L&T-CHIYODA LIMITED

FLANGES & DESIGN OF NON STANDARD FLANGENON-STANDARD FLANGE

TABLE OF CONTENTSTABLE OF CONTENTS

•Introduction•Type of Flanges•Type of Flanges•Classification of flanges based on Pressure temperature rating•Type of Flange faces•Gasket and their properties•Bolting data as per TEMA•Forces acting on a flangeg g•Design of Loose Ring Flange•Design of Weld Neck Flange

FLANGES

Fl i i t d f ti iFlanges are piping components used for connecting pipes which needs dismantling & periodic maintenance, other piping components like valves, specialties, instrument items like orifice, flow meters etc on to the pipes.

A flanged joint is composed of three separate & independentA flanged joint is composed of three separate & independent although interrelated components; the flanges, the gaskets & the fasteners.

FLANGE TYPESFLANGE TYPES

Welding neck flange

Slip-on flange

Lap joint flange

Screwed flange

Blind flangeBlind flange

WELDING NECK FLANGEWELDING NECK FLANGE

Th h l t d h bThey have a long, tapered hub between the flange ring and the weld joint. This hub provides a gradual transition from the flangegradual transition from the flange ring thickness to the pipe wall thickness thereby decreasing the discontinuity and increasing thediscontinuity and increasing the strength.

P f d f t i diti h hi h t t hi hPreferred for extreme service conditions such as high temperature, high pressure, wide fluctuations in pressure and temperature and subzero temperature.

SLIP-ON FLANGESLIP ON FLANGEThe use of this type of flange should be limited to moderate services where

fl ipressure fluctuations, temperature fluctuations, vibrations and shock are not expected to be severe.

The strength of this flange is around 2/3 times to that of weld neck flange.

The fatigue life of this type of flange is 1/3 that of a weld neck flange.

The slip-on type of flange is widely used because of its greater ease of li t i ldi bl d b f it l i iti l talignment in welding assembly and because of its low initial cost.

LAP JOINT FLANGE

The principal advantage of theseThe principal advantage of these flanges is that the bolt holes are easily aligned, and this simplifies the erection of the vessel.

They are also useful in cases where frequent dismantling for cleaning or inspection is requiredinspection is required

Its fatigue life is about 10% of the fatigue life of the weld neck flangesflanges.

SCREWED FLANGE

The screwed flanges are used on pipelines where welding cannot be carried out.out.

BLIND FLANGEBLIND FLANGE

The blind flanges are used to close the ends which need to be reopened later.

FLANGE CLASSIFICATION BASED ON PRESSURE TEMPERATURE RATING

• 125 # (CI)125 # (CI)• 150 #• 250 # (CI)• 300 #• 400 #• 600 #• 600 #• 900 #• 1500 #• 2500 #• 5000 #• 10000 #• 10000 #

TYPES OF FLANGE FACE

• Raised Face (RF)• Tongue & Groove (T/G)

• Ring Type Joint (RTJ)

g ( )• Male & Female (M/F)• Ring Type Joint (RTJ)• Flat Face (FF)

RAISED FACE (RF)RAISED FACE (RF)

•They are suitable for average service conditions. For severe y gservice involving high pressure, high temperature, thermal shock, or cyclic operations, this type of flange facing may not be satisfactorynot be satisfactory.•Raised face is 1/16” for 150# & 300# which ¼” for higher rating.•Unconfined gasket.

MALE & FEMALE (M/F)MALE & FEMALE (M/F)•Male & Female facings have the advantage of confining the gasket and thereby minimizing the possibility of blowout of the gasketand thereby minimizing the possibility of blowout of the gasket.•The two mating flanges are not identical. For this reason these flanges are not widely used on pipe-line connections as are the

i d f flraised face flanges.•They offer no protection against forcing the gasket into the vessel.•Recessed O.D. normally is not more than 1/16" larger than the O.D. of the male face.•Joint must be pried apart for disassembly

TONGUE & GROOVE (T/G)( )

•Fully Confined Gasket•Groove usually not over 1/16" wider than tongue y g•Gasket dimensions will match tongue dimensions •The flange is less subject to erosive and corrosive contact with the vesselthe vessel•The tongue is more likely to get damaged than the groove. Therefore the tongue is normally attached to the part which can b il d f h lbe easily removed from the vessel.

RING TYPE JOINT (RTJ)RING TYPE JOINT (RTJ)

•This type of facing is used severe service conditions and for hazardous fluidshazardous fluids .•It is used in petroleum, petrochemical and high-pressure equipments.•Close tolerances and high standards of machining are required , as a result this type of flange is seldom used for diameters larger than 36”.•The main disadvantage of this type of facing is the high cost of manufacturing. It is the most expensive face.

FLAT FACE (FF)FLAT FACE (FF)

They are mainly used for rubber lined equipments for chemical plantsplants. They are used for equipments operating under low pressure.Since the width of the gasket is more, the gasket seating force is more.

GASKETSGASKETS

Gaskets are relatively softer material which are inserted between flanges to avoid leakage. Tightening the bolts causes the gasket material to flow into the minor machining imperfections, resulting in a fluid tight seal.p , g g

Gaskets are made of materials which are not chemically affected by the fluid in the pipe and which are resistant to deterioration by temperaturedeterioration by temperature.

PROPERTIES OF IDEAL GASKET

•Be sufficiently deformable to flow into imperfections on the seating surfaces to create an initial sealseating surfaces to create an initial seal.

•Have sufficient strength to resist crushing under the applied load and defy rupture under pressure.y p p

•Chemically resist fluid under all temperatures and pressures.

•Never promote corrosion of the seating surfaceNever promote corrosion of the seating surface.

DESIGN OF FLANGE

1-BOLT LOAD2-HYDROSTATIC END FORCE

1

3-INTERNAL PRESSURE

3

2

OPERATING CONDITIONRequired bolt load for the operating conditions Wm1 should be sufficient enough to resist the hydrostatic end force H and also maintain the gasket joint-contact surface load HpWm1 = H + Hp

= 0.785G2P + 2b x 3.14GmPG = Diameter at the gasket load reactionb ff i k id hb = Effective gasket widthP = Internal pressurem = Gasket factor ( It is ration of the gasket stress when the vessel is under internal pressure to the internal pressure )vessel is under internal pressure to the internal pressure )

GASKET SEATING CONDITIONMinimum required bolt load for gasket seatingMinimum required bolt load for gasket seating Wm2 = 3.14bGyy = gasket-contact surface seating stress

LOOSE RING FLANGE

4.00

70 CAF

650650

Select M20 x 24 No. of boltsFillet size = 8 mmBCD C = 650 + 2 x 8 + 2 + 23.81 = 725 mmBCD C 650 2 x 8 2 23.81 725 mmOD of flange A = 725 + 2 x 23.81 = 775 mmWidth of gasket = 20 mmGasket OD = 690 mmGasket ID = 650 mmGasket ID 650 mmMinimum spacing of bolts = 52.39 mm

20b0 = basic gasket seating width = N / 2 = 10 mmb ff ti k t idth b0 h b0 ¼ “20

10

674.06

7.97

b = effective gasket width = b0 when b0 < ¼ “else b = 0.5 ( b0)0.5

G = O.D. of gasket – 2bb

b0

Maximum bolt spacing = 2d + 6t / ( m+0.5) = 2x20 + 6x40/(2+0.5) = 136 mmd hk f fl i

112.49

2

94.9

29 5

52.39

23 81

assumed thk of flange is 40 mm

29.5

25

23.81

23.81

1406.17

1406.17

1758

1758

19185 86 1079 9819185.86

14268.5

2698.9

55250.15

5209.22

1079.98

16967.48

19.355

HD = hydrostatic end force on the area inside of flangeHT = difference between the hydrostatic end force & hydrostatic end force on the area inside of& hydrostatic end force on the area inside of flangeHP = gasket load

13273.23 37.5 497.745

2698.9

1000.5

25.46

31.48 31.51

68.76

598.032

1.19

11.1365055250.22 25.46 1407.72

62

1

41.4

41.426.98

1

FLANGE ROTATION OR FLANGE RIGIDITY

Angular distortion of a flange under the influence of bolt and reaction forces. Measured with respect to the pcenter of the cross section of the flange.

Flanges have been designed based on allowable stress limits alone may not be sufficiently rigid enough to control leakage.

J 109 4M / Et3l (K)KJ =109.4MO / Et3ln(K)KL= 109.4 x 1407720 / 19475.03 x 623 In(1.19) x 0.2= 0.953

WELD NECK FLANGE

343.00

fgg

fgg

fgg

fgg

fgg

FLANGE ROTATION OR FLANGE RIGIDITYJ =52.14MOV / LEgo

2hoKIO o o= 52.14 x 19657140 x 0.3375

10.44 x 18280.25 x 102 x 129.23 x 0.3= 0.46

OPTIONAL TYPE FLANGE

This type covers designs where the attachment of the flange to the nozzle neck vessel or pipe wall is such that the assembly is considered to act as a

i hi h h ll b l l d i l fl h funit, which shall be calculated as an integral flange, except that for simplicity the designer may calculate the construction as a loose type flange provided none of the following values is exceeded :g = 5/8” ( 16 mm )go = 5/8 ( 16 mm )B / go = 300P = 300 psiOperating temperature = 700 oFOperating temperature 700 F