Your SlideShare is downloading. ×
Webinar Series: Overview of How Piping Design & Analysis Influences              Pipe Support Selection & Design          ...
If you have any questions, comments orsuggestions, please email us atenews@pipingtech.comTo request a PDH certificate, ema...
PT&P Subsidiaries                     PIPING TECHNOLOGY                     & PRODUCTS, INC.                              ...
Webinar Series: Overview of How Piping Design &Analysis Influences Pipe Support Selection & DesignTopic            Session...
The Total System - Overview   Types of Piping Systems   Network Analysis   Series Piping   Parallel Piping   Branchin...
Types of Piping Systems     Water Piping Systems     Process Piping        High Temperature System        Low Temperat...
Water Piping Systems      Distribution Systems       a) Loop      b) Gridiron     c) TreeImage Source: The Piping Handbook
Water Piping Systems Transmission Lines    Carry water from main source of supply to the distribution     system In-Pla...
Water Piping SystemsCondenser Systems Condenser systems use circulating water to  condense steam exhausted by the turbine...
Process Piping Refers to all piping within the physical boundaries of a  chemical or petroleum processing unit Usually i...
Power Piping Refers to all piping within the physical boundaries of  a facility intended to generate electricity Usually...
Network Analysis      Hardy Cross Method – Method for determining the        flow inside pipe network systems where the i...
Network Analysis Continued
Network Analysis Continued
Series Piping     Series Piping has the same fluid flowing through all       the piping, and the head losses are cumulati...
Series PipingFor the above example when two pipes of different sizes or roughness areconnected, the relationship between h...
Series Piping Series pipes may be solved by the method of equivalent lengths. Two-pipe systems are said to be equivalent ...
Parallel Piping    When the flow is divided between two or more pipes       and then joined again this is called a parall...
Parallel Piping To calculate head loss in parallel piping use the    following equation. For a parallel piping system:•  ...
Parallel Piping Example
Parallel Pipe Example
Parallel Pipe Example Checking the values of h1, h2, h3:
Parallel Pipe Example There are two types of problems when you know the inlet and outlet flows.   The elevation of the g...
Parallel Pipe Example
Parallel Pipe Example For turbulent flow (Reynolds numbers above 2000) For viscous flow (Reynolds numbers below 2000)
Branching pipes  For branching pipes  where pipes run  neither completely  parallel or in series, a  combination of both ...
Pipe Sizing Criteria There are two values critical to sizing the piping network:  1. Allowable pressure drop for the enti...
The Siphon Effect A siphon system is one in which the siphon principle  is employed to carry the water through elevated  ...
The Siphon Effect – Backflow Backflow or Reverse flow is caused through one of two conditions, back pressure or back siph...
The Siphon Effect – Backflow Backflow due to pressure loss: back-siphonage                              •   Backflow due...
System Static & Dynamic Head Static Head – the internal energy of a fluid due to the pressure exerted on its container D...
Visualizing Energy Addition/Losses Most piping systems use pumps to develop the  pressure or head required to maintain th...
Other considerations in Piping Design Once the    piping    configuration    has been    determined,    analysis of the  ...
Oil and other Liquid Systems When considering oil flow in pipes, the most  important variable physical property is viscos...
Two Phase Flow The term multicomponent is used to describe flows in  which the phases do not consist of the same chemical...
Troubleshooting Piping Systems Some problems occur in piping systems resulting from faulty plant design and from faulty o...
Rules of Thumb for Piping Layout Proper planning - early  stages of a project. Space conservation and a  symmetric pipin...
Rules of Thumb for Piping Layout    Avoid interference     with other facilities     in the plant    Be careful of other...
Rules of Thumb for Piping Layout              View overall plant design to plan for interference-free routeImage Source: T...
Rules of Thumb for Piping Layout Do not overlook the effects of thermal expansion The piping stress analyst:    Transla...
Rules of Thumb for Piping Layout Route piping with flexibility designed into it and  consider the following:   Avoid str...
Rules of Thumb for Piping Layout When the expected thermal expansion in any given run of pipe is high, consider the use o...
Rules of Thumb for Piping Layout On large-diameter main and  smaller branch lines, be  sure the branches are  flexible en...
Rules of Thumb for Piping Layout System or equipment bypass  lines may be cold due to lack  of flow while the main runs  ...
Rules of Thumb for Piping Layout In addition, the piping designer may use a variety of single-  and multi-plane piping ar...
Rules of Thumb for Piping Layout Valve guidelines    Install with stems between the vertically upward and     horizontal...
Rules of Thumb for Piping Layout Locate valves in acid and caustic applications below eye level Locate valves in the nat...
Rules of Thumb for Piping Layout Valves in overhead piping with their stems in the horizontal position – Locate them so t...
Rules of Thumb for Piping Layout A minimum of 4 in (100  mm) of knuckle  clearance should be  provided around all  valve ...
Rules of Thumb for Piping Layout When routing piping at pumps, the designer should follow the manufacturer’s recommendati...
Rules of Thumb for Piping Layout      The suction of any centrifugal pump must be continuously       flooded, and the suc...
Rules of Thumb for Piping Layout Design pump suction lines to accommodate a  conical-type temporary strainer. Consider t...
Rules of Thumb for Piping Layout Provide high-point vent and low-point drain connections during the course of physical ro...
Rules of Thumb for Piping Layout    Consider that it is       cheaper to bury pipe       underground than install       i...
Rules of Thumb for Piping Layout Pipe Racks - Pipe layout on pipe racks should follow the Pipe Planning Study concepts.  ...
Rules of Thumb for Piping Layout Pipe supports require structural  support, which means that piping  should be located in...
Rules of Thumb for Piping Layout Pipe Supports    Piping should be routed such that the support designer can     make us...
Rules of Thumb for Piping Layout Specific industry rules of thumb Power Plants    All piping in this service should be s...
Rules of Thumb for Piping Layout Specific industry rules of thumb for Power Plants    Provide a drain pot at the low poi...
Rules of Thumb for Piping Layout Specific industry rules of thumb Power  Plants    Valves in all steam services should b...
Rules of Thumb for Piping Layout Steam Turbines   The routing should be as short and as direct as   possible with consid...
Rules of Thumb for Piping Layout Steam Turbines    Bleeder trip valves must be located as close to the     turbine extra...
Rules of Thumb for Piping Layout Steam Turbines    A drain should be located at the low point in the     extraction pipe...
Rules of Thumb for Piping Layout     Steam Turbines        Provide a minimum of five diameters of straight pipe         ...
Rules of Thumb for Piping Layout Condensate   Where two or more condensate pumps are used, the    individual runs to eac...
Rules of Thumb for Piping Layout Condensate Lines   Provide a minimum of three to four diameters of straight pipe in the...
Rules of Thumb for Piping Layout Feed Water    The pump suction piping from the deaerator storage tank should     drop v...
Rules of Thumb for Piping Layout Turbine Drains    Turbine drain lines and valve ports should be sized for the maximum  ...
Rules of Thumb for Piping Layout Turbine Drains    Drainage from other vessels, such as feedwater heaters, steam     jet...
Rules of Thumb for Piping Layout    Heater Drains          Drain piping from feedwater heaters without an internal drain...
Rules of Thumb for Piping Layout Heater Drains    The heater drain system arrangements must be coordinated with     the ...
Rules of Thumb for Piping Layout Compressed Air    Refer to the compressor manufacturer’s instruction manual for the    ...
Rules of Thumb for Piping Layout      Cooling Water Systems            Where butterfly valves are used, follow the      ...
Next Webinar Session: August 1, 2012 Session 4: Basic Concepts of Stress Analysis - Flexibility Analysis Part 4 of our con...
Upcoming SlideShare
Loading in...5
×

WS 3-preliminary piping design-total system

10,144

Published on

Continuing our series on the Overview of Piping Design, Part 3 will take a detailed look at the total piping system. Understand the different types of equipment and components that define various types of piping systems. Familiarize yourself with key piping system concepts and how to calculate flow between two pressure sources. Learn the differences between series piping, parallel piping and branch piping as well as their specialized applications. See how the piping system conditions such as static and dynamic head loss influence the selection and distribution of piping components throughout the entire system. Finally, eliminate potential danger areas using our piping system trouble shooting guide.

Published in: Technology, Business
4 Comments
40 Likes
Statistics
Notes
No Downloads
Views
Total Views
10,144
On Slideshare
0
From Embeds
0
Number of Embeds
4
Actions
Shares
0
Downloads
0
Comments
4
Likes
40
Embeds 0
No embeds

No notes for slide
  • Thank you for attending this class on preliminary piping design. Today we are going to go into a little more depth on piping design. Please make sure to type in your questions and one of our panelists will answer your questions.
  • We are going to cover several types of piping systems. We are going to cover briefly water piping, process piping, and power piping. We will cover the network analysis, how to calculate flow between two pressure sources,series and discuss parallel and branch piping, the siphon effect, dealing with Static and Dynamic head, figuring energy addition losses, and how to trouble shoot piping systems and discussing typical rules of thumb for various piping systems. The experienced piping designer needs to have a working knowledge of plant layout, equipment arrangement, and system functionality associated with one or more fields of endeavor, such as commercial, industrial, refinery, petrochemical, or power. In addition, the designer must have an understanding of the practical application of piping materials, valves, pumps, tanks, pressure vessels, heat exchangers, power boilers, vendor-supplied skid assemblies, steam turbine drivers, and other machinery and equipment
  • There are three types of piping systems that are most commonly dealt with, water piping systems, process piping which consists of items other than water, and power piping systems. Process and Power piping are covered under ASTM specifications B31.1 and B31.3 respectively
  • Water-distribution systems that serve populated areas and industrial complexes, including offices and light and heavy industry, are classified broadly as being of the loop, gridiron, or tree types.
  • There are four general types of piping systems in water distribution utilities: transmission lines, in-plant piping systems, distribution mains, and service lines. Transmission lines carry water from a source of supply to the distribution system. The prime objective of a distribution network is to supply a sufficient quantity of water to all parts of the system, at pressures adequate for the requirements of the users at all times and under all conditions of their demands, including sufficient flow and pressure for fire-fighting purposes. Therefore, the selection of pipe sizes, material, geometry, and configuration in distribution networks is influenced more by the necessity of maintaining adequate water pressure than by the economics of pumping costs.
  • In a large steam-power plant this requires a considerable amount of water to be continuously circulated. Consequently, since the circulating water directly affects the plant’s efficiency and reliability, an efficient, reliable, and economical circulating water system is required. Due to current environmental regulations, recirculation-type systems in which the same water is used repeatedly must be applied in most cases.
  • i.e. you might have a steam line which is significantly different than a drain line which is significantly different than a feed-water line, etc.
  • Illustrative Example C1.1Make a skeleton drawing of the network. Indicate by appropriate arrows the points of constant flow input or outputof the system, constant head input or output (see Fig. C1.2). Number all loops in the system in arbitrary sequence. Do not include ‘‘loops around loops.’’ For example, in Fig. C1.3 there are two loops, not three. The large loop (abcdefg) is not numbered. The two basic loops (abfg and bcdef ) are numbered.3. Number each line. A line has two ends. An end may be a point at which fluid is drawn from or added to the system, or one at which pipe characteristics change, or a tee joint.
  • Fig. C1.4, the point x is the meeting of three lines, not two; point y is the meeting of two lines where an NPS 8 (DN 200) pipe joins a NPS 10 (DN 250) pipe; point z is simply a bend in the single pipe and is not the end of any line, although it could have been specified as one, if desired. Figure C1.4 shows the complete numbering of the system shown in Fig. C1.2. Note that each line is numbered once and only once, even though it may be in more than one loop. Also note that the numbering is serial; that is, if there are n branches, each of the numbers from 1 to n must be used in the numbering. 4. Assign a base direction. Put an arrow on each line in loop 1, indicating the clockwise direction (as shown in Fig. C1.5). Then put an arrow on each line in loop 2, indicating clockwise direction, except where a line which previously has been assigned a direction is encountered. Then the original assignment is not changed. In Fig. C1.5, line 4 is a member of loop 1 and also of loop 2 but has been given a base direction of loop 1. The line 4 assignment is not changed. This process is continued for every loop in the network, an arrow being assigned in a clockwise direction whenever it has not been assigned previously. 5. In network-distribution systems, the situation often is encountered where system pressure must be raised by the use of booster pumps in series with the supply pipeline. If the higher pressure area is connected to the remainder of the system at one point only, the two pressure-zone networks are hydraulically independent problems. If the pressure zones are connected at two or more points, the booster pumps must be included in the appropriate loops. For all loops containing booster pumps, an unbalanced or residual head H0 must be determined. This is done by algebraically summing the assumed constant head changes at the boosters in a clockwise direction. Note that head losses are considered as positive in sign, so proceeding from the suction side of a pump to the discharge side gives a negative head loss. Following the hydraulic analysis, a check should be made to assure that the pumping head assumptions are sufficiently accurate. The resulting flow-rate values should allow optimum hydraulic design of the booster-station installations. 6. Additional ‘‘pseudo-loops’’ must now be added to the list if there is more than one constant head input (see Fig. C1.6). If the number of such inputs is m, trace (m 1) paths between inputs in the same manner in which the loops were traced, making sure that each constant head input is used at the end of at least one of these loops. If the direction of procedure is from the lower to the higher input in each path, H0 will be the positive difference in the head loss between the two inputs. If booster pumps are encountered, the head change across such pumps must be algebraically added to the head difference between the inputs in order to obtain the H0 for the pseudo loops. When the listing of all the loops has been completed (including the consideration of booster pumps), the work should be carefully checked, preferably by a second person, since any errors will completely upset the calculations. Note that pseudo loops do not introduce any new lines. Note also that each pseudo loop must be assigned its own number.7. The only remaining task is to supply initial flow values and pipe characteristics which the computer can use as starting values for the calculations. The only restriction on these values is that they satisfy the mass balance condition at each junction. That is, the sum of the flow into a junction must equal the sum of the flows out of the junction. For example, Fig. C1.7 shows the junction of lines 3, 4, and 6; flows of 50 gpm in line 3 and 100 gpm in line 6 would satisfy the condition. Proceeding in this manner, balance every junction in the network, working toward the variable-flow (constant- head) inputs which can take up the slack. When all flows are specified, check the accuracy of the work by summing the inputs and outputs. If these sums are unequal, some computational error has been made and must be corrected. The complete schematic for this system is shown Fig.
  • C1.8. This schematic includes the assumed starting values of the flows.
  • The head losses in a parallel piping system is the same in each branch and the flows are cumulative. This is an example of a parallel piping system.
  • Hr1 2 and three are the same for each branch and an assumption that all branches must be the same length. Za and Zb are elevation points. Gamma is the density of the fluid and the flow rate is Q. An example is shown on this slide.
  • With our known flow rate, Step 1 in our calculation would be to assume a flow rate in pipe #1. In our example, we will assume a flow rate of 3 cubic feet per second. Then we can solve for our other flow properties and determine a head loss for our pipe #1 with our assumed flow rate. Next we will use that assumed flow rate to calculate the assumed flow rates pipe sections #2 and #3.
  • In this step of the calculation, we will compare our total assumed flow rate (10.04 total) to our actual flow rate (12 total) and determine a corrected flow at pipes #1, #2, and #3.
  • Now here we can compute the actual true operating conditions at pipe sections #1, #2, and #3 knowing our actual flow characteristics.
  • The first type is the solution of a traditional pipe discharge problem, as the head loss is the drop in the hydraulic grade line. The individual discharges are then added to determine the total discharge. The second type is more complex, as neither the head loss nor the discharge for any one pipe is known. This type of problem is what we are going to cover next.
  • The goal is to economically transport the fluid from point a to point b without putting the system in danger by damaging the equipment or causing problems with pumps. If your pressure drop causes the fluid pressure to drop below the vapor pressure of the fluid you could get gas entrainment or cavitation. This is why pumps have minimum net positive suction head. Pumps are used to move most liquids through the system. Sometimes by pushing the fluid and pulling the fluid using the siphon effect.
  • For pumps and other systems that use the siphon effect, it is important to prevent the entry of air or any other gas into the system, or it will break the siphon effect. For complex systems an extensive load analysis is performed to establish a seal elevation that is adequate for all operating conditions. One means of providing this seal is through the use of a seal well, that is, a basin with a water level controlled by an overflow weir.
  • Back pressure due to pressure can be prevented with valves
  • Backsiphonage due to pressure loss;Backflow from recirculated system.
  • The process of using static and dynamic head is important in the selection of equipment, and running the pipe. This will aid in optimizing energy costs and material costs. The basic method of system design is to first establish values that are fixed, such as fixture operating pressure and the difference in static height of that fixture from the pressure source. The pipe size, which is adjustable, is then selected so that the remaining system pressure, in the form of friction loss of the water flowing through the pipe, will be used while not exceeding recommended velocity figures.
  • The optimum pipe size is based on an economic tradeoff between the installed capital cost of the piping system and the sum of the capital plus lifetime operating costs of the pumping system.
  • as the pipe diameter decreases, the flow velocity increases, which decreases the cost of erected piping, including fittings, hangers, supports, and labor as represented by cost a in Fig. B8.7. However, the piping pressure drop ratio increases to the 5th power with reduction in the pipe internal diameter ratio, as shown in the accompanying table. The same is true with the pumping power, which is proportional to the pressure drop in the line, as represented by cost bThe total cost, which is the sum of these three costs (TCOST = a + b + c) in $/year, is shown on Fig. B8.7 as reaching a minimum value at the optimum flow velocity. The analysis for each piping system should consider the optimization of flow velocity (optimum internal diameter) of the pipe under consideration. It is important to note that cost b depends strongly on the plant operating mode or the load factor, and on other economic indicators for a particular project.
  • The calculation of oil flow through pipes is a much more complicated process thana similar calculation for water flow.
  • Cocurrent, simultaneous flows of gases and liquids occur in numerous components of plant equipment such as steam generators, drain lines, and oil and natural gas pipelines. Ever since the earliest visual observations of two-phase flow, it has been recognized that there are natural varieties of flow patterns. In addition to the random character of each flow configuration, two-phase flows are never fully developed. Very often, severe problems can occur if multi-phase flow is present in the pipeline. A number of circumstances will lead to the generation of multi-phase flow. For instance, if an oil-gas mixture flows along a pipe on the seabed and then rises to a platform level up a vertical pipe, the liquid may collect upstream of the bend until it reaches a given level, at which point it is swept up the vertical leg, giving rise to mechanical problems in the platform equipment. Should a two-phase flow condition be unavoidable in the system operation, the impact of two-phase flow transient condition should be taken into consideration in system design and piping support evaluation.
  • Proper planning is an important activity performed by the piping designer in the early stages of a project. Space conservation and a symmetric piping arrangement are achieved when all the systems are evaluated in the preliminary stages of design.
  • One of the most important aspects of piping layout is the avoidance of interferences with other facilities in the plant such as other piping systems; structural steel and concrete; heating, ventilating, and air-conditioning (HVAC) ductwork; and electric cable trays and conduit.
  • This process is extremely complex at best. Traditionally, this has been accomplished by the use of area composite drawings (see Fig. B3.2) and plastic scale models. The composite drawings and plastic models show all plant facilities designed to date and are used by the designers to select an interference-free route for the system currently under design however, the designer still must search out those systems or facilities in design concurrently.
  • The effects of the thermal expansion of pipes and fittings as a result of system operating temperature changes cannot be overlooked during the layout and routing of any piping system.The piping stress analyst translates and enters the piping design data into the computer, reviews the output data, and if the system is too rigid, may suggest appropriate corrective redesigns. However, it is the piping designer’s responsibility to ensure that the final stress analysis results are incorporated into the final pipe support and pipe routing design.However, it is the piping designer’s responsibility to ensure that the final stress analysis results are incorporated into the final pipe support and pipe routing design
  • The piping designer should route piping with flexibility designed into it, using the minimum amount of pipe, fittings, and expansion loops by considering the following:Avoid the use of a straight run of pipe between two pieces of equipment or between two anchor points.A piping system between two anchor points in a single plane should, as a minimum, be L-shaped, consisting of two runs of pipe and a single elbow. This type of arrangement should be subjected to a ‘‘quick-check’’ analysis to determine if a formal computer stress analysis is required. A preferred solution in this case may be a series of two or more L-shaped runs of pipe.
  • A three-plane configuration may consist of a series of L-shaped runs and/or U shaped expansion loops designed into the normal routing of the system.Consider the use of an anchor at or near the center of the run, when the expected thermal expansion in any given run of pipe is high, thereby distributing the expansion in two directions
  • For systems consisting of a large-diameter main and numerous smaller branch lines, the designer must ascertain that the branches are flexible enough to withstand the expansion in the main header.Systems which are to be purged by steam or hot gas must be reviewed to ensure that they will be flexible during the purging operation.
  • Valves should be installed with the stems between the vertically upward and horizontal positions with particular attention given to avoiding head and knee knockers, tripping hazards, and valve stems in the horizontal plane at eye level that may be a safety hazard. Large motor-operated valves should be installed in the vertical upright position where possible to facilitate support and maintenance.
  • Valves in acid and caustic services should be located below the plant operator’s eye level or in such a manner as to not present a safety hazard.The location of valves, with consideration for operating accessibility, should be accomplished in the natural routing of the system from point to point, avoiding the use of vertical loops and pockets.
  • Valves in overhead piping with their stems in the horizontal position should be located such that the bottom of the hand wheel is not more than 6.5 ft (2 m) above the floor or platform. Only infrequently operated valves should be located above this elevation, and then the designer should consider the use of a chain operator or a platform for access.Where chain operators are used, the valves should be located such that the chain does not present a safety hazard to the operating personnel
  • Improper application and placement of valves in the piping system can be detrimental to system function. This can result in malfunction of the valve and in waterhammer, and this can cause the valves to literally self-destruct.
  • When routing piping at pumps, the designer should follow the manufacturer’s recommendations, the Hydraulic Institute Standards, and the following guidelines: The suction and discharge piping must be supported independently of the pump such that very little load is transmitted to the pump casing. The designer may consider the use of expansion joints on either the suction or discharge, or both, as necessary. However, expansion joints should be used only when it is unavoidable.
  • All pump suction lines must be designed to accommodate a conical-type temporary strainer.A pipe anchor must be provided between any expansion joint or non-rigid coupling and the pump nozzle that it is designed to protect.When pump flanges are cast-iron flat-faced, the mating flanges must also be flat-faced and the joint made up with full-face gaskets and common steel bolts (ASTM A 307, Grade B), not high-strength bolts (ASTM A193, Grade B7). Refer to the Hydraulic Institute Standards for arrangement of pump piping.
  • During the course of physical routing of any system, the designer should provide high-point vent and low-point drain connections for the following purposes:The filling of the piping system with water for hydrostatic testing and operation and the evacuation of entrapped air in the processThe evacuation of all water used for hydrostatic testing and operation during periods of start-up and maintenance
  • The economics of installing piping systems have proved that burying pipe in lieu of installing pipe above ground provides a significant cost savings in both bulk footage and pipe supports.
  • Pipe Racks - Pipe layout on pipe racks should follow the Pipe Planning Study concepts. Avoid designing one pipe at a time in order to avoid unnecessary overcrowding and fittings for pipes to enter and depart from the rack. Where possible, pipes should rest directly on the rack with the use of an insulation shield, if required.Steam piping should exit the rack with a vertical up- and-over to avoid condensate collection points, while water piping should exit the rack with a vertical down-and-under to avoid a high-point air pocket collection point
  • it is the responsibility of the piping designer to give serious consideration to the means of support during the piping layout, and in doing so, many pipe support problems may be either minimized or avoided altogether. the piping designer should be familiar with the commercially available pipe support components and their application
  • In any power plant, be it a base-loaded electric power generation station or an industrial facility power plant, the main steam system is the backbone of the installation since it ties together the two most important and most costly pieces of equipment, the steam generator and the turbine, and is also usually the first system designed, giving it the preference in space allocation and routing. The recommendations of the following references should be incorporated in the design of the main steam and reheat steam piping systems.1. ANSI/ASME TDP-1-1985, Recommended Practices for the Prevention of WaterDamage to Steam Turbines Used for Electric Power Generation (Fossil), AmericanSociety of Mechanical Engineers, New York.2. ANSI/ASME TDP-2-1985, Recommended Practices for the Prevention of WaterDamage to Steam Turbines Used for Electric Power Generation (Nuclear), AmericanSociety of Mechanical Engineers, New Yo
  • The condensate collection system from the condenser hotwell presents a unique set of parameters since we are dealing with water at slightly elevated temperatures and at a vacuum pressure. These conditions make the condensate pump suction piping susceptible to flashing and cavitation. The following guidelines apply to the design of condensate pump suction and discharge piping:
  • The boiler feedwater pumps normally take suction from the deaerator storage tank, discharge to the feedwater heaters, and then supply the boiler. Here, too, the designer has to deal with the possibility of flashing fluid and must ensure that the deaerator storage tank is located at an elevation that will provide sufficient net positive suction head (NPSH) at the pump. The following guidelines apply to the design of this piping:
  • This system consists of the turbine casing drains from the turbine to the condenser,a drain collection manifold at the condenser, or other drain vessel as indicated onthe system P&ID. The designer should comply with the following standards andconsider the guidelines listed below for the physical design of these drains:
  • The heater drains system consists of the feedwater heater drains from one heater to another at a lower pressure, to a drain tank, or to the dump line to the condenser. The designer should comply with the following standards and consider the guidelines listed below for the physical design of these drains:
  • The compressed-air systems provide service air and instrument air throughout the plant. The following guidelines apply to the design and layout of these systems:
  • There are several types of cooling water systems utilized today in the engineering and design of power generation, petrochemical, and industrial plants. The most common system in use for many years in power generation was the direct use of the water from the nearby river, bay, or ocean. Use the following guidelines in desinging the piping systems
  • Transcript of "WS 3-preliminary piping design-total system"

    1. 1. Webinar Series: Overview of How Piping Design & Analysis Influences Pipe Support Selection & Design Piping Design Webinar Series Webinar Session # 3 July 25, 2012 By Piping Technology & Products
    2. 2. If you have any questions, comments orsuggestions, please email us atenews@pipingtech.comTo request a PDH certificate, email enews@pipingtech.com
    3. 3. PT&P Subsidiaries PIPING TECHNOLOGY & PRODUCTS, INC. Member of MSS, SPED, APFA, Fronek AnchorU.S. Bellows, Inc. Sweco Fab, Inc. Pipe Shields, Inc. Darling Ent., Inc.Member of EJMA ASME U-Stamp ISO 9001-2000 ASME Nuclear R-Stamp Certified Qualified
    4. 4. Webinar Series: Overview of How Piping Design &Analysis Influences Pipe Support Selection & DesignTopic Session / DateIntroduction I. Overview of Piping (completed)Preliminary I. Piping System II. The Total SystemPiping Design Components July 25, 2012 (completed)Basic Concepts I. Part 1 II. Part 2of Stress August 1, 2012 August 8, 2012AnalysisInfluences on I. Rigid Supports II. Spring Supports III. RestraintsPipe Support August 15, 2012 August 22, 2012 August 29, 2012Design
    5. 5. The Total System - Overview Types of Piping Systems Network Analysis Series Piping Parallel Piping Branching Piping Pipe Sizing Criteria The Siphon Effect System Static and Dynamic Head Visualizing Energy Addition and Losses Troubleshooting Piping Systems Rules of Thumb
    6. 6. Types of Piping Systems  Water Piping Systems  Process Piping  High Temperature System  Low Temperature Systems  Power Piping  High Temperature Systems Process PipingImage Source: santek.com.tr
    7. 7. Water Piping Systems  Distribution Systems a) Loop b) Gridiron c) TreeImage Source: The Piping Handbook
    8. 8. Water Piping Systems Transmission Lines  Carry water from main source of supply to the distribution system In-Plant Utility Systems  Common industrial use water systems are condenser- circulating system and service cooling water systems Distribution Mains  Pipelines that carry water from the transmission lines and distribute it to the service area. Service lines  Small diameter pipes that run from distribution main to the user change, or a tee joint.
    9. 9. Water Piping SystemsCondenser Systems Condenser systems use circulating water to condense steam exhausted by the turbines in the plants. Service Water Systems• Provide cooling water to a plant’s component, heat exchangers, and other service required by the plant
    10. 10. Process Piping Refers to all piping within the physical boundaries of a chemical or petroleum processing unit Usually intended to convey  Petroleum products  Raw, intermediate, and finished chemicals  Gas, steam, air, and water  Fluidized solids  Refrigerants  Cryogenic fluids Governed by ASME B31.3 Must be designed to accommodate both the minimum and maximum pressure and temperature conditions expected during service
    11. 11. Power Piping Refers to all piping within the physical boundaries of a facility intended to generate electricity Usually intended to convey  Steam  Water Governed by ASME B31.1 Pipe lines are in many instances sub-classfied per their particular service and/or operating conditions
    12. 12. Network Analysis  Hardy Cross Method – Method for determining the flow inside pipe network systems where the inputs and outputs are known but the flow inside the network is unknown.Source: Wikipedia – Image Source: The Piping Handbook
    13. 13. Network Analysis Continued
    14. 14. Network Analysis Continued
    15. 15. Series Piping  Series Piping has the same fluid flowing through all the piping, and the head losses are cumulative.Image Source: balticnordic.com
    16. 16. Series PipingFor the above example when two pipes of different sizes or roughness areconnected, the relationship between head loss and flow can be found from:
    17. 17. Series Piping Series pipes may be solved by the method of equivalent lengths. Two-pipe systems are said to be equivalent when the same head loss produces the same discharge in both systems.
    18. 18. Parallel Piping  When the flow is divided between two or more pipes and then joined again this is called a parallel systemImage Source: The Piping Handbook
    19. 19. Parallel Piping To calculate head loss in parallel piping use the following equation. For a parallel piping system:• For the total flow rate of 12 cu ft/s what is the flow through each pipe and the pressure at B?
    20. 20. Parallel Piping Example
    21. 21. Parallel Pipe Example
    22. 22. Parallel Pipe Example Checking the values of h1, h2, h3:
    23. 23. Parallel Pipe Example There are two types of problems when you know the inlet and outlet flows.  The elevation of the grade lines at point A and B are known and you are trying to find the total discharge Q  Q is known and you are trying to find the distribution of flow and head loss. All other properties are known.
    24. 24. Parallel Pipe Example
    25. 25. Parallel Pipe Example For turbulent flow (Reynolds numbers above 2000) For viscous flow (Reynolds numbers below 2000)
    26. 26. Branching pipes  For branching pipes where pipes run neither completely parallel or in series, a combination of both principles of head loss must be used to calculate head loss and intermediate flow.
    27. 27. Pipe Sizing Criteria There are two values critical to sizing the piping network: 1. Allowable pressure drop for the entire network 2. Adjusted volumetric flow rates at the design point of the network.
    28. 28. The Siphon Effect A siphon system is one in which the siphon principle is employed to carry the water through elevated parts of the system, such as a condenser, in order to reduce the pumping power required. Elevated portions of the system operate under a partial vacuum which pulls the fluid using positive head throughout the system.
    29. 29. The Siphon Effect – Backflow Backflow or Reverse flow is caused through one of two conditions, back pressure or back siphonage.  Back Pressure - If a high pressure system is cross connected with a lower-pressure system, then the high pressure system can force fluid into the low pressure system  Back Siphonage - If an open system is connected to a closed system and the pressure in the closed system falls below atmospheric pressure, then the open system can force fluid into the closed system.
    30. 30. The Siphon Effect – Backflow Backflow due to pressure loss: back-siphonage  • Backflow due to back pressure  Image Source: The Piping Handbook
    31. 31. System Static & Dynamic Head Static Head – the internal energy of a fluid due to the pressure exerted on its container Dynamic Head – The equivalent height of a fluid that is to be pumped, taking into account the friction losses in the pipe
    32. 32. Visualizing Energy Addition/Losses Most piping systems use pumps to develop the pressure or head required to maintain the system design flow rates. Piping system pressure drops must be maintained within reasonable values to limit the installed size of the system pumps and their prime movers. Fluid velocity is controlled to prevent operational problems such as water hammer or steam hammer, or relief valve discharge loading, or vibrational loads.
    33. 33. Other considerations in Piping Design Once the piping configuration has been determined, analysis of the system begins with system pressure drop due to piping components, friction, and equipment.Image Source: The Piping Handbook
    34. 34. Oil and other Liquid Systems When considering oil flow in pipes, the most important variable physical property is viscosity. Viscosity changes with pressure and temperatures. Viscosity affects the pressure drop in the piping, The most common information is the specific gravity and the viscosity of the liquid. When two or more liquids are blended, it is necessary to determine the properties of the mixture. This can be found in literature such as The Petroleum Processing Handbook.
    35. 35. Two Phase Flow The term multicomponent is used to describe flows in which the phases do not consist of the same chemical substance. These occur in evaporators, steam generators, and oil and natural gas pipelines. Two Phase flow can be avoided in piping by  Reducing line sizes to the minimum permitted by available pressure differentials to achieve a safe mass flow rate,  Designing for parallel pipe runs that will permit increasing mass flux per pipe at low load conditions by removing one pipe from service;  Arranging the pipe configurations to protect against two phase flow (for example, in a pocketed line where liquid might collect and slug flow develop).
    36. 36. Troubleshooting Piping Systems Some problems occur in piping systems resulting from faulty plant design and from faulty operating procedures. These problems can cause water hammer or cavitation. Some of the things that need to be known are the minimum and maximum design pressures for components, isometric drawings, and support locations.
    37. 37. Rules of Thumb for Piping Layout Proper planning - early stages of a project. Space conservation and a symmetric piping arrangement are achieved when all the systems are evaluated in the preliminary stages of design.
    38. 38. Rules of Thumb for Piping Layout  Avoid interference with other facilities in the plant  Be careful of other piping systems, heating, el ectrical cables, a/c etc.Image Source: The Piping Handbook
    39. 39. Rules of Thumb for Piping Layout View overall plant design to plan for interference-free routeImage Source: The Piping Handbook
    40. 40. Rules of Thumb for Piping Layout Do not overlook the effects of thermal expansion The piping stress analyst:  Translates and enters the piping design data into the computer  Reviews the output data  May suggest corrective redesigns. Incorporate final stress analysis results into the final pipe support and pipe routing design
    41. 41. Rules of Thumb for Piping Layout Route piping with flexibility designed into it and consider the following:  Avoid straight runs between two anchor points • A piping system between two anchor points in a single plane should, as a minimum, be L-shaped, consisting of two runs of pipe and a single elbow. • Preferred solution: Series of two or more L-shaped runs of pipe
    42. 42. Rules of Thumb for Piping Layout When the expected thermal expansion in any given run of pipe is high, consider the use of an anchor at or near the center of the run, thereby distributing the expansion in two directions
    43. 43. Rules of Thumb for Piping Layout On large-diameter main and smaller branch lines, be sure the branches are flexible enough for expansion Review systems purged by steam to make sure they will be flexible during purging
    44. 44. Rules of Thumb for Piping Layout System or equipment bypass lines may be cold due to lack of flow while the main runs are at operating design temperature, resulting in excessive stresses. Temperatures during initial start-up and testing are often greater than those at operating conditions. Closed relief valve and hot blow-down systems should be given special attention due to rapid transients in temperature.
    45. 45. Rules of Thumb for Piping Layout In addition, the piping designer may use a variety of single- and multi-plane piping arrangements, such as the L- shaped, the U-shaped, and the Z-shaped configurations, in the normal routing of any system, as shown below
    46. 46. Rules of Thumb for Piping Layout Valve guidelines  Install with stems between the vertically upward and horizontal positions  Avoid head and knee knockers, tripping hazards, etc  Install large motor-operated valves in the vertical upright position
    47. 47. Rules of Thumb for Piping Layout Locate valves in acid and caustic applications below eye level Locate valves in the natural routing of the system from point to point – avoid vertical loops
    48. 48. Rules of Thumb for Piping Layout Valves in overhead piping with their stems in the horizontal position – Locate them so that the bottom of the hand wheel is not more than 6.5 ft (2 m) above the floor or platform. Do not allow chains to interfere with valves where chain operators are used.
    49. 49. Rules of Thumb for Piping Layout A minimum of 4 in (100 mm) of knuckle clearance should be provided around all valve hand wheels. Valves should not be installed upside down. Space should be provided for the removal of all valve internals.
    50. 50. Rules of Thumb for Piping Layout When routing piping at pumps, the designer should follow the manufacturer’s recommendations, the Hydraulic Institute Standards, and the following guidelines:  Suction and discharge piping must be supported independently of the pump  Consider using expansion joints on either the suction or discharge, or both, as necessary.
    51. 51. Rules of Thumb for Piping Layout  The suction of any centrifugal pump must be continuously flooded, and the suction piping shall contain no vertical loops or air pockets.  When a reduction in pipe size is required at the pump suction, provide an eccentric reducer flat side up.Image Source: The Piping Handbook
    52. 52. Rules of Thumb for Piping Layout Design pump suction lines to accommodate a conical-type temporary strainer. Consider the use of pipe anchors between expansion joints and the pump nozzle When pump flanges are cast-iron flat-faced, the mating flanges must also be flat-faced and the joint made up with full-face gaskets and common steel bolts (ASTM A 307, Grade B), not high-strength bolts (ASTM A193, Grade B7). Refer to the Hydraulic Institute Standards for arrangement of pump piping.
    53. 53. Rules of Thumb for Piping Layout Provide high-point vent and low-point drain connections during the course of physical routing of any system for these purposes:  Hydrostatic testing and evacuation of entrapped air in the process  Evacuation of all water used for hydrostatic testing and operation during periods of start-up and maintenance
    54. 54. Rules of Thumb for Piping Layout  Consider that it is cheaper to bury pipe underground than install it above groundImage Source: coab.us
    55. 55. Rules of Thumb for Piping Layout Pipe Racks - Pipe layout on pipe racks should follow the Pipe Planning Study concepts.  Do not design one pipe at a time  Pipes should rest directly on the rack with an insulation shield  Steam piping should exit the rack with a vertical up- and-over to avoid condensate collection points  Water piping should exit the rack with a vertical down- and-under to avoid a high-point air pocket collection point
    56. 56. Rules of Thumb for Piping Layout Pipe supports require structural support, which means that piping should be located in close proximity to steel or concrete  Do not locate the pipe too close to the structure, so as to allow adequate space for the pipe support hardware to facilitate installation  The pipe insulation needs to be considered for clearances and insulation saddles. The most preferred location is either resting directly on structural steel for bottom support or using a single rod to the structure directly above the pipe.
    57. 57. Rules of Thumb for Piping Layout Pipe Supports  Piping should be routed such that the support designer can make use of the surrounding structure to provide logical points of support, anchors, guides, or restraints, with ample space for the appropriate hardware  Banks of parallel pipelines at different elevations should be staggered horizontally and spaced sufficiently apart to permit independent pipe supports for each line  The piping designer should work closely with the structural engineer in the spacing of the pipe rack supports and the method of intermediate support to prevent pipe sagging.
    58. 58. Rules of Thumb for Piping Layout Specific industry rules of thumb Power Plants  All piping in this service should be sloped down a minimum of ¹⁄₈ in/ft (10 mm/m), in the direction of flow. Extensive evaluation and design are required for lines that do not slope in the direction of flow to ensure that condensate is collected and drained adequately  The final design of the main steam and hot reheat lines should be reviewed, with consideration for thermal growth, to determine the location of any necessary low point drains and to ensure that the system can be completely drained in both the hot and cold conditions
    59. 59. Rules of Thumb for Piping Layout Specific industry rules of thumb for Power Plants  Provide a drain pot at the low point of each cold reheat line, which should be fabricated from NPS 6 (DN 150) or larger pipe and be no longer than required to install the level-sensing devices.  Steam lines that are fitted with restricting devices such as orifices or flow nozzles should be adequately drained upstream of the device Orifice Plates by Piping Technology
    60. 60. Rules of Thumb for Piping Layout Specific industry rules of thumb Power Plants  Valves in all steam services should be installed with the valve stem in the vertical upright position to prevent the entrapment of fluid in the bonnet. Where this is not practical, the stem may be positioned between the vertical and horizontal positions, but in no case below horizontal.  Main steam safety relief valves should be fitting-bound to the main steam headers.  Sufficient space should be provided around any steam line to allow for insulation, pipe supports and anchors, thermal growth, machine welding, and maintenance repairs and replacements.
    61. 61. Rules of Thumb for Piping Layout Steam Turbines  The routing should be as short and as direct as possible with consideration for thermal growth and piping flexibility.
    62. 62. Rules of Thumb for Piping Layout Steam Turbines  Bleeder trip valves must be located as close to the turbine extraction point as possible, while at the same time keeping the total volume of the system within the turbine manufacturer’s recommendations.  When extraction steam piping is routed through the condenser neck, an expansion joint must be provided in each line and located at the turbine nozzle. The bleeder trip valves in these lines must be located just outside the condenser neck.
    63. 63. Rules of Thumb for Piping Layout Steam Turbines  A drain should be located at the low point in the extraction pipe between the turbine and block valve and routed separately to the condenser. A power- operated drain valve should be installed in this line that opens automatically upon the closure of the block valve in the extraction pipe.  There should be no bypasses around the extraction line shutoff or non return valves.  Unavoidable vertical loops which create low points in the piping downstream of the bleeder trip valves must be provided with continuously drained drip pots.
    64. 64. Rules of Thumb for Piping Layout  Steam Turbines  Provide a minimum of five diameters of straight pipe downstream of all bleeder trip valves.  Provide maintenance access to all bleeder trip valves including any miscellaneous platforms, if needed.Image Source: steam-boilers.net
    65. 65. Rules of Thumb for Piping Layout Condensate  Where two or more condensate pumps are used, the individual runs to each pump must be similar, and if a suction manifold or header is used, the individual pump suction lines from that manifold or header must be similar.  When the manifold or header is larger than the pump suction size, the manifold or header should be made up of full-sized tees and eccentric reducers, flat side up.  Each individual pump suction run should be sloped down a minimum of 1⁄₈ in/ft (10 mm/m) toward the pump and be self-venting back to the condenser.
    66. 66. Rules of Thumb for Piping Layout Condensate Lines  Provide a minimum of three to four diameters of straight pipe in the pump suction line; in addition, these lines must be fitted with expansion joints and startup strainers.  The condensate pump discharge check valve must be located below the hotwell water level and be continuously flooded.  The discharge header outlet should not be located between the pump discharge connections to the header, to avoid a counter flow condition.
    67. 67. Rules of Thumb for Piping Layout Feed Water  The pump suction piping from the deaerator storage tank should drop vertically, avoiding any long horizontal runs of pipe. If short horizontal runs are unavoidable, they should be angled vertically down.  A minimum of 3 diameters of straight pipe is required at the pump suction. The pump suction strainer may be located in this run of pipe.  If a reducer is required at the pump suction, it must be eccentric and installed with the flat side up.  The feed pump discharge swing check valves should be located in horizontal runs of pipe only.  The feed pump recirculation line control valve should preferably be located at the deaerator storage tank. Horizontal runs are to be avoided in this line at the tank. If the control valve is located in a branch from the pump discharge, the line downstream of the valve must be continuously flooded.
    68. 68. Rules of Thumb for Piping Layout Turbine Drains  Turbine drain lines and valve ports should be sized for the maximum amount of water to be handled under any operating condition, but in no case may they be less than NPS 3/4 inch (DN 20).  Drain lines should be designed for both hot and cold conditions and should slope continuously downward in the direction of flow. Flexibility loops, when required, should be in the plane of the slope or in vertical downward runs.  Continuous drain orifices, when used, should be located and designed so that they may be cleaned frequently and will not be susceptible to plugging by debris.  Steam traps are not satisfactory as the only means of draining critical lines; however, they may be used in parallel with automatically operated drain valves.  No part of any drain line may be below its terminal point at the condenser, drain collection header, or other drain vessel.  Only drain lines from piping systems of similar pressure may be routed to a common manifold.  All drain and manifold connections to the condenser must be above the maximum hotwell water level.
    69. 69. Rules of Thumb for Piping Layout Turbine Drains  Drainage from other vessels, such as feedwater heaters, steam jet ejectors, and gland steam condensers, that drain water continuously must not be routed to turbine cycle drain manifolds.  Drain lines should be connected at a 45 angle to the manifold axial centerline with the drain line discharge pointing toward the condenser. Drain line connections at the manifold should be arranged in descending order of pressure, with the highest pressure source farthest from the manifold opening at the condenser.  Drain connections to flash tanks must be above the maximum water level in the tank.  Drains from the upstream and downstream sides of shutoff valves must not be interconnected.  Drain lines in exposed areas should be protected from freezing.  All turbine drain drawings must be reviewed and approved by the turbine supplier.
    70. 70. Rules of Thumb for Piping Layout  Heater Drains  Drain piping from feedwater heaters without an internal drains cooler must immediately drop vertically to provide as much static head as possible upstream of the heater level control valve. Thereafter any horizontal runs must be sloped down a minimum of ¹⁄₄ in/ft (20 mm/m) in the direction of flow. • Drain piping from feedwater heaters with an internal drain cooler may be routed horizontally without sloping upon leaving the heater. • Heater level control valves should be located as close as possible to the receiving vessel, with consideration for ease of access and maintenance.Image Source: ndt.net
    71. 71. Rules of Thumb for Piping Layout Heater Drains  The heater drain system arrangements must be coordinated with the system engineer for analysis to ensure that single-phase water flow is maintained upstream of the heater level control valves and to determine where downstream velocities may require tees and target plates in lieu of elbows for minimizing erosion.  Heater drain dump lines should enter the condenser at approximately the horizontal centerline of the tube bundle. This location should be coordinated with the condenser manufacturer, who will provide the necessary baffle plates to prevent impingement on the condenser tubes.  Only long-radius elbows should be used in heater drain piping.  The use of reducers should be avoided, except at the control valves, which are generally smaller than the line size.
    72. 72. Rules of Thumb for Piping Layout Compressed Air  Refer to the compressor manufacturer’s instruction manual for the recommended relative lengths of intake and discharge piping versus compressor revolutions per minute (rpm).  The compressed-air system equipment arrangement and piping design should be such that the air receiver is the lowest point in the system and any condensate in the system will drain to the air receiver, particularly during periods of shutdown when large amounts of condensate can form. The point here is to preclude any possibility of condensates draining back to the air compressor, where it could cause extensive damage. The compressor discharge piping should be as short and direct as possible through the after-cooler and into the air receiver. The compressed- air system distribution lines and risers should originate from a separate outlet connection on the air receiver and should be sloped back to the air receiver.  Compressed-air line header branches should have vertical risers and be drained at their terminations.  Individual service branches should be taken off the top of the headers.
    73. 73. Rules of Thumb for Piping Layout  Cooling Water Systems  Where butterfly valves are used, follow the guidelines provided for valves. Any given heat exchanger inlet and outlet valves should be located close together for balancing the system.  Avoid unnecessary vertical loops in any closed cooling water system. This type of system will usually include an expansion tank, which should be located at or above the highest point in the system, and the outlet from this tank should be piped directly to the pump suction. • For piping at centrifugal pumps, follow the guidelines provided for piping of centrifugal pumps. • Consult the Hydraulic Institute standards and the pump manufacturer’s guidelines for layout and arrangement of deep well type pumpsImage Source: generalsteel.ir
    74. 74. Next Webinar Session: August 1, 2012 Session 4: Basic Concepts of Stress Analysis - Flexibility Analysis Part 4 of our continuing series will take an historical perspective of how earlier analysis techniques were developed in the absence of todays computer technology. Learn how earlier techniques have evolved ultimately leading to todays finite element practices. The basic concepts of analysis will be covered, including failure theories, stress intensification factors and the overall purpose of stress analysis. If you have any questions, comments or suggestions, please email us at enews@pipingtech.com To request a PDH certificate, email enews@pipingtech.com

    ×