Piping Engineering / Design Blog.



Posted by Antony Thomas at Sunday, August 16, 2009


Wind Load:

The majority of all piping system installations are indoors where the effects of wind
loading can be neglected. However, there are sufficient numbers of outdoor piping
installations where wind loading can be a significant design factor. Wind load, like
deadweight, is a uniformly distributed load that acts along the entire length, or that portion of the piping system that is exposed to the wind. The difference is that
while deadweight loads are oriented in the downward vertical direction, wind loads
are horizontally oriented and may act in any arbitrary direction. Since wind loads
are oriented in the horizontal direction, the regular deadweight support system of
hangers and anchors may have little or no ability to resist these loads. Consequently,when wind loading is a factor, a separate structural evaluation and wind load supportsystem design is required.

Determination of the magnitude of the wind loadings is based upon empirical
procedures developed for the design of buildings and other outdoor structures.
Analysis of piping system stresses and support system loads is accomplished by
using techniques that are similar to those applied for deadweight design.

Snow and Ice Loads:

Snow and ice loads, like wind loads, need to be considered in the design of piping
systems which are installed outdoors, particularly if the installation is made in the
northern latitudes. Since snow and ice loads act in the vertical direction, they are
treated the same as deadweight loads. In design, they are simply added as distributed
loads in the deadweight analysis.

Snow Loads.

ANSI/ASCE 7–95, Minimum Design Loads for Buildings and Other
Structures, provides recommendations and data for developing design loadings due
to snow. The methods used in this standard are generally applicable to sloping or
horizontal flat surfaces such as building roofs or grade slabs.

Ice Loads:

Ice storms are sporadic in the frequency of their occurrence and in
their intensity. Weather records dating back to the turn of the 20th century for a
typical midwestern state relate instances of ice storm deposits of 1/8 in (3.2 mm) to
4 in (102 mm) in thickness. The American Weather Book10 cites examples of ice
accumulations of up to 8 in (203 mm) in northern Idaho (1961) and 6 in (152 mm)
in northwest Texas (1940) and New York State (1942).

Seismic (Earthquake) Loads

Under certain circumstances it is necessary or desirable to design a piping system to
withstand the effects of an earthquake. Although the applications are not extensive,
piping system seismic design technology is well developed and readily accessible.
Many currently available piping stress analysis computer programs are capable of
performing a detailed seismic structural and stress analysis, in addition to the
traditional deadweight and thermal flexibility analyses. Most of these programs run
on desktop microcomputers.
Because of the higher construction costs and design complexities introduced by
the application of seismic design criteria, this type of work is normally done only
in response to specific regulatory, code, or contractual requirements.



Posted by Antony Thomas at Friday, August 14, 2009


Part A: Piping Fundamentals

Chapter A1. Introduction to Piping Mohinder L. Nayyar A.1
Chapter A2. Piping Components Ervin L. Geiger A.53
Chapter A3. Piping Materials James M. Tanzosh A.125
Chapter A4. Piping Codes and Standards Mohinder L. Nayyar A.179
Chapter A5. Manufacturing of Metallic Piping Daniel R. Avery and
Alfred Lohmeier A.243
Chapter A6. Fabrication and Installation of Piping Edward F. Gerwin A.261
Chapter A7. Bolted Joints Gordon Britton A.331
Chapter A8. Prestressed Concrete Cylinder Pipe and Fittings
Richard E. Deremiah A.397
Chapter A9. Grooved and Pressfit Piping Systems
Louis E. Hayden, Jr. A.417
Chapter A10. Selection and Application of Valves Mohinder L. Nayyar,
Dr. Hans D. Baumann A.459

Part B: Generic Design Considerations

Chapter B1. Hierarchy of Design Documents Sabin Crocker, Jr. B.1
Chapter B2. Design Bases Joseph H. Casiglia B.19
Chapter B3. Piping Layout Lawrence D. Lynch,
Charles A. Bullinger, Alton B. Cleveland, Jr. B.75
Chapter B4. Stress Analysis of Piping Dr. Chakrapani Basavaraju,
Dr. William Saifung Sun B.107
Chapter B5. Piping Supports Lorenzo Di Giacomo, Jr.,
Jon R. Stinson B.215
Chapter B6. Heat Tracing of Piping Chet Sandberg,
Joseph T. Lonsdale, J. Erickson B.241
Chapter B7. Thermal Insulation of Piping Kenneth R. Collier,
Kathleen Posteraro B.287
Chapter B8. Flow of Fluids Dr. Tadeusz J. Swierzawski B.351
Chapter B9. Cement-Mortar and Concrete Linings for Piping
Richard E. Deremiah B.469
Chapter B10. Fusion Bonded Epoxy Internal Linings and External
Coatings for Pipeline Corrosion Protection Alan Kehr B.481
Chapter B11. Rubber Lined Piping Systems Richard K. Lewis,
David Jentzsch B.507
Chapter B12. Plastic Lined Piping for Corrosion Resistance
Michael B. Ferg, John M. Kalnins B.533
Chapter B13. Double Containment Piping Systems
Christopher G. Ziu B.569
Chapter B14. Pressure and Leak Testing of Piping Systems
Robert B. Adams, Thomas J. Bowling B.651

Part C: Piping Systems

Chapter C1. Water Systems Piping Michael G. Gagliardi,
Louis J. Liberatore C.1
Chapter C2. Fire Protection Piping Systems Russell P. Fleming,
Daniel L. Arnold C.53
Chapter C3. Steam Systems Piping Daniel A. Van Duyne C.83
Chapter C4. Building Services Piping Mohammed N. Vohra,
Paul A. Bourquin C.135
Chapter C5. Oil Systems Piping Charles L. Arnold, Lucy A. Gebhart C.181
Chapter C6. Gas Systems Piping Peter H. O. Fischer C.249
Chapter C7. Process Systems Piping Rod T. Mueller C.305
Chapter C8. Cryogenic Systems Piping Dr. N. P. Theophilos,
Norman H. White, Theodore F. Fisher, Robert Zawierucha,
M. J. Lockett, J. K. Howell, A. R. Belair, R. C. Cipolla,
Raymond Dale Woodward C.391
Chapter C9. Refrigeration Systems Piping William V. Richards C.457
Chapter C10. Hazardous Piping Systems Ronald W. Haupt C.533
Chapter C11. Slurry and Sludge Systems Piping Ramesh L. Gandhi C.567
Chapter C12. Wastewater and Stormwater Systems Piping
Dr. Ashok L. Lagvankar, John P. Velon C.619
Chapter C13. Plumbing Piping Systems Michael Frankel C.667
Chapter C14. Ash Handling Piping Systems Vincent C. Ionita,
Joel H. Aschenbrand C.727
Chapter C15. Compressed Air Piping Systems Michael Frankel C.755
Chapter C16. Compressed Gases and Vacuum Piping Systems
Michael Frankel C.801
Chapter C17. Fuel Gas Distribution Piping Systems Michael Frankel C.839

Part D: Nonmetallic Piping

Chapter D1. Thermoplastics Piping Dr. Timothy J. McGrath,
Stanley A. Mruk D.1
Chapter D2. Fiberglass Piping Systems Carl E. Martin D.79

Part E: Appendices

Appendix E1. Conversion Tables Ervin L. Geiger E.1
Appendix E2. Pipe Properties (US Customary Units)
Dr. Chakrapani Basavaraju E.13

Appendix E2M. Pipe Properties (Metric) Dr. Chakrapani Basavaraju E.23
Appendix E3. Tube Properties (US Customary Units) Ervin L. Geiger E.31
Appendix E3M. Tube Properties (Metric) Troy J. Skillen E.37
Appendix E4. Friction Loss for Water in Feet per 100 Feet of Pipe E.39
Appendix E4M. Friction Loss for Water in Meters per 100 Meters of
Pipe Troy J. Skillen E.59
Appendix E5. Acceptable Pipe, Tube and Fitting Materials per
the ASME Boiler and Pressure Vessel Code and the ASME Pressure
Piping Code Jill M. Hershey E.61
Appendix E6. International Piping Material Specifications
R. Peter Deubler E.69
Appendix E7. Miscellaneous Fluids and Their Properties Akhil Prakash E.83
Appendix E8. Miscellaneous Materials and Their Properties
Akhil Prakash E.101
Appendix E9. Piping Related Computer Programs and Their
Capabilities Anthony W. Paulins E.109
Appendix E10. International Standards and Specifications for Pipe, Tube,
Fittings, Flanges, Bolts, Nuts, Gaskets and Valves Soami D. Suri

See Also:

Piping Materials Selection and Applications


Posted by Antony Thomas at


Joint design and selection can have a major impact on the initial installed cost, the
long-range operating and maintenance cost, and the performance of the piping
system. Factors that must be considered in the joint selection phase of the project
design include material cost, installation labor cost, degree of leakage integrity
required, periodic maintenance requirements, and specific performance requirements.
In addition, since codes do impose some limitations on joint applications,
joint selection must meet the applicable code requirements. In the paragraphs that
follow, the above-mentioned considerations will be briefly discussed for a number
of common pipe joint configurations.

Butt-welded Joints

Butt Welded Joint

Butt-welding is the most common method of joining piping used in large commercial,
institutional, and industrial piping systems. Material costs are low, but labor costs
are moderate to high due to the need for specialized welders and fitters. Long term
leakage integrity is extremely good, as is structural and mechanical strength.
The interior surface of a butt-welded piping system is smooth and continuous which
results in low pressure drop. The system can be assembled with internal weld
backing rings to reduce fit-up and welding costs, but backing rings create internal
crevices, which can trap corrosion products. In the case of nuclear piping systems,
these crevices can cause a concentration of radioactive solids at the joints, which
can lead to operating and maintenance problems. Backing rings can also lead to
stress concentration effects, which may promote fatigue cracks under vibratory or
other cyclic loading conditions. Butt-welded joints made up without backing rings
are more expensive to construct, but the absence of interior crevices will effectively
minimize ‘‘crud’’ buildup and will also enhance the piping system’s resistance to
fatigue failures. Most butt-welded piping installations are limited to NPS 21⁄₂ (DN
65) or larger. There is no practical upper size limit in butt-welded construction.
Butt-welding fittings and pipe system accessories are available down to NPS 1⁄₂ (DN
15). However, economic penalties associated with pipe end preparation and fit-up,
and special weld procedure qualifications normally preclude the use of butt-welded
construction in sizes NPS 2 (DN 50) and under, except for those special cases where
interior surface smoothness and the elimination of internal crevices are of paramount
importance. Smooth external surfaces give butt-welded construction high aesthetic

Socket-welded Joints

Socket Welded Joint

Socket-welded construction is a good choice wherever the benefits of high leakage
integrity and great structural strength are important design considerations. Construction
costs are somewhat lower than with butt-welded joints due to the lack of
exacting fit-up requirements and elimination of special machining for butt weld end
preparation. The internal crevices left in socket-welded systems make them less
suitable for corrosive or radioactive applications where solids buildup at the joints
may cause operating or maintenance problems. Fatigue resistance is lower than
that in butt-welded construction due to the use of fillet welds and abrupt fitting
geometry, but it is still better than that of most mechanical joining methods. Aesthetic
appeal is good.

Brazed and Soldered Joints

Soldered Piping Joint

Brazing and soldering are most often used to join copper and copper-alloy piping
systems, although brazing of steel and aluminum pipe and tubing is possible. Brazing
and soldering both involve the addition of molten filler metal to a close-fitting
annular joint. The molten metal is drawn into the joint by capillary action and
solidifies to fuse the parts together. The parent metal does not melt in brazed or
soldered construction. The advantages of these joining methods are high leakage
integrity and installation productivity. Brazed and soldered joints can be made up
with a minimum of internal deposits. Pipe and tubing used for brazed and soldered
construction can be purchased with the interior surfaces cleaned and the ends
capped, making this joining method popular for medical gases and high-purity
pneumatic control installations.
Soldered joints are normally limited to near-ambient temperature systems and
domestic water supply. Brazed joints can be used at moderately elevated temperatures.
Most brazed and soldered installations are constructed using light-wall tubing;
consequently the mechanical strength of these systems is low.

Threaded or Screwed Joints

Threaded or screwed piping is commonly used in low-cost, noncritical applications
such as domestic water, fire protection, and industrial cooling water systems. Installation
productivity is moderately high, and specialized installation skill requirements
are not extensive. Leakage integrity is good for low-pressure, low-temperature
installations where vibration is not encountered. Rapid temperature changes may
lead to leaks due to differential thermal expansion between the pipe and fittings.
Vibration can result in fatigue failures of screwed pipe joints due to the high stress
intensification effects caused by the sharp notches at the base of the threads. Screwed
fittings are normally made of cast gray or malleable iron, cast brass or bronze, or
forged alloy and carbon steel. Screwed construction is commonly used with galvanized
pipe and fittings for domestic water and drainage applications. While certain
types of screwed fittings are available in up to NPS 12 (DN300), economic considerations
normally limit industrial applications to NPS 3 (DN 80). Screwed piping
systems are useful where disassembly and reassembly are necessary to accommodate
maintenance needs or process changes. Threaded or screwed joints must be used
within the limitations imposed by the rules and requirements of the applicable code.

Grooved Joints

The main advantages of the grooved joints are their ease of assembly, which results
in low labor cost, and generally good leakage integrity. They allow a moderate
amount of axial movement due to thermal expansion, and they can accommodate
some axial misalignment. The grooved construction prevents the joint from separating
under pressure. Among their disadvantages are the use of an elastomer seal,
which limits their high-temperature service, and their lack of resistance to torsional
loading. While typical applications involve machining the groove in standard wall
pipe, light wall pipe with rolled-in grooves may also be used. Grooved joints are
used extensively for fire protection, ambient temperature service water, and low pressure
drainage applications such as floor and equipment drain systems and roof
drainage conductors. They are a good choice where the piping system must be
disassembled and reassembled frequently for maintenance or process changes.

Flanged Joints

Flanged connections are used extensively in modern piping systems due to their
ease of assembly and disassembly; however, they are costly. Contributing to the
high cost are the material costs of the flanges themselves and the labor costs for
attaching the flanges to the pipe and then bolting the flanges to each other. Flanges
are normally attached to the pipe by threading or welding, although in some special
cases a flange-type joint known as a lap joint may be made by forging and machining
the pipe end. Flanged joints are prone to leakage in services that experience rapid
temperature fluctuations. These fluctuations cause high-temperature differentials
between the flange body and bolting, which eventually causes the bolt stress to
relax, allowing the joint to open up. Leakage is also a concern in high-temperature
installations where bolt stress relaxation due to creep is experienced. Periodic
retorquing of the bolted connections to reestablish the required seating pressure
on the gasket face can minimize these problems. Creep-damaged bolts in hightemperature
installations must be periodically replaced to reestablish the required
gasket seating pressure. Flanged joints are commonly used to join dissimilar materials,
e.g., steel pipe to cast-iron valves and in systems that require frequent maintenance
disassembly and reassembly. Flanged construction is also used extensively
in lined piping systems.

Compression Joints

Compression sleeve-type joints are used to join plain end pipe without special end
preparations. These joints require very little installation labor and as such result
in an economical overall installation. Advantages include the ability to absorb a
limited amount of thermal expansion and angular misalignment and the ability to
join dissimilar piping materials, even if their outside diameters are slightly different.

Disadvantages include the use of rubber or other elastomer seals, which limits their
high-temperature application, and the need for a separate external thrust-resisting
system at all turns and dead ends to keep the line from separating under pressure.
Compression joints are frequently used for temporary piping systems or systems
that must be dismantled frequently for maintenance. When equipped with the
proper gaskets and seals, they may be used for piping systems containing air, other
gases, water, and oil; in both aboveground and underground service. Small-diameter
compression fittings with all-metal sleeves may be used at elevated temperatures
and pressures, when permitted by the rules and requirements of the applicable
code. They are common in instrument and control tubing installations and other
applications where high seal integrity and easy assembly and disassembly are desirable

PDMS Software-3D CADD System

Posted by Antony Thomas at Saturday, August 08, 2009

PDMS Software

PDMS is a specification-driven, 3-dimensional (3D) modeling system, consisting of a single relational database management program and several separate and distinct modules, each performing a unique function. Unlike many CADD systems, many of which began with a graphics package and later added database capabilities, PDMS' designers approached plant design as a true data management problem. Their solution was to establish a database core and provide methods to display the contents graphically. This approach eliminated the problem of synchronizing the graphic and data components of a graphics-based CADD system.

PDMS' database architecture imposes no unnecessary limitations on a project. It doesn't require that a project be broken into separate "sub-models" for simultaneous data input (which must subsequently be merged in order to view the entire structure). Instead, several designers can be working on the model at one time, and each can view the entire project or a selected portion of it as he builds the elements in his part of the model. With PDMS, project management can monitor the progress of a project at any point in the design cycle without disrupting the work.

From information provided by supplier drawings, engineering sketches, piping layouts, and mechanical flow diagrams (MFDs), designers build equipment, structures, and piping into the PDMS database at full size. As work progresses, operators routinely monitor data consistency via the Datacon module or via the interactive design module. This function ensures that all components are connected and that all connection types are compatible. It also ensures that lines have consistent bore and alignment. In addition to data consistency, the system is used to check for interference.

The Clasher facility checks any designated section against the model to detect "hard" clashes (such as pipe hitting cable trays) and "soft" clashes (such as brace members protruding into walkways). Maintenance areas used for rodding or pulling tubes are designated as restricted areas, and any intruding objects can be identified. The system can also detect lines that are too close for insulation application and hand wheels with insufficient clearance for operation.

Like its plastic counterpart, the computer model is a true representation of the project. Each component is a distinct element in the PDMS database. Unlike its plastic counterpart, however, the computer model can be modified to accommodate design changes and to correct errors without having to start over each time such an error is found. Additionally, the computer model provides the drawings and the documentation required to fabricate and construct the facility.

At any point in the project, "snapshots" can be taken of the model. These snapshots can take the form of a perspective view of the structure, a report listing the completed lines, a preliminary material takeoff, an input file to the dynamic model review program, or any other graphic or data report that may be required. Once the model or a designated section of the model is complete, the program can produce the following:

  • Piping isometric drawings, with material lists and cut lengths
  • Material takeoff reports formatted for input into JRME's estimating, ordering, and tracking system
  • Conventional piping plans and section drawings
  • Descriptive drawings to clarify congested or unique areas
  • Overall perspective views for fabrication/construction planning
  • Input files for the model review program (Review)
  • Reports formatted for input to center-of-gravity programs
  • Drawing files for use in AutoCAD
  • Weld count reports
  • Input files to the pipe-stress analysis program
  • Structural plans and elevation drawings
  • Exploded sub-assembly drawings to aid fabrication/construction.

Completion of the project's design phase doesn't signal the end of the model's usefulness, because the database can be transferred to CADCentre's Review software to allow real-time, color-shaded, walk-through plant review. Review was designed to be operated by people with no PDMS experience. It is mouse-driven and has pop-up menus that allow the user to "walk" down plant corridors well before the facility is constructed. It can be effectively used for orientation and operator training (since it allows users to get inside the plant) and can be projected onto a screen for several people to see at once. An added benefit is that lines, equipment, nozzles, and even support steel can be located by name, and member names can be obtained by clicking on the element.

There are many advantages to assembling a 3D numerical model. All the justifications for building a plastic model apply for the 3D model, with the added benefit that the 3D model costs much less and its cost is included in the design phase. Additionally, the 3D model helps ensure an error-free design by producing accurate drawings and reports. However, the two most important benefits are significantly reduced fabrication and erection errors and faster startup time.

PDMS Lesson-1 (Model Editor)

PDMS Commands

PDMS Latest Commands

Piping PDMS Designer - Jakarta

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