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Discussion Forums - The Hendrix Group
HomeHomeDiscussionsDiscussionsMaterial Select...Material Select...VENT LINE FAILUREVENT LINE FAILURE
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8/7/2003 9:00 AM
 
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We just had failure of a large vent header that was replaced 10 years ago. It is carbon steel on concrete posts but at ground level. The pipe ends up half in the ground (muck and mud). The pipe was wrapped but the sun degraded the wrapping on the upper half. The failure occurred on pressure test and the location of failure was on the lower half of the pipe. It seems to be just a case of water being trapped between the wrapping and pipe wall with the resulting corrosion. We do not have chemicals in this area and see no other special problems but this is in Southeast Texas. Without a test of the ground would there be any reason why a 304 or 316 wouldn't hold up in this condition? The process side is not the problem.
 
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8/28/2003 9:00 AM
 
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Wayne, It sounds like you have experienced what is called "corrosion beneath insulation". This type of corrosion has occured before in many chemical and petrochemical plants. The typical solution is pipeline replacement and application of a good exterior coating. The NACE organization has a study called: " Corrosion Under Wet Thermal Insulation" Edited by W.I. Pollock and C.N. Steely 1990 by NACE, 8-1/2" x 11", softbound, 9 papers, 104 pages, 17 tables, 80 figures, and references, ISBN 1-877914-14-2 You also may be interested in these links: www.nace.org/NACE/Content/Conferences/c2003/techpro/STG_02(3).asp www.rg2400.com/Data%20Sheets%20ETC/NACE%20Corrosion%20under%20Insulation.pdf let us know what you decide...... Good Luck MJC
 
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