Groove Flange
Long Weld Neck Flange
Flanges
Flanges
Flanges
Flanges
A pipe flange connects piping and components in a piping system by use of bolted connections and gaskets. Most commonly used flanges are weld neck flange, slip on flange, blind flange, socket weld flange, threaded flange and lap joint flange (RTJ Flange). This type of connection in a pipe flange allows for ease of disassembly and separation for repair and regular maintenance. Most common specification for carbon steel and stainless steel flange is ANSI B16.5 / ASME B16.5.
A slip-on flange is connected to the pipe or the fittings by two fillet welds, one executed inside and one outside the cavity of the flange. The bore size of a slip-on flange is larger than the outside diameter of the connecting pipe, as the pipe has to slide inside the flange to be connected by the execution of a fillet weld. Slip-on flanges are also defined Hubbed Flanges and they are easy to recognize due to their slim and compact shape.
A welding neck flange (WN) features a long tapered hub that can be welded with a pipe. This flange type is used, normally, in high-pressure and high/low temperatures applications that require an unrestricted flow of the fluid conveyed by the piping system (the bore of the flange matches with the bore of the pipe). The absence of pressure drops prevents negative effects as turbulence and erosion/corrosion of the metals in the proximity of the flanged joints. The tapered hub allows a smooth distribution of the mechanical stress between the pipe and the weld neck flange and facilitates the execution of radiographic inspections to detect possible leakages and welding defects. The dimension of the flange (NPS and the pipe schedule) shall match the dimension of the connecting pipe.
Long weld neck flanges (LWN) are similar to weld neck flanges, with the exception that the neck (tapered hub) is extended and acts like a boring extension. Long weld neck flanges are generally used on vessels, columns or barrels. These flange types are available also in the heavy barrel (HB) and equal barrel (E) types
Threaded flanges are joined to pipes by screwing the pipe (which has a male thread, generally NPT per ASME B1.20.1) onto the flange, without seam welds (in certain cases, though, small welds are applied to increase the strength of the connection). Threaded flanges are available in sizes up to 4 inches and multiple pressure ratings, however, they are used, mostly, small size piping in low pressure and low-temperature applications, like water and air utility services. Threaded flanges are also a mandatory requirement in explosive areas, such as gas stations and plants, as the execution of welded connections in such environments would be dangerous.
Blind Pipe Flange is used whenever a line must be capped off at a flange. It is good practice to install blind pipe flange at the end od header or at location where future tie-ins are anticipated. Blind pipe flanges are also used extensively for manways, in which case a davit is recommended for ease in handling the unbolted manway cover. Blind pipe flange is specified by ANSI B16.47. We offers blind pipe flange in A105, A105N, SS316, SS304, A20, High Yield & Nickel Alloys.
Socket weld flanges are connected to pipes using a single fillet weld executed on the outer side of the flange (different from the slip-on flange type that requires two welds). According to ASME B31.1, to execute a flanged connection using a socket weld flange, the pipe shall be at first inserted in the socket of the flange until it reaches the bottom of the flange, then it should be lifted by 1.6 mm and finally welded. This gap shall be left to allow proper positioning of the pipe inside the flange socket after the solidification of the weld. Socket Weld Flanges are used for small-size and high-pressure piping that do not transfer highly corrosive fluids. This due to the fact that these flange types are subject to corrosion in the gap area between the end of the pipe and the shoulder of the socket. Their static strength of socket weld flanges is similar to slip-on flanges, but their fatigue strength is higher due to the presence of a single, instead of double, fillet weld.
Ensures a watertight seal where pipes pass through the walls of any structure below groundwater level. Puddle Flanges are used to seal around the outside of pipes that are required to pass through concrete structures. They are installed during construction. Pipes passing through concrete will not bond to the concrete and water can pass along the external surface of the pipe. Puddle Flanges act as a barrier to this flow. The seal is clamped onto the pipes and stops this direct route. The seal body is compressed during the pouring process and should the concrete shrink during curing the rubber relaxes and maintains a seal against this flow path. Puddle Flanges provide an effective solution against water penetration along the external surface of pipes that pass through concrete structures such as tanks, manhole chambers, shafts, floor slabs and basements.
A split flange is a type of flange that can be easily installed on pre-existing piping. It is made up of two interlocking pieces that fit securely together using nuts and bolts or welding it into place. Because it is made of two parts, split flanges are used to reinforce weakened areas of piping, or to add an attachment in places conventional flanges cannot. Split-flange fittings use rubber O-rings to seal joints and contain pressurized fluid. The O-ring sits in a groove on the flange, and then mates with a port's flat surface. The flange is then attached to the port with four mounting bolts. The bolts tighten downward onto the clamps of the flange, thereby eliminating the need for large wrenches to connect the components of large-diameter tubing.
Lap joint flanges feature a flat face and are always used in conjunction with a stub end. Lap joint flanges resemble, in shape, slip-on flanges except for the radius at the crossing of the flange face and the bore to accommodate the flanged portion of the stub end. A lap joint flange slips over the pipe and seats on the back of the stub end and the two are kept together by the pressure of the bolts. The use of lap joint flanges in combination with stub ends is a cost-effective solution for stainless steel or nickel alloy pipelines, as the material of the lap joint flange can be of a lower grade (generally carbon steel) than the material of the stub end (which has to match the pipe grade, as in contact with the conveyed fluid). This arrangement, therefore, has these two advantages: reduces the overall cost of the pipelines flanged joints, as the use of higher grade materials is minimized; bolting operations are simplified, as the lap joint flange can be rotated around the pipe to help with bolts alignment.
ANSI flanges facilitate the alignment of the bolt holes between the two mating flanges, a feature that is helpful in many circumstances, such as the installation of large diameter pipelines, subsea and offshore pipelines, pipe works in shallow waters and similar environments. ANSI flanges suit oil, gas, hydrocarbons, water, chemical and other demanding fluids in petrochemical and water management applications. In the case of a large diameter pipeline, for instance, the pipe is fitted, at one end, with a standard welding neck flange, and with a swivel flange at the other end: by simply rotating the swivel flange on the pipe, the operators can achieve a perfect alignment of the bolt holes in a way easier and faster way
Reducing flanges, otherwise called reducer flanges, have an opposite function than expander flanges seen above, i.e. they are used to decrease the bore of a pipeline. The bore of the run pipe can be safely reduced by only 1 or 2 sizes (otherwise a solution based on the combination of a butt weld reducer and a standard flange has to be used). Reducing flanges are available in most sizes and material grades, and are not generally available from stock. Reducing flanges follow the same considerations in terms of specifications, sizes and material grades as expander flanges.
A ring joint face design has a grooved slot in which a metal ring gasket is inserted to creating a seal with mating flange. The metal ring is available in oval or octagonal shape. Most common material for ring joint gasket is 316 stainless steel which makes it ideal for corrosive applications A ring joint face design has a grooved slot in which a metal ring gasket is inserted to creating a seal with mating flange. The metal ring is available in oval or octagonal shape. Most common material for ring joint gasket is 316 stainless steel which makes it ideal for corrosive applications
Flat flanges have a gasket surface in the same plane as the bolting circle face. It is also known as flat face flange. Applications using flat face flanges are frequently those in which the mating flange or flanged fitting is made from a casting. Flat face flanges are used when the counter-flanges are flat face. This condition occurs mainly on connection to Cast Iron equipment, valves, and specialties. ASME B31.1 says that when connecting flat face cast iron flanges to carbon steel flanges, the raised face on the carbon steel flange must be removed, and that a full face gasket is required.
