Thermal water hammer is a special type of water
hammer which rarely occurs in heat exchangers. In biphasic fluids, if
steam bubbles are surrounded by condensate, regarding lower
condensate temperature than steam, they will suddenly collapse. As a
result, the vacuum caused by an extreme change in volume lead to
movement of the condensates in all directions and their collision the
force produced by this collision leads to a severe stress in the pipe
wall. This phenomenon is a special type of water hammer. According
to fluid mechanics, this phenomenon is a particular type of transient
flows during which abrupt change of fluid leads to sudden pressure
change inside the tube. In this paper, the mechanism of abrupt failure
of 80 tubes of 481 tubes of a methanol heat exchanger is discussed.
Initially, due to excessive temperature differences between heat
transfer fluids and simultaneous failure of 80 tubes, thermal shock
was presupposed as the reason of failure. Deeper investigation on
cross-section of failed tubes showed that failure was, ductile type of
failure, so the first hypothesis was rejected. Further analysis and more
accurate experiments revealed that failure of tubes caused by thermal
water hammer. Finally, the causes of thermal water hammer and
various solutions to avoid such mechanism are discussed.
[1] TEMA Standard, TEMA_9TH EDITION_2007
[2] ASTM A334A334M, Standard Specification for Seamless and Welded
Carbon and Alloy-Steel Tubes for Low-Temperature Service
[3] ASTM E415, Standard Test Method for optical Emission Vacuum
Spectrometric Analysis of Carbon and Low-Alloy Steel, 2005
[4] ASTM E10 , Standard Test Method for Brinell Hardness of Metallic
Materials, 2004
[5] ASTM E23, Standard Test Methods for Notched Bar Impact Testing of
Metallic Materials 2006
[6] ASTM A1016 , Standard Specification for General Requirements for
Ferritic Alloy Steel, Austenitic Alloy Steel, and Stainless Steel Tubes
,2004
[7] William F.Hosford, Robert M.Caddell," Metal Forming Mechanics and
Metallurgy", Third Edition
[8] Fred Truman, "Operation and Maintenance of heat exchangers"
S.A.Armstrong Limited 1963 Toronto, Canada
[1] TEMA Standard, TEMA_9TH EDITION_2007
[2] ASTM A334A334M, Standard Specification for Seamless and Welded
Carbon and Alloy-Steel Tubes for Low-Temperature Service
[3] ASTM E415, Standard Test Method for optical Emission Vacuum
Spectrometric Analysis of Carbon and Low-Alloy Steel, 2005
[4] ASTM E10 , Standard Test Method for Brinell Hardness of Metallic
Materials, 2004
[5] ASTM E23, Standard Test Methods for Notched Bar Impact Testing of
Metallic Materials 2006
[6] ASTM A1016 , Standard Specification for General Requirements for
Ferritic Alloy Steel, Austenitic Alloy Steel, and Stainless Steel Tubes
,2004
[7] William F.Hosford, Robert M.Caddell," Metal Forming Mechanics and
Metallurgy", Third Edition
[8] Fred Truman, "Operation and Maintenance of heat exchangers"
S.A.Armstrong Limited 1963 Toronto, Canada
@article{"International Journal of Chemical, Materials and Biomolecular Sciences:50628", author = "D. Sufi Ahmadi and B. Bagheri", title = "Failure Analysis of Methanol Evaporator", abstract = "Thermal water hammer is a special type of water
hammer which rarely occurs in heat exchangers. In biphasic fluids, if
steam bubbles are surrounded by condensate, regarding lower
condensate temperature than steam, they will suddenly collapse. As a
result, the vacuum caused by an extreme change in volume lead to
movement of the condensates in all directions and their collision the
force produced by this collision leads to a severe stress in the pipe
wall. This phenomenon is a special type of water hammer. According
to fluid mechanics, this phenomenon is a particular type of transient
flows during which abrupt change of fluid leads to sudden pressure
change inside the tube. In this paper, the mechanism of abrupt failure
of 80 tubes of 481 tubes of a methanol heat exchanger is discussed.
Initially, due to excessive temperature differences between heat
transfer fluids and simultaneous failure of 80 tubes, thermal shock
was presupposed as the reason of failure. Deeper investigation on
cross-section of failed tubes showed that failure was, ductile type of
failure, so the first hypothesis was rejected. Further analysis and more
accurate experiments revealed that failure of tubes caused by thermal
water hammer. Finally, the causes of thermal water hammer and
various solutions to avoid such mechanism are discussed.", keywords = "Thermal water hammer, Brittle Failure, Condensate
thermal shock", volume = "6", number = "1", pages = "14-4", }