Pressure Vessel Support

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Design of Vessel Supports 167longitudinal bending at saddles tension at top compression at bottom)

S 4 circumferential stressin stiffener

IdL12 L12 I4

L S , = longitudinal bending atmidspan

I

5- = tangential shear-resultsin diagonal lines in shellSe = tangential shear in head A 5 R12/ l l= additional tension in head A 5 R12

I I

Figure3 43. Stress diagram

3circumferential compressionin plane of saddle= circumferential bending athorn of saddleL

Mz is negative for M2 is positive forHemi-heads.If any of the below conditions are exceeded. Flat heads where A/R < 0 707100 -6 F&D heads where A/R < 0.44.2:l S E heads where A/R < 0.363.

Figure3 44. Moment diagram

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168 Pressure Vessel Design ManualLongitudinal Forces, FLCase 1: Pier Deflect ion

sa s

Case 2: ExpansionIContract ionFLZ PQsa=sCase 3: WindF L ~F ~ L =iCfGqzsa 1.33sCase 4: SeismicF L ~F ChWsa 1.33sCase 5: Shipp ingrr ranspor ta t ionFL5 See Chapter 7.Sa 0.9FyCase 6: Bundle Pul l ingF L ~ pSa 0.9F

Full load applies to fixed saddle onlyX = Fixed Saddle

K Fixed SaddleX

Note: For Cases 5 and 6 assume the vessel is cold and not pressurized.


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Design of essel Supports 69

Transverse Load: Basis for Equationsethod

FBEw =

W

Unit load at edge of base plate, w .

e Derivation of equation for WZMZc=

ThereforeM 6FBZ E2

Equiualent

E2M = F B Z = 6

3tal load Q Z

This assumes that the maximum load at the edge of thebaseplate is uniform across the entire baseplate. This isvery conservative, so the equation is modified as follows:

Using a triangular loading and 2 3 rule to dezjelop amor e realistic unvor oadFB 3FB

2/3)E 2EFI=

Therefore the total load, QF, due to force F is3FB 3FBQF w ~ E 2 E

ethod

Q

1 E 1This method is based on the rationale that the load i

no longer spread over the entire saddle but is shifted o oncside.

Combined force, 9 2Q2 JFT

Angle, 8.F8~ arctan)-Q

Modi ed saddle angle, e l81 2[J H


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170 Pressure Vessel esign ManualTypes of Stresses and Allowables

e S o S longitudinal bending.Tension: S I , S7 or + o x < SECompression: Se, S3, or 5 4 oe S,

where S = factor B or S or t,E1/16rwhichever is less.

1. Compressive stress is not significant where R,/t < 200and the vessel is designed for internal pressure only.2. When longitudinal bending at midspan is excessive,move saddles away from heads; however, do notexceed A 0.2L.3. When longitudinal bending at saddles is excessive,move saddles toward heads.

4. I f longitudinal bending is excessive at both saddles andmidspan, add stiffening rings. If stresses are still exces-sive, increase shell thickness.

e S.5 to S,v< 0.8s: tangential .shear.1. Tangential shear is not combined with other stresses.2 . If a wear plate is used, t, may be taken as t,+t,, pro-

viding the wear plate extends W10 above the horn ofthe saddle.

3 If the shell is unstiffened, the maximum tangentialshear stress occurs at the horn of the saddle.

4. If the shell is stiffened, the maximum tangential shearoccurs at the equator.

5 When tangential shear stress is excessive, move saddlestoward heads, A s 0 . 5 R, add rings, or increase shellthickness.

6. When stiffening rings are used, the shell-to-ring weldmust be designed to be adequate to resist the tangentialshear as follows:

allowable shearQ . lbr r in. circumference in. of welds t = - .

e S l 1 a/ , 1.25 SE : additional .stress in head.

1. S is a shear stress that is additive to the hoop stress inthe head and occurs whenever the saddles arelocated close to the heads, A i 0 . 5 R. Due to theirclose proximity the shear of the saddle extends intothe head.2. If stress in the head is excessive, move saddles awayfrom heads, increase head thickness, or add stiffeningrings.

e Sg and S l o < 1.5 S and 0.9Fy: circumferential bending athorn of saddle.1. If a wear plate is used, t, may be taken as t,+t, pro-

viding the wear plate extends W10 above the horn ofthe saddle. Stresses must also be checked at the top ofthe wear plate.

2 If stresses at the horn of the saddle are excessive:a. Add a wear plate.b. Increase contact angle 8.c. Move saddles toward heads, A < R.d. Add stiffening rings.

e S 2 < 0.5Fyor 1 5 S : circumferential compressioe stress.1. If a wear plate is used, t, may be taken as t, ,, pro-

viding the width of the wear plate is at leastb 1 . 5 6 6 .2 If the shell is unstiffened the maximum stress occurs at

the horn of the saddle.3. If the shell is stiffened the maximum hoop compression

occurs at the bottom of the shell.4. If stresses are excessive add stiffening rings.

e S I 3 o 1.5 S : circumferential tension stress-shelle S13 o 0.5Fy: ircumferential compression stress-e Sll u < 0.9FY: ircumfe rential compre ssion stres.9 in

stiffened.

shell stiffened.stiffening ring.

Procedure for Locating SaddlesTrial 1: Set A=0.2 L and t 3 = 120 and check stress at the

horn of the saddle, S g or Slo. This stress will govern formost vessels except for those with large L/R ratios.Trial 2 : Increase saddle angle 8 to 150 and recheck stressesat horn or saddle, S9 or SloTrial : Move saddles near heads A= W2) and return 8 to120 .This will take advantage of stiffness provided by theheads and will also induce additional stresses in the heads.Compute stresses Sq, S g and S g or Slo. A wear plate maybe used to reduce the stresses at the horn or saddle whenthe saddles are near the heads A


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Design of Vessel Supports 171

igure 3-45. Chart for selection of saddles for horizontal vessels. Reprinted by permission of the American W elding Society.

~ ~~ ~

Wind and Seismic Forcesongitudinal forces FL

Seismic: UBC see Procedure 3 - 3FL ChWoWind: A X E 7-95 Exposure C, Type 111)FL Af Cf G,qz

7sD2where AfCf 0 8G 0.85q, 0.00256KzV21K from Table 3-23

1 15V basic wind speed, 70 100mph

see Procedure 3 -2

Table 3 21Seismic Factors, C, For I 1 OZone cs12A2B34

0.0690.1380.1840.2750.367

Table 3 22Effective Diameter, DeDiameter in.) D.

3636-5454-7878-1 02> 102

1.5D1.37D1.28D1.2D1.18D


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172 Pressure Vessel Design ManualTable 3-23

Coefficient, KHeight ft) Kz

0 1 5205

30405060

0.850.90.940.981.041.091.13

Transverse o rces Ft pe r saddle.Seismic:Ft = ChWo)0.5Wind:Ft = AfCfGdqz)O.5A f = De L 2 H )Total saddle reaction for ces Q.Q=greater of Q1 or QzLongitudinal, Q1

Transverse, QzW, 3FtB

Q 2 = 3 - ~

Shell StressesThere are 4 main stresses to be considered in the design

of a horizontal vessel on saddle supports:

feners, tensionfeners, compression

S1 =longitudinal bending at saddles without stif-

S2 = ongitudinal bending at saddles without stif-S = ongitudinal bending at saddles with stiffeners

a,Figure 3 46. Saddle reaction forces.

S = ongitudinal bending at midspan, tension atS5 =tangential shear-shell stiffened in plane ofS6 =tangential shear-shell not stiffened, A > lU2S7 =tangential shear-shell not stiffened except byheads, A W2S8 = angential shear in head-shell not stiffened,

A 5 W 2S9 = circumferential bending at horn of saddle-

shell not stiffened, L ? 8RSI0 =circumferential bending at horn of saddle-

shell not stiffened, L 8 RSI1=additional tension stress in head, shell not stif-fened, A lU2

S 12 = circumferential compressive stress-stiffenedor not stiffened, saddles attached or not

S 3 = circumferential stress in shell with stiffener inplane of saddleS14=circumferential stress in ring stiffener

bottom, compression at topsaddle

Longitudinal BendingS I longitudinal bend ing at saddles-without stiffenerstension.

AH 6A2 3R2 3H2[ 3 L + 4 H= 6 QM

Klr2t,i = +)-S2 longi tudin al ben din g at saddles-without stiffenerscompression.

MK7r2tss = -)-

S3 longitudinal bend ing at saddles-with stifenem.

S4 longitudinal bending at m idspan.L2 6R2 6H 12AL 16AH

3L 4H2 = 34

Tangential ShearS5 tangential shear-shell sti fen ed in the plane of thesaddle.


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esignof Vessel upports 73

e S6 tangential shear-shell not stiffen ed, > 0.SR.fi.=-[p]z Q L - 2 A

rt L + HS7, tangential shear-shell not stiffen ed, 0.S R.

K3Qs

e Sg tangential shear in head-shell not stiffen ed, 5 0.5R.K3QS8 t h

Note: If shell is stiffened or A > 0.5R, S 0.Circumferential Bendinge Sg, circumferential bending at hor n of saddle-shell notstiffened L2 8R) .

Note: t, , , an d tf ttwear plate extends W O above horn of saddle.

only if 5 0.5R andS l o , circumferential bend ing at horn of saddle-shell notstiffened L< 8R) .

Q 12K6QR4ts(b 1 . 5 6 6 ) tflO (-1

Note: Requirements for t, are same as for Sg.Additional Tension Stress in Heade SI1, additional tension stress in head-shell not st if en ed ,

0 .5R.

Note: If shell is stiffened or > 0.5R, SI1 0.Circumferential Tension Compressione S12, circumferential compression.

K5Qt , ( b 1 . 5 6 f i )2 -1

Note: t, , , only if wear plate is attach ed to shell andwidth of wear plate is a minimum of b 1 .5 6f i.e S13 circumferential stress in shell with stiffener seeNote 8).

Note: Add second expression if vessel has an internalstiffener, subtract if vessel has an external stiffener.e S I 4 circumferential compressive stress in stiffen er seeNote 8).

Pressure Stresses

a h a ,maximum circ umfere ntial stress in head is equal tohoop stress in shell


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174 Pressure Vessel esign Manual

St resss1 ox

COMBINED STRESSES

A l lowab le S t ress A l lowab leSE s2 e S

TENSION COMPRESSION

s3+ oxs4 ox

SE S3 ue s,SE s4 e S,

Con tac t Con tac tAng le f3 K1 K2 K3 K4 K5 K7 K8 Kg A n g le K1* K2 K3 K5 K7 K8 Kg120 0.335122 0.345124 0.355126 0.366128 0.376130 0.387132 0.398134 0.409136 0.420138 0.432140 0.443142 0.455144 0.467146 0.480148 0.492150 0.505

~~ ~

1.1711.1391.1081.0781.0501.0220.9960.9710.9460.9230.9000.8790.8580.8370.81 80.799

~~

0.8800.8460.81 30.7810.7510.7220.6940.6670.6410.61 60.5920.5690.5470.5260.5050.485

0.4010.3930.3850.3770.3690.3620.3550.3470.3400.3340.3270.3200.3140.3080.3010.295

0.7600.7530.7460.7390.7320.7260.7200.7140.7080.7020.6970.6920.6870.6820.6780.673

0.6030.61 80.6340.6510.6690.6890.7050.7220.7400.7590.7800.7960.8130.8310.8530.876

0.3400.3380.3360.3340.3320.3300.3280.3260.3240.3220.3200.31 60.31 20.3080.3040.300

0.0530.0510.0500.0480.0470.0450.0430.0420.0400.0390.0370.0360.0350.0340.0330.032

152154156158160162164166168170172174176178180

0.518 0.781 0.4660.531 0.763 0.4480.544 0.746 0.4300.557 0.729 0.4130.571 0.713 0.3960.585 0.698 0.3800.599 0.683 0.3650.613 0.668 0.3500.627 0.654 0.3360.642 0.640 0.3220.657 0.627 0.3090.672 0.614 0.2960.0687 0.601 0.2830.702 0.589 0.2710.718 0.577 0.260

0.289 0.669 0.894 0.2980.283 0.665 0.913 0.2960.278 0.661 0.933 0.2940.272 0.657 0.954 0.2920.266 0.654 0.976 0.2900.261 0.650 0.994 0.2860.256 0.647 1.013 0.2820.250 0.643 1.033 0.2780.245 0.640 1.054 0.2740.240 0.637 1.079 0.2700.235 0.635 1.097 0.2660.230 0.632 1.116 0.2620.225 0.629 1.137 0.2580.220 0.627 1.158 0.2540.216 0.624 1.183 0.250

0.0310.0300.0280.0270.0260.0250.0240.0240.0230.0220.0210.0200.0190.01 80.01 7

K, =3 14 f the shell is st if fened by ring or head ( A < Ri2 .Figure 3-47. Coefficients.


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868788

Table 3 24Coef f i c ien ts for Z ick s An a lys i s (An g les 80' to 120 )

0.1914 2.0264 1.7831 0.5808 0.9417 0.0216 0.0873 0.3575 0.3592 0.08730.1949 1 9891 1.7441 0.5741 0.9344 0.0215 0.0861 0.3637 0.3591 0.08610.1985 1.9528 1.7061 0.5675 0.9273 0.0212 0.0849 0.3700 0.3590 0.0849

85 0 1879 20648 1 18233 05877 09492 00221 1 00885 03513 03593 1 0 0 8 8 5 1

1. These coefficients are derived from Zick s equations.2 he ASME Code does not recommend the use of saddles with an included angle, 8 less than 120-.Therefore the values in this table should be use d for verysmall-diameter vessels or to evaluate existing vessels built prior to this ASME recommendation.3. Value s of for R ratios between 0.5 and 1 can be interpolated.


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176 Pressure Vessel Design Manual

30 16,700 27 2436 15,700 33 2742 15,100 38 3048 25,330 44 3354 26,730 48 3660 38,000 54 3966 38,950 60 42

A

9 4 16.5 120 10012 6 18.8 125 170

20.0 123 20022.3 127 23022.7 121 2700

23 25.0 124 31026 27.2 127 35D

~ ;:

G lLC_l_c l

72 50,700 64 45 10 28 0.i75 27.678 56,500 70 48 11 0.75 31 29.8

30.24 57,525 74 51 1290 64,200 80 54 1396 65,400 86 57 14 39 34.7ii ; 32.5

L OFigure 3 48. Saddle dimensions.

122 420124 71121 81123 880125 940

102 94,500 92 60 15108 85,000 96 63 16114 164,000 102 66 17120 150,000 106 69 18132 127,500 118 75 20144 280,000 128 81 22156 266,000 140 87 24

Table 3 25lot Dimensions

42 b 0.500 37.0 1 126 1,35044 37.3 123 1,43047 0.625 39.6 125 1,76049 40.0 122 1,800

125 2,180124 2,500126 2,730

556066 51.6

Distance Between SaddlesTemperatureF l o f t 2 ft 3 t 40 ft 5 f t

501002003004005600700800900

000.2500.3750.3750.5000.6250.7500.750

00.2500.3750.6250.7501 oo1.1251.2501.375

0.250.1250.3750.6250.8751.1251.3751.6251.6252.000

0.250.1250.3750.7501.1251.50013752.1252.3752.500

0.3750.2500.5001 oo1.3751.6252.2502.6253.0003.375

Bolt diameter L See+ 8 in. TableTable 3 26

Typical Saddle Dimensions.MaximumVessel Operating Bolt ApproximateO.D. Weight A B C D E F G H Diameter WeighVSet


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Design of Vessel Supports 77Notes

1. Horizontal vessels act as beams with the followingexceptionsa. Loading conditions vary for full or partially full ves-

sels.b. Stresses vary according to angle and distance A.c. Load due to weight is combined with other loads.

2 Large-diameter, thin-walled vessels are best supportednear the heads, provided the shell can take the loadbetween the saddles. The resulting stresses in theheads must be checked to ensure the heads are stiffenough to transfer the load back to the saddles.

3 Thick-walled vessels are best supported where thelongitudinal bending stresses at the saddles are aboutequal to the longitudinal bending at midspan.However, A should not exceed 0.2 L.

4. Minimum saddle angle Q = O , except for small ves-sels. For vessels designed for external pressure only 0should always 120 . The maximum angle is 168 if awear plate is used.

5. Except for large L/R ratios or A > lU2 the governingstress is circumferential bending at the horn of thesaddle. Weld seams should be avoided at the horn ofthe saddle.

6. A wear plate may be used to reduce stresses at the hornof the saddle only if saddles are near heads (A W2 ,

and the wear plate extends W10 (5.73 deg.) above thehorn of the saddle.

7 . If it is determined that stiffening rings will be requiredto reduce shell stresses, move saddles away from theheads (preferable to A= 0 . 2 L). This will preventdesigning a vessel with a flexible center and rigidends. Stiffening ring sizes may be reduced by using asaddle angle of 150 .

8. An internal stiffening ring is the most desirable from astrength standpoint because the maximum stress in theshell is compressive, which is reduced by internal pres-sure. An internal ring may not be practical from a pro-cess or corrosion standpoint, however.

9. Friction factors:

S u a c e sLubricated steel-to-concreteSteel-to-steelLubrite-to-steel

Temperature over 500FTemperature 500F or lessBearing pressure less than 500psi

Teflon-to-TeflonBearing 800psi or moreBearing 300psi or less

PROCEDURE 3 11

FrictionFactor0.45

0.40.150.100.150.060.1

DESIGN O F SADDLE SUPPO RTS FOR LA RGE VESSELS [4 15-17, 211Notation

A, cross-sectional area of saddle, in.'Ab =area of base plate, in.2A,-= projected area for wind, ft2A, =pressure area on ribs, in.2A, =cross-sectional area, rib, in.2Q =maximum load per saddle, lb

Q i = Q o + Q K , 1b4 2 Qo QL, 1bQI,=load per saddle, operating, lbQT=load per saddle, test, lbQL=vertical load per saddle due to longitudinal loads, lbQK=vertical load per saddle due to transverse loads, lbFL maximum longitudinal force due to wind, seismic,

pier deflection, etc. (see procedure 3-10 fordetailed description)

Fa allowable axial stress, psi (see App. L)N number of anchor bolts in the futed saddlea, =cross-sectional area of bolts in tension, i n 2Y =effective bearing length, in.T =tension load in outer bolt, lbnl modular ratio, steel to concrete, use 10F1, =allowable bending stress, psiF, =yield stress, psif,, saddle splitting force, lbE axial stress, psif b =bending stress, psif unit force, Ib/in.

B, =bear ing pressure , psiM =bending moment, or overturning moment, in.-lbI moment of inertia, in.4z =section modulus, in.3

r radius of gyration, in.K I saddle splitting coefficient


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3230282624222018160 . 6 r 0 75 0 875 1 0 1 125 1 25 1 375 1 5 1 625 1 75

I n . . . . . . . - . .Y V I i iWeb and Rib Thickness t and J in.

Figure 3 49. Graph for determining web and rib thicknesses.

A Optional 168 saddle optimum size for large vesselsFigure 3 50. Dimensions ot horizontal vessels and saddles.


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Design of Vessel Supports 79n =number of ribs, including outer ribs, in one saddleP = equivalent column load, lbd = distance from base to centroid of saddle arc, in.

W, =operating weight of vessel contents, lbW, =vessel weight full o water, Ib

UT =tension stress, psiw= uniform load, lb

Forces and oadsVertical oad per Saddle

Longitudinal

0 55

TransverseFigure 3 51. Saddle loadings.

For loads due to the following causes, use the givenformulas.

Operating weight.wQ =O

Test weight.

Longitudinal wind or seismic.

Transverse wind or seismic.

Maximum oadsVertical.greater of Q1, Qz, or QTQ ~ = Q ~ + Q RQZ = Qo QLLongitudinal.F L= greater o FL1 hrough FL ,see procedure 3-1 for definitions)

Saddle PropertiesPreliminary web and rib thicknw.r.es t t c atid J FroinFigure 3-45:J = t,Number of ribs required

An = - + l24Round up to the nearest even number.Minimum width of .snddle t top, G T , n

where FL and F1, are in kips and ksi or 11 and psi, and J 11.A are in in.Minimum wear plate diuiensiori yWidth:H = GT 1 . 5 6 f iThickness:

(H GT)2.43Rt, =

Moinent of inertici of saddle I

Cross-sectional area of saddle escliiding ,shell).A = A - A 1


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A

Q

to center

in.

Y A Y A V 1

NO^: io or mangles bh32Figure 3 52. Cross-sectional properties of saddles.

~~ ~~esign of Saddle PartsWeb

Web is in tension and bending as a result of saddle split-ting forces. Th e sadd le splitting for ces, fl,, are th e s um of allthe horizontal reactions on the saddle.e Saddle coefficient.

1 cos j 0.5 sin2Bj sin j cos jK i

A ote: j is in radians. See Table 3-18.

fh

Varying unit radialpressure

Figure 3 53. Saddle splitting forces.

Note Circumferential bending athorn is neglected forthis calculation.

Figu re 3 54. Bending in saddle due to splitting forces.

e Saddle splitting force.f i ,=K, Q or QTe Tens ion stress.

Note: For tension assume saddle depth hmaxim u m

e Bending moment .R s i n ed = B - -

6 is in radians.M fhd

e Bending stress.

f l , C1 < 0.66FY

Table 3 27Values of kl

as W

ki 20.204 1200.214 126'0.226 132'0.237 1380.248 1440.260 1500.271 1560.278 162'0.294 168


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Design of essel Supports 181f b

igure 3 55. Loading diagram of base plate

Base plate with center webe Area.

Ai, = A Fe Bearing pre ssure.

AI,Be Ba.se plate thickness.

QFNOW M = 8

Therefore

Assumes uniform load fixed in center.Base plate analysis for offset web se e Figure 3-56e Overall length L

Webribs L, = n G ,

= A 2dl 2J

EL L L,

d 2

igure3 56. Load diagram and dimensions for base plate with an offsetweb

e Unit linear load j i i= lb/linear in.CL

e Distance.7 e l and .

e Load.9 moment

weM = - 6e Bending .stres.y ; .

6Mh =


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182 Pressure Vessel Design Manualnchor Bolts

f c

Pivot Pt.Yx ,

Anchor bolts are governed by one of the three following1 Longitudinal loud: If Qo> QL , then no uplift occurs,

and the minimum number and size of anchor boltsshould be used.If o< QL, then uplift does occur:

load cases:

QL - Qo = load per boltN2. Shear: Assume the fixed saddle takes the entire shearload.FL shear per boltN

3. Trunszjerse load: This method of determining upliftand overturning is determined from Ref. 21 seeFigure 3-57).M = 0.5F, or F*T)B

Me = -QIf e , then there is no uplift.

If e , then proceed with the following steps. This is aniterative procedure for finding the tension force, T in theoutermost bolt.

Step 1:Find the effective bearing length, Y. Start by calcu-lating factors K1-3K1 = 3 e - 0.5A)

6n 1atK2 = - f + e)F

Step : Substitute values of K1-3 into the following equationand assume a value of Y= %A as a first trial.

1

Figure 3-57. Dimensions and loading for b ase plate and anchor boltanalysis.Y 3 K1Y2+ K2Y+K3 OIf not equal to 0 then proceed with Step 3.Step 3: Assume a new value of Y and recalculate the equa-tion in Step until the equation balances out to approxi-mately 0 Once Y is determined, proceed to Step 4Step 4:Calculate the tension force, T in the outermost boltor bolts.

A Y

Step 5: From Table 3-28, select an appropriate bolt materialand size corresponding to tension force, T.Step 6: Analyze the bending in the base plate.Distance, x = 0.5A + - YMoment, M = Tx

6MBending stress, f = i

Table 3-28Allowable Tension Load on Bolts, Kips, per AlSCNom. BoltDia., in. 1 1 1 1 1

Table 3-28Allowable Tension Load on Bolts, Kips, per AlSC

Cross-sectional Area, ab, 0.3068 0.441 0.6013 0.7854 0.994 1.227 1.485 1.767in.A-307 Ft= 20 ksi 6.1 8.8 12.0 15.7 19.9 24.5 29.7 35.3A-325 Ft= 44 ks i 13.5 19.4 26.5 34.6 43.7 54.0 65.3 77.7


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Design of Vessel Supports 183Ribs

Outside Ribsr J I

0.5e or h Irib spacing

A == e ressure area, = 0.5FeFigure 3 58. Dimensions of outside saddle ribs and webs.

area of rib and web, in.?

Outside Ribs

e Axial load P.P = B A

e Compressiue stress J .P

f a = Ae Radius o gyration rr=ge Slenderness ratio f21lr

l l r =F = See App. L .

e Unit force f;FIf , , =

e Bending moment M .M = 0.5f ell

e Bending stress h = 0.66 Fy .MC1f b =

e Combined stress.f a f ha F h- -< 1

nside RibsInside rib

1 eo1 1A =A =a ressure area, x eI

Lrib spacingarea of rib and web, in.2

JG3l2 = moment o inertia, 12 C2 = 0.5GbFigure 3-59. Dimensions of inside saddle ribs and webs.

e d oad P.P = B A

e Compressiue stre.as n.P

f a = Ae Radius o gyration r.

e Slenderness ratio /r .zlr =

Fa =e Unit force f; .

FLf 2A


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84 Pressure Vessel Design Man uale Bending moment M .

M f,&ee Bending stress fb.

MC2I

e Combined stress.f b

f a f hF a F b- - < I

Notes1. The depth of web is important in developing stiffness

to prevent bending about the cross-sectional axis ofthe saddle. For larger vessels, assume 6 in. as the

minimum depth from the bottom of the wear plateto the top of the base plate.

2 The full length of the web may be assumed effectivein carrying compressive stresses along with ribs. Ribsare not effective at carrying compressive load if theyare spaced greater than 25 times the web thicknessapart.

3. Concrete compressive stresses are usually consideredto be uniform. This assumes the saddle is rigid enoughto distribute the load uniformly.

4. Large-diameter horizontal vessels are best supportedwith 168 saddles. Larger saddle angles do not effec-tively contribute to lower shell stresses and are moredifficult to fabricate. The wear plate need not extendbeyond center lines of vessel in any case or 6 beyondsaddles.5. Assume fixed saddle takes all of the longitudinalloading.

PROCEDURE 3 12DESIGN OF BASE PL TES FOR LEGS [ZO 211Notation

Y effective bearing length, in.M overturning moment, in.-lb =ax ia l load, lbft =tension stress in anchor bolt, psiA =actual area of base plate,A, area required, base plate, in.f; =ultimate 28-day strength, psif, =bearing pressure, psif l equivalent bearing pressure, psi

Fb=allowable bending stress, psiFt =allowable tension stress, psiF, =allowable compression stress, psiE, modulus of elasticity, steel, psiE, modulus of elasticity, concrete, psin modular ratio, steel-concreten equivalent cantilever dimension of base plate, in.B, allowable bearing pressure, psi

M h =bending moment, in.-lb

K 1 2 3=factorT=tension force i n outermost bolt, lC compressive load in concrete, lbV base shear, IbN =total number of anchor boltsN t =number of anchor bolts in tensionb cross-sectional area of one bolt, in.

A, =total cross-sectional area of bolts in tension, in.2Y coefficient

T, shear stress

Calculationse Axiul loading only no moment

Angle legs:Pf BD

L greater of m, n, or n'

Beam legs:PA A 0.7fL

0.95d2m =


19/36


Assumedload areaB E A M

A N G L E

For pipe legs;massume B D

D 0 707 W2

P I P EFigure 3 60. Dimensions and loadings of base plates

B 0.8d2n =

b ,2 d 2tf)

Y

or from Table 3-29Pipe legs:B 0 707W

2

Axid loud plus bending load condition I, full compres-sion up/$ , D /6 .Eccentricity:

M DP - 6e = - D/6Eccentricity:

M De = - - >P 6


20/36

186 Pressure Vessel Design ManualLoad Condi t ion 1 Load Condi t ion 2

I =I XFull compression no uplif t e D/6 Partial compression uplift e > D/6

Figure 3-61. Load conditions on base plates.

Table 3-29Values of n for Beams Table 3-30Average Properties of ConcreteColumn SectionW 1 4 ~ 7 3 O - W l 4 ~ 1 4 5W14 x 132 W14 x 90

W 1 4 ~ 5 3 - W 1 4 ~ 4 3W 1 2 ~ 3 3 6 - W l 2 ~ 6 5w 1 4 x 8 2 - w 1 4 6 1

~ 1 2 x 5 8 - 1 2 x 5 3W12 x 50 - W12 x 40W10 x 112 W10 x 49

n5.775.644.434.774.273.613.92

3.68

Column SectionW10 x 4 5 - W 1 0 x 33wax 6 7 - w a X 31wa X 2a -wa X 24

W 6 x 25 W6 x 15W 6 x 1 6 - W 6 x 9W 5 x 19 W5 x 16W 4 x 13

n3.423.142.771.771.911.532.38

Coefficient:EEn see Table 3-30)

Dimension:f 0.5d+zBy trial and error, determine Y effective bearing length,utilizing factors K1-3.Factors:K I = 3 e +

Ult f; AllowableWater 28-Day Compression, Allowable Coefficient,ContenUBag Str psi) F, psi) B, Psi) n7.5 2000 aoo 500 156.75 2500 1000 625 126 3000 1200 750 105 3750 1400 938 aReprinted by permission of John Wiley Sons, Inc.

By successive approximations, determine distance Y.Substitute K1-3 into the following equation and assumean initial value of Y as a first trial.

Tension force:D Y_ _

T = - ) P [ b--- f 3

Bearing pressure:

-=zf:B


21/36


t E t iwv

1Figure 3-62. Dimensions or base plates-beams.

Dimens ions for Type 1+2 Bo lt Base Plate Dimens ions for Type 2- 4) Bo lt Base PlateColum n Min Plate MaxSize D in . 6 , in . E in. W, in. Thk, in. Bolt 4 in. Co lumn D, 6 G, E W, Min Plate Max BoltSize in. in. in. in. in. Thk, in. 4 in.w 4 8 8 4W6 8 8 4 710 10 6 /4 7W10 -33thru4 5 12 12 6 7W10-49thru 112 13 13 6 5 16 74 1W 1 2 - 4 0 t h ~ 50 14 10 6 5 16 1W12-53 th ru58 14 12 6 1W12-65 thru 152 15 15 8 5 16 1

1W8w 4 10 10 7 7W6 12 12 9 9 5 16W8 15 15 11 11 74W10 -33thru4 5 17 15 13 11 Y 8W10 -49thru1 12 17 17 13 13W12 -53thru5 8 19 17 15 13 Y 1W12 -65thru1 52 19 19 15 15 1W12 -40thru5 0 19 15 15 11 1

1111741741Y11Y2

; wAngle Legs Pipe Legs

Figure 3-63. Dimens ions or base plates-angle/pipe.


22/36

88 Pressure Vessel Design ManualDimensions for ngle Legs Dimensions for Pipe Legs

Min PlateLea Size D X m Thk

~~ Min PlateLeg ize E m Thk

L2 in. x 2 in. 4 in. 1.5 1 in.L2 in. x 2 in. 5 in. 1.5 1.25 in.L3 in. x 3 in. 6 in. 1.75 1.5 in.L4 in. x 4 in. 8 in. 2 2 in.L5 in. x 5 in. 9 in. 2.75 2 Y in.L6 in. x 6 in. 10 in. 3.5 2 in.

~~3in. NPS 7 in. 4 in. 2.5 in. in.4in. NPS 8 in. 5 in. 2.7 in. in.6in. NPS 10 in. 7 in. 2.7 in. in.8in. NPS 11 in. 8 in. 2.7 in. ? in.lo in. NPS 14 in. 10 in. 3.2 in. /8 in.12 n. NPS 6 in. 12 in. 3.5 in. 1 in.

Moment: where M is greater of MT or M,.0 5D+

Mt TXY - a

l =

Thickness:

nchor boltsWithout uplift: design anchor bolts for shear only.

VTs =&With uplift: design anchor bolts for full shear and tensionforce T.

PROCEDURE 3-13DESIGN OF LUG SUPPORTS

Notation~~ ~ ~~

Q =vertical load per lug lbQa=axial load on gusset IbQ b =bending load on gusset lb

n number of gussets per lugF allowable axial stress psiF1 =allowable bending stress psif =axial stress psifb =bending stress psi

cross-sectional area of assumed column i n 2Z =section modulus in.3

w uniform load on base plate lbhn.E =modulus of elasticity of vessel shell at designE modulus of elasticity of compression plate at design

I =moment of inertia of compression plate in.4temperature psitemperature psi

M h =bending moment in.-lbM nternal bending moment in compression plate

e =log base 2.71

in.-lbK spring constant o r foundation modulus

damping factor


23/36

esignof Vessel Supports 89

esign o Gussets

4 = Bolt

Single gusset

Fb = 0.6Fy

hole diameter

Q = Q sinQ b = Q OS

ibh

sinm=Base plate

Double gusset

b sin2

c =

Figure3 64. Dimensions and forces on a lug support.

Assume gusset thickness f rom Table 3-31.Q d = Q sin 8 6Q = Q c se

b s i n 8c =A = t C

F = Q.4Fy


24/36

19 ressure Vessel Design ManualDesign of ase Plate

Single Gusse t

e Bending Assume to be a simply supported bea m.

e BearingQa1w = -

WdM be Thickness required base plate

where Mk, is greater moment from bending or bearing.

earing

b/in

Figure3 65. oading diagram o base plate with one gusset

Double Gussete Bending Assume to be between simply supported andfixed.

Bending

earing

Iblin

igure 3 66. oading diagram of base plate with two gussets

e Bearing

e Thickness required base plate

(b 4 Fbwhere M b s greater moment from bending or bearing.

Compression PlateSingle Guss et

I\

Figure3 67. oading diagram o compression plate with one gusset


25/36

Design of Vessel Supports 191Assume thickness t, and calculate I and Z:

tcy3I=--. 12

Z = t Y6

fMx q

0 6FYxfb =Note These calculations are based on a beam on elasticfoundation methods.

ouble Gusset

f = - Qe2hE,,tK = - H2

I = cy312

p 4E,I

fM l (e-Bx(cos x in Bx ]48x s in radians. See Procedure 5 2.

MxZf b = 0 6FY

RFigure 3-68. Loading diagram of compression plate with two gussets.

able 3-31Standard Lug DimensionsX t = b Capacity b)Type e b

1 4 6 2 6 6 23 5002 4 6 2 6 9 7/16 45 0003 4 6 2 6 12 i 45 00070 000

70 00070 0005 5 7 2.5 7 184 5 7 2.5 7 15 9 16

7 6 8 3 a 24 100 000I 16 5 7 2.5 7 21 6


26/36


PROCEDURE 3 14DESIGN OF BASE DETAILS FOR VER TICAL VESSELS 1[ 5 10, 14 18, 191

NotationA b required area of anchor bolts,Bd =anchor bolt diameter, in.B allowable bearing pressure, psi see

Table 3-35b =bearing stress, psiC compressive load on concrete, lbd diameter of bolt circle, in.

db hameter of hole in base plate of compres-sion plate or ring, in.FLT longitudinal tension load, lb/in.

F L C ongitudinal compression load, lb/in.F b allowable bending stress, psiF, allowable compressive stress, concrete, psiF, =allowable tension stress, anchor bolts, psiF, minimum specified yield strength, psifb =bending stress, psif =compressive stress, concrete, psif =equiva lent tension stress in anchor bolts,

see Table 3 - 35see Table 3 - 33

psiM b =overturning moment at base, in.-lbM =overturning moment at tangent line, in.-lbM =unit bending moment in base plate,My =unit bending moment in base plate, radial,

circumferential, in. lb/in.in. 1b/in .H =overall vessel height, ft

6 =vessel deflection, in. see Procedure 4-4)M =bending moment per unit length in.-lb/in.

N =number of anchor boltsn ratio of modulus of elasticity of steel to con-P maximum anchor bolt force, IbPI =maximum axial force in gusset, lbE =joint efficiency of skirt-head attachment

R,=roo t area of anchor bolt, i n 2 see

crete see Table 3-35

weldTable 3-32

r radius of bolt circle, in.b =weight of vessel at base, lb

W, =weight of vessel at tangent line, lbw width of base plate, in.

Z1 =section modulus of skirt, in.3S allowable stress tens ion) of skirt, psiS allowable stress compress ion) of skirt, psiG =wid th of unreinforced opening in skirt, in.

y1 yz coefficients for moment calculation in com-C CT J Z K =coefficients see Table 3 - 38

pression ringS code allowable stress, tension, psit, =equivalent thickness of steel shell whichT =tensile load in steel, lbu =Poissons ratio, 0.3 for steelB code allowable longitudinal compressive

E l modulus of elasticity, psirepresents the anchor bolts in tension, in.

stress, psi


27/36

Design of Vessel Supports 193Lap welded Butt welded

E 0 5

Pedestal

Smal l -d iametervessels only

E 0 7Shear ring rslip band

Figure 3-69. Skirt types.

Type 3: Chairs

Conical

Type 1: Without gussetsh 2 in.c 1 in.

Bolt 6 in.

Ship looseand attachin fieldl ylbolt 1 inType : With gussets

in.cmn 1 in.

b

Type 4: Top ring

5 in . min imum

Bond 1 in .Washer

oll 1 in.

Figure 3-70. Base details o various types of skirt-supported vessels.


28/36

194 Pressure Vessel Design ManualTable 3 32

Bolt Chair DataTable 3 35

Average Properties of Concrete

Y4-1 o 5.50 0.302 2 3.50 1.51-8 5.50 0.551 2 3.50 1.51Ye-7 5.50 0.693 2 3.50 1.511/4-7 5.50 0.890 2 3.50 1.51Y2-6 5.75 1.294 2.25 3.50 2174-5 6.00 1.744 2.5 4.00 2.251%-5 6.25 2.049 2.63 4.00 2.52 4 % 6.50 2.300 2.75 4.00 2.52'/ ,4' /2 7.00 3.020 3 4.50 2.752Y2-4 7.25 3.71 5 3.25 4.50 3~ 7 ~ 4 - 4 7.50 4.618 3.50 4.75 3.253 4 8.00 5.621 3.75 5.00 3.50

7/8-9 5.50 0.419 2 3.50 1.5

17*+ 5.50 1.054 2.13 3.50 1.7515/8-5'/2 5.75 1.515 2.38 4.00 2

Table 3 33Number of Anchor Bolts, N

Skirt Diameter in.) Minimum Maximum24-36 4 442-54 4 86C-78 8 1284-1 02 12 16108-1 26 16 20132-1 44 20 24

Table 3 34Allowable Stress for Bolts, F

Diameter Allowable StressSpec in.) KSOA-307 AllA-36 AllA-325 c1-1/2A-449 c1

1-1/8 o 1-1121-5/8 o 3

20.019.044.039.634.729.7

Ult28-Day AllowableWater Str Compression, Fc Allowable Coefficient,ContenVBag psi ) Psi) B, Psi) n7.5 2000 800 500 156.75 2500 1000 625 126 3000 1200 750 105 3750 1400 938 8Reprinted by permission of John Wiley Sons, Inc.

Table 3 36Bending Moment Unit Length

~ ~

0 0 -o.5fce20.333 0.0078fcb2 -o.428fce20.667 0.0558fcb2 -o.227fce21.5 0.123fcb2 -0.1 24fce22.0 0.1 31fcb2 -0.1 25fce23.0 0.1 33fcb2 -o.125fce2cy 0.1 33fcb2 -o.i25fcez

0.5 0.0293fcb2 -0.31 9fct21 o 0.0972fcb2 -0.1 19fC@

Reprinted by permission of John Wiiey Sons, Inc.

Table 3 37Constant for Moment Calculation, y and y

ble Y1 Y1 o1.21.41.61.82.0cy

0.5650.3500.21 10.1250.0730.042

0

0.1350.1150.0850.0570.0370.023

0Reprinted by permission o John Wiley Sons, Inc.

Table 3 38Values of Constants as a Function of K

K ct J z K c c ct J z0.1 0.852 2.887 0.766 0.480 0.55 2.113 1.884 0.785 0.3810.15 1.049 2.772 0.771 0.469 0.6 2.224 1.765 0.784 0.3690.2 1.218 2.661 0.776 0.459 0.65 2.333 1.640 0.783 0.3570.25 1.370 2.551 0.779 0.448 0.7 2.442 1.510 0.781 0.3440.3 1.510 2.442 0.781 0.438 0.75 2.551 1.370 0.779 0.3310.35 1.640 2.333 0.783 0.427 0.8 2.661 1.218 0.776 0.3160.4 1.765 2.224 0.784 0.416 0.85 2.772 1.049 0.771 0.3020.45 1.884 2.113 0.785 0.404 0.9 2.887 0.852 0.766 0.2860.5 2.000 2.000 0.785 0.393 0.95 3.008 0.600 0.760 0.270Reprinted by permission of John Wiley Sons, Inc.


29/36


1 TRIAL 1

ANCHOR BOLTS: EQU IVALENT AREA METH OD

T d-- F.GIN

R Table3-33)Use )

wb I2 Approximate K U d n g A l k r r r b b a Coeff lclents

cc1IK--1 I?. tnFc JI 2

Jd I4 Number of Anchor Bohr Rwulrsd

8 unprowtve Lo8d In Concrete7 Stroaa In ComreteC = T + W b

I8 Fiecheck K UJ ng Actua l f.8nd 1K-- 1

1 L

1. Cakul r te re l lmlna K valuo bud on a l h b k r .2 Make p r d k l n r r y &tion of anchor bdtr and width of bawd tr3 k e h d S nd w .4. C a k u k t o K baaed o n actual oases and compare wlth valuo

o InStop 2.5 Gncr excoeds .01, oloct a new K batweonbothvahm andrOPO.1 S t v -6. WNote 6.

TRIAL 2I1 Data

12 Approxlmate K UJng A l k w a b b a

3 Tendk Load InSteel

4 Number of Anchor B o b Requiredin.2

bolts 5 Stress In Equlvaknt Steal and

6 Compre8dvo Load In Concrete7 St rem In Concrete

See example of completed form on nexl page.


30/36

196 Pressure Vessel Design anualANCHOR BOLTS: EQUIVALENT AREA METHOD EXAMPLE

33b.74 Number of Anchor Bdtr Required

PROCEDURE

TRIAL 1

p c Mi6

I Tend k Load In Steal

r . .N u m kr o f Ancho r Bolts Raaulrod

1. Calculate reihinar K value bsmd on a i kw abks .2 Make p r e l h f w y w L k n f anchor bolts and width of sse3. ate loads and stresses.4. Calculate K based on actucrl stresses and compare with vr lue

e n Step 2.5 iT~encex- .o1 wlsct a new K between both valuer andrepeat Steps 2-8. See ote 6.

I TRIAL 2

12 Approx inuto K Udng A l k w a M r

I3 Tmdb Load in Steel


31/36

Design of Vessel upports 197

bIfcfEM Maximumbearing loadfc P1Figure 3 71. Loading diagram of base plate with gussets and chairs

Type 1: Without Chairs or GussetsK = rom Anchor Bolts.ef, = rom Anchor Bolts.d =

e Bending moment per unit lengthM = 0.5f 12

e Maximum bearing load2Kd +wb, = f c 2Kd , see Table 3-35)

e Thickness required

Type : With Gussets Equally Spaced StraddlingAnchor Boltse W ith same number s anchor bolts

ndb = - Nb

M,=greater o M r My rom Table 3-36/6M,

tb = ig

Figure 3 72. Dimensions of various base plate configurations

e W ith twice s many gussets s anchor boltsndN

b

b =

M, = greater of M or My from Table 3-36

Type 3 or 4: With Anchor Chairs or Full Ringe Between gussets

P = F,R,PbM = 8


32/36

98 Pressure Vessel esign ManualBetween chairs

M, =greater of M or y rom Table 3-36

Top Plate or Ring Type 3 or 4)e Minimum required height of unchor chair Ty pe 3 or 4 .

hlllin 7 296d < 18in.H

Minimum required thickness of top plate of unchor chair.

Top plate is assumed as a beam, e x with partially ftvedends and a portion of the total anchor bolt force P/3,distributed along part of the span. See Figure 3-73.)Bending moment, M,, in top ring Ty pe 4 .b

y1= see Table 3-37y = see Table 3-371 If a = t / 2 and b/e > 1,My governs

M =pn [(1+ u)log@ (1 n)]2 . If a U 2 but b/e > 1, My governs

3 . If b/e < 1. invert b/e and rotate axis X-X and Y-Y 90

nr D 1

Figure3 73. op plate dimensions and loadings.

ashers

X

Figure 3 74. ompression plate dimensions.

Minim um required thickness of top ring Ty pe 4 .

Gussetse Type 2. Assume each gusset shares load with each adjoin-ing gusset. The uniform load on the base is fc and the area

supported by each gusset is x b. Therefore the load onthe gusset isPI=f,CbThickness required istg = Pi 6a eFhe2

e Type or 4 .> n .Pt 18,000e 8


33/36

esignof Vessel upports 199kirt

Thickness required in skirt at compression plate or ringdue to muximum bolt load reaction.For Type 3:- 10

For Type :Consider the top compression ring as a uniform ring withN number of equally spaced loads of magnitude.PahSee Procedure 5-1 for details.The moment of inertia of the ring may include a portion ofthe skirt equal to 16t,k on either side of the ring seeFigure 3-75).Thickness required at opening o skirt.Note: If skirt is stiffened locally at the opening to compen-sate for lost moment of inertia of skirt cross section, thisportion may be disregarded.G = width of opening, in.

1 48Mhf b n D - 3 G [ o Wh

Actual weights and moments at the elevation of the open-ing may be substituted in the foregoing equation ifdesired.

P[aPah

ah

I IFigure 3 75. Dimensions and loadings on skirt due to load P

Skirt thickness required:

f b fl4,640,000

whichever is greaterDetermine allowable longitudinal stresses.TensionSt esser of 0.6F, or 1.33sCompression

S 0.333 F,1.33x factor BtskEl16R1.33s

whichever is less.Longitudinal forces

Skirt thickness required

whichever is greater.Thickness required at skirt head attachment due to Mt.Longitudinal forces

Skirt thickness required

F L Cor 0 707SCE

FLTtsk 0.707S t Ewhichever is greater.


34/36

2 Pressure Vessel esign ManualNotes

~~

1. Base plate thickness:0 If t in., use Type 1.0 If0 If t > n., use Type 3 or 4.

2 To reduce sizes of anchor bolts:

in. t n., use Type 2.

0 Increase number of anchor bolts.0 Use higher-strength bolts.0 Increase width of base plate.

3 Number of anchor bolts should always be a multiple of4 If more anchor bolts are required than spacingallows, the skirt may be angled to provide a largerbolt circle or bolts may be used inside and outside ofthe skirt. Arc spacing should be kept to a minimum ifpossible.

4 . The base plate is not made thinner by the addition of acompression ring. th would be the same as required forchair-type design. Use a compression ring to reduceinduced stresses in the skirt or for ease of fabricationwhen chairs become too close.

5 Dimension a should be kept to a minimum to reduceinduced stresses in the skir t . This will provide a moreeconomical design for base plate, chairs, and anchorbolts.

6. The value of K represents the location of the neutralaxis between the anchor bolts in tension and the con-crete in compression. A preliminary value of K is esti-mated based on a ratio of the allowable stresses of theanchor bolts and concrete. From this preliminary value,anchor bolt sizes and numbers are determined andactual stresses computed. Using these actual stresses,the location of the neutral axis is found and thus anactual corresponding K value. A comparison of theseK values tells the designer whether the location of theneutral axis he assumed for selection of anchor boltswas accurate. In successive trials, vary the anchor boltsizes and quantity and width of base plate to obtain anoptimum design. At each trial a new K is estimated andcalculations repeated until the estimated K and actualK are approximately equal. This indicates both abalanced design and accurate calculations.

7 The maximum compressive stress between base plateand the concrete occurs at the outer periphery of thebase plate.

8. For heavy-wall vessels, it is advantageous to have thecenter lines of the skirt and shell coincide if possible.For average applications, the O.D. of the vessel andO D of the skirt should be the same.

9. Skirt thickness should be a minimum of R/200.

PRO EDURE 3 15DESIGN OF B SE DET ILS FOR VERTIC L VESSELS 2

Notation~

E =joint efficiencyE modulus of elasticity at design temperature, psiAI,=cross-sectional area of bolts, in.2

d diameter of bolt circle, in.Wl, =weight of vessel at base, lbWT =weight of vessel at tangent line, Ibw width of base plate, in.S code allowable stress, tension, psiN =number of anchor boltsF: allowable bearing pressure, concrete, psiF, minimum specified yield stress, skirt, psiF, =allowable stress, anchor bolts, psi

fLT axial load, tension, Ib/in.-circumferencefIdc axial load, compression, lb/in.-circumferenceFT allowable stress, tension, skirt, psiF, allowable stress, compression, skirt, psiFl, allowable stress, bending, psi

f =tension force per bolt, lbf =bearing pressure on foundation, psiMb overturning moment at base, ft-lbMT overturning moment at tangent line, ft-lb

llowable Stresses

0.6F,1 33sFT lesser of

F, lesser of0.333FY1.33 Factor BtskEl16 R1.33s


35/36

Design of Vessel Supports 2 1

Bun welded Lap weldedE = 0 7 E = 0 5at=T/ n . 2 in . llh in.? Minimums

= YIS in. minimumx 3 x in.

min imum Ih 1 in.

Figure 3-76. Typical dimensional data and forces for a vertical vesselsupported on a skirt.

Fk =500 psi for 2000 lb concrete750 psi for 3000 lb concrete

O.125tskactor A = R

Factor B = from applicable materialchart of ASME Code, Section 11Part D Subpart 3

nchor Bolts

a Force per bolt du e to up lift.

e Required bolt area, Ah.A b = - =S

FsUse ) diame ter boltsNote: Use four -in.-diame ter bolts as a minimum.

Base Platea Bearing pressure, fc average at bolt circle).

e Required thickness o base plate. th

Skirte Longitudinal forces, f L T and fLc.

48Mb Wbf L T=fLC = - 1 7

D XD48Mb Wbr T

Notes1. This procedure is based on the neut ra l axis methodand should be used for relatively small or simple ver-

tical vessels supported on skirts.2 If mom ent ML is from seismic, assu me Wb as the oper-

at ing weight at the base. If Mb is du e to wind, assum eempty weight for comp uting the maximum value of fLTand operating weight for fLc .


36/36

2 2 Pressure Vessel esign Manuale Thicknew required of skirt at base plate, t .

f LTt,k greater of FTf1,CorFC

Tliickries~ eyiiiretl of skirt at skirt-head attachment.Longitudinal forces:

Thickness required:~ L T0.707 FTE,k greater of

0.707 Fc Er

REFERENCES1.

2

3.4

5.6.

8

9.10.11.

12.

ASCE 7-95, Minimum Design Loads for Buildingsand Other Structures, American Society of CivilEngineers.Recommended Practice 11, Wind and EarthquakeDesign Standards, Chevron Corp., San Francisco,CA, March 1985.Unqororni Building Code, 1997 Edition, InternationalConference of Building Officials, Whittier, CA, 1997.Bednar, H. H., Pressure Vessel Design Han dbook , VanNostrand Reinhold Co., 1981, Section 5.1.Brownell, L. E., and Young, E. H ., Process Eq uipm entVerign Tohn Wiley and Sons, Inc. , 1959, Section 1 0 . 2 ~ .Fowler, D. W., New Analysis Method for PressureVessel Column Supports, Hydrocarbon Processing,May 1969.Manual of Steel Construction, 8th Edition, AmericanInstitute of Steel Construction, Inc., 1980, TablesC1.8.1 and 3-36.h a r k , R. J . Fomnulns f i r Stress and Strain, 4thEdition, McGraw Hill, 1971, Table VIII, Cases 1, 8, 9and 18.Wolosewick, F. E. , Support for Vertical PressureVessels, Petroleum Refiner, July 1981, pp. 137-140,Blodgett, O., Design o Weldments , The James F.Lincoln Arc Welding Foundation, 1963, Section 4.7.Local Stresses in Spherical and Cylindrical Shells Dueto External Loadings, WRC Bulletin 107, 3rd revisedprinting, April 1972.Bijlaard, P. P., Stresses from Radial Loads andExternal Moments in Cylindrical Pressure Vessels,

August 1981, pp. 101-108.

13.

14

15.

16.17.

18.

19.20.21.

Welding Journal Research Supp lement, DecemberBijlaard, P. P., Stresses from Radial Loads andExternal Moments in Cylindrical Pressure Vessels.Weld ing Journal Research Supp leme nt, DecemberMegyesy, E . F.,Pressure Vessel Handbook, 3rd Edition,Pressure Vessel Handbook Publishing Co., 1975, pp.72-85.Zick, L. P., Stresses in Large Horizontal CylindricalPressure Vessels on Two Saddle Supports, WeldingResearch Journal Supplement, September 1951.Moody, G . B. How to Design Saddle Supports,Hydrocarbon Procesing, November 1972.Wolters, B. J Saddle Design-Horizontal Vesselsover 13 Feet Diameter, Fluor Engineers, Inc.,Irvine, CA, 1978.Committee of Steel Plate Producers, Steel PlateEngineering Datu, Volume 2, Useful Information onthe Design of Plate Structures, American Iron andSteel Institute, Part VII.Gartner, A. I., Nomographs for the Solution of AnchorBolt Problems, Petroleum Refiner, July 1951, pp.101-106.Manual of Steel Construction, 8th Edition, AmericanInstitute of Steel Construction, Inc., 1980, Part 3.Blodgett, O., Design of Welded Structures, The JamesF. Lincoln Arc Welding Foundation, 7th printing, 1975,Section 3 3

1955, pp. 608-617.

1954, pp. 615-623.

Documents

Pressure Vessel Support