Line sizing (Liquid Phase Case)

1. LINE SIZING
Liquid Phase Case
Chemical Engineer
Juan Pablo Hernández Castillo

2. PROCESS ENGINEERS TASKS
 Process engineers play an important role in the design of plants.
Some of the most common activities process engineers do are relating to:
1. Design of pipelines
2. Design of equipments
3. Design of instruments, such as control and safety relieve valves.
4. P&ID’s construction
5. Design of control strategy of differents parts of the plant.
6. Checking As Built’s
7. Design of the philosophy of operation of a particular section of the plant.
Among others…

3. Today, i would like to share with all of you, the steps taken into account when
designing pipelines.
Currently, one the most known international standard to design pipelines is
provided by the American Petroleum Institute.
API 14E. Recommended Practice for Design and Installation of Offshore
Production Platform Piping Systems.
API 14E design for the following states:
1. Liquid phase
2. Single Phase Gas
3. Gas-Liquid Phase lines.
DESIGN OF PIPELINES

4. Considerations
 API 14E stablish that in order to have a accurate pipe design, two main
conditions must be met: Velocity and Pressure Drop
 Velocity: In order to avoid
Sedimentation of particles 𝟑
𝐟𝐭
𝐬
Erosion (due to high velocity) 15
𝐟𝐭
𝐬
 Pressure Drop: In order to meet pressure drop conditions.
API stablish 1
𝒑𝒔𝒊
𝟏𝟎𝟎 𝒇𝒕
<

5. Flow Diagram

6. Example
 A process engineer is asked to design a pump
which can transport water from one deposit to
another.
PARAMETER SYMBOL VALUE UNIT
TEMPERATURE T 77 °F
VISCOSITY µ 1,85E-05 lb/(ft.s)
DENSITY ρ 1,92 slugs/ft3
SPECIFIC GRAVITY s 1
VOLUMETRIC FLOW RATE 2 ft3/s
30776,9031 barrels/day
PIPE LENGHT L 60 ft
PIPE ROUGHNESS ε 1,50E-04 ft
PUMP EFICCIENCY %
POTENTIAL HEAD ∆z 50 ft
SPECIFIC WEIGHT γ 62,2 lb/ft3
Q
INITIAL DATA

7. Assumptions
 The area in which the system is located : Industry sector
 1 Month= 30 days
 The system works 24h/30 days/1 year
 Average kWh (according to CREG) =$599,722 COP
 Suction and discharge same pipe size
 Comercial Steel Schedule 40 and Schedule 80 design try
 Pipeline lenght of 60 ft

8. Results
For Schedule 40 Comercial Steel:
For Schedule 80 Comercial Steel:
V(ft/s) Elbows Valves Line
1 231,41 1154,72 6543,42 10836,53 18534,6789 18584,6789 19417 3134,56224 $ 4.901.665 $ 18.136.160.855
2 59,60 63,28 358,57 312,51 734,354596 784,354596 560 132,292212 $ 200.029 $ 740.108.907
3 27,05 12,35 69,99 40,35 122,686563 172,686563 72,29 29,1259687 $ 42.695 $ 157.971.260
4 15,71 3,93 22,29 9,97 36,1998787 86,1998787 17,87 14,5387975 $ 20.832 $ 77.077.751
5 10,00 1,50 8,50 3,15 13,1419988 63,1419988 5,64 10,6497683 $ 15.063 $ 55.733.044
6 6,92 0,67 3,82 1,24 5,7340002 55,7340002 2,22 9,40030725 $ 13.223 $ 48.925.559
8 4,00 0,21 1,19 0,31 1,7113024 51,7113024 0,56 8,72182383 $ 12.229 $ 45.247.677
10 2,54 0,08 0,48 0,10 0,6638566 50,6638566 0,18 8,54515766 $ 11.972 $ 44.295.237
Nominal Diameter(in)
hL(ft)
∑hL(ft) ha(ft) $COP$(USD)PA(kW)∆P(psi)
∆P(psi) PA(kW) $(USD) $COP
Elbows Valves Line
1 278,05 1666,98 9446,25 17548,38 28661,6114 28711,6114 31443,67 4842,60896 $ 7.610.740 $ 28.159.736.856
2 67,73 81,71 463,04 435,91 980,66872 1030,66872 781,08 173,836484 $ 264.039 $ 976.943.993
3 30,28 15,47 87,67 53,97 157,10938 207,10938 96,70 34,9318513 $ 51.469 $ 190.435.597
4 17,40 4,82 27,33 12,95 45,1058345 95,1058345 23,21 16,0409097 $ 23.076 $ 85.381.495
5 10,99 1,81 10,27 4,01 16,0918776 66,0918776 7,18 11,147306 $ 15.800 $ 58.461.385
6 7,67 0,83 4,69 1,61 7,12831215 57,1283121 2,88 9,63547718 $ 13.570 $ 50.208.479
8 4,38 0,25 1,43 0,39 2,07145528 52,0714553 0,70 8,78256857 $ 12.318 $ 45.576.435
10 2,78 0,10 0,58 0,13 0,8053278 50,8053278 0,23 8,56901872 $ 12.006 $ 44.423.454
ha(ft)V(ft/s)Nominal Diameter
hL(ft)
∑hL(ft)

9. Analysis
 From the previous results, it must be highlighted that the only schedule pipe which met the
velocity-pressure drop requierements was the Schedule 40.
Schedule 40
 Despite the velocity was aceptable from 5 to 8 in nominal diameter. It was noted that the only
diameter which met the requierement of pressure drop(∆P= below 0,6 psi) was the 8 in pipe.
 In the other hand, it was seen that the proper selection of the pipe size does affects the cost of
operation.
 If for example: A process engineer had chosen a 6 inch pipe without taking into account the
requirements, then the cost of operation would have exceed 994 USD per year of operation.
Schedule 40
 Although 5, 6 and 8 inch diameter did meet the velocity requirements, the pressure drop conditions
were not reached.
Bad decisions during the piping design and pump selection can lead to years of unnecessarily high
cost of operation.

10. Schedule 40- Conditions analysis

11. Schedule 40- Cost analysis

12. REFERENCES
[1] R. Mott, Mecánica de fluidos, Dayton: Pearson, 2006.
[2] A. 14E, Recommended Practice for Design and Installation of Offshore Production Platform
Piping Systems., Washington: American Pretroleum Institute, 1991.
[3] C. d. R. d. E. y. G. (CREG), «TARIFAS DE ENERGÍA ELÉCTRICA ($/kWh) REGULADAS POR LA
COMISIÓN DE REGULACIÓN DE ENERGÍAY GAS (CREG) JUNIO DE 2020,» ENEL CODENSA, 2020.
[4] B. d. l. R. d. Colombia, «Tasa Representativa de Mercado (TRM-Peso por dolar),» Banco de la
Republica de Colombia, Colombia, 2020.

13. ¡THANKS FOR
WATCHING!
 Juan Pablo Hernández Castillo
Contact:
Email: juanpaheca@outlook.es
Cel: +57 304 395 5569
LinkedIn:
www.linkedin.com/in/juanhdezcastillo