Loquid gas transportation

1. PIPE SIZE (DIAMETER & THICKNESS)
TYPES OF PIPELINE SYSTEM
OIL SYSTEMS(LIQUID SYSTEM)
ARE COMMONLY DIVIDED INTO CRUDE OIL AND REFINED PRODUCT
SYSTEMS.
BOTH SYSTEMS COLLECT AND DELIVER HYDROCARBON MIXTURE THAT
NORMALLY EXIST AS LIQUID AT AMBIENT CONDITIONS.
LIQUEFIED PETROLEUM GAS (LPG) IS CONSIDERED ALSO A REFINED
PRODUCT THOUGH IT IS STORED AND HANDLED UNDER PRESSURE OR AT
REDUCED TEMPERATURE.
GAS SYSTEMS
CAN BE DIVIDED INTO DRY GAS SYSTEMS AND CONDENSATE GAS SYSTEM.
DRY GAS P/LINE SYSTEMS GATHER AND TRANSPORT IN GASEOUS STATE.
DRY GAS IS COMPRISED MAINLY OF METHANE AND ETHANE WITH A SMALL
PERCENTAGE OF HEAVIER COMPONENTS. DRY GAS OFTEN CONTAINS
SMALL QUANTITIES OF NON-HYDROCARBON COMPONENTS LIKE N2, CO2 AND
H2S.
CONDENSATE GAS NORMALLY COMPRISED OF METHANE AND ETHANE
ALONGWITH HEAVIER HYDROCARBON LIKE PROPANE, BUTANE, PENTANE,
HEXANE ETC.

2. GAS CONDENSATE MAY BE IN THE GASEOUS STATE AT THE
DISPATCH POINT BUT IT TENDS TO LIQUIFY AS A RESULT OF
CONDENSATION OF HEAVIER HYDROCARBON DURING
TRANSPORTATION DUE TO FALL IN TEMPERATURE OR PRESSURE
(RETROGRADE CONDENSATION).
THE SYSTEM BECOMES AS MULTIPHASE FLUID FLOW SYSTEM.
SPECIAL CARE HAS TO BE TAKEN IN COURSE OF
TRANSPORTATION OF SUCH TYPE OF GAS.
FLOW OF FLUIDS – HYDRAULIC CALCULATIONS
SEVERAL GENERALLY ACCEPTED FORMULAS FOR THE
CALCULATION OF PRESSURE DROP AND FLOW RATE FOR
PIPELINES.
SOME CO-RELATIONS TAKEN FROM RULES OF THUMB HAND
BOOK.
DIFFERENT FLOW EQUATIONS FOR LAMINAR & TURBULENT FLOW
OF COMPRESSIBLE AND NON- COMPRESSIBLE FLUIDS
(NEWTONIAN)

3. LIQUID PIPELINES:
DELIVERY PRESSURE AND THE VOLUMES ARE KNOWN.
THE ALLOWABLE WORKING PRESSURE CAN BE DETERMINED
USING THE PIPE SIZE , TYPE AND SPECIFIED SAFETY FACTORS.
INITIALLY, LINE SIZE MAY BE ASSUMED IN ORDER TO DETERMINE
MAXIMUM OPERATING PRESSURE AND THE PRESSURE DROP IN A
GIVEN LENGTH OF PIPELINE FOR A GIVEN FLOW VOLUME.
IF THE SUM OF DELIVERY PRESSURE AND PRESSURE DROP
EXCEEDS THE ALLOWABLE WORKING PRESSURE, A LARGER SIZE
PIPE MUST BE CHOSEN.
IT IS ALSO POSSIBLE TO CHANGE THE BOOSTER RATING AND THE
DISTANCE IBETWEEN STATIONS TO LOWER THE PRESSURE
REQUIREMENT AND ADJUST THE EVALUATED PIPE SIZE.
HOWEVER ALL DEPENDS UPON THE ECONOMY OF THE
OPERATION ON LONG TERM PERSPECTIVE.

4. PRESSURE DROP:
BERNOULLI THEOREM DESCRIBES THE FLOW OF FLUIDS IN A
PIPE.
TO DETERMINE THE PRESSURE DROP, THE FOLLOWING
EQUATION IS USED:
ΔP= ρ* F*L*V2/ 144D2 *G
WHERE
ΔP= PRESSURE DROP OVER LENGTH L (PSIG)
ρ = DENSITY OF THE FLUID (LB PER FT3)
F = FRICTION FACTOR DIMENSIONLESS
L = LENGTH OF PIPE FT
V = VELOCITY OF FLOW, FT PER SEC
D = INSIDE DIAMETER OF PIPE, FT
G = ACCELERATION DUE TO GRAVITY= 32 FT PER SEC2

5. MAXIMUM ALLOWABLE OPERATING PRESSURE (MOAP) (P)
CAN USUALLY BE CALCULATED USING THE FORMULA:
P = 2ST/D * F * E*T
WHERE;
P = DESIGN PRESSURE, PSIG
S = MIN. YIELD STRENGTH STIPULATED IN THE SPECIFICATION UNDER
WHICH THE PIPE WAS MANUFACTURED.
D = NOMINAL OUTSIDE DIAMETER OF THE PIPE, INCHES
T = NOMINAL WALL THICKNESS OF THE PIPE, INCHES
F = CONSTRUCTION PIPE DESIGN FACTOR
E = LONGITUDINAL FACTOR
T = TEMPERATURE DERATING FACTOR

6. IN ALL LIQUID AS WELL AS GAS TRANSPORTING PIPELINES
LENGTH, DELIVERY PRESSURE AND THE VOLUMES ARE KNOWN.
ACCORDINGLY, BASED ON THIS INFORMATION, PIPE SIZE
(DIAMETER) AND THE PUMPING/ COMPRESSION PRESSURES MAY
BE CALCULATED AND THE FINANCIAL IMPLICATIONS CAN BE
WORKED OUT.
HIGHER PUMPING PRESSURE AND LARGER DIAMETERS
INCREASE THE CAPITAL AS WELL AS THE OPERATING &
MAINTENANCE COST.
TO IMPROVE UPON THE ECONOMY OF THE PROJECT, VARIOUS
SET OF PIPE SIZE, THEIR THICKNESS, THE ALLOWABLE WORKING
PRESSURE AND LENGTH OF THE PIPE CAN BE DETERMINED
USING THE PIPE SIZE AND TYPE AND ALSO CONSIDERING ALL THE
PARAMETERS AFFECTING THE PIPELINE DESIGN INCLUDING
NECESSARY & WELL SPECIFIED SAFETY FACTORS.
INITIALLY, A LINE SIZE MAY BE ASSUMED IN ORDER TO DETERMINE
MAXIMUM OPERATING PRESSURE AND THE PRESSURE DROP IN A
GIVEN LENGTH OF PIPELINE FOR A GIVEN FLOW VOLUME.

7. IF THE SUM OF DELIVERY PRESSURE AND PRESSURE DROP EXCEEDS
THE ALLOWABLE WORKING PRESSURE, A LARGER SIZE PIPE MUST BE
CHOSEN.
IT IS ALSO POSSIBLE TO CHANGE THE BOOSTER RATING AND THE
DISTANCE IN STATIONS TO LOWER THE PRESSURE REQUIREMENT AND
ADJUST THE EVALUATED PIPE SIZE. HOWEVER ALL DEPENDS UPON
THE ECONOMY OF THE OPERATION ON LONG TERM PERSPECTIVE.
AN INDICATIVE LOCATION OF BOOSTER STATION, BASED ON THE
DELIVERY PRESSURE AND THE FRICTION LOSSES WILL DICTATE THE
BOOSTER RATING AND DISTANCES AMONG THEM.
A PARALLEL LINE CONCEPT MAY BE ONE OF THE EXAMPLES TO
ECONOMIZE THE OPERATION IF THE DEMAND AND SUPPLY AS WELL AS
DELIVERY PRESSURE REQUIREMENTS ARE NOT CONSTANT/ UNIFORM
OR VARY VERY FREQUENTLY.

8. REYNOLDS’S NUMBER:
NUMBER EXHIBITS THE TYPE OF FLOW AND MAINLY DEPENDS UPON
THE DIAMETER OF PIPE AND VOLUMETRIC FLOW RATE OF THE
FLOWING FLUID.
THESE TWO PARAMETERS ARE RELATED TO PIPELINE GEOMETRY
THE DENSITY AND VISCOSITY OF THE FLUID ARE THE PHYSICAL
PROPERTIES OF FLUID.
THE FLOW PATTERN CULMINATES INTO THE REYNOLDS’S NO. WHICH
FURTHER CO RELATES TO FRICTION FACTOR/ FRICTION LOSSES IN
PIPE LINE.
THIS TYPE OF FLOW INCLUDES LAMINAR FLOW & TURBULENT FLOW.
THESE TERMINOLOGIES ARE REDEFINED WITHIN SPECIFIC VALUE
LIMITS I.E. LAMINAR FLOW.
WHEN REYNOLDS’S NUMBER IS BELOW 1000, IT IS CALLED AS
STREAMLINED FLOW, BETWEEN 1000 AND 2000 AS UNSTABLE FLOW
AND TURBULENT FLOW IF IT IS GREATER THAN 2000.
THIS FACTOR GENERALLY DENOTES THE EFFECT ON PRESSURE DROP.
01.08.12

9. PHYSICAL PROPERTIES OF THE PIPELINES:
ROUGHNESS OF PIPELINE:
THESE FACTORS ARE DETERMINED EMPIRICALLY AND ARE RELATED TO
THE ROUGHNESS OF THE INSIDE PIPE WALL. THIS FACTOR IS DRAWN
BASED ON ACTUAL PRESSURE DROP IN THE SIMULATED CONDITIONS AND
ASSUMED VARIABLES. BASED ON THE SET OF SUCH FACTORS, MOST
APPROPRIATE VALUE IS FIXED FOR SIMILAR CONDITIONS.
VALVES AND FITTINGS:
VALVES AND FITTINGS PLAY VITAL ROLE IN ADDING TO PRESSURE LOSS.
THE VALUES OF SUCH LOSS CAN BE DETERMINED BASED ON
EXPERIMENTAL DATA.
MINIMUM YIELD STRENGTH & DUCTILITY:
ARE THE KEY PROPERTIES OF STEEL FOR PIPELINE DESIGN. THE MINIMUM
YIELD STRENGTH IS THE KEY PROPERTY OF STEEL USED IN DESIGN. THE
MINIMUM YIELD STRENGTH IS DEFINED AS THE TENSILE STRESS
REQUIRED PRODUCING A TOTAL ELONGATION OF 0.5 %.

11. MAXIMUM ALLOWABLE OPERATING PRESSURE
THE KEY PARAMETER IN PIPELINE DESIGN AND OPERATIONS IS THE
MAXIMUM ALLOWABLE OPERATING PRESSURE (MAOP).
THIS IS DEFINED AS THE MAXIMUM PRESSURE UNDER ROUTINE
OPERATING CONDITIONS. THESE PRESSURE ARE EVALUATED BASED ON
THE FLUID CHARACTERISTICS AND THE VOLUMETRIC FLOW RATES BUT
THE OVERALL LIMIT OF THE MAXIMUM ALLOWABLE PRESSURE ALSO
DEPENDS UPON THE PHYSICAL PROPERTIES NAMELY TENSILE STRENGTH
AND THE DUCTILITY OF THE CONSTRUCTION OF MATERIAL OF PIPELINE.
PIPELINE CODES TYPICALLY PERMIT THE MAOP TO BE SET EQUAL TO THE
DESIGN PRESSURE (DP).
THE CODES ALLOW A PRESSURE INCREASE ABOVE THE DESIGN
PRESSURE OF 10 % TO ACCOMMODATE FOR PRESSURE SURGES, WHICH
ARE INCIDENTAL IN NATURE AND OF SHORT DURATION. THIS IS KNOWN AS
MAXIMUM ALLOWABLE INCIDENTAL PRESSURE (MAIP).
THE MAXIMUM OPERATING PRESSURE (MOP) AND PRESSURE
RECORDER/ALARM (PRA) ARE USUALLY SET AT 5% BELOW THE MAOP.
THIS IS TO ALLOW OPERATOR SUFFICIENT TIME TO TAKE REMEDIAL
ACTION BEFORE PIPELINE TRIPS/RELIEF VALVES START TO LIFT.

13. DETERMINATION OF WALL THICKNESS:
THE DETERMINATION OF PIPELINE WALL THICKNESS IS MOST
IMPORTANT IN PIPELINE MECHANICAL DESIGN.
WALL THICKNESS IS A FUNCTION OF THE PIPELINE’S MAXIMUM
ALLOWABLE OPERATING PRESSURE AND THE YIELD STRENGTH OF THE
STEEL PIPE USED.
OPERATING PRESSURE AND WALL THICKNESS DETERMINE THE NUMBER
AND LOCATIONS OF PUMP OR COMPRESSOR STATIONS ALONG THE
PIPELINE.
IF A HIGHER PIPELINE OPERATING PRESSURE IS CHOSEN, THE POWER
AT EACH STATION CAN BE GREATER, AND THE STATIONS CAN BE
FARTHER APART. THIS BENEFIT CAN BE OFFSET BY ADDITIONAL
EXPENSE OF THICKER WALL PIPE.
THE INTERNAL PRESSURE OF THE TRANSPORT FLUID INDUCES A
CIRCUMFERENTIAL STRESS IN THE PIPE WALL, WHICH IS COMMONLY
KNOWN AS HOOP STRESS

15. HOOP STRESS CAN BE CALCULATED BY USING A SIMPLIFIED FORMULA,
USUALLY KNOWN AS BARLOW’S
BARLOW’S FORMULA IS NOT THE MOST ACCURATE FORMULA TO
CALCULATE PIPELINE WALL STRESS. IT OVERESTIMATES THE MAXIMUM
HOOP STRESS. BUT MOST PIPELINE CODES SPECIFY THAT BARLOW’S
FORMULA BE USED IN PIPELINE DESIGN.

16. THIS FORMULA TAKES INTO ACCOUNT AN ADDITIONAL PARAMETER, CALLED A
DESIGN FACTOR, F. THE PURPOSE OF USING A DESIGN FACTOR IS TO KEEP
THE CIRCUMFERENTIAL STRESS OF THE PIPE AT A FRACTION OF THE YIELD
STRESS, AS A SAFETY PRECAUTION.

19. Design of liquid pipeline
The introduction to the pipeline network is given as under:
Overview of Oil and gas field production:
For oil and gas field production, various types of facilities exist, including
surface and subsea production systems. The surface production system
typically is made up of a fixed offshore platform generally in shallow water
depths (up to 200m). Oil, gas, or both are transported to shore via submarine
pipeline.
Types of Onshore /Offshore - Subsea pipelines
There are four general classifications of pipelines, depending on the line
function. Certain pipe sizes and operating pressure may also be associated
with each line classification. These classifications are flow lines, collector /
gathering lines or inter-field lines, trunk lines and loading (Unloading) lines.

20. Flow lines (Intra field lines)
A flow line connects a wells to a GGS/ platform or subsea manifold. Usually the line has a
small diameter. Flow inside of it may be at high pressure. Flow lines include well fluid;
water injection and gas lift lines. A well fluid line carries reservoir fluids before separation.
Water injection lines are used for injecting treated water in the reservoir for reservoir
pressure (secondary recovery) maintenance. Gas lift lines are used to inject gas in the
tubing string for lifting of well fluid on decline of reservoir pressure.
Increasing the length of well fluid flow lines increases wellhead back pressure on wells.
However, development of multiphase pumping and metering is a major milestone in
achieving long distance well fluid transportation.

21. The design of well fluid transportation and gathering system
should take into consideration the following:
1. The wellhead pressure should be as low as possible to
enhance self flow and recovery of fluid.
2. Minimum pressure loss in pipeline.
3. Easy to monitor and control the wells.
4. Minimum loss of hydrocarbons.
5. Accurate metering of well fluid.
6. Flexibility for future expansion.
7. Operational safety.
8. Optimum production cost.

22. Different types of gathering systems;
•Wellhead separation system
•Group gathering system
•Centralized gathering system.
Wellhead separation system:
•Main gathering lines are laid in the form of a loop around. the field. Individual wells have their
own separation and testing facility and the oil and gas lines are connected to the main collector
lines.
•Highest recovery from the field, by maintaining lowest wellhead pressure, is possible in this
system.
•This system is generally adopted in isolated small pools alongwith tanker based transportation,
Group gathering system:
•Main collector lines are laid from a central processing facility to group gathering facility or
process platform facility.
•This type of system is generally applicable when moderate to large amounts of liquid is
produced. Two phase flow of liquid and gas causes more pressure drop in the individual flow
lines and consequently high back pressure on the wells. However this is an economical and
flexible system for most of the fields.

23. Centralised gathering system
•Main gathering multiphase lines run through the field and wells are produced
directly into the main line from either side. A test line is run parallel to the mainline to
carry out periodic testing of wells.
•The system is generally used in oil and gas fields where getting ROU is normally
difficult and the wells are densely located in the field.
•Use of clustered well location system, in both offshore and onshore, necessitated
well platforms with separation and test facility in offshore or underwater manifold
centre (UMC) in subsea locations and group and test gathering lines in onshore
locations.
•A header in a gathering or distribution system provides a means of joining several
flow lines into a single gathering line. Valves are provided on each pipeline entering or
leaving the header so that lines can be isolated during operation and maintenance.
Collector / Gathering lines (Inter-field lines)
A collector line connects from one (multi-well) platform/GGS to another Central
Processing platform/Facility and is usually a small to medium-diameter line but can be
large diameter too. They generally carry process fluids. The range of operating
pressure is usually 1,000 – 1,400 psi. Flow in the line is done by booster pumps or
compressors, which are often installed on the Central Processing Platform/ Facility.

24. Loading (Unloading lines)
These lines are used in offshore operations and usually connect a production
platform or a subsea manifold to a loading facility (Single Buoy Mooring,
SBM). The lines can be small or large diameter and carry liquid only i.e. Oil can
be loaded to tankers at SBM.
Trunk lines/ Cross-country lines
Trunk/ Cross country lines transport oil and gas from one or many platforms to
shore terminal for quality maintenance in case of offshore operation whereas
to refining/ process plant in case of onshore operations..
Trunk line System
Transportation of crude oil by trunk pipeline makes it economically feasible to
produce oil in areas remote from processing points and markets.
Great advances have been and continue to be made in trunk line
transportation of crude oil. These include improvements in materials and
methods of pipe manufacture and better design and construction methods for
both pipelines and stations.

25. Hydraulic Analysis and Line Sizing
Economic Pipe Diameter
For a given flow rate of a given fluid, piping cost increases with diameter. But,
pressure loss decreases, which reduces potential pumping or compressing
costs. An economical balance between material costs and pumping costs is
important for designing the pipelines.
•The optimum pipe size is found by calculating the smallest
capitalization/operating cost; or using the entire pressure drop available; or
increasing velocity to highest allowable.
•The economic diameter will be the one which makes the sum of amortized
capital cost plus operating cost minimum. The total cost can be per unit time
or per unit of production.
•An approximate correlation for estimation of economic diameter is as
below:
Am0.45 0.027
D e = ------------------
0.31
Where
de = Economic diameter, inch
m = Mass flow rate lb/hr
 = Fluid density, lb/ft3
A = Constant = 1.7
 = Viscosity, cp

26. However, in order to work out the overall economics of the
system on long term operation of the pipeline, other relevant
factors can not be ignored. The purpose of pipeline hydraulics
analysis is to optimize pipeline size and to determine pumping or
compressor requirements.
1. Relevant Pipeline Parameters,
2. Liquid Pipeline Sizing,
3. Waxy Crude,
4. Gas Pipeline Sizing,
5. Two-phase Flow.

27. RELEVANT PIPELINE PARAMETERS
•FLUID VOLUME,
•DISTANCE,
•PRESSURE LOSSES
FLUID VOLUME
THE ANTICIPATED VOLUME OF THE FLUID TO BE TRANSPORTED IS
THE MAIN PARAMETER IN PIPELINE SIZING.
USUALLY THE AMOUNT OF GAS, CRUDE OIL OR PRODUCT THAT IS
DELIVERED TO THE MARKET VARIES FROM SEASON TO SEASON AND
EVEN DURING THE SAME DAY.
DESIGNERS MUST DESIGN TO DELIVER FUTURE PEAK VOLUME
PROJECTION AND ONE SATISFYING THE CURRENT PEAK MARKET
REQUIREMENT ONLY.
EXCESS CAPACITY WILL REDUCE THE PIPELINE PROFITABILITY,
WHEREAS TOO SMALL A LINE MIGHT NEED TO BE EXPANDED IN THE
FUTURE.

28. DISTANCE
THE P/LINE LENGTH BETWEEN THE SOURCE AND DELIVERY POINTS MUST
BE KNOWN.
NEEDS TO KNOW THE TYPE OF TERRAIN THE PIPELINE IS GOING TO
TRAVERSE AND THE ELEVATION PROFILE ALONG THE RIGHT-OF-WAY AS
IT AFFECTS PRESSURE LOSS AND POWER REQUIREMENTS.
DESIGNERS MUST ALSO CONSIDER ENVIRONMENTAL CONDITIONS,
ECOLOGICAL, HISTORICAL AND ARCHEOLOGICAL SITES AS IT MIGHT
IMPACT PIPELINE ROUTING THUS INCREASING PIPELINE LENGTH.
PRESSURE LOSS
KEY PARAMETER IN PIPELINE DESIGN. ACCURATE PRESSURE LOSS
PROJECTIONS ARE CRITICAL AS DIRECTLY IMPACTS THE ABILITY OF THE
PIPELINE TO MEET DESIGN SPECIFICATIONS.
AVAILABLE PIPELINE INLET PRESSURE AND OUTLET PRESSURE
REQUIREMENT AT THE DELIVERY POINT MUST BE KNOWN TO DETERMINE
THE PRESSURE LOSS / PUMPING HORSE POWER REQUIREMENT AS WELL
AS TO DESIGN PIPELINE SIZING

29. KEY PHYSICAL PROPERTIES OF FLUID
PLAY IMPORTANT ROLE IN DETERMINING THE PIPELINE
DIAMETER, SELECTING THE PIPE MATERIAL AND THE ASSOCIATED
EQUIPMENT AND THE POWER REQUIRED TO TRANSPORT THE
FLUID.
THE MOST IMPORTANT FLUID PROPERTIES THAT AFFECT
PIPELINE DESIGN ARE:
WATER, CO2, AND H2S CONTENT.
COMPRESSIBILITY
POUR POINT:
TEMPERATURE
SPECIFIC HEAT OF LIQUIDS
SPECIFIC GRAVITY & DENSITY
VISCOSITY,
VAPOR PRESSURE,

30. 1. WATER, CO2, AND H2S CONTENT
WATER CONTENT, AND CO2 AND H2S LEVEL IN THE TRANSPORT FLUID
WILL CAUSE INTERNAL CORROSION IN PIPELINES. THESE ARE
REQUIRED TO SELECT THE RIGHT PIPELINE MATERIAL (OR PROPER
COATING) TO PREVENT THE PIPELINE FROM INTERNAL CORROSION.
2. COMPRESSIBILITY:
NOT SIGNIFICANT WHILE DESIGNING PRESSURE DROPS IN LIQUID
PIPELINES. BUT SIGNIFICANT IN CASE OF GAS PIPELINE DESIGN.
MOST GASES DEVIATE FROM THE IDEAL GAS LAW.
THE TERM, SUPER COMPRESSIBILITY FACTOR IS MORE SIGNIFICANT
AT HIGH PRESSURE AND TEMPERATURE CONDITIONS.
3. POUR POINT:
USUALLY DIFFICULT TO PUMP OILS BUT CAN BE PUMPED BELOW
THEIR POUR POINT UNDER SPECIAL CONDITIONS WHICH NEED TO BE
GENERATED DURING PUMPING HENCE IMPORTANT AT DESIGNING
STAGE

31. 4. TEMPERATURE:
AFFECTS PIPELINE CAPACITY BOTH DIRECTLY AND INDIRECTLY. IN CASE OF GAS,
LOWER THE OPERATING TEMPERATURE, GREATER THE CAPACITY. TEMPERATURE
ALSO AFFECTS THE PHYSICAL PROPERTIES OF THE LINE PIPE WHICH MAY AFFECT
THE STRENGTH OF THE PIPE BODY AS WELL AS THE ULTIMATE UPSTREAM
PRESSURE LIMIT. LIQUIDS OF LOWER POUR POINT MAY STOP FLOWING ON
REDUCTION OF THE TEMPERATURE, REQUIRE HIGHER PRESSURE TO FLOW THE
OIL.
5. SPECIFIC HEAT OF LIQUIDS:
PLAYS IMPORTANT ROLE IN MAINTAINING THE FLOW ASSURANCE IN THE
PIPELINE. HIGHER THE SPECIFIC HEAT OF THE FLUID HIGHER THE CAPACITY TO
RETAIN HEAT ENERGY AND LESSER THE HEAT LOSS TO THE ENVIRONMENT
DURING FLUID TRANSPORTATION.
ALSO, EXPANSION AND CONTRACTION PROPERTIES VARY WITH EFFECT OF TEMP.
CHANGE. THE TEMPERATURE CHANGES ARE INVERSELY PROPORTIONAL TO THE
SPECIFIC HEATS OF THE FLUID SUBJECT TO NO CHANGE IN HEAT ENERGY OF THE
SYSTEM.
6. SPECIFIC GRAVITY AND DENSITY:
THESE ARE THE SYNONYMOUS OF THE WEIGHT OF THE FLUID AND DIRECTLY
AFFECT THE DESIGN PARAMETER/ RESULTS. HIGHER THE DENSITY MORE IS
THE PRESSURE DROP.

32. 7. VISCOSITY
IS A MEASURE OF A FLUIDS INTERNAL RESISTANCE TO FLOW.
IT IS DETERMINED EITHER BY MEASURING THE SHEAR FORCE REQUIRED
TO PRODUCE A GIVEN SHEAR GRADIENT
OR
BY OBSERVING THE TIME REQUIRED FOR A GIVEN VOLUME OF LIQUID TO
FLOW THROUGH A CAPILLARY OR RESTRICTION.
FLUID VISCOSITY VARIES WITH TEMPERATURE.
FOR LIQUIDS, VISCOSITY DECREASES WITH INCREASING TEMPERATURE.
GAS VISCOSITY DEPENDS ON TEMPERATURE, RELATIVE DENSITY, AND
PRESSURE.
8. VAPOR PRESSURE
IS THE PRESSURE EXERTED BY THE VAPOR IN THE LIQUID PHASE IN A
CONFINED CONTAINER AT A GIVEN TEMPERATURE. VAPOR PRESSURE
INCREASES WITH TEMPERATURE.
VAPOR PRESSURE DETERMINES THE OPERATING CONDITIONS AT WHICH A
FLUID MOVES FROM SINGLE-PHASE FLOW (LIQUID PHASE) INTO TWO-
PHASE FLOW, A MIXTURE OF GAS AND LIQUID.

33. PRESSURE LOSSES
IS THE SINGLE MOST IMPORTANT PARAMETER IN PIPELINE DESIGN.
AN ACCURATE PRESSURE LOSS PROJECTION DETERMINES THE DIA
METER AND THICKNESS OF A PIPELINE FOR A SPECIFIC THROUGHPUT
REQUIREMENT.
PRESSURE LOSS DURING FLOW IN A PIPELINE OCCURS FOR THE
FOLLOWING REASONS:
1. FRICTION LOSS,
2. ELEVATION LOSS,
3. ACCELERATION LOSS, AND
4. SPECIAL LOSS

34. THE TOTAL PRESSURE LOSS ACROSS A PIPELINE SYSTEM IS THE SUMMATION OF
THESE INDIVIDUAL LOSSES

35. FRICTION LOSS
MAJOR COMPONENT OF THE PRESSURE LOSS THAT OCCURS DURING
FLOW THROUGH A PIPELINE.
CAUSED BY THE RESISTANCE TO FLOW DUE TO FLUID VISCOSITY.
FRICTIONAL PRESSURE LOSS DEPENDS UPON THE FOLLOWING:
•VISCOSITY OF THE FLUID,
•FLUID VELOCITY,
•DENSITY OF THE FLUID,
•INTERNAL DIAMETER OF THE PIPE,
•INTERNAL ROUGHNESS OF THE PIPE.
FRICTION LOSS INCREASES WITH DENSITY, WHILE IT DECREASES
DRAMATICALLY WITH THE INCREASE IN PIPE DIAMETER.
FRICTION LOSSES INCREASE WITH THE INCREASING INTERNAL PIPE
ROUGHNESS.
TURBULENT FLOW PRODUCES A HIGHER-PRESSURE DROP THAN LAMINAR
FLOW.

36. FRICTIONAL PRESSURE LOSS IS USUALLY DETERMINED USING WHAT IS COMMONLY
KNOWN AS DARCY’S FORMULA, NAMED AFTER THE NINETEENTH CENTURY FRENCH
ENGINEER, HENRY DARCY, WHO EXPERIMENTED WITH FLUID HYDRAULICS

37. FRICTION FACTOR, F, LARGELY DEPENDS ON
1. THE REYNOLDS NUMBER OF THE FLUID FLOW
2. RELATIVE ROUGHNESS OF THE PIPE SURFACE
REYNOLDS NUMBER IS A DIMENSIONLESS NUMBER RELATING
VELOCITY AND VISCOSITY INDICATING WHETHER FLUID IS IN
LAMINAR OR TURBULENT FLOW CONDITIONS. MOST FLUID
FLOWS ENCOUNTERED ARE USUALLY IN THE TURBULENT
FLOW REGION, WITH THE ONLY EXCEPTION OF VERY HEAVY
VISCOUS CRUDES, WHICH MAY EXHIBIT LAMINAR FLOW.
THE RELATIVE ROUGHNESS IS THE ROUGHNESS OF THE
INTERNAL SURFACE OF THE PIPE WALL DIVIDED BY THE
INTERNAL DIAMETER OF THE PIPE. IT IS DIMENSIONLESS.

39. ELEVATION LOSS
IT IS ESSENTIAL TO KNOW THE ELEVATION PROFILE OF THE TERRAIN TO
BE TRAVERSED BY THE PIPELINE.
PRESSURE DIFFERENCES CORRESPONDING TO THE DIFFERENCE IN
ELEVATION OR "HEAD" BETWEEN THE PUMPING STATION AND THE
DELIVERY POINT MUST BE CONSIDERED.
THIS DIFFERENCE IN PIPELINE ELEVATION CAUSES WHAT IS KNOWN AS,
THE ELEVATION PRESSURE LOSS OR GAIN DEPENDING ON WHETHER THE
ELEVATION IS POSITIVE OR NEGATIVE. IT IS GIVEN BY THE EQUATION .

40. ACCELERATION LOSS
ACCELERATION LOSS IS THE PRESSURE LOSS ASSOCIATED WITH
ACCELERATION OF THE FLUID IN THE PIPELINE.
WHENEVER THERE IS A CHANGE IN PIPELINE DIAMETER, FLUID VELOCITY
CHANGES CAUSING EITHER ACCELERATION OR DECELERATION. ACCELERATION
LOSS IS GIVEN BY THE FOLLOWING EQUATION .
COMPARED TO THE OTHER LOSSES, ACCELERATION LOSSES IN A PIPELINE ARE
VERY SMALL AND ARE USUALLY IGNORED IN PIPELINE DESIGN.

41. SPECIAL LOSS
VARIOUS DEVICES INSTALLED IN A PIPELINE, SUCH AS, VALVES,
FITTING, ELBOWS, METERS, AND PRESSURE REGULATORS, ALSO
CONTRIBUTE TO PRESSURE LOSS IN PIPELINES.
THESE LOSSES ARE NORMALLY DETERMINED EXPERIMENTALLY
AND ARE EXPRESSED EITHER BY THE RESISTANCE COEFFICIENT
OR AS AN EQUIVALENT PIPE LENGTH.
THESE LOSSES ARE COMPARATIVELY SMALL AND ARE OFTEN
NEGLECTED.
HOWEVER, IN PLANT PIPING WITH MANY FITTINGS, VALVES AND
PUMPS, THESE LOSSES CAN BECOME SIGNIFICANT.

42. DIAMETER SIZING
PIPELINE DIAMETER IS NORMALLY DETERMINED BY A TRIAL AND ERROR
ITERATIVE PROCESS.
FIRST, A TENTATIVE PIPE DIAMETER IS SELECTED FOR THE DESIGN THROUGHPUT
RATE.
THEN, USING THE EQUATIONS GIVEN IN FIGURE 1 AND IGNORING ACCELERATION
LOSS, THE TOTAL PRESSURE DROP IS CALCULATED.
OUTLET PRESSURE IS THE DELIVERY PRESSURE, AND IS USUALLY DETERMINED
BY THE CUSTOMER’S REQUIREMENTS, SALES OR CONTRACTUAL OBLIGATIONS.
IF THE CALCULATED PRESSURE LOSS FOR THE CHOSEN DIAMETER IS TOO HIGH,
THE INLET PRESSURE MAY EXCEED THE ALLOWABLE DESIGN PRESSURE.
IF THIS IS THE CASE, A LARGER PIPE DIAMETER IS SELECTED AND THE PROCESS
IS REPEATED. THE AIM IS TO SELECT AN OPTIMUM PIPE DIAMETER THAT CAN BE
SAFELY USED WITHIN THE PIPELINE OPERATING PRESSURE.
THE SAFE OPERATING PRESSURE IS DETERMINED BY DIVIDING THE YIELD
STRESS OF THE PIPE BY THE REQUIRED SAFETY FACTOR AS SPECIFIED BY THE
APPLICABLE REGULATIONS.

43. PUMPING POWER
IT IS NECESSARY TO CONSIDER THE WHOLE SYSTEM, INCLUDING THE AVAILABLE
INLET PRESSURE, REQUIRED OUTLET PRESSURE AND ANY PUMPING
REQUIREMENTS.
IF NOT ENOUGH PRESSURE AVAILABLE IN THE SYSTEM, PUMPS MAY BE
NECESSARY TO MOVE THE FLUID.
PUMPING POWER REQUIRED TO TRANSPORT A LIQUID CAN BE CALCULATED BY
EQUATION SHOWN AS UNDER.
THIS IS A SIMPLIFIED EQUATION, WHICH IGNORES THE EFFECT OF FLUID
TEMPERATURE AND VISCOSITY. HOWEVER, THIS FORMULA IS WELL ACCEPTED IN
THE INDUSTRY AND IS WIDELY USED.

44. DESIGN OF GAS PIPELINES: -
FACTORS AFFECTING THE PIPELINE DESIGN
GAS DENSITY
COMPRESSIBILITY
UNLIKE LIQUID, WHICH IS INCOMPRESSIBLE, GAS IS COMPRESSIBLE.
GAS DENSITY IS A FUNCTION OF PRESSURE, TEMPERATURE AND
MOLECULAR WEIGHT. THE EQUATION FOR GAS DENSITY IS SHOWN
HEREUNDER:

45. DUE TO THE NON-IDEAL BEHAVIOR OF NATURAL GAS, AN EXTRA
COMPRESSIBILITY FACTOR Z IS USED IN THE EQUATION .
THIS EXTRA COMPRESSIBILITY FACTOR, Z IS AN EMPIRICAL NUMBER,
AND IS DEPENDENT UPON THE CHARACTERISTICS OF THE INDIVIDUAL
GAS. FOR PERFECT GAS, IT IS EQUAL TO 1. FOR A NON-IDEAL GAS, IT IS
GREATER OR LESS THAN ONE DEPENDING UPON THE TEMPERATURE,
PRESSURE AND COMPOSITION AND IS DETERMINED BY EXPERIMENT.

47. GAS FLOW PRESSURE LOSS
THE AGA EQUATION IS USED TO CALCULATE PRESSURE LOSSES IN
GAS PIPELINES.

48. LIKE THE DARCY EQUATION, IT ALSO REQUIRES A FRICTION FACTOR, F,
WHICH IS CALCULATED FROM THE MOODY EQUATION .

49. THERE ARE SEVERAL OTHER EQUATIONS AVAILABLE, SUCH AS
WEYMOUTH, PANHANDLE AND MODIFIED PANHANDLE FORMULA, BUT AGA
EQUATION IS WIDELY ACCEPTED AND USED.
THESE EQUATIONS ARE EXPRESSED BOTH IN METRIC UNIT AND BRITISH
UNIT.
•Panhandle - A :
q =K (Ts/Ps) 1.0788 X [(P1
2 – P2
2)/ (T f L Z a)] 0.5394 X (1/G) 0.4606 X (d) 2.6182 X (E)
Where,
fM = 0.085/ (NRe)
0.147
q = 435.87 [d2.6182/ γ g
0.0460] [Tb /P b] 1.07881 [(P1
2 – P2
2 /T z L)] 0.5394
Metric English
K = 3290 K = 435.87
1/f = 101(QG/d)0.1461 1/f = 52(QG/d)0.1461

50. Metric English
K = 3973 K = 737
(1/f)0.5 = 18.26(QG/d)0.1961 1/f = 16.7(QG/d)0.1961
•(Modified) Panhandle (Panhandle – B) :
q =K (Ts/Ps) 1.02 X [(P1
2 – P2
2)/ (TfLZaG0.961)] 0.510 X (d) 2.530 X (E)
Where,
f M = 0.015/ (NRe ) 0.392
q = 737 d2.530] [Tb /P b] 1.02 [(P1
2 – P2
2 /T z L γ g
0.961)] 0.510

51. Metric English
K = 1740 K = 433.49
f = 0.0109/d0.33 1/f = 0.008/d0.33
•Weymouth ( Equation for horizontal flow)
q =K (Ts/Ps) 1.02 X [(P1
2 – P2
2)/ (GTf L Za)] 0.5 X (d) 8/3 X (E) --------------1
Where,
f M = 0.015/ ( NRe ) 0.392 --------------------------------------------------------------2
qh = [18.062Tb / P b] [ (P1
2 – P2
2) D 16/3/ T Z L γ g ] 0.5 -------------------------3

52. GAS COMPRESSION – POWER REQUIREMENT
COMPRESSOR POWER REQUIRED TO TRANSPORT GAS THROUGH A
PIPELINE IS DETERMINED BY USING AN EQUATION, WHICH REQUIRES
SEVERAL PARAMETERS.
THESE PARAMETERS INCLUDE
FLOW RATE,
TEMPERATURE,
SUCTION PRESSURE,
DISCHARGE PRESSURE,
COMPRESSIBILITY FACTOR
AND SPECIFIC HEAT OF THE FLUID