4. CONTENTS OF PRESENTATION
1. Introduction of pipelines
2. History of pipelines
3. Importance of pipelines
4. Types of pipelines
5. Components of pipelines
6. Advantages of pipelines
7. Oil pipelines hydraulics (working fluid)
8. Properties of crude oil
9. Hydraulic design
10. Laws or principles involves
11. Pressure Losses calculation in pipelines
12. Measurement devices
13. Sensors involved in pipelines
14. Protection of pipelines against abrasion ,freezing and corrosion
15. Leak detection
16. Piping codes
17. Analysis of pipeline using software's
( structural and flow analysis)
5. Introduction to pipelines
Definition
The term pipe is defined herein as a closed conduit,
usually of circular cross section. It can be made of any
appropriate material such as steel or plastic. The term
pipeline refers to a long line of connected segments of
pipe, with pumps, valves, control devices, and other
equipment/facilities needed for operating the system.
Purpose
It is used for transporting a fluid (liquid or gas),
mixture of fluids, solids, fluid-solid mixture, or capsules
(freight-laden vessels or vehicles moved by fluids through a
pipe). The term pipeline also implies a relatively large pipe
spanning a long distance.
6. History of Pipelines
The use of pipelines has a long history.
For instance, more than 1,000 years ago, the
Romans used lead pipes in their aqueduct
system to supply water to Rome. As early as
400 B.C., the Chinese used bamboo pipes
wrapped with waxed cloth to transport natural
gas to their capital Beijing for lighting. Clay
pipes were used as early as 4000 B.C. for
drainage purposes in Egypt and certain other
countries.
7. Continued ……..
In 1879, following the discovery of oil in Pennsylvania, the first long-
distance oil pipeline was built in this state. It was a 6-inch-diameter, 109-mi-
long steel pipeline. Nine years later, an 87-mi-long, 8-inch-diameter pipeline
was built to transport natural gas from Kane, Pennsylvania to Buffalo, New
York. The development of high-strength steel pipes made it possible to transport
fluids such as natural gas, crude oil, and petroleum products over long distances.
Initially, all steel pipes had to be threaded together, which was difficult to do for
large pipes, and they often leaked under high pressure. The development of
electric arc welding to join pipes in the late 1920s made it possible to construct
leak proof, high-pressure, large-diameter pipelines.
8. Continued . . . .
The U.S. has far more oil and natural gas pipelines than any other
nation in the world: approximately 1.3 million mi (2.1 million km) of gas
pipeline and 0.25 million mi (0.4 million km) of oil pipeline. The amount of
oil transported by pipeline in the U.S. in 2000 was approximately 500
billion tons, which constitutes about half of the oil transported in the nation.
The largest natural gas producing state in the U.S. is Texas. A network of
pipelines totaling 4300 mi (6920 km) transports natural gas from Texas to
the Central and Eastern U.S., and California.
9. Importance of Pipelines
Pipelines are the least understood and least appreciated mode of
transport. Pipelines are poorly understood by the general public because
they are most often underground and invisible out of sight, out of mind!
Despite the low degree of recognition by the public, pipelines are vitally
important to the economic well-being and security of most nations.
10. Continued …..
All modern nations rely almost exclusively on pipelines to transport
the following commodities:
Water from treatment plants to individual homes and other buildings
Sewage from homes to treatment plants
Natural gas all the way from wells to the consumers who may be located more
than a thousand miles away—be it a home, a factory, a school, or a power plant
Crude oil from oil fields to refineries
Refined petroleum products (gasoline, diesel, jet fuel, heating oil, etc.) from
refineries to various cities over hundreds of miles
11. Continued . . . .
In addition, hundreds of other liquid, gas, and solid commodities (freight) are
transported via pipeline over long and short distances.
A pump house of the 273-mi-long Black Mesa Coal Slurry Pipeline that
transports 5 million tons of coal per year from Arizona to Nevada.
12. Continued …
The cargo loading station of a pneumatic
capsule pipeline used successfully in Japan
by Sumitomo Metal Industries, Ltd. Each
capsule in this 1-m-diameter, 3.2-km (one-
way length) pipeline carries 1.6 tonnes of
limestone from a mine to a cement plant.
13. Types of pipelines
Pipelines can be categorized in many different ways
1. According to Commodity Transported
Water pipelines
Sewage pipelines (sewers)
Natural gas pipelines
Oil pipelines (for crude oil)
Product pipelines (for petroleum products such as gasoline, diesel, jet fuel,
etc.)
Solid pipelines (coal, other minerals, sand, solid wastes, wood pulp, mail,
parcels, consumer goods, etc.)
Others (air, chemicals, hazardous waste, etc.)
14. continued ….
2 According to Fluid Mechanics
Single-phase compressible flow
Single-phase incompressible flow
Two-phase flow solid-liquid mixture (hydrotransport)
Two-phase flow of solid-gas mixture (pneumotransport)
Two-phase flow of liquid-gas mixture
Two-phase flow of capsules
Non-Newtonian fluids
3 According to Pipe Material
Steel pipelines
Cast-iron pipelines
Plastic pipelines
Concrete pipelines
Others (clay, glass, wood stave, etc.)
15. Continued …
4 According to Environment
Offshore pipelines
Inland pipelines
In-plant pipelines
Mountain (or cross-mountain) pipelines
Space pipelines (pipelines to be built in outer space, such as for space
exploration on another planet)
5 According to the Type of Burial or Support
Underground pipelines
Aboveground pipelines
Elevated pipelines
Underwater (submarine) pipelines
16. COMPONENTS OF PIPELINE
The important components of pipelines are:
Fittings
Valves
Joints
Flow meters
Sensors and components etc
17. Fittings
Screwed pipe fittings are to be used with threaded pipes. Welding fittings
and socket-welding fittings, on the other hand, are used with non threaded
pipes. The purposes of different fittings are :
18.
19. Valves
A valve is a device that regulates,
directs or controls the flow of
a fluid (gases, liquids, fluidized solids,
or slurries) by opening, closing, or partially
obstructing various passageways. Valves are
technically pipe fittings, but are usually
discussed as a separate category. In an open
valve, fluid flows in a direction from higher
pressure to lower pressure.
20. Types of valves
The various types of valves along with their functions are as follows.
Gate valve
A gate valve is closed and opened by turning the handle connected to
it, which raises or lowers a stem (shaft) connected to the gate. The gate
valve used in oil or natural gas pipelines has a conduit with a full round bore
for smooth passage of pigs or scrapers. They are called conduit gate valves
or fullbore gate valves.
Globe valve
Outside is globe shaped. Flow changes direction as it goes through
the valve. Consequently, large headloss is generated even when the valve is
fully open. This valve gives better control of flow than gate valves— good
for flow throttling.
21. Continued…
Angle valve
Same as globe valve except that the flow direction is changed by
90° as the flow leaves the valve. It is used only in locations of 90° bends
and is good for flow throttling.
Ball valve
The gate is a large bead (i.e., a large sphere having a central piercing).
The gate is turned from a completely closed to a fully open position in 90°.
When fully open, it causes little blockage to the flow and hence has little
head loss.
Plug valve
Similar to ball valve except that instead of a pierced ball, a pierced
plug is used. Used mainly in small lines (tubing’s) where it is usually
referred to as a cock valve. The valve can be either lubricated or non-
lubricated. It can have multiple ports, such as a 3-way valve.
22. Butterfly valve
Uses a center-pivoted disk gate This is the most economical type
for use in large pipes as in penstocks. Must be closed slowly or else the
valve can be damaged easily. Not for pipeline transportation of solids
due to wear by solids.
Diaphragm valve
A diaphragm separates the valve from the fluid. Consequently,
the valve can be used with corrosive fluids or abrasive slurry.
Pinch valve
Pinches a flexible tube to restrict or control the flow; is suitable
for small tubes only.
23. Check valve
Flow cannot reverse through a check valve; the valve produces
unidirectional flow. Three types of check valves are swing check valves
(horizontal or vertical lift types), tilt disk check valve (does not slam), and
ball check valve.
Foot valve
A special vertical-lift type check valve embedded in the vertical end
of a pipe connected to a reservoir below. The foot valve is used there to
prevent the pump from losing priming when the flow is stopped .
Pressure relief valve
The pressure relief valve, also called the safety relief valve, or
simply the safety The pressure relief valve is usually a spring-loaded
valve with the spring preset to withstand certain pressure. When the
pressure in the pipeline is within the preset value of the valve, the valve
is closed, and it has no influence on the flow in the pipe. However, when
the pressure in the pipe rises to a dangerous level, which is the preset
pressure of the safety valve, the spring is pushed back by this pressure,
and the valve is opened.
24. Pressure regulating valve (PRV)
Pressure regulating valve (PRV) is an automated special valve
mounted in a pipeline to regulate the pressure (i.e., maintain the pressure
within a predetermined range) in the pipe downstream of the regulator.
Unlike the safety valve, which is a small valve mounted on the pipe wall
and can affect only a small portion of the flow through the pipe, the PRV is
mounted in the main pipe
25. Flow meters
Flow meter is the devices that is used to
measure flow rate through any cross sectional area.
Types of flow meter
Flowmeter usually refers to the instrument for
measuring the flow rate through a pipe, either the
volumetric flow rate (discharge Q, in units such as cfs and
m3/s), or the mass or weight flow rate as in the units of
lb/s, or kg/s. Flowmeters play a central role in pipeline
instrumentation and monitoring. There are many types of
flowmeters.
Elbow Flowmeter
An elbow flowmeter uses an existing elbow
or bend of a pipe to measure the discharge through
the pipe The meter is based on the principle that
whenever a flow passes through a pipe bend, a
centrifugal force is generated. This force causes the
pressure on the outer side of the bend to rise beyond
that on the inner side of the bend, by an amount
proportional to the square of the velocity or
discharge
26. Rotating Flowmeter
Many types of rotating flow meters are available commercially. They
include propeller type, turbine type, vane type, gear type, and cup type. They are
unsuitable for flows that contain solids. They are used widely in both liquid and
gas pipelines in branches (distribution lines) where pigs do not go through.
Water meters used for rate charges to the customers most often use rotating flow
meters. Most of them are the positive-displacement type, with the volume of
flow passing through the meter being directly proportional to the number of
turns of the meter.
Vibratory Flowmeter
Vibratory flowmeters have a loose part exposed to the flow, vibrating at
a frequency proportional to the fluid velocity and the discharge. A common
type is a wobbling disk. The disk wobbles at a frequency proportional to the
volumetric discharge of the liquid through the pipe. Another type is based on
the vibration of a circular cylinder held perpendicular to the flow. The
vibration is caused by vortex shedding, which is a phenomenon discussed in
elementary fluid mechanics texts. Vibratory flowmeters can be used for both
liquid and gas that do not contain solids and where pigs or capsules do not
pass through.
27. Rotameters
Rotameters use a float inside a
transparent vertical tube to determine
the flow rate The meter must be
mounted in a vertical part of the pipe
with the flow going upwards. The
transparent tube is tapered, having an
expanded diameter with height. As the
flow rate increases, the float moves to a
higher location in the meter tube. The
meter is calibrated and graduated to
determine the flow rate (discharge Q)
from the location of the float.
28. SENSORS AND EQUIPMENT
Various sensors and equipment other than flowmeters are used in
monitoring and controlling pipelines. The most important ones are:
Manometers
Manometers provide the most economical, reliable, and accurate way
to measure pressure—both gage pressure and differential pressure.
Unfortunately, because the practical range of pressure that can be
determined with a manometer is limited, and because manometers can only
measure steady-state and slowly varying pressures, in many cases a pressure
transducer instead of a manometer is used Because the sensitivity of a
manometer is inversely proportional to the density of the liquid used in the
manometer, for low-pressure cases (water head less than 4 inches) it may be
advisable to use a liquid having a density lower than that of water, such as
an oil or ethanol. To prevent capillary effect from causing errors in pressure
readings, manometer tubes should have a minimum diameter of ½ inch or 6
mm.
29. Pressure transducers
A pressure transducer is a transducer that converts
pressure into an analog electrical signal. Although there are
various types of pressure transducers, one of the most
common is the strain-gage base transducer.
Other types are:
1. absolute-pressure transducers that measure the absolute
pressure instead of the relative or gage pressure,
2. relative-pressure transducers that measure the gage
pressure,
3. differential-pressure transducers that measure the
differential pressure between two taps,
4. static-pressure transducers that measure both the steady-
state pressure and a slowly varying pressure that varies at
a frequency within the frequency range of the transducer
capability,
5. dynamic-pressure transducers that are used only for high-
frequency variation of pressure and do not measure or
under-represent the low-frequency part of the signal,
6. high-temperature pressure transducers that are capable of
operating in a high-temperature environment, and
7. miniature pressure transducers for measuring pressures
connected to small taps and in situations where the
measuring equipment must be compact, etc.
30. •Temperature sensor
There are two general categories of temperature sensors—the contact type and the
noncontact type. The noncontact type is also called a pyrometer. Temperature transducers
come in three general types:
1. resistance temperature detectors,
2. thermally sensitive resistors, and
3. thermocouples.
Velocity Sensors
Sometimes, it is necessary or desirable to measure the fluid velocity at
specific locations in a pipe, such as the centerline of the pipe. When that happens,
one should carefully choose the most appropriate velocity sensor for the
measurement.The most fundamental and accurate method to measure the velocity
of fluid, be it a liquid or a gas, is by using a Pitot tube. Two common types of Pitot
tubes are the simple Pitot tube (also called stagnation tube) and the Prandtl-type
Pitot tube.
31. Vibration sensors
In critical parts of a pipeline system where vibration may be a
problem, vibration sensors should be used to monitor the vibration of
such parts. The two most common types of vibration sensors are
accelerometers and displacement sensors. The accelerometer, as its
name suggests, measures the acceleration of any structural part.
Strain gages
For safe operation of a pipeline system, one must make sure that
all parts of a pipeline including valves and pumps are operating within
the elastic limit of the material. When there is doubt as to whether a
pipe or any other part is stressed to beyond the elastic limit of the
material, strain gages can be used to find the answer. Strain gages are
transducers that measure directly the strain (i.e., unit elongation) of
any part of a structure or machine that is under stress. Once the strain
is measured, the stress can also be calculated from the strain by using
Hooke’s law
32. Advantages of pipelines
For the transport of large quantities of fluid (liquid or gas), a pipeline is
undisputedly the most favored mode of transportation. Even for solids, there are
many instances that favor the pipeline over other modes of transportation. The
advantages of pipelines are:
Economical in many circumstances
Low energy consumption
Friendly to environment.
Safe for humans
Unaffected by weather
High degree of automation.
High reliability.
Less sensitive to inflation.
Less susceptible to theft.
Efficient land use.
High degree of security
Convenience.
33. Oil pipelines hydraulics
Oil pipeline hydraulics covers the steady state analysis of compressible fluid
flow through pipelines. Mathematical derivations are reduced to a minimum, since
the intent is to provide the practicing engineer a practical tool to understand and
apply the concepts of oil flow in pipes. In particular, we will cover crude oil pipeline
transportation including how pipelines are sized for a particular flow rate, the
pressure required to transport a given volume of gas and the compression
horsepower required. The properties of crude oil that affect pipe flow will be
reviewed first followed by the concepts of laminar and turbulent flow and Reynolds
number. Frictional pressure loss and the method of calculating the friction factor
using the Moody diagram and the Colebrook and AGA methods will be illustrated
with examples. Several other popular flow equations, such as the Darcy-Weisbach
Formula and Hazen-Williams Formula will be introduced and explained with
example problems. Increasing pipeline throughput using intermediate pumping
stations as well as pipe loops will be discussed. The strength requirement of pipes,
allowable operating pressure and hydrostatic test pressure will be reviewed with
reference to the DOT code requirements. Several fully solved example problems are
used to illustrate the concepts introduced in the various sections of the course.
34. Properties of crude oil
Crude oil varies greatly in appearance depending on its composition. It is
usually black or dark brown (although it may be yellowish or even greenish). In
the reservoir it is usually found in association with natural gas, which being
lighter forms a gas cap over the petroleum, and saline water which, being
heavier than most forms of crude oil, generally sinks beneath it. Crude oil may
also be found in semi-solid form mixed with sand and water.
Mass
Mass is measured in slugs or pound mass (lbm) in the U.S. In the System
International (SI) units, mass is measured in kilograms (kg).
Weight
weight of a substance is a force (vector quantity), while mass is a scalar
quantity. Weight depends upon the acceleration due to gravity and hence
depends upon the geographical location. Weight is measured in pounds (lb). In
SI units weight is expressed in Newton (N). The relationship between weight W
in lb and mass M in slugs is as follows:
W = mg
Where g is the acceleration due to gravity at the specific location. At sea level, it
is equal to 32.2 ft/s2 in USCS units and 9.81 m/s2 in SI units.
35. SPECIFIC GRAVITY
The specific gravity of a fluid is defined as a ratio of the density of the
fluid to that of a standard fluid such as water or air at some standard temperature.
For liquids, water is the standard of comparison, while for gases air is used as the
basis. "The specific gravity of petroleum usually ranges from about 0.8 (45.3 API)
for the lighter crude oils to over 1.0 (less than 10 API) for heavy crude oil and
bitumen.
SPECIFIC VOLUME
Volume is the quantity of three-dimensional space enclosed by some
closed boundary, for example, the space that a substance (solid, liquid, gas, or
plasma) or shape occupies or contains. Volume is often quantified numerically
using the SI derived unit, the cubic metre. The volume of a container is
generally understood to be the capacity of the container, i. e. the amount of
fluid (gas or liquid) that the container could hold, rather than the amount of
space the container itself displaces. Barrels per day (abbreviated BPD, BOPD,
bbl/d, bpd, bd or b/d) is a measurement used to describe the rate of crude oil
production or consumption by an entity. For example, an oil field might
produce 100,000 bpd, and a country might consume 1 million bpd
36. Density p
The density of a fluid is obtained by dividing the mass of the fluid by the
volume of the fluid. Density is normally expressed as kg per cubic meter.
p = kg/m3
Water at a temperature of 20°C has a density of 998 kg/m3
Sometimes the term ‘Relative Density’ is used to describe the density of a
fluid. Relative density is the fluid density divide by 1000 kg/m3 Water at a
temperature of 20°C has a Relative density of 0.998
SPECIFIC VOLUME
Another term, called the specific volume is the inverse of the
specific weight, expressed in ft3/lb in the USCS units and m3/N in SI
units. Specific volume = volume of oil / weight of oil.
37. VISCOSITY
Viscosity describes a fluid's internal resistance to flow and may be thought
of as a measure of fluid friction. All real fluids (except superfluids) have some
resistance to stress and therefore are viscous, but a fluid which has no resistance to
shear stress is known as an ideal fluid or inviscid fluid.
38. Kinematic Viscosity v
The units of Kinematic viscosity are area / time v = ft2/s
1.00 ft 2/s = 929.034116 Stokes = 92903.4116 Centistokes
Water at a temperature of 70°F has a viscosity of 10.5900 x 10-6 ft2/s
(0.98384713 Centistokes)
Venezuela Oil Specifications
Anaco
Wax
Characteristics Units Typical
value
API Gravity °API 43.3
Sulphur WT % 0.15
Kinematic
Viscosity at 100 °F
CST
1.98
Vanadium ppm 1.04
Pour Point °C 70
39. Hydraulic design
Hydraulic diameter of ducts and tubes
The hydraulic diameter - dh - is used to calculate the dimensionless
Reynolds Number to determine if a flow is turbulent or laminar. A flow is
1. laminar if Re < 2300
2. transient for 2300 < Re < 4000
3. turbulent if Re > 4000
The hydraulic diameter is also used to calculate the pressure loss in a ducts or
pipe. The hydraulic diameter is not the same as the geometrical diameter in
a non-circular duct or pipe and can be calculated with the generic equation
dh = 4 A / p
where
dh = hydraulic diameter (m, ft)
A = area section of the duct (m2, ft2)
p = wetted perimeter of the duct (m, ft)
40. Hydraulic Diameter of a Circular Tube or Duct
The hydraulic diameter of a circular duct can be expressed as:
dh = 4 π r2 / 2 π r
= 2 r
where
r = pipe or duct radius (m, ft)
Hydraulic Diameter of a Circular Tube with an inside
Circular Tube
the hydraulic diameter of a circular duct or tube with an inside duct or tube can
be expressed as
dh = 4 (π ro
2 - π ri
2) / (2 π ro + 2 π ri)
= 2 (ro - ri)
where
ro = inside radius of the outside tube (m, ft)
ri = outside radius of the inside tube (m, ft)
41. •Hydraulic Diameter of Rectangular Tubes or Ducts
The hydraulic diameter of a rectangular duct or pipe can be calculated as
dh = 4 a b / (2 (a + b))
= 2 a b / (a +b)
where
a = width/height of the duct (m, ft)
b = height/width of the duct (m, ft)
Reynolds Number
The Reynolds number (Re) of a flowing fluid is obtained by dividing
the kinematic viscosity (viscous force per unit length) into the inertia force of
the fluid (velocity x diameter)
Kinematic viscosity = dynamic viscosity / fluid density
Reynolds number = (Fluid velocity x Internal pipe diameter)
/ Kinematic viscosity
42. Laws or principles involves
Bernoulli's principle
Bernoulli's principle states that for an inviscid flow, an increase in
the speed of the fluid occurs simultaneously with a decrease in pressure or a
decrease in the fluid's potential energy. Bernoulli's principle is named after
the Dutch-Swiss mathematician Daniel Bernoulli who published his
principle in his book Hydrodynamica in 1738. Bernoulli's principle can be
derived from the principle of conservation of energy. This states that, in a
steady flow, the sum of all forms of mechanical energy in a fluid along a
streamline is the same at all points on that streamline. A common form of
Bernoulli's equation, valid at any arbitrary point along a streamline where
gravity is constant, is:
43. Darcy–Weisbach equation
In fluid dynamics, the Darcy–Weisbach equation is
a phenomenological equation, which relates the head loss or pressure loss due
to friction along a given length of pipe to the average velocity of the fluid flow. The
equation is named after Henry Darcy and Julius Weisbach. The Darcy–Weisbach
equation contains a dimensionless friction factor, known as the Darcy friction factor.
This is also called the Darcy–Weisbach friction factor or Moody friction factor. The
Darcy friction factor is four times the Fanning friction factor, with which it should not
be confused
The Darcy-Weisbach equation
Weisbach first proposed the equation we now know as the Darcy-Weisbach formula or Darcy-
Weisbach equation:
hf = f (L/D) x (v2/2g) (2.14)
where:
hf = head loss (m)
f = friction factor
L = length of pipe work (m)
d = inner diameter of pipe work (m)
v = velocity of fluid (m/s)
g = acceleration due to gravity (m/s²)
44. Hazen-Williams Formula
Empirical formulae are occasionally still used to calculate the approximate
head loss in a pipe when water is flowing and the flow is turbulent
The imperial form of the Hazen-Williams formula is:
hf = 0.002083 L (100/C)1.85 x (gpm1.85/d4.8655)
where:
hf = head loss in feet of water
L = length of pipe in feet
C = friction coefficient
45. Pressure Loss calculation in pipelines
Major loss - head loss or pressure loss - due to friction in pipes
Pressure and Pressure Loss
The pressure loss is divided in
1. major loss due to friction and
2. minor loss due to change of velocity in bends, valves and similar.
The pressure loss in pipes and tubes depends on the flow velocity, pipe
or duct length, pipe or duct diameter, and a friction factor based on the
roughness of the pipe or duct, and whether the flow us turbulent or laminar -
the Reynolds Number of the flow. The pressure loss in a tube or duct due to
friction, major loss, can be expressed as:
ploss = λ (l / dh) (ρ v2 / 2)
where
ploss = pressure loss (Pa, N/m2)
λ = friction coefficient
l = length of duct or pipe (m)
dh = hydraulic diameter (m)
46. Head and Head Loss
The head loss in a pipe,tube or duct due to friction, major loss, can be
expressed as:
hloss = λ (l / dh) (v2 / 2 g)
where
hloss = head loss (m, ft)
λ = friction coefficient
l = length of duct or pipe (m)
dh = hydraulic diameter (m)
47. Protection of pipelines against abrasion ,freezing and corrosion
Lining is the application of a protective coating on the inside surface of
pipes, whereas coating refers to the same except for its application to the pipe
exterior. Both lining and coating are intended to reduce corrosion and abrasion
of pipes. Lining also serves the purpose of forming a smooth pipeline interior,
which reduces frictional loss, and it helps reduce damage to pipes by cavitation
in some situations.
PROTECTION AGAINST CORROSION
Corrosion is the second largest cause of pipeline damage. Corrosion is
defined as being the gradual damage of pipe due to chemical or electrochemical
reactions of pipes with their environment. The environment includes the fluid in
the pipe, the soil, water, and atmosphere around the pipe, and other metals
attached to or in contact with the pipe. Important types of corrosion are:
1. Electrolytic Corrosion
2. Chemical Corrosion
3. Electrochemical Corrosion
4. Galvanic Corrosion
48. LEAK DETECTION
The U.S. has an enormous network of aging pipelines for transporting
water, sewage, petroleum, and natural gas. The average age of these
pipelines is over 30 years; some are over 100 years. A large number of them
are either seriously corroded, or in disrepair in other ways. Many of them
are leaking. To replace all of this aging underground infrastructure with new
pipeline at once would be enormously costly for the public, posing
unacceptable financial burden.The leakage or rupture of a crude-oil or
petroleum-product pipeline is more serious because it poses a threat to both
the environment and public health due to the pollution of surface water,
groundwater, and/or soil. Product pipelines such as those transporting
gasoline are more dangerous than crude-oil pipelines, due to the high
volatility of the product and the resultant danger of fire and explosion.
49. The need for preventing and detecting leaks and rupture of pipelines
varies greatly with the type of fluid transported by the pipeline. However,
whatever the need is and whatever type of pipeline one is dealing with, some
common or similar methods exist to detect pipeline leaks.
Pressure-Drop Method
Leakage in a pipeline can also be detected by sudden pressure drop
along the pipe measured by pressure transducers. Because the pressure drop
along a pipe having turbulent flow is proportional to the square of the
discharge Q, the relative pressure drop caused by leakage is double that of the
relative drop of the discharge due to the same leakage. For example, if a leak
causes a 2% decrease in discharge Q or mass flow rate m in the pipe, the
corresponding pressure drop will be 4% and so forth.
Visual and Photographic Observations
Often, leaks have been discovered through visual observation of pipes
or their immediate surroundings. This can be done not only for exposed pipes
but also for underground and submarine pipelines. For instance, one can
patrol the right-of way of a buried petroleum or natural gas pipeline; withered
vegetation in an area above the pipe may indicate leakage in that area.
50. Ground-Penetrating Radar
A ground-penetrating radar is capable of detecting the spilled natural
gas and petroleum that exists in the soil above the leak point of a buried
pipeline. By moving this radar along the right-of-way in an all-terrain vehicle,
the pipeline can be surveyed for leaks, and the location of any leak can be
pinpointed.
Pigs
Pigging is a good way to find leaks because the pig moves inside the
pipe in close contact with the pipeline. Smart pigs that carry special sensors
(acoustic or electromagnetic sensors) can detect leaks.
Dogs
The same Labrador retrievers used by law enforcement agencies to
sniff out illegal drugs and explosives can be trained to detect natural gas
leaks, provided that a special odorant is mixed with the gas. The dogs have
proven to be very reliable, with a success rate of detecting leaks in excess of
90%. They can detect the scent at concentrations as low as 10-18 molar (1
part per billion billion). The dogs are reliable, and demand no reward other
than room and board.
51. PIPING CODES
A piping system is designed and
constructed based on codes and standards.
Therefore, it is important that we have a good
understanding of the applicable codes and
standards. Engineers have always strived to build
the safest plant at the lowest cost. Because it is
impossible for them to build an absolutely safe
plant at any cost, they have to settle for a
reasonably safe plant at a reasonable cost.
In the United States, the piping code is divided
into two main categories:
(1) nuclear power plant piping, which is governed
by the ASME B&PV Code,
(2) non-nuclear piping, which is governed by
ASME B31.
The piping code in our design are ASME B31.3 and
ASME B31.4
52. Analysis of pipeline using software's
( structural and flow analysis)
The important software used in this analysis are
1. Pipe flow expert (for flow analysis)
2. CAE Pipe (for structural analysis)
53. Pipe flow expert
Pipe Flow Expert is designed to help today’s engineers analyze and solve a wide
range of problems where the flow and pressure losses throughout a pipe network must
be determined. The Pipe Flow Expert program will allow us to draw a complex pipeline
system and analyze the features of the system when flow is occurring.
The reported results include:
flow rates for each pipe
fluid velocities for each pipe
Reynolds numbers
friction factors
friction pressure losses
fitting pressures losses
component pressure losses
pressures at each node
pump operating points
NPSHa at pump inlet
Pipe Flow Expert has been designed for the professional engineer who needs a
powerful tool that has a class leading, easy to use and robust interface that makes it
simple to design and analyze pipe networks.
54. Proposed model in Pipe Flow Expert and its flow analysis
A small pipe network comprises 6 Cast Iron (Asphalt Dipped) pipes.
A crude oil source has a surface elevation of 500 ft. At each node in the pipe
network water is removed the system. Calculate the flow rate and head loss
in each pipe. Calculate the pressure and Hydraulic Grade Line at each node.
Fluid data: Crude Oil at 50° F. (Assumed)
56. Other results which we can obtain from pipe flow experts are:
1. flow rates for each pipe
2. fluid velocities for each pipe
3. Reynolds numbers
4. friction factors
5. friction pressure losses
6. fitting pressures losses
7. component pressure losses
8. pressures at each node
9. pump operating points
10. NPSHa at pump inlet
57. CAE Pipe
CAEpipe is a very versatile program for
solving a variety of piping design/analysis
problems. You can perform static and dynamic
analyses (impose loads, calculate support loads,
stresses, displacements, mode shapes etc.) of
piping systems. The piping system can be
subjected to multiple loads of different types like
thermal and seismic loads and checked for code
compliance (ASME, Norwegian, Swedish etc.).
Extensive graphical display of the piping model
is possible with abilities to rotate, zoom, pan the
image and view it from different points. As the
model is input and modified, the graphics is
simultaneously updated to give visual feedback.
58. Proposed model in CAE pipe and its structural analysis
General procedure:
The following steps are taken in order
to get the desired results.
1. Enter Title
2. Select Analysis options (piping
code etc.)
3. Define Material, Section and Loads
for the model
4. Input Model Layout
5. Select Load Cases for Analysis
6. Analyze
7. View Results
59. After following all the steps we analyze the model and get the results as
follows.
The different color shows the
stresses at different points .
Red color indicate the maximum
stress at that region. In order to
prevent the pipe from damaging,
we have to provide support at
that position ,so that stresses may
be reduced to minimum level
60. After the analysis we can find many results from the data sheets
obtained from the software. These important results are
1. Sorted Stresses
2. Code compliance
3. Hanger report
4. Support load summary
5. Support loads
6. Element Forces
7. Displacements
