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Material Matters
Alloy tube liners prevent corrosion in crude unit overhead condenser
magnesium chloride (MgCl2 chloride (CaCl2 (H2
S) damage; use of H2 ) and calcium
# _M\ PaLZWOMV []TÅLM S scavengers in
crude tankage; and corrosion due to the presence of ammonium chloride (NH4
Cl) and carbon dioxide (CO2 ), explains
NACE International member Michael Silverman, corrosion and metallurgy [XMKQITQ[\ I\ \PM +IZ[WV ZMÅVMZa )\ \PM \QUM \PM ZMÅVMZa _I[ XZWKM[[QVO [WUM aggressive crude oils; however, these cor- rosion mechanisms are fairly typical for I KZ]LM ]VQ\ ;QT^MZUIV KWUUMV\[ Although corrosion inhibitors and a
An inlet feed chuck is used for hydraulic expansion of liners using pressures up to 7,500 psi. Photo courtesy of Michael Silverman.
S 14 MATERIALS PERFORMANCE April 2012
everal years ago, at *8¼[ +IZ[WV ZMÅVMZa (Los Angeles County, California), carbon [\MMT +; ÅVVML \]JM[
QV I KZ]LM ]VQ\ W^MZPMIL ÅV NIV KWVLMV[MZ IQZ KWWTMZ were experiencing excessive KWZZW[QWV ) XQVPWTM NIQT]ZM QV WVM \]JM ZM[]T\ML QV I XIZ- \QIT [P]\LW_V WN \PM ]VQ\ IVL I ZML]K\QWV WN KZ]LM WQT XZW- cessing.
The damage mechanisms affecting
this overhead heat exchanger included corrosion due to the formation of hydro- chloric acid (HCl) from the hydrolysis of
water wash were always part of the cor- rosion control strategy, the refinery's metallurgists and engineers were inter- ested in upgrading the unit's metallurgy to better manage and control corrosion of the heat exchanger tubes and extend \PMQZ [MZ^QKM TQNM ;QT^MZUIV VW\M[ \PI\ Hastelloy†
C-276 (UNS N10276), used in
conjunction with an effective water wash, is much more resistant than CS to the typical corrosion mechanisms affecting \PM W^MZPMIL KWVLMV[MZ
C-276 tube liners that would isolate the +; \]JM[ NZWU KWZZW[Q^M XZWKM[[ Æ]QL[ Tube liners, thin-walled tubes con-
structed of corrosion-resistant alloys that are inserted into heat exchanger tubes and then expanded with hydraulic pres- sure to fit tightly against the original (parent) tubes, had been used for many years in power plants and ships as a cor- ZW[QWV XZM^MV\QWV \MKPVQY]M *]\ ][M WN
†