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FLANGE

• Flanges with rating class designations 150, 300, 400, 600, 900, 1500, and 2500 in sizes NPS 1⁄2 through NPS 24

• ASME B16.5: Pipe Flanges and Flanged Fittings (NPS ≤ 24”)

• ASME B16.47: NPS 26” < Pipe Size < NPS 60”

FLANGE

Flanges used for

• Mate to equipment, vessels, valve, …

• The component or pipe section must be frequently removed for service (periodic cleaning)

• Flanges are normally used for pipe sizes above NPS 1½”.

• The components cannot be serviced in line.

• The components being joined are not capable of being welded.

• Quick field assembly is required.

FLANGE

Marking on Flanges:

• The manufacturer’s name or trademark shall be applied.

• Materials marked with the ASTM specification grade identification symbol (letters and numbers)

• Pressure rating class designation (i.e., 150, 300, 400, 600, 900, 1500, or 2500).

• Conformance standard designation B16 or B16.5

• The NPS designation

• Facing of Flange

• Heat Number

FLANGE

Type of Flanges:

The most used flange types according to ASME B16.5 are:

• Welding Neck flange

• Slip On flange

• Socket Weld flange

• Lap Joint flange

• Threaded flange

• Blind flange.

FLANGE

FLANGEType of Flanges:

FLANGE – Weld Neck Flange

• Welding neck flanges are easy to recognize at the long tapered hub, that goes gradually over to the wall thickness from a pipe or fitting.

• The long tapered hub provides an important reinforcement for use in several applications involving high pressure, sub-zero and / or elevated temperatures.

• The smooth transition from flange thickness to pipe or fitting wall thickness effected by the taper is extremely beneficial, under conditions of repeated bending, caused by line expansion or other variable forces.

• This flange type will be welded to a pipe or fitting with a single full penetration, V weld (Butt weld).


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• Long tapered butt weld hub and the inside diameter of flange matches the inside diameter of the pipe used

• Preferred in an environment with extreme temperature conditions

• Used where we need 100% RT inspection, since joint is butt weld


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FLANGE – Slip-On Flange

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• The connection with the pipe is done with 2 fillet welds, as well at the outside as also at the inside of the flange.

Advantage:

• Most commonly stocked flange due to the fact that one size fits all pipe schedules.

• Fabricators can more easily cut pipe to length for slip-on flanges and their smaller thickness allows for easier alignment of bolting holes


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Disadvantage:

• Internal welds is slightly more subject to corrosion than the butt-weld (0 – 1/16”)

• Strength under internal pressure is 1/3 of corresponding welding neck flange

• Poor resistance to shock and vibration

• A combination of flange and elbow or flange and tee is not possible, because named fittings have not a straight end, that complete slid in the Slip On flange.


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The X measure on the image, are approximately:

Wall thickness of pipe + 3 mm.


• ASME B16.5 code limits their usage for 1500#-2500# (lbs.) applications and they are generally not preferred for high pressure temperature environments.

FLANGE – Socket Welding Flange


• The connection with the pipe is done with 1 fillet weld, at the outside of the flange. But before welding, a space must be created between flange or fitting and pipe.

• Socket Weld flanges were initially developed for use on small-size high pressure piping.

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Advantage:

• These flanges fit up easily and they do not have alignment problems. This makes them widely usable for moderate services.

• The recess on the inside diameter allows for a good fit of the pipe allowing for a smooth flow of liquid

• Work well for smaller sizes and higher pressure temperature conditions.

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Disadvantage:

• The disadvantage of this flange is the right gap, that must be made.

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• In assembly of the joint before welding, the pipe or tube shall be inserted into the socket to the maximum depth and then withdrawn approximately 1/16" (1.6 mm) away from contact between the end of the pipe and the shoulder of the socket. (ASME B31.1 127.3)

• The purpose for the bottoming clearance in a Socket Weld is usually to reduce the residual stress at the root of the weld that could occur during solidification of the weld metal.

FLANGE – Lapped Flanges

• Lap joint flanges have all the same common dimensions as other flanges, however it does not have a raised face, they are used in conjunction with a "Lap Joint Stub End".

• These flanges are nearly identical to a Slip On flange with the exception of

– Radius at the intersection of the flange face

– Bore to accommodate the flanged portion of the Stub End.

• Used with a matching stub-end insert


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• These flanges slip over the pipe, and are not welded

or otherwise fastened to it. Bolting pressure is

transmitted to the gasket by the pressure of the flange

against the back of the pipe lap (Stub End).

Advantage:

• Recommended in applications that require frequent dismantling of the flanges and pipe


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Disadvantage:

• Not recommended in extreme pressure temperature

applications

• Freedom to swivel around the pipe facilitates the lining

up of opposing flange bolt holes.

• Lack of contact with the fluid in the pipe often permits

the use of inexpensive carbon steel flanges with

corrosion resistant pipe.

• In systems which erode or corrode quickly, the flanges

may be recovered for re-use.


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Serrated Surface Finish

FLANGE – Stub End

• A Stub End always will be used with a Lap Joint flange, as a backing flange.

• This flange connections are applied, in low-pressure and non critical applications, and is a cheap method of flanging.

• In a stainless steel pipe system, for example, a carbon steel flange can be applied, because they are not come in contact with the product in the pipe.

• Stub Ends are available in almost all pipe diameters. Dimensions and dimensional tolerances are defined in the ASME B.16.9 standard.

FLANGE – Stub End

FLANGE – Threaded Flange

• Can be attached to the pipe without welding

• Sometimes a seal weld is also used in conjunction with the threaded connection.

• The pipes to be attached are completely recovered during the process of dismantling.

• Ideal for higher pressure and temperature applications for small pipe sizes

• Not recommended for larger loads, especially when subjected to higher torque


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• A threaded flange or fitting is not suitable for a pipe system with thin wall thickness, because cutting thread on a pipe is not possible. Thus, thicker wall thickness must be chosen

• What is thicker?

ASME B31.3 Piping Guide says:Where steel pipe is threaded and used for steam service above 250 psi or for water service above 100 psi with water temperatures above 220° F, the pipe shall be seamless and have a thickness at least equal to schedule 80 of ASME B36.10.


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FLANGE – Blind Flange

• Blind Flanges are manufactured without a bore and used to blank off the ends of piping, Valves and pressure vessel openings.

• Suitable for a wide variety of pressure temperature environments


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Blind Flange with Opening for Flow Out

• Special Flanges are basically identical to standard flanges, but have a number of special features.

• Other Special Types:

– Split Flange

– Reducing Flange

– Long Welding Neck flange

– Orifice Flange

– Weldoflange / Nipoflange

– Expander Flange

– Jack Screw Flange

– Flangeolet

– Spectacle Blind

SPECIAL FLANGES

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SPECIAL FLANGE – Split Flange

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• Split Flange

– Used for reinforcing the weak areas of the piping system.

– They consist of two interlocked parts that contributes to the secure and easy installation of these split flanges on pre existing pipelines.


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SPECIAL FLANGE – Reducing Flange

• Reducing Flanges are suitable for changing line size

• A reducing flange consists of a flange with one specified

diameter having a bore of a different and smaller, diameter.

• Except for the bore and hub dimensions, the flange will have

dimensions of the larger pipe size.


• Specify by size of smaller pipe and outside diameter of flange to be mate

» RED FLG 4”×11”

• Should not be used if abrupt transition of size would create undesirable turbulence as at pump


SPECIAL FLANGE – Long Welding Neck flange


• Long Neck Welding (abbreviated LWN) flanges are similar to a standard Welding Neck flange, but the "Neck" is considerably longer.

• This type is often used as a nozzle for a barrel or column.

SPECIAL FLANGE – Orifice Flange

Provision for outlet

• Orifice Flanges are used with orifice meters for the purpose of measuring the flow rate of either liquids or gases in the respective pipeline.

• Available with raised face or RTJ face

• Same as weld neck and slip-on flanges with extra machining.

• The additional bolts act as a jack to allow the separation of the two flanges to change the orifice plate or for other inspection services.


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Orifice


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SPECIAL FLANGE – Weldoflange / Nipoflange

• The Weldoflange and Nipoflange is a

combination of a Welding Neck flange and a

supposedly Weldolet or Nipolet.

• The 2 components are manufactured in one

piece, and not welded. These flanges are

primarily in Branch connections.

SPECIAL FLANGE – Weldoflange / Nipoflange

SPECIAL FLANGE – Expander Flange

• Reducer + welding neck flange

– Expander Flanges is a Welding Neck pipe flange where the nominal size of the non-flanged end is larger than the nominal size of the flanged end.

• They can be used to change the size of a pipe run. These are usually used to increase the line


• This is an alternative to using a separate reducer and weld neck flange combination.

• The expander flange can be used to connect pipe to pumps, compressors and Valves.


• Flange with jack screw

SPECIAL FLANGE – Jack Screw Flange

• Flageolet

SPECIAL FLANGE – Flageolet

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FLANGE – Spectacle Blind

• Also known as a figure-8 blind

• Spectacle Blinds are generally applied to permanently separating pipes systems, or just to connect with each other. A Spectacle Blind is a steel plate cut into two discs of a certain thickness.

• The two discs are attached to each other by section of steel similar to the nose piece of a pair of glasses. One of the discs is a solid plate, and the other is a ring, whose inside diameter is equal to that of a flange.

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• Fit between two pipe flanges and usually sandwiched between two gaskets

• One end of the blind will have an opening to allow flow through the pipe during operation and the other end is solid to block flow during maintenance

• Equipment is properly and securely blanked off with no possibility of any flow or leakage through a valve during maintenance (Positive Isolation)

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SPECIAL FLANGE – Spectacle Blind

SPECIAL FLANGE – Spade

SPECIAL FLANGE – Spacer

SPECIAL FLANGE – Spade / Spacer

• Spades and Ring Spacers are basically the same as Spectacle Blinds, except that both are not attached to each other.

• So as for the Spectacle Blind already described, maintenance on a pipesystem can be a reason to temporarily replace a Ring Spacer for a Spade. By loosening of all bolts, and half of the bolts temporarily remove, the Spade or Spacer can be placed.

• After replacing the gaskets (new gaskets are to recommend), the bolts can be re-assembled and tightened.

SPECIAL FLANGE – Spade/ Spacer

• Handle is solid for Spade and hole will be there in handle for Spacer for easy identification while in service

• Flange Facing Types

– Flat Face

– Raised Face

– Ring Joint

– Male-Female

– Tongue and Groove

– Groove to Flat

FLANGE – Facing

FLANGE FACING – Flat

• Flat Face

– Mating faces of both flanges are flat

– Gasket may be ring type, or full face, which covers the entire face both inside and outside the bolts

FLANGE FACING – Flat

FLANGE FACING – Raised

• In Pressure Classes 150 and 300 Lbs, the height of raised face is approximately 1.6 mm (1/16 inch) (Fig 1)

• In Pressure Classes 400, 600, 900, 1500 & 2500 Lbs, the height of raised face is approximately 6.4 mm (1/4 inch) (Fig 2)


• Raised Face

– Mating face is flat, but the area inside the bolt holes is raised 1/16" or 1/4"

– Gasket is usually ring type, entirely within bolts


FLANGE FACING – Ring Joint

• Both flange faces have matching flat-bottomed grooves with sides tapered from the vertical at 23º

• Gasket seats on flat section of flange between bore and ring joint groove

• Garlock spiral wound gaskets can replace solid metal ring gaskets

FLANGE FACING – Ring Joint

FLANGE FACING – Tongue and Groove

• Tongue and Groove Facing

– Groove depth is equal to or less than tongue height

– Groove usually not over 1/16" wider than tongue

– Gasket dimensions will match tongue dimensions

FLANGE FACING – Tongue and Groove

• Male-Female Facing

– Depth of female (recessed) face normally equal to or less than height of male (raised) face, to prevent metal-to-metal contact during gasket compression

– Recessed O.D. normally is not more than 1/16" larger than the O.D. of the male face

FLANGE FACING – Male-Female Facing

Advantages and disadvantages of Tongue & Groove and Male & Female flange faces

Advantages:Better sealing properties

Disadvantages:

• Commercial availability and cost.

FLANGE FACING – M&F and T&G

• Groove to Flat Facing

– One flange face is flat, the other is recessed

– For applications requiring accurate control of gasket compression

– Only resilient gaskets are recommended —spiral wound, hollow metal O-ring, pressure-actuated, and metal-jacketed gaskets

FLANGE FACING – Groove to Flat

• A serrated finish, either concentric or spiral, is required with 30 to 55 grooves per inch and a resultant roughness between 125 and 500 micro inches.

• This allows for various grades of surface finish to be made available by flange manufactures for the gasket contact surface of metal flanges.

FLANGE FACING – Finishing

The most used Surfaces

FLANGE FACING – Finishing

FLANGE BOLT HOLES

For a vertical flange face (the flange face in the vertical and the line is horizontal) the bolt holes want to be orientated to straddle the vertical and horizontal centre lines.

FLANGE BOLT HOLES

For a horizontal flange face (the flange face is horizontal and the line is vertical above or vertical down) the bolt holes want to be orientated to straddle the Plant North centre lines.

FLANGE – Dimensions


From ASME B16.5

• Flange Rating Class:

– Pressure/Temperature combinations

– Normally used classes (150, 300, 400, 600, 900, 1500, 2500)

– Flange strength increases with class number

– The material specifications are grouped within Material Group Numbers.

PRESSURE TEMPERATURE RATING

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For remaining group of material, Refer ASME B16.5


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FLANGE – Equipment Nozzle

FLANGES

FLANGED FITTINGS

Bolt type:

• Stud Bolt

– Easily remove if corroded

– Material can be readily made

• Machine bolt

• Has to be strong enough to seat the gasket

BOLT

BOLT - Grade

BOLT – For Flange (ASME Class 150)

TORQUE TIGHTENING

IMPROPER BOLT LENGTH

Improper flange connections - the bolts are too short

flange - seabird groupsseabirdgroups.com/upload/pdf/46894boltedjoints.pdf · reinforcement for use...

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