guidelines for piping design
TRANSCRIPT
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Piping Design Fundamentals
Thomas XavierSr Mechanical Engineer
December 12, 2007
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Piping Design fundamentals
Introduction
Designation of pipe size and thickness
Piping Components
Piping Material
Piping Codes and Standards
Piping Layout
Piping Design bases
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Introduction
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Introduction
Piping system are like arteries and veins of our
bodies. They carry the life blood of the modern
civilization
In a modern city they transport water, waste water,crude oil, natural gas, chemicals, gases, vapors,
solids from one location to another.
Piping includes pipes, flanges, fittings, bolting,
gaskets, valves, pipe supports, pipe hangers, andother items necessary to prevent over pressurization
and over stressing.
Define Piping : ?
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Introduction
Definition of Piping :
Pipe sections when joined with fittings,
valves, and other mechanical equipment
and properly supported by hangers andsupports are called piping.
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Designation of Pipe size andthickness
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Pipe size
NPS Nominal pipe size, without the inch symbol
DN- Diameter nominal Up to size 12 inch the outside diameter is less than the size designator
(i.e. 2,3,4,6....).
Outside diameter of NPS 14 and larger pipe is the same as the sizedesignator in inches.
The inside diameter will depend upon the pipe wall thickness specifiedby the schedule number
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Pipe wall thickness
Schedule is expressed in numbers(5,5S,10,10S,20,20S,30,30S,40,40S,60,80,80S,100,120,140,160)
The higher the schedule number the thickerthe pipe is.
The outside diam is standardized and theinside diam will change based on the
thickness.
The inside diameter will depend upon the pipewall thickness specified by the schedulenumber
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Piping Components
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Piping components
The term pipingrefers to the overall networkof pipes, fittings, flanges, valves and other
components that comprise a conduit system
used to convey fluids.
Piping componentsplays a important role in
the composition and operation of the system.
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Piping componentsPressure Pipe
Steel and alloy pressure piping available in cast, wrought,seamless and seamwelded forms.
Welded and seamless wrought steel pipe is supplied under
ASME B36.10M. SS pipe is supplied conforming to ASME
B36.19M
Commonly specified pipe materials
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Piping components Pipe fittings
Ductile and cast Iron fittings
Cast Iron threaded fittings
Malleable Iron Threaded fittings
Cast Brass and Cast Bronze threaded fittings
Soldered-joint fittings
Cast Iron Flanged Fittings
Cast and Forged Steel and Nickel Alloy Flanged Fittings
Forged Steel Threaded and Socket Welding fittings
Wrought Steel Butt welded fittings
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Piping components
Cast Steel Flanged fittings
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Piping components Forged Steel Threaded / Socket welded fittings
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Piping components
Wrought-steel welding fittings include elbows,
tees, crosses, reducers, laterals, lap joint stub
ends, caps and saddles.
Wrought steel fittings are made to the
dimensional requirements of ASME B16.9
and ASME B16.28.
Fittings made as per ASME B 16.9 is
available in sizes NPS (DN 15) through
NPS 48 (DN 1200) and as per ASME B 16.28
are available in sizes NPS to NPS 24.
Wrought steel butt welded fittings
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Piping components
Wrought steel butt welded fittings
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Piping componentsWrought steel butt welded fittings
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Piping componentsWrought steel butt welded fittings
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Piping componentsStrainers
Wye strainer
Basket strainer
Conical startupstrainer
Air Release Valve
Air/ Vaccum
Release ValveCombination Valve
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Piping componentsExpansion Joint
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Piping componentsFlanges
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Piping componentsGaskets
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Piping componentsJoining Ductile or Cast Iron Pipe
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Piping componentsJoining Ductile or Cast Iron Pipe
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Piping components - ValvesFunction
Stopping flow Allowing flow
Regulating and controlling flow to
fulfill the objectives of the system
Types of valves
Gate valve
Globe valve
Check valve
Ball valve
Plug valve
Butterfly valve
Diaphragm valve
Pinch valve
Pressure relief valve
Control valve
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Piping componentsValves
Classification of valves based on Mechanical motion Linear motion valves Gate, globe, diaphragm, pinch and lift check valves
Rotary motion valves - Butterfly, ball, plug, eccentric and swing check valves
Classification based on valve size
Pressure Temperature Rating
Cold Working Pressure (CWP)Rating (29o C to 38oC )
NFPA Rating
Classification based on Rating
Smaller valves NPS 2 (DN 65 and smaller
Large valves- NPS 2 (DN 65) and larger
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Piping componentsMajor Valve parts
Body
Bonnet or Cover
Bonnet or Cover Bolting
Disc
Valve Trim The removable and replaceable valve Internal parts that come incontact with flow medium
Valve seats, Disc, Glands, Spacers, Guides, Bushings & Internal springs
Non Pressure Retaining partsValve seats, stem, yoke, packing, gland
bolting,
bushing, hand wheel, and valve actuators
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Piping components - Valves
Rising stemGate Valve NonRisingstem
Gate Valve
Wafer type butterfly valve
Flanged butterfly valve
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Piping components - Valves
Flanged endglobe valve Angle globe valve
with screwed ends Needle valve with
screwed ends
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Piping components - Valves
Lift Check valve Flanged Swing check valve
Folding Disc check valve
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Piping components - Valves
Ball valve
Needle valve
Diaphragm valve
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Piping components - Valves
Flanged Safety Valve
Threaded Safety Valve
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Piping components - Actuators
Function of Actuators
Assist in operating of large valves
Assist the operator in operating the valves against high fluid pressure
To reduce the time required for operation
Valve is required to operated from a remote location
When the valve is to attain a position (open or close) in the event of accident
Types of Actuators
Gear Actuators When rim pull exceeds a given value varying between 50lb (22
kgf) to 250 lb (113 kgf)
Electric Motor actuators Pneumatic Actuator
Hydraulic Actuator
Solenoid Actuator
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Piping components Control ValveDefn : They areconsidered the final control elementin an automated andusually very sophisticated control loop.
Aside from the control valve, the loop consists of a transmitter, that
measures the variables (pressure, flow, level or temperature) and a
controller (computer)
Components of a Control Valves Valve body (reciprocating or rotating stem)
Actuating device (spring diaphragm type)
Valve positioner (convert signal to air signal to control position)
Airset or regulator (to supply air pressure to the positioner)
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Piping Materials
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Piping materialsFactors to be considered for selecting materials Code Requirements
Must be suitable for the flow medium
Must be suitable for meeting the temperature and pressure safely during thedesign life.
Operating environmental conditions
Cost
Availability
Carbon and low alloy steel come closest to being the idealconstruction material. Due to the fact that the majority of pipingapplication employ iron based metals, these will be onlyemphasized in this presentation.
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Piping materials
Properties of Metal
Chemical Properties
Mechanical Properties
Physical Properties
Other Properties
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Piping materialsChemical Properties of metal
Chemical properties are the dictated by the various elemental constituency of thesolid. This is usually measured by the relative atomic weight percent of thevarious elements within the material
Steel always contain Carbon, manganese, phosphorous, sulfur and silicon invarying amounts.
Hydrogen, oxygen and nitrogen enter as gases during manufacturing.
To make steel nickel, copper, molybdenum, chromium, tin, antimony etc areadded. Each of this addition causes a specific effect on the steel.
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Piping materials
Physical Properties of metal Density.
Thermal Conductivity
Thermal Expansion
Specific Heat
Mechanical Properties of metal
Modulus of Elasticity (Youngs Modulus).
Yield Strength
Ultimate Tensile Strength
Elongation and Reduction of Area
Hardness
Toughness
Fatigue resistance
Elevated Temperature Tensile and Creep strength
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Piping Codes and Standards
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Piping Codes and Standards
What is the difference between Codes and Standards?
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Piping Codes and Standards
What is the difference between Codes and Standards?
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Piping Codes and Standards
Code ASME B31: Code for Pressure Piping ASME B31.1, 31.2, 31.3, 31.4, 31.5, 31.8, 31.9 & 31.11
ASME performance test codes
NFPA Codes
International Plumbing Codes Uniform Plumbing Codes
Local authority codes etc.
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Piping Codes and Standards
Standards American National Standard Institiute (ANSI) American Society for Testiing and Materials (ASTM)
American Gas Association
American Petroleum Institute (API)
American Water Works Association (AWWA) American Welding Society (AWS)
Air Conditioning and Refrigeration Institute
American Society of Heating and Refrigerating and Air-conditioning Engineers(ASHRA)
Institute of Electrical Engineers (IEEE)
Instrument Society of America
National Fire Protection Association (NFPA) Publications
Indian (IS), British, German (DIN), Japanese (JIS), ISO standards etc.
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Piping Layout
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Piping layoutconsiderationORHierarchyofReferenceDesignInformation System P&ID
P&ID implementation and Physicalization
Piping specification
Equipment Outlines
GA or Equipment layout drawings
Collection of as built drawings
Piping layout considerations and planning studies for improved pipingeconomics
Interference
Piping flexibility
Valve location
Drain location, Instrument location etc.
PipingLayout
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Example : Piping ofcentrifugal pump
Piping of centrifugal pumps, particularly the suction piping, can seriously affect theoperating efficiency and life expectancy of the pump. Problems like vibration, erosioncavitation out of balance conditions etc.
Suction and discharge must be independently supported. Designer can consider use ofexpansion joints on either suction or discharge if required.
Suction piping should not contain vertical loops or air pockets
When reduction is required at pump suction use eccentric reducer flat side up. Provide at least 3 to 4 diameter of straight pipe between pump suction and first elbow for
horizontal suction.
Only long radius elbow to be used at or adjacent to any pump suction connection.
When pump flanges are cast iron flat faced, the mating flanges must also be flat faced andthe joint made up with full face gaskets.
Piping Layout
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Example : Modern Piping Layout
Piping Layout
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Piping Design bases
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Factors to be considered for Design
Physical attributes Size, layout, dimensional limits, dimensional standards, specialdesign practices for configuration control ( weld joints, slope, plugging etc.)
Loading and Service conditions Loading conditions Dead weights, pressure changes, temperature changes, Snow
loads, ice loads, wind loads, Earthquake loads
Service conditions Combination of loads occurring simultaneously ( Water hammer,Relief valve discharge loads, Acoustically induced vibration loads
Environmental Factors
Corrosion/ erosion
Flow assisted corrosion
Material related considerations
Pressure integrity Leak tight condition in piping systems
Piping Design BasesDefn. : Design bases are the physical attributes, loading, service conditions,environmental factors and materials related factors which must be considered in the
detailed design of a piping system to ensure its pressure integrity over its design life
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Sizing of a Piping system Fluid flow design Reasonable design velocities for Water flowing through pipes
The detailed fluid flow design of a piping system requires the consideration of a numberfluid parameters including flow rate, viscosity, density and pipe wall frictional drag
Piping Design Bases - Sizing
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Sizing of a Piping system Pressure Integrity Design
Determination of Pipe wall thickness :
1. From minimum inside diameter select the Outside diameter from standards.
2. Based on fluid service suitable piping material required to be found (strengthallowances, corrosion, erosion allowances, joining)
3. As per code calculate the required minimum wall thickness.
4. Select an appropriate nominal wall thickness from standard (i.e. schedule)
5. Confirm the standard manufacturing tolerance will not reduce the nominal wallthickness
6. Confirm that the inside diam of the pipe is compatible with the minimum inside
diameter requirements obtained from the fluid flow evaluation.
Piping Design Bases - Sizing
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Questions ???
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Thank You