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Condensation-Induced Water Hammer
in District Steam Systems— Circumstances Resulting in Catastrophic Failures. |
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Proceedings of 2005 ASME Pressure Vessels and Piping Division Conference
July 17-21, 2005, Denver, Colorado USA Waterhammer accidents in district steam systems which kill operators are, in the author's experience, due to Condensation-Induced Waterhammer. The other classifications of waterhammer that can occur in steam systems: column-closure, sudden choking at an orifice due to flashing hot water, sudden valve closure, and steam-blown slug flow don’t generally result in overpressures powerful enough |
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| to breech steam components. This paper describes the most prevalent circumstances, in order of their frequency of occurrence, which | |||||||||||||||||
| coalesce to cause catastrophic condensation-induced waterhammer . Examples are drawn from actual accidents investigated by the author. This paper is available from the ASME Digital Store, reference PVP2005-71590 | |||||||||||||||||
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Sept. 2003 HPAC Engineering Magazine Each time [the feedwater] pump goes On or Off, it makes a terrible bang, and pipes shakes like creazy. Anyone have a idea how to eliminate (or decrease) water hammering in the steam boiler feeding line? --Posted on May 22, 2002 at www.boilerroom.com/forum.html |
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| If there is water hammer when a condensate or feedwater pump starts, especially if the fluid being pumped is at or near its saturation temperature, the cause of the hammering is probably Column-Closure Waterhammer . The term "column-closure waterhammer" is little known to HVAC | |||||||||||||||||
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engineers and power plant operators because, unlike Condensation-Induced Water hammer, it generally does not lead to catastrophic steam ruptures and operator deaths and, thus, has remained largely anony-mous in the non-nuclear engineering world. Like its |
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| potentially more potent cousin, however, Column-Closure Waterhammer is a common type of water hammer in steam systems. |
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Download Author's Un-edited Version in PDF format . Magazine version entitled "Resolving Water Hammer in Boiler Plants" is available at www.hpac.com. Search "kirsner".
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Flooding of a manhole or culvert containing a live steam line is more dangerous than people imagine. In a nutshell, if flooding submerges a high pressure steam main causing insulation to slough off the line or other-wise become ineffective, the heat transfer regime from the surface of the pipe to the surround- ing flood water will likely transition to "nucleate boiling". The rate of heat transfer due to nucleate boiling is on the order of 1000 times greater than that normally expected from an insulated steam main. Essentially a steam main submerged in flood water becomes a condenser generating hundreds of pounds of condensate per linear foot of pipe. Steam traps, even though they typically have a safety factor on the order of 25 times that needed to drain a well- insulated system, cannot handle this condensate load. (1st Qtr 2002 issue of District Energy Magazine and May 2002 HPAC Engineering Magazine. | ||||
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| Click pages for May 02 HPAC Magazine Article, Page 1, Page 2, Page 3, Page 4, Page 5, Page 6 | |||||
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Surviving a Steam Rupture in an Enclosed Space
Heating/Piping/Air Conditioning, July 1999, Wayne Kirsner, PE At Brookhaven National Laboratory in 1986, four men working in a utility vault were engulfed by steam when waterhammer blew out the gaskets in the steam main. Two men died; two survived. Why? Download article in PDF format (176k) pdf furnished compliments of HPAC |
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| Published in Heating/Piping/Air Conditioning Magazine, Jan 1999, by Wayne Kirsner, PE. Republished by the Canadian Institute of Power Engineers, April, July 2005.
This article describes a steam explosion that took place at Ft. Wainwright Alaska as asbestos workers were removing insulation from a live steam main. It explains the mechanism of condensation-induced waterhammer in the context of that accident. If you're going to get a grip on understanding water hammer in steam systems, you must understand condensation-induced waterhammer. Download article in PDF format (571k) pdf furnished compliments of HPAC |
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What Caused the Steam Accident that Killed Jack Smith?
Heating/Piping/Air Conditioning, Jul 1995, Wayne Kirsner, PE An investigation into the factors contributing to a little understood class of steam system accidents--"condensation induced water hammer"-- and how accidents like this can be avoided . Download article in PDF format (520k) pdf furnished compliments of HPAC |
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Is Reducing Boiler Steam Pressure Such a Hot Idea? HPAC Magazine, December 1987. Exposes the oft-times erroneous energy saving justification for reducing boiler steam pressure, discusses the actual potential energy savings, then enumerates the pitfalls of lowering systemsteam pressure that the engineer will need to avoid. This was Mr. Kirsner's first article published in a major engineering magazine. Click to go to artice followed by follow-up debate in April 1988 issue of HPAC Magazine.
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When Removing Insulation Turns Deadly--Insulation Outlook Magazine, June 2000 |
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