Data required for steady state pressure and temperature profiles:

flow rates
fluid properties ( density, viscosity, bulk modulus, thermal expansion coefficient, heat capacity, vapor pressure, pour point)
pipe grade, pipe size, wall thickness and roughness
pipe length and elevation profile
injection and delivery locations
delivery pressure
injection and ground temperature
depth of burial and soil conductivity
operating data such as operating and ground temperatures

design is a plan according to given set of parameters
parameters are physical properties that affect behaviour of system
criteria are conditions and guidelines for design
optimal design optimises these factors
restraints imposed by codes and standards
prime consideration in design is safety
standards become codes when they are incorporated into a set of government regulations
need for a pipeline needs to exist before pipeline is built
pipeline could be new or an increase in capacity of existing pipeline according to demand and volume specified in request
optimal design should account for pipeline system growth
determine supply and demand and respective locations
seasonal variations should be taken into account for design
cost,timing and environmental impact are the major considerations of design
right of way affects construction and land acquisition cost
elevation profile affects hydraulics, pumping requirement and costs
depth of burial affects hydraulics due to heat of conduction, pipe integrity and construction cost
soil types affect construction cost and heat conduction
water crossings affect construction costs
geotechnical considerations like slope stability, earthquakes, ...etc
operating parameters include operating flow range, operating pressures and temperatures, fluid properties, ambient conditions
design does not only predict future growth, it also takes into account daily maximums and minimums and annual throughputs
optimum pipe diameter is a balance between material costs and pumping costs
low viscosity fluids (less than 10 cSt) --> use charts with recommended velocities ( slide 9)
high viscosity fluids (more than 10 cSt) use lower velocities, not purely economic factors, rather keeping pressure drop to an acceptable limit
minimum and maximum pressures for pipeline operations
maximum operating pressures constrained by pipe yield strength, pipe diameter and wall thickness, fluid density and elevation of the lowest point of the pipe
minimum pressures determined by vapour pressures of liquids
temperature affects density, viscosity and specific heat.
high temperature is beneficial because it lowers density, viscosity and hence the pressure drop
cooling non newtonian fluids leads to increase in viscosity which causes a very high pressure drop
to reduce pipe cooling, pipe can be insulated and or operated at a high temperature
it can also be blended with lighter HCs
temperature along pipeline is very hard to control because it depends on variable soil thermal conductivity and and ambient temperature
max temperature for buried pipe determined by: 1. ground conditions 2. stress before buckling 3. economics of pipe flow
minimum temperature limit determined by metallurgical properties of pipe and by ground conditions
higher density--> higher pressure drop due to friction
compressibility for controlling surges ( not important for pipeline design
viscosity is important in calculating size, hydraulics and pumping requirement
vapor pressure determines minimum pressure in pipeline, must be high to avoid 2 phase flow and pump cavitation
pour point is the lowest temp at which fluid flows and beyond which will start behaving like a non newtonian fluid
specific heat affects heat transfer rate through conduction process
ambient conditions play critical role in design especially in extreme environments such as deserts or the arctic
in permafrost fluid has to be chilled to avoid melting surrounding soil
air temp affects turbine driver thermodynamics and affects fluid properties due to conduction
burial advantages slide 11
greater depth of burial--> lower rate of heat transfer
effect of soil thermal conductivity depends on differential temperature between soil and fluid
soil colder--> fluid temp drops--> increase in viscosity --> higher pressure drop
parameters required to determine temperature profile --> slide 11
profitability of pipeline directly related to volume
pipe grade, diameter and wall thickness most important factors in determining capacity, and also affect pressures
large diameter--> more volume, smaller pressure drop per unit length
thickness determines steel, CAPEX and operating pressure
pipe grade determines steel strength and operating pressure
pipe roughness affects pressure drop and pigging operations
pipe coating protects from corrosion
nominal pipe size (NPS) indicates outer diameter of pipe (mm or inches)
design pressure (barlow equation)--> slide 13
effective pipe roughness affects frictional pressure drop and pipeline efficiency
higher roughness--> higher friction--> higher pressure loss
roughness reduced by coating inside of pipe or by pigging
maximum allowable pressure proportional to pipe strength
maximum pressure allowed for steady state pipeline operations
maximum allowable pressure is sum of pressure required to overcome friction loss, static head pressure, back pressures or delivery pressures
values of MAOP vary with elevation changes
hydrostatic test used to test integrity of pipeline
divided to multiple segments tested individually
hydrostatic test--> slide 15
pipe wall thickness requires an allowance of 10% over internal design pressure, 80% of minimum yield strength
allowance takes into account surges and changes in pressure
thickness increased and decreased according to local transient pressure requirement or decreased to reduce pipe cost
pipe thickness larger in river crossings or deep valleys, smaller in highest elevations
components designed to withstand maximum pressure differential between internal and external design pressures
external surface loading requires extra pipeline thickness
factors affecting cost: (slide 17)
mechanical ( pipe grade, size, and wall thickness, pipeline route and depth of cover)
capacity (operating parameters, station spacing anf pumping costs)
reliability (valve spacing, other valve related costs)
phases of design: conceptual design, system planning, detailed engineering
conceptual design --> product properties, flow profile, pipeline length and route, macro economic data ( may include hydraulic and economic studies)
hydraulic design procedure --> slide 19-20

	Created by nada.h.aly over 8 years ago

Normal-level (N-level) Oil & Gas Transmission & Storage Note on 3B - Design Process, created by nada.h.aly on 27/10/2015.