroleum, light and heavy industry, freezing, health, water heating, fire, power, aerospace, shipbuilding and other basic engineering.

Pressure Rating

According to ASME B16.5, steel flanges have seven pressure classes: Class150-300-400-600-900-1500-2500.  The pressure level of flanges is very clear. For example, flanges of Class300 can withstand more pressure than those of Class150, because Class300 flanges need to be made of more materials, so they can withstand more pressure.  However, the compression capacity of the flange is affected by many factors.  The pressure rating of the flange is expressed in pounds. There are different ways to express a pressure rating.  For example: 150Lb, 150Lbs, 150# and Class150 mean the same thing.

ASME B16.5 class 150 Flange fittings are available Weld Neck Flange, Slip On Flange, Socket Weld Flange, Threaded Flange, Blind Flange, Lap Joint Flange.

ASME B16.5 Class 150 Flange Connection

       Flange connection is by a pair of flanges, a gasket and a number of bolts and nuts. A flange connection is a detachable connection. The gasket is placed between the sealing surface of the two flanges. After tightening the nut, the specific pressure on the surface of the gasket will deform after reaching a certain value, and fill the uneven part of the sealing surface, so that the connection is tight and not leaking.

Precautions for Flange Connection

• The flange connection shall be kept on the same axis, the center deviation of the bolt hole shall not exceed 5% of the aperture, and the bolt shall be perforated freely.  The connection bolts of the flanges shall have the same specifications, the installation direction shall be the same, and the bolts shall be tightened symmetrically and evenly.

• Do not use oblique washers of different thicknesses to make up for the non-parallelism of the flange.  Do not use double washers.  When large diameter washers need to be spliced, they should not be joined with flat ports, but should be in the form of diagonal lap loops or mazes.  

• For the convenience of flange installation and removal, fastening bolts and flange face shall not be less than 200mm.  

• When tightening bolts, symmetry and intersection should be carried out to ensure uniform force of washers.  

• Bolts and nuts should be coated with molybdenum disulfide, graphite oil or graphite powder for subsequent removal: stainless steel, alloy steel bolts and nuts;  Pipe design temperature below 100℃ or 0℃ and open air facilities, atmospheric corrosive or corrosive media.  

• Metal washers such as copper, aluminum and mild steel should be annealed before installation.  

• Direct buried flange connection is not allowed.  The flange connection of the buried pipeline shall be an inspection well.  If it must be buried, anti-corrosion measures should be taken.

ASME B16.5 Class 150 Flange Specification