Flanges

Flange is piping component that functions to link between the pipes with the other components such as valve, strainer, expansion joint, tools instruments, etc.. and to close the flow fluida. Besides these functions in the design of special flange installed for maintenance (break flange). In terms of the strength of the pressure and temperature, is classified in the flange of the rating are: 150 #, 300 #, 400 #, 600, 900 #, 900 #, 1500 #, and # 2500. 

1 Types of Flange 

Welding Neck Flange: Flange type is differentiated from the other flange of the hub and a long taper (taper) with a thick hub gradually decline towards the edges. Hub such as this form of cultivation that gives both the flange of the angle and strength of the dishing. Besides, is also very beneficial to the SEVIS occurred where bending , which repeatedly caused expansion pipe or styles that other variables. Welding neck flange is suitable for service with the heavy conditions (severe condition) 

Slip-on flange: It is preferred by contractors because the price is relatively cheap, installation is easier than with welding neck flange. Welding of pipe with 2 fillet Weld. However, slip-on flange has a limitation on the condition of fatigue more than one third (1 / 3) of the strength of welding neck 

Lap Joint Flange: Flange is a loose type flange where the flange is not linked directly to the pipe. Flange type is usually combined with other components, called Stub-end. Stub-end components that are directly in the weld to the pipe and also functions as a flange surface (flange facing) the surface contact with the other flange. Lap joint flange is very easy for installation and alignment requirement and very economical service to the need for stainless steel flange material can be carbon steel. 

Socket Flange: The flange of the socket, the ends of the pipe is input into the space in the socket and weld on the hub. Flange type is usually used for small size (small Bore). 

Threaded Flange: Flange is installed without the welding which is highly dependent on the thread for sealing. Flange is not suitable for cyclic conditions (often dead-alive) from the thread where leakage can occur. Seal Weld sometimes used to overcome the leakage but will not be considered as a satisfactory solution. 

Blind Flange: Used to close the end of the piping, valve, Nozzle, and equipment. From the point of internal pressure and load bolts, blind flange suffer the most high-voltage compared with other types of flange, in which bending stress occurs at the center of the blind flange. 

2 Surface Flange (Flange facing) 

Flat face: On the steel flange rating applied for 150 # and 300 #. Use to adjust the main cast iron flange rating 125 # and 250 #. Brittle nature of cast iron is always a problem if piping with the steel material with a valve, pump and equipmen of iron. By using the steel flange with a flat face to get the full contact surface cracks on the flange so that the iron can be avoided. 

Face raised: It is the form of the surface of the most commonly used in the steel flange. High surface 1 / 16 "to flange rating 150 # and 300 # and ¼" for a higher rating. Fabricated surface with a small spiral-shaped groove with a goal to bite and hold the gasket. 

Ring Joint: This type of use as a seal ring of steel called a ring joint gasket. Fabricated ring groove on the surface of the flange with the specification that has been set based on international standards. Surface of the ring type joint is very expensive and most appropriate use for the service with a high pressure because internal pressure increases the sealing force of the ring joint. 

Reference Standard 3 

1. ASME B16.5, Pipe Fitting Flange and Flanfed (NPS ½ Through NPS 24) 
2. ASME B16.47, Large Diameter Steel Flange (NPS 26Through NPS 60)

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