Making the world a safer and better place – A plea for more data, validation cases and guidelines for waterhammer simulation
AFT Impulse™ Technical Paper
Authors: Trey Walters, P.E., Applied Flow Technology, USA and G G Orieux, Q Li, L Thomson, Enbridge Pipelines Inc, Canada
13th International Conference on Pressure Surges 2018, Bordeaux, France, November 14-16, 2018
Abstract
Engineers tend to overdesign systems when uncertainty exists. Overdesign is an important part of the engineering process, but unnecessary overdesign will only increase the cost of systems without enhancing safety. An experience between a major pipeline company, their engineering design firm, and the waterhammer simulation software products used by both is described.
A disagreement between software package results and ultimately the two companies developed into an issue that could significantly increase costs. More and better validation cases would have helped everyone navigate this situation more quickly, easily and inexpensively. More and better application guidelines may have helped the engineering design firm achieve higher certainty in their recommendations with potentially less overdesign.
CONCLUSION
Many previous authors have made bold calls for improved guidelines for waterhammer simulation. This includes validation and verification of simulation software. An experience between an EPC, an O/O (2nd, 3rd and 4th authors) and a software tool developer (the 1st author) reaffirms the need for more and better guidelines and more data. Some of the unique aspects of this experience points to additional considerations that guideline creators may wish to address in the future.
The authors hope the end result of addressing these issues is that industry can build and operate fluid transfer systems that are safer and better.
Below is an excerpt. Use the link above to view the full paper.
Introduction
Fukishima in 2011. Deepwater Horizon in 2010. Hurricane Katrina (and the many failed pumping stations around New Orleans) in 2005. TWA Flight 800 (New York to France) in 1996. Piper Alpha offshore rig in the North Sea, in 1988. Apollo 13 in 1970, somewhere between the Earth and the Moon (subsequently called a successful failure).
Aside from Apollo 13, these spectacular failures had significant and tragic human, environmental and economic impacts. Some affected a large geographic area. All depended on safe and reliable fluid transfer systems which, for various reasons, failed. As engineers, it never hurts for us to remind ourselves of our failures and our responsibility to move our world towards safer and more reliable systems.
Over the last five to six decades, the progress in the ability to simulate waterhammer in piping systems is truly breathtaking. In the lifetime of some of our senior waterhammer experts, we have progressed from graphical methods (before digital computers) to todays visually interactive, menu-driven computational tools that run on laptop computers e.g., see Ghidaoui et al., 2005 (1). This progress has been backed by broad research in computational methods as well as targeted research on transient behavior of piping system equipment and components such as pumps, check valves, air valves and relief valves.
One estimate is that there are more than two billion pumping systems in the world (Walters, 2014 (2)). It goes without saying that transporting fluids safely is of critical importance to todays world. However, one might reasonably ask if the number of fluid systems in the world is growing faster than our ability to develop and deploy pragmatic guidelines for how to properly analyze them. Related to this, and of equal importance, are guidelines for the tools used by engineers in the detailed design of often very complicated systems.
It can certainly be agreed that the first goal of the waterhammer community is the safe design and operation of fluid transfer systems. A second goal is that fluid transfer systems be economical to build and operate which means avoiding unnecessary overdesign whenever possible.
The purpose of this paper is to discuss the two issues of safety and the economics of overdesign. A recent experience between Enbridge Pipelines Inc, Canada, a major pipeline company (an Owner/Operator, or O/O) and their Engineering, Procurement and Construction firms (EPCs) illustrates this issue. As the experience is related, it will be shown how yet more guidance is needed.