fuel oil storage vessel design

Fuel oil Storage Vessel Design Plant & Equipment Design

Welahetti W.P.K 080533H Level 04 4/5/2012

Fuel oil Storage Vessel Design 2012

Prasanna Welahetti

Contents 1 Data .................................................................................................................................... 4

2 Fuel oil Details .................................................................................................................... 4

3 Pressure vessel codes and standards ................................................................................ 5

4 Material Selection .............................................................................................................. 5

5 Design Pressure Calculation ............................................................................................... 6

6 Design Temperature Calculation ....................................................................................... 8

7 Design Stress Calculation ................................................................................................... 8

8 Wall thickness calculation .................................................................................................. 9

9 Selection of ends .............................................................................................................. 10

9.1 Head selection ........................................................................................................... 10

9.2 Bottom selection ....................................................................................................... 13

9.2.1 Bottom wall thickness calculation ..................................................................... 13

9.2.2 Checking for reinforcement ............................................................................... 14

10 Fabrication Procedure...................................................................................................... 16

10.1 Shell Fabrication .................................................................................................... 16

10.2 Head and cone fabrication .................................................................................... 19

10.3 Assembly of shell and head ................................................................................... 19

10.4 Assembly of shell and cone ................................................................................... 20

11 Technical Drawing ............................................................................................................ 21

11.1 Torispherical head heights calculation .................................................................. 21

11.2 Thickness reducing length calculation ................................................................... 21

11.3 Front Elevation ...................................................................................................... 22

11.4 Top elevation ......................................................................................................... 23

12 References ....................................................................................................................... 24


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Table of figure Figure 5.1 Vessel Pressures ........................................................................................................ 6

Figure 7.1 Typical design Stress for Plate .................................................................................. 8

Figure 8.1 Minimum Practical Wall thickness ............................................................................ 9

Figure 9.1 Torispherical Head .................................................................................................. 10

Figure 9.2 Stress concentration ............................................................................................... 12

Figure 9.3 Calculaded Stress concentration ............................................................................ 13

Figure 9.4 Reinforcement Checking Table ............................................................................... 14

Figure 9.5 Reinforcement for Conical Bottom ......................................................................... 15

Figure 10.1 Prepinging of Plates Edges .................................................................................... 17

Figure 10.2 Single V-joint ......................................................................................................... 18

Figure 10.3 Single V-groove welded Butt Joins ........................................................................ 18

Figure 11.1 Front Elevation ...................................................................................................... 22


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1 Data A vertical storage vessel is used to store fuel oil according to the class stipulated by the

appropriate codes and standards. The vessel is to be designed for the following conditions

2 Fuel oil Details

There are 6 types of fuel oil coming from petroleum refinery. Those are types are shown in

below,

Number 1 fuel oil (also called the kerosene)

Number 2 fuel oil

Number 3 fuel oil

Number 4 fuel oil

Number 5 fuel oil

Number 6 fuel oil

Fuel oil numbers 1 and 2 are referred to as distillate fuels oil, while fuel oil numbers 4, 5,

and 6 are labeled residual.

Number 5,6 fuel oil need to pre heat before feed to boiler or furnace. This is also call the

furnace oil. According to literature survey furnace oil should be store in 30-35˚C rage.

Therefore I have selected fuel oil as furnace oil.

Following priorities are important for selection of material for the vessel (According to

“Ceypetco Product Specifications; Specification For Furnace Oil 800 Sec (P-026)”)

Absolute pressure - 1.1 atm Operating temperature - 30-35˚C Mean diameter -4.5 m Length of cylindrical shell - 12 m


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Density Max 970kg/m3

Flash point Min 60˚C

Pour point Max 21˚C

Our operating temperature is 30-35 ˚C. Pour point is less than operating temperature

therefore it cannot achieve semi solid conditions and flow property losses.

3 Pressure vessel codes and standards

Here I have followed the American Society

of Mechanical Engineers (ASME) Boiler

and Pressure Vessel Code. It is

internationally recognized code,

establishes rules of safety governing the

design, fabrication, testing and inspection

of boilers and pressure vessels.

Vessels, designed, fabricated and

inspected to meet ASME code division1

section VIII requirements are marked with

U. according to this vessel following

recommendations are suitable.

U-70 for non toxic gases and liquids(Light duty vessels)

temperature limit 250 F

Pressure below 100 psi

4 Material Selection

There are several factors affecting to material selection. Those are Strength, Corrosion Resistance, Resistance to Hydrogen Attack, Fracture Toughness, Fabricability. According to ASME Section Viii, Division 1, and Subsection C; material selection was done.

Most of the pressure vessels are fabricating using low carbon steel. Carbon steel is not

resistance to corrode. Sometimes there can be mercaptance, acid, water droplets with the

fuel oil therefore it is better to go corrosion resistance material.

According to my trial calculation low alloy steel is give high tensile strength. It is more than

enough to operating vessel pressure and temperature. Therefore low alloy steel suitable for

this vessel.


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According to above table; Low –Alloy Steel SA-202 grade A is suitable.

5 Design Pressure Calculation

Assumptions

Considered fuel oil as furnace oil

Figure 5.1 Vessel Pressures

𝐴𝑡𝑚𝑜𝑠𝑝𝑕𝑒𝑟𝑖𝑐 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 = 1 𝑎𝑡𝑚

Therefore;

𝑃𝑖𝑛 > 𝑃𝑒𝑥

To calculate the design pressure following equation can use;


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Assume maximum furnace oil level is 12m.

Density of fuel oil (furnace oil) = 890𝑘𝑔/𝑚3

chydrostatiP = 𝑕𝜌𝑔

chydrostatiP = 12 × 970 × 9.81

chydrostatiP = 114188.4𝑁/𝑚2

𝑃𝑚𝑎𝑥𝑖𝑚𝑢𝑚 𝑜𝑝𝑒𝑟𝑎𝑡𝑖𝑛𝑔 𝑏𝑦 𝑔𝑎𝑢𝑔𝑒 = 𝑃𝑎𝑏𝑠𝑜𝑙𝑢𝑡𝑒 − 𝑃𝑎𝑡𝑚

𝑃𝑔𝑎𝑢𝑔𝑒 = 1.1 − 1 𝑎𝑡𝑚

𝑃𝑔𝑎𝑢𝑔𝑒 = 0.1𝑎𝑡𝑚 = 10132.5 𝑁/𝑚2

𝑃𝑚𝑎𝑥𝑖𝑚𝑢𝑚 𝑜𝑝𝑒𝑟𝑎𝑡𝑖𝑛𝑔 𝑏𝑦 𝑔𝑎𝑢𝑔𝑒 = 10132.5 𝑁/𝑚2

5% 0f Pmax. Operating by gauge =506.625N/m2

506.625N/m2<114188.4𝑁/𝑚2

Therefore

gaugechydrostati PP by ingmax.operat%5

Therefore;

𝑃 𝑑𝑒𝑠𝑖𝑔𝑛 = 10132.5 𝑁/𝑚2 + 114188.4𝑁/𝑚2

𝑃 𝑑𝑒𝑠𝑖𝑔𝑛 = 124320.9𝑁/𝑚2

=0.124MPa

chydrostatigaugedesign

gaugechydrostati

PPP

PP

by ingmax.operat

by ingmax.operat%5


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6 Design Temperature Calculation

The strength of metals decreases with increasing temperature so the maximum allowable

design stress will depend on the material temperature. The design temperature at which the

design stress is evaluated should be taken as the maximum working temperature of the

material.

There is no any reaction inside the vessel; therefore body is non-directly heating. So we

have to go for following equation;

𝑇𝑑𝑒𝑠𝑖𝑔𝑛 = 𝑕𝑖𝑔𝑕𝑒𝑠𝑡 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑜𝑓 𝑠𝑡𝑜𝑟𝑒𝑑 𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙

𝑇𝑑𝑒𝑠𝑖𝑔𝑛 = 35℃

oCTT bodyofetemperaturhighesto

designo 10

= 35 + 10

= 45℃

7 Design Stress Calculation According to above material selection; fabrication material was low-alloy steel.

Figure 7.1 Typical design Stress for Plate

According to above table design stress is 240N/mm2.

𝜎𝑑𝑒𝑠𝑖𝑔𝑛 = 240𝑁/𝑚𝑚2


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8 Wall thickness calculation

𝑡𝑡𝑕𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 = 𝑃𝑑𝑒𝑠𝑖𝑔𝑛 𝐷𝑖𝑛𝑛𝑒𝑟

2Ψ𝜎𝑑𝑒𝑠𝑖𝑔𝑛

=124320.9×4.5

2×0.85×240×106

= 1.37𝑚𝑚

For the safety corrosion allowances need to include with the wall thickness.

𝐶 = 3𝑚𝑚

Therefore;

𝑡 = 1.37 + 3

= 4.37 𝑚𝑚

There will be a minimum wall thickness required to ensure that any vessel is sufficiently rigid

to withstand its own weight, and any incidental loads.

As a general guide the wall thickness of any vessel should not be less than the values

specified by standards including a corrosion allowance.

Figure 8.1 Minimum Practical Wall thickness

Diameter of vessel is 4.5m but wall thickness was 4.37mm with including corrosion

allowances. Therefore diameter needs to increase 14mm. (by referring chemical engineering

volume 6 and interpolating)

𝑡 𝑎𝑐𝑡𝑢𝑎𝑙 = 14𝑚𝑚


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9 Selection of ends

9.1 Head selection Plat heads are use for small vessel for low pressure and covers for man. Flanged only ends

are used for diameter less than 0.6m. This vessel diameter is 4.5m. Therefore flanged only

ends are not suitable for this vessel.

Flanged and dished elliptical ASME code type heads are used extensively in the construction

of tanks for liquefied petroleum gas, air receivers, and other unfired pressure vessels and

Pdesign > 1.5 MPa . But fuel is in liquid phase and Pdesign < 1.5 MPa. Therefore elliptical heads

are not suitable for this vessel.

Torispherical heads are suitable for inner pressure less than 13 bar. Therefore We have to

go to torispherical head because P internal is slightly grater than atmospheric pressure. It

minimizes the total cost of the plate material and its formation.

Figure 9.1 Torispherical Head

The ratio of the knuckle to crown radii should not be less than 0.06, to avoid buckling; and

the crown radius should not be greater than the diameter of the cylindrical section.

𝐷𝑜𝑢𝑡𝑒𝑟 = 4.5 + 0.028 = 4.528𝑚

𝑃𝑑𝑒𝑠𝑖𝑔𝑛 = 124320.9𝑁/𝑚2

𝜎 𝑑𝑒𝑠𝑖𝑔𝑛 = 240 𝑀𝑁/𝑚2

Assume;

R crown = D outer

r knuckle = 6% D outer


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Therefore;

𝑅 𝑐𝑟𝑜𝑤𝑛 = 4.528𝑚

𝑟 𝑘𝑛𝑢𝑐𝑘𝑙𝑒 = 0.272𝑚

Calculate the effective external head height he;

Substituting to above equation;

𝑕𝑒 = 0.767𝑚


𝑕𝑒 = 1.132𝑚


𝑕𝑒 = 2.89𝑚

From above three values of he; need to select minimum value for calculate the head

thickness. Therefore

𝑕𝑒 = 0.767𝑚


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Stress concentration factor for formed heads:

t/Do

h E / Do 0.00075 0.0005 0.001 0.002 0.005 0.01 0.02 0.04

0.15 5.34 5.50 5.18 4.55 2.66 2.15 1.95 1.75

0.20 2.55 2.60 2.5 2.3 1.7 1.45 1.37 1.32

0.25 1.48 1.50 1.46 1.38 1.14 1 1 1

0.30 0.98 1.00 0.97 0.92 0.77 0.77 0.77 0.77

0.40 0.59 0.59 0.59 0.59 0.59 0.59 0.59 0.59

0.50 0.55 0.55 0.55 0.55 0.55 0.55 0.55 0.55

Figure 9.2 Stress concentration

𝑕𝑒

𝐷0=

0.767

4.528

𝑕𝑒

𝐷0= 0.17

Calculation of shape factor C; by interpolating from above table

CPD

tdesign

designouter

ltheorotica *2

*

Assume =1; therefore substituting to above equation;

𝑡𝐷𝑜𝑢𝑡𝑒𝑟

=124320.9

2 × 0.85 × 240 × 106

×𝐶


= 3.05 × 10−4

×𝐶

And also;

𝑡′𝐷𝑜𝑢𝑡𝑒𝑟

= 𝑡𝑎𝑏𝑙𝑒 𝑔𝑖𝑣𝑒𝑛 𝑣𝑎𝑙𝑢𝑒


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C value can determine using above intersection point;

𝐶 − 4.21

5.81 − 4.528=

3.65 − 𝐶

9.056 − 5.04

𝐶 = 4.07



= 3.05 × 10−4

× 4.07

𝑡 = 5.62 𝑚𝑚

There should be corrosion allowances for;

Thickness of the head =5.62+3

=8.62mm

Therefore thickness of head is 8.62mm. But there is no low-alloy steel plate for this

thickness in market. Therefore for head fabrication 10mm thickness low-alloy steel sheet is

needed.

9.2 Bottom selection Furnace oil has high viscosity at 35℃ (10,000SSU). Therefore it is more suitable for conical

bottom for vessel. Then furnace oil is easy flow.

9.2.1 Bottom wall thickness calculation

Assume this vessel;𝛼 = 30°

t/ Douter

0.0005 0.00075 0.001 0.002 0.005 0.01 0.02 0.04

hE/Douter =0.17 4.34 4.22 4.21 3.65 2.276 1.87 1.718 1.578

t(mm) 5.99 5.82 5.81 5.04 3.14 2.58 2.37 2.18

t’(mm) 2.264 3.396 4.528 9.056 22.64 45.28 90.56 181.12

Figure 9.3 Calculaded Stress concentration

c

D

design

.P6.0cos2

Pt

design

design

actual


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𝑡 =0.1243 × 4.528

2 cos 30 240 × 0.85 − 0.6 × 0.124

𝑡𝑎𝑐𝑡𝑢𝑎𝑙 = 1.59+3

= 4.59𝑚𝑚

But there is plates available in market 4.59mm thickness. Therefore 6mm thickness plate

needs to fabricate conical bottom.

9.2.2 Checking for reinforcement

Figure 9.4 Reinforcement Checking Table

𝑃

𝜑.𝜎=

0.1240.85 × 240

=6 × 10−4

By extrapolating

∆=6 × 10−4 − 1 × 10−3

1 × 10−3 − 2 × 10−3× 13 − 18 + 13

∆= 11°

11 < 30

Therefore;

∆< 𝛼.

Therefore conical bottom required reinforcement.


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9.2.2.1 Calculation of reinforcement

Figure 9.5 Reinforcement for Conical Bottom

𝐴 =0.1243

240 × 0.85×

4.5282 × 𝑡𝑎𝑛30

8 × 1 −

11

30

= 5.71 × 10−4

𝑡𝑠𝑕𝑒𝑙𝑙 =Pdesign × Di

2σφ − P design

𝑡𝑠𝑕𝑒𝑙𝑙 =0.1243 × 4.5

2 × 240 × 0.85 − 0.1243= 1.37mm

Let’s assume reinforcement thickness is t’ ;

𝐴 = 8𝑡 × 𝑡′ × 2 + (8𝑡𝑐 × 𝑡′ × 2)

5.71 × 10−4 = 8 × 0.00459 × 2 × 𝑡′ + 8 × 0.00137 × 2 × 𝑡′

𝑡′ = 5.99𝑚𝑚

1

8

tan2

iDpA


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10 Fabrication Procedure

10.1 Shell Fabrication 1. Cutting

The most commonly used process for the cutting and edge preparations of carbon

steel plates is oxyacetylene cutting, and that for stainless steel plates in plasma-arc

cutting. The cut edges will have excessive oxide deposition that is black in color. This

is to remove by grinding, and the acceptable level is at least 1.0mm deep into the

presence of oxides shall be completely removed. Here the maximum and minimum

low alloy steel plates thicknesses are 14mm and 6mm.

Here we can use laser cutting also for this. Compare to Oxy-acetylene flame; quality

of the edge can be mirror smooth, and a precision of around 0.1mm, Cutting speeds

on thin (1.2mm) sheet can be as high as 25m a minute form laser cutting.

2. Crimping

Plate rolling roundness and efficiency is enhanced by the use of the crimping process

prior to rolling. Crimping sets the correct radius on the ends of the plate and

eliminates the waste of excess material. Following tools can use for the fabrication

Hand Crimping Tools, Crimping Pliers, Hydraulic Hand Pumps crimpers, Separable

Hydraulic crimper.

3. Heating

To increase the bending ability of plate, it is important to heating. Inside the furnace

heating is normally doing.

4. Rolling

Using rolling machines, ends of

plates are connecting properly

according to required diameter is

the challenge of rolling. The shell

plate will have more strength in

the direction of rolling compared

to its transverse direction. Hence,

as far as possible, the direction of

the bending of the plate shall be

same as that of the original

direction of rolling, which is the

direction of rolling, which is the

direction of the length of the plate

as shown in below.


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5. Prepinging

Once the shell plate is fed into the bending machine, first both the ends are pressed

to the required shape, as below.

Figure 10.1 Prepinging of Plates Edges

6. Welding

Longitudinal seam is fitted for welding. When the thickness of the plate is less than

16mm single-V welded joints are recommended. This wall thickness is 14mm.

Therefore single V-groove welded butt joints are suitable this welding.


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Figure 10.2 Single V-joint

Figure 10.3 Single V-groove welded Butt Joins

7. Heat Treating

It is important that your fabrications are properly heat treated. Thermal heat

treatments are specified to steel materials that have been cold-formed, flame cut, or

fabricated, and prior to final machining to reduce residual stresses for dimensional

stability and to improve service life. Temperature is increased up to 1750°.

8. Testing

There are several types of testing methods to test the fabrication. When vessel

carried out with lethal substances and thickness is greater than 38.1mm; fully

radiography is more suitable. But here thickness is less than 38.1mm. Therefore fully

Radiography is unwanted (more economical). Spot Radigraghy also use to measure

the efficiency of weld joints.


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10.2 Head and cone fabrication

Usually head manufactures are following above three steps. Nowadays automatic head

design machines can use for the head design.

10.3 Assembly of shell and head


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10.4 Assembly of shell and cone


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11 Technical Drawing

11.1 Torispherical head heights calculation

𝑆𝑖𝑛∅ =

𝐷2 − 𝑟

𝑅 − 𝑟

R=4.5m

r=0.272m

by substituting;

∅ = 27.89°

𝑕 𝑘𝑛𝑢𝑐𝑘𝑒𝑙 = 𝑟 𝑐𝑜𝑠∅ = 240.3𝑚𝑚

𝑕 𝑑𝑖𝑠𝑕𝑒𝑑 = 𝑅𝑐𝑟𝑜𝑤𝑛 − 𝑅𝑐𝑟𝑜𝑤𝑛 𝑐𝑜𝑠∅ = 522.6𝑚𝑚

for calculate h flanged;

𝑕𝑡𝑜𝑡𝑎𝑙 = 𝑕𝑓𝑙𝑎𝑛𝑔𝑒𝑑 + 𝑕𝑘𝑛𝑢𝑐𝑘𝑒𝑙 + 𝑕𝑑𝑖𝑠𝑕𝑒𝑑

and

𝑕𝑡𝑜𝑡𝑎𝑙 =2

3𝑕𝑓𝑙𝑎𝑛𝑔𝑒𝑑

by solving above eq;

𝑕𝑓𝑙𝑎𝑛𝑔𝑒𝑑 = 1525.8𝑚𝑚

11.2 Thickness reducing length calculation

According to the ASME code; thickness different into three times those values were

calculated.


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11.3 Front Elevation

Figure 11.1 Front Elevation


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11.4 Top elevation

Φ4.772 𝑚

Φ4.5 𝑚

Top elevation


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12 References http://www.simetric.co.uk/si_liquids.htm

http://www.nature.nps.gov/hazardssafety/toxic/fueloil.pdf

http://www.ceypetco.gov.lk/Ceypetco_Products.htm#CP17

http://www.rodewelding.com/plate-rolling/

http://www.rodewelding.com/heat-treating/

Chemical engineering Volume 6; Richardson& Clusion

ASME Section VIII

fuel oil storage vessel design

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