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AFT President to Present Three Papers at ASME Pressure Vessels & Piping (PVP) Conference

The ASME 2018 PVP Conference promises to be the outstanding international technical forum for participants to further their knowledge-base by being exposed to diverse topics, and exchange opinions and ideas both from industry and academia in a variety of topics related to Pressure Vessel and Piping technologies for the Power and Process Industries. 

AFT President Trey Walters will present the following three papers at the conference in Prague: 

1. WHEN THE JOUKOWSKY EQUATION DOES NOT PREDICT MAXIMUM WATER HAMMER PRESSURES

Co-author: Robert A. Leishear, Ph. D., P. E., Leishear Engineering, LLC., author of Fluid Mechanics, Water Hammer, Dynamic Stresses and Piping Design

ABSTRACT

The Joukowsky equation has been used as a first approximation for more than a century to estimate water hammer pressure surges. However, this practice may provide incorrect, non-conservative, pressure calculations under several conditions. These conditions are typically described throughout fluid transient text books, but a consolidation of these issues in a brief paper seems warranted to prevent calculation errors in practice and to also provide a brief understanding of the limits and complexities of water hammer equations.

To this end, various issues are discussed here that result in the calculation of pressures greater than those predicted by the Joukowsky equation. These conditions include reflected waves at tees, changes in piping diameter, and changes in pipe wall material, as well as frictional effects referred to as line pack, and the effects due to the collapse of vapor pockets. In short, the fundamental goal here is to alert practicing engineers of the cautions that should be applied when using the Joukowsky equation as a first approximation of fluid transient pressures.

 

2.  A PROPOSED GUIDELINE FOR APPLYING WATERHAMMER PREDICTIONS UNDER TRANSIENT CAVITATION CONDITIONS PART 1: PRESSURES 

Co-authors: Matthew Stewart, P.E. and Greg Wunderlich, P.E., both of AECOM (and customers of AFT) and Erin Onat, Applied Flow Technology

ABSTRACT

Waterhammer analysis (herein referred to as Hydraulic Transient Analysis or simply "HTA") becomes more complicated when transient cavitation occurs (also known as liquid column separation). While standard HTA transient cavitation models used with analysis based on the Method of Characteristics show good correlation when compared to known test/field data, the great majority of test/field data are for simple systems experiencing a single transient. Transient cavitation in more complicated systems or from two or more independently initiated transients have not been validated against data.

Part 1 of this paper describes the various safety factors already provided by ASME B31.3 for pressure containment, provides criteria for accepting the results of HTA calculations that show the presence of transient cavitation, and makes recommendations where the user should include additional safety factors based on the transient cavitation results.

Situations are discussed where waterhammer abatement is recommended to reduce hydraulic transient pressures and forces, and for increasing confidence in HTA results in specific cases. The result is a proposed comprehensive and pragmatic guideline which practicing engineers can use to perform waterhammer analysis and apply pressure predictions to pipe stress analysis.

 

 3.  A PROPOSED GUIDELINE FOR APPLYING WATERHAMMER PREDICTIONS UNDER TRANSIENT CAVITATION CONDITIONS PART 2: IMBALANCED FORCES

Co-authors: Matthew Stewart, P.E. and Greg Wunderlich, P.E., both of AECOM (and customers of AFT)

ABSTRACT

Waterhammer analysis (herein referred to as Hydraulic Transient Analysis or simply "HTA") becomes more complicated when transient cavitation occurs (also known as liquid column separation). This complication is exacerbated when trying to predict imbalanced forces as this often involves comparing pressure times area ("PxA") forces at two locations (for example at elbow pairs). Whereas the pressure at each elbow location has increased uncertainty because of transient cavitation, the difference in PxA forces at elbow pairs involves subtracting one potentially uncertain pressure from another uncertain pressure. Exacerbating this uncertainty yet further, the existence of vapor in a liquid system can dramatically affect the fluid wavespeed and, hence, the timing of the pressure wave travel between two locations such as elbow pairs; so the pressure calculated at each location would not actually occur at exactly the same time.

This Part 2 discusses methods of accounting for uncertainty in HTA imbalanced force predictions due to cavitation. The criteria in this paper assume that cavitation in the HTA has been assessed and accepted per the criteria in Part 1 of this paper.

A guideline is proposed for accepting and applying such results and, in particular, makes recommendations on safety factors to use in pipe stress analysis for different cases. The specific recommendations depend on numerous factors including:

  • Presence or absence of cavitation in hydraulically connected or isolated parts of the system
  • If cavitation occurs, whether the peak forces occur before or after cavitation first occurs
  • Size of the cavitation vapor volumes with respect to the computing volumes
  • Use of point forces as a conservative substitute in place of potentially less certain elbow pair forces or the manual assessment of maximum envelope values for the force. 

Situations are discussed where waterhammer abatement is recommended to reduce hydraulic transient forces, and for increasing confidence in HTA results in specific cases. The result is a proposed comprehensive and pragmatic guideline which practicing engineers can use to perform waterhammer analysis and apply imbalanced force predictions to pipe stress analysis.

 

 

 

AFT Impulse Adds ROHR 2 Force Files Interface

 

With the February 21, 2018 maintenance release of Impulse 6 came a cool new feature. AFT added the capability to interface piping layout and dimensional data from ROHR2 force files.

This capability was already available for CAESAR II and TRIFLEX force files and will also be available in the AFT Fathom & AFT Arrow maintenance releases soon. 

Applied Flow Technology (AFT) strives to continuously enhance our interfaces to give users extended flexibility when designing their piping systems. Be on the lookout for even more partnering as AFT is soon to release AFT Fathom 10 this Spring and shortly followed by AFT Arrow 7 and AFT Impulse 7. 

With powerful solutions and user-friendly interfaces, Applied Flow Technology (AFT) is a leader in the pipe flow modeling software market. Our software is used to analyze, model, and simulate piping and ducting systems to help industries around the world design safer, more efficient systems and solve operational problems. AFT’s products are developed by engineers with extensive experience in the design and construction of piping systems and the development of analytical modeling methods. For information, visit www.aft.com or contact one of our 70 international Channel Partners.

Support, Upgrade & Maintenance Agreement Price Adjustment

 

Please note that as of March 31, 2018, the prices of the Support, Upgrade, and Maintenance Agreements (SUM Agreements) will adjust.
 
If you are an AFT direct customer, Click here to view the updated price list. If you purchase your AFT software through one of our Channel Partners, please contact them directly

FAQ's:
Q. Why are we being notified now?
A. Because AFT Fathom 10 will be released this spring. We want all expired SUM holders to be able to reinstate their SUM agreement and receive AFT Fathom 10 while the cost of the SUM is honored through March 31, 2018. Arrow 7 and Impulse 7 are also expected to release in 2018.

Q. Can you tell me what new features will come with Fathom 10?
A. Yes! Click here to view the full list of new features in Fathom 10. 

Q. How is this structure set-up?
A. All customers receive one year of support, upgrade and maintenance when they purchase the software. After the first year, a SUM agreement can be continued for 20% of the cost of the retail price of a full standalone license (network licenses are not charged extra). This SUM entitles customers to receive any new version of our software at no extra cost, as well as access to world-class technical support. If you let your agreement expire, the price to reinstate your agreement is two times the SUM and after 2+ years the cost goes up to three times the SUM.

Q. How do I find my license(s) that need to be reinstated?
A. Easy - send an e-mail to This email address is being protected from spambots. You need JavaScript enabled to view it. or contact your Channel Partner. They will send you all of your license numbers along with a quote to have them reinstated. 

Q. I use add-on modules with my AFT Fathom / Arrow / Impulse. Will they be affected? 
A. Yes. Add-on Modules also have SUM agreements and will follow the same pricing structure. Send an e-mail to This email address is being protected from spambots. You need JavaScript enabled to view it. or contact your Channel Partner if you need to reinstate your add-on modules. 

Please let us know if we can help you further.

 

4 Reasons to Check Out AFT Fathom Student

 

Here is why you should put AFT Fathom Student to work for you: 


 
#1. Work smarter, it’s the best help with homework you can find.  Our very own recent graduate, Abby, was bummed she didn’t learn about it sooner. Try it out with any common textbook problem and you’ll see a whole new way to get results quickly and efficiently.

 
#2. You’re eventually going to graduate and get a job… right? Oil & Gas, Aerospace, Power, Mining, Water / Waste Water, HVAC, (and more!) are all industries that use AFT to analyze, model, and simulate their pipe systems. 

 
#3. Knowing AFT Fathom will take you places. Seriously, it looks amazing on a job application. The companies you hope will give you a paycheck probably use AFT. We even offer super cheap hands-on training classes. It includes lunch for each day of the class! You can even sleep on our couch.

 
#4. You will have a Senior Project. Use a FREE full version. Yes, AFT will give you a $5,000 product for free. Learn the basics with the AFT Fathom Student so you will be on top of your game to dive into the full version when it’s time.

 

-------------------   How do you get it?  -------------------

It is $10 to access to a simplified version of our industry-leading 

software that normally sells for thousands of dollars to top engineers all around the world. 

See all of the features at: www.aft.com/students/fathom

 


 
See even more! 
Find out how AFT Software products are being used by research students around the world. 

University of Alabama Reduces Energy Usage

UAB Saves $60,000 a Year with AFT FathomTM  

COLORADO SPRINGS, Colo., January 25, 2017 – University of Alabama at Birmingham obtained an annual energy savings of $60,000 after Bernhard TME Engineering (TME) optimized the university’s district chilled water system. The chilled water is distributed to 48 buildings on campus to supply the air conditioning systems in the hot and humid southeastern U.S.

Brandon Smith, commissioning technician, and Wei Guo, energy engineer, at TME, used AFT Fathom to create a hydraulic model of the existing system. 

Smith and Guo were able to run simulations with the chilled water plants’ pumps in several different arrangements in order to determine the most efficient way to run the plants. 

A major step to reduce overall energy cost was to determine the most hydraulically remote building and add booster pumps to that building. However, with the size of the campus and the extensiveness of the piping layout, this was no easy feat. 

Smith and Guo turned to AFT Fathom to determine which building’s control valve was most open, which indicates poor temperature control of that building. This discovery helped determine the most hydraulically remote building, to which TME added booster pumps and ran several different scenarios to find the best operating condition for the plant. By adding a booster pump to that building, the campus is able to obtain an annual savings of $60,000 a year.

“We were very impressed by how quickly AFT Fathom is able to process and calculate solutions for such a large piping network,” said Smith. “Without the speed of AFT Fathom, this type of modeling project would not have been economically feasible for the university to invest in.”

Smith and Guo submitted the University of Alabama project to AFT’s Platinum Pipe Award Contest and received the 2016 award for the Operational Benefits and Sustainability category. The award recognizes excellence in piping and ducting system modeling using AFT software. 

“The application of AFT’s system modeling software at the University of Alabama continues to demonstrate the value of system modeling and the power and versatility of our software products,” said AFT President Trey Walters, P.E. “There is much work to be done to improve the energy efficiency of installed pumping systems and to change the paradigm of how pumping systems are initially designed to reduce their environmental footprint. This application is an important step in that direction.”

For the full case study, click here

About Applied Flow Technology

Founded in 1993, Applied Flow Technology has grown to be a leader in the pipe flow modeling software market. With a primary focus on developing high quality fluid flow analysis software, AFT has a comprehensive line of products for the analysis and design of piping and ducting systems.

With channel partners around the world and customers in more than 70 countries, AFT software has helped companies in many industries design safer, more efficient systems and solve operational problems.

Located in Colorado Springs, Colorado, USA, our professional staff consists of engineers with extensive experience in both the design and construction of piping systems and the development of analytical modeling methods.

About Bernhard TME Engineering

Bernhard TME is a full-service energy, mechanical, electrical, plumbing, fire protection and structural engineering firm. With a staff of more than 180 individuals in 14 locations across the country, the company is comprised of expert professionals dedicated to providing clients with innovative engineering design and energy conservation.

Bernhard TME is the engineering firm within Bernhard, a group that creates value for clients through turnkey energy services designed to achieve and sustain energy cost reduction.