Gasket Tornillos
-
Upload
fernando-sanabria -
Category
Documents
-
view
221 -
download
1
Transcript of Gasket Tornillos
-
7/29/2019 Gasket Tornillos
1/12
-
7/29/2019 Gasket Tornillos
2/12
-
7/29/2019 Gasket Tornillos
3/12
PART UG GENERAL REQUIREMENTS Fig. UG-34
ts ts
ts
ts t
ts
tf
d d
d
Yt
t tt
C= 0.17 or
C= 0.10(a)
C= 0.13
(d)
C= 0.33m
Cmin. = 0.20
(i)
C= 0.3[Use Eq. (2) or (5)]
(j)
C= 0.3[Use Eq. (2) or (5)]
(k)
C= 0.33
(h)
C= 0.30
C= 0.25
C= 0.75
C= 0.33 C= 0.33
C= 0.30 C= 0.30
(m)
(p)
(q)
(r) (s)
(n) (o)
(e) (f) (g)
C= 0.33mCmin. = 0.20
(b-2)
Continuationof shelloptional
Sketches (e), (f), and (g) circular covers, C= 0.33m, Cmin. = 0.20
See Fig. UW-13.2 sketches (a) to (g),inclusive, for details of welded joint
tsnot less than 1.25tr
See Fig. UW-13.2 sketches (a) to (g),inclusive, for details of outsidewelded joint
Threaded ring
30 deg min.45 deg max.
Seal weld
When pipe threads are
used, see Table UG-43
0.8tsmin.
3/4tmin.
ormin. t1 = tor tswhichever
is greater
Retainingring
rmin. = 0.375 in. (10 mm)for ts 1
1/2 in. (38 mm)
rmin. = 0.25tsfor ts 1
1/2 in. (38 mm)
but need not be greaterthan 3/4 in. (19 mm)
C= 0.17
(b-1)
Center of weld
Taper
Tangentline
r= 3tmin.
d
Y
tsts
t
ts ts
ts
t1
d
t
hG
ttddd
d
d d d
hG
d
Projectionbeyond weldis optional
Bevel is optional
45 deg max.
tw= 2trmin. nor less than 1.2tsbut need not be greater than t
tfmin. = 2ts
0.7ts0.7ts0.7ts
0.7ts
0.7ts
t
C= 0.30
C= 0.20 or 0.13(c)
Center of lap
Tangentline
r= 3tmin.
r= 3tfmin.
r= 1/4tmin.
t
t t t
ddd
dd
d
ttt
t
t
t
t
t
FIG. UG-34 SOME ACCEPTABLE TYPES OF UNSTAYED FLAT HEADS AND COVERS 01
The Above Illustrations Are Diagrammatic Only. Other Designs That Meet
the Requirements of UG-34 Are Acceptable.
39
-
7/29/2019 Gasket Tornillos
4/12
-
7/29/2019 Gasket Tornillos
5/12
-
7/29/2019 Gasket Tornillos
6/12
-
7/29/2019 Gasket Tornillos
7/12
-
7/29/2019 Gasket Tornillos
8/12
-
7/29/2019 Gasket Tornillos
9/12
4.3.6-2 4.3 SHELL-AND- TUBE DESIGN CODES 4.3.6 TEMA Type AJS
(c) Order calculation
For a heat exchanger with a floating tubesheet, assuming
that the tube layout is known, it is advisable to design
the floating-head cover first. This will confirm if there
is sufficient space within the shell and outer tube limit
circle diameter to fit the required gasket. The shell,
channel, and shell cover cylinder thicknesses may then
be calculated. The remaining components may then be
designed at random. For this design, the selected tube
wall thickness is checked, followed by the design of the
flanges and end enclosures. The tubesheets and nozzles
calculations complete the calculations for components
subjected to pressure. Finally, the dimensions of the
nonpressure components are determined.
The units used for pressure are and for material
stresses are as specified in the nomenclature
(1 = 1 newton per square meter).
B. Floating-head cover
(a) Flange and dish
The floating-head cover is a spherically dished cover
designed to UA-6 (4)(b), Fig.
see also Sec. The minimum dish thickness is the
greater of the tube-side or shell-side requirements.
= tube-side corrosion allowance = 3 mm
= shell-side corrosion allowance = 3 mm
For internal pressure (tube side),
where P = = 500 L is the dish corroded inside
radius (mm), and is the maximum allowable stress =
121
Assuming that the shell-to-floating tubesheet,
radial clearance is mm and assuming a gasket width
of 13 mm (TEMA minimum = 12.7 mm), then the
flange corroded inside diameter
B = 635 + 13) = 599 mm
The flange uncorroded inside diameter is
Assume that the dish uncorroded inside radius is 0.75 X
593 = 445 mm; then
L = 445 + = 445 + 3 = 448 m m
Therefore
5 500 448=6X 121
For external pressure (shell side), the rules in
UG-33 apply. A thickness is assumed, and the procedure
appropriate to the shape of the formed end is followed.
From TEMA R-3.13, the minimum allowable corroded
plate thickness is 6.35 mm. Assume that tfhd = mm
and confirm this, using the procedure in
UG-33(c).
0.125 0.125
= maximum allowable design pressure
B ch(3)
From materials chart, Fig. UCS-28.2,
= 14 500 = 14 500 X 6.895
= 99 978
Therefore
a 99 978
This is less than the shell-side design pressure (2 000
therefore assume that 9 mm and repeat the
calculation.
factor A3
factor = 15 200 = 15 200 X 6.895
= 104 804
Therefore
104 804a 105
This is greater than the shell-side design pressure; there-
fore a corroded dish thickness of 9 mm is satisfactory.
= dish uncorroded thickness
15mm
= dish uncorroded inside radius
(b) Flange design
The flange design thickness is the greatest thickness of
that required for gasket seating, tube-side pressure, and
shell-side pressure, or from geometric considerations to
allow for sufficient crossover flow area. The positioning
of the dish relative to the flange centroid is an important
part of the design calculations; there are numerous
methods of approach. For this example the procedure
used is as follows.
1983 Hemisphere Publishing Corporation
-
7/29/2019 Gasket Tornillos
10/12
-
7/29/2019 Gasket Tornillos
11/12
4.3.6-4 4.3 SHE LL- AND- TUB E DESI GN CODE S 4.3.6 TEMA Type AJS
18374Nm and = 121
18 374 X 702 + 599t==121 X 599 702 - 5 9 9
For crossover flow area, from TEMA R-8.12 the actual
crossover flow area is to be at least 1.3 times the flow
area through one tube pass. There are 468 tubes,
19.05 mm OD X 2.11 mm wall thickness, arranged infour tube passes.
Flow area/tube pass = (19.05 2 X 2.1
The total required crossover area is
The segmental area of the dish = 46 012
If the effect of the pass partition plates is neglected,
the area available under the dish for crossover flow per
pass is
46 012 X 0.5 = 23 006
If the dish is excluded, the depth of flange required
for crossover flow area per pass is
593 x 0.5
Obviously, even allowing for the dish, the gasket seat-
ing will require a greater thickness than that for cross-
over flow area.
Assume a corroded flange thickness of 57 mm and
position the dish at the back of the flange; check the
thickness for internal and external pressures.For internal pressure (tube side):
121
where
500 X X X
8 X 599)
121 X 599 702 599= 415.64
For external pressure (shell side):
S = = 121
where
2 000 X X X 8
8 X 599)
=121 X 599 702
1 566.62599
t = 8.00 + + 1 566.62 = 48.38 mm
Therefore, with the dish positioned at the back of
the flange, a corroded flange thickness of 57 mm is
satisfactory. The cover will have a pass partition plate
13 mm thick, tapered at one end to 10 mm to suit the
gasket web; see TEMA R-8.13. The flange will be re-
cessed to confine the gasket. The cover dimensions
are given in Fig. and a summary of the flange dimen-
sions is given in Table 11 (flange no. 6).
(c) Floating-head backing device
The backing device clamps the floating-head cover to
the tubesheet. There are various types; for this design
a single split ring is used, designed to UG-53(a).
The split ring is designed as if it were a solid flange
(without splits) using 200% of the greater of or
calculated in the mating flange design. From Tableis greater than for either the tube-side or
side operating conditions.
The effective thickness,
(7)
Shape constant,
B 599
Hence
Y = 12.31 from Fig. UA-5 1
18374Nm from Table 1
121 B = 599 m m
12.31 X 18 374 X 2=
121 x 599 x
There will be a recess (5 mm) deep to locate the spit
ring on the tubesheet. The dimensions of the backing
ring are given in Table 11 (flange no. and in Fig. 1.
C. Cylindrical shells
The minimum allowable wall thickness for cylindrical
shells is the greater of the or TEMA require-
ments; see also Sec.
The minimum thickness, exclusive of corrosion
allowance will be the greater thickness from the for-
mulas in UG-27.
For circumferential stress (longitudinal joints):
1983 Hemisphere Publishing Corporation
-
7/29/2019 Gasket Tornillos
12/12
4.3 SHELL-AND -TUBE DESIGN CODES 4.3.6 TEMA Type AJS 4 . 3 . 6 - S
2244
H
HOOLLEESS2244DDIIAA
Figure 1 Floating-head cover and backing device.
For longitudinal stress (circumferential joints):
For this example the weld examination is spot
throughout, thus the joint efficiency E = 0.85 for all
welded joints (see UW-12); Eq. (9) can therefore
be neglected. The calculations of cylinder thickness are
summarized in Table 2.
In practice, the selected plate thickness is not
necessarily the minimum allowable thickness rounded
up to the nearest millimeter. The availability of material
may be the deciding factor, or the designer may select
a thicker wall to increase the area available for reinforce-
ment at the nozzle locations. The channel will have pass
partition plates, of the same material, 13 mm thick,tapered at both ends to 10 mm thick to suit the webs of
the gaskets.
D. Tubes
The minimum allowable wall thickness is determined
from UG-31; see also Sec. The tube
dimensions are specified by the thermal designer. The
1983 Hemisphere I Corporation
wall thickness is usually the preferred gauge from TEMA
Table R, C, or B, -2.21. The tube length plays an im-
portant part in the thermal performance of the ex-
changer, so the length should not be altered without
the agreement of the thermal designer.
= tube outside diameter = 19.05 mm
tube wall thickness = 2.11 mm
= tube-side (internal) pressure = 500
= shell-side (external) pressure = 2 000
S = maximum allowable stress = 121
E = joint efficiency = 1
= tube inside radius = 2 X 2.11)
= 7.415 mm
For internal pressure the minimum allowable thick-ness is calculated using Eq. (8):
- - = 5 0 0 x
X 7.415= 0.031 mm
121 X 1.00 -0.6 X 500 X
For external pressure the rules in UG-28 are