L&T-CHIYODA LIMITED
FLANGES & DESIGN OF
NON STANDARD FLANGE
NON-STANDARD
TABLE OF CONTENTS
•Introduction
•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
g on a flange
g
•Design of Loose Ring Flange
•Design of Weld Neck Flange
FLANGES
Flanges are piping
Fl
i i components
t usedd for
f connecting
ti pipes
i
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 & independent
although interrelated components; the flanges, the gaskets &
the fasteners.
FLANGE TYPES
¾Welding neck flange
¾Slip-on flange
¾Lap joint flange
¾Screwed flange
¾Blind flange
WELDING NECK FLANGE
They have
Th
h
a long,
l
tapered
t
d hub
h b
between the flange ring and the
weld joint. This hub provides a
gradual transition from the flange
ring thickness to the pipe wall
thickness thereby decreasing the
discontinuity and increasing the
strength.
Preferred
P
f
d ffor extreme
t
service
i conditions
diti
suchh as high
hi h temperature,
t
t
high
hi h
pressure, wide fluctuations in pressure and temperature and subzero
temperature.
SLIP-ON
SLIP
ON FLANGE
The use of this type of flange should
be limited to moderate services where
pressure fluctuations,
fl
i
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
alignment
li
t in
i welding
ldi assembly
bl and
d bbecause off it
its llow iinitial
iti l cost.
t
LAP JOINT FLANGE
The 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 required
Its fatigue life is about 10% of the
fatigue life of the weld neck
flanges.
flanges
SCREWED FLANGE
The screwed flanges are
used on pipelines where
welding cannot be carried
out.
BLIND 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)
150 #
250 # (CI)
300 #
400 #
600 #
900 #
1500 #
2500 #
5000 #
10000 #
TYPES OF FLANGE FACE
• Raised Face (RF)
• Tongue
g & Groove (T/G)
(
)
• Male & Female (M/F)
• Ring Type Joint (RTJ)
• Flat Face (FF)
RAISED FACE (RF)
•Theyy are suitable for average
g service conditions. For severe
service involving high pressure, high temperature, thermal
shock, or cyclic operations, this type of flange facing may
not be satisfactory.
satisfactory
•Raised face is 1/16” for 150# & 300# which ¼” for higher
rating.
•Unconfined gasket.
MALE & FEMALE (M/F)
•Male & Female facings have the advantage of confining the gasket
and thereby minimizing the possibility of blowout of the gasket.
gasket
•The two mating flanges are not identical. For this reason these
flanges are not widely used on pipe-line connections as are the
raised
i d face
f
flanges.
fl
•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 usuallyy not over 1/16" wider than tongue
g
•Gasket dimensions will match tongue dimensions
•The flange is less subject to erosive and corrosive contact with
the vessel
•The tongue is more likely to get damaged than the groove.
Therefore the tongue is normally attached to the part which can
b easily
be
il removedd from
f
the
h vessel.
l
RING TYPE JOINT (RTJ)
•This type of facing is used severe service conditions and for
hazardous 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)
They are mainly used for rubber lined equipments for chemical
plants.
plants
They are used for equipments operating under low pressure.
Since the width of the gasket is more, the gasket seating force is
more.
GASKETS
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,
p
, resultingg in a fluid tight
g seal.
Gaskets are made of materials which are not chemically
affected by the fluid in the pipe and which are resistant to
deterioration by temperature.
temperature
PROPERTIES OF IDEAL GASKET
•Be sufficiently deformable to flow into imperfections on the
seating surfaces to create an initial seal.
seal
•Have sufficient strength to resist crushing under the applied
load and defyy rupture
p
under ppressure.
•Chemically resist fluid under all temperatures and pressures.
•Never
Never promote corrosion of the seating surface.
surface
DESIGN OF FLANGE
1-BOLT LOAD
2-HYDROSTATIC END FORCE
3-INTERNAL PRESSURE
1
3
2
OPERATING CONDITION
Required 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 Hp
Wm1 = H + Hp
= 0.785G2P + 2b x 3.14GmP
G = Diameter at the gasket load reaction
b = Effective
ff i gasket
k width
id h
P = Internal pressure
m = Gasket factor ( It is ration of the gasket stress when the
vessel is under internal pressure to the internal pressure )
GASKET SEATING CONDITION
Minimum required bolt load for gasket seating
Wm2 = 3.14bGy
y = gasket-contact surface seating stress
LOOSE RING FLANGE
4.00
70
CAF
650
Select M20 x 24 No. of bolts
Fillet size = 8 mm
BCD C = 650 + 2 x 8 + 2 + 23.81
OD of flange A = 725 + 2 x 23.81
Width of gasket
Gasket OD
Gasket ID
Minimum spacing of bolts
= 725 mm
= 775 mm
= 20 mm
= 690 mm
= 650 mm
= 52.39 mm
b0 = basic gasket seating width = N / 2 = 10 mm
b = effective
ff ti gasket
k t width
idth = b0 when
h b0 < ¼ “
else b = 0.5 ( b0)0.5
G = O.D. of gasket – 2b
20
b0
b
10
7.97
674.06
112.49
2
Maximum bolt spacing = 2d + 6t / ( m+0.5) = 2x20 + 6x40/(2+0.5) = 136 mm
assumedd thk
hk off fl
flange is
i 40 mm
94.9
52.39
29 5
29.5
23 81
23.81
25
23.81
1406.17
1758
1406.17
1758
19185 86
19185.86
1079 98
1079.98
2698.9
5209.22
14268.5
55250.15
16967.48
19.355
HD = hydrostatic end force on the area inside of
flange
HT = difference between the hydrostatic end force
& hydrostatic end force on the area inside of
flange
HP = gasket load
13273.23
37.5
497.745
2698.9
25.46
68.76
1000.5
31.48
31.51
598.032
55250.22
650
1407.72
25.46
11.13
1.19
26.98
41.4
41.4
62
1
FLANGE ROTATION OR FLANGE RIGIDITY
Angular distortion of a flange under the influence of
bolt and reaction forces. Measured with respect
p to the
center 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
109 4MO / Et3ln(K)K
l (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
FLANGE ROTATION OR FLANGE RIGIDITY
J =52.14MOV / LEgo2hoKI
=
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
unit,
i which
hi h shall
h ll be
b calculated
l l d as an integral
i
l flange,
fl
except that
h for
f
simplicity the designer may calculate the construction as a loose type flange
provided none of the following values is exceeded :
go = 5/8”
5/8 ( 16 mm )
B / go = 300
P = 300 psi
Operating temperature = 700 oF