Failure Analysis: Wastewater Drum Bulging
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CASE HISTORY—PEER-REVIEWED
Failure Analysis: Wastewater Drum Bulging P. R. Vormelker Æ J. C. Guy
Submitted: 5 November 2008 / Accepted: 17 November 2008 / Published online: 30 December 2008 ASM International 2008
Abstract A 55 gallon wastewater drum lid was found to bulge during storage in a remote area. This bulging was of concern because it suggested that the drum was pressurized and that the integrity of the drum could be in question. Drum samples were obtained for analysis. The interior surface of these samples revealed blistering and holes in the epoxy phenolic drum liner and corrosion of the underlying carbon steel drum. It is suspected that osmotic pressure drove permeation of water through the epoxy phenolic coating which was weakened from exposure to low pH water. The permeating water accumulated at weak spots along the coating/carbon steel interface and caused blistering and failure of the coating. The coating failed at locations throughout the drum interior. Subsequent corrosion of the carbon steel released hydrogen which pressurized the drum, thus causing deformation of the drum lid. Additional samples from other wastewater drums on the same pallet were also evaluated, and limited corrosion was visible on the interior surfaces. It is suspected that, with time, the same degradation process would have caused pressurization of the entire batch of sealed drums that contained similar wastewater solutions. Keywords Wastewater Corrosion Hydrogen Carbon steel
P. R. Vormelker (&) Savannah River National Laboratory, PO Box 616, Aiken, SC, USA e-mail: [email protected] J. C. Guy Savannah River Nuclear Solutions, Inc., PO Box 616, Aiken, SC, USA e-mail: [email protected]
Introduction The Savannah River Site (SRS) stores various waste forms, including liquids from normal operations and processes, prior to consolidation and disposal. Legacy wastewater from a nuclear material production reactor area was consolidated into a Tuff Tank (vented container). The transportable Tuff Tank is a 330 gallon low density polyethylene square bottle inside a heavy-duty wire mesh cage. A year later, the Tuff Tank was transferred to a Liquid Waste Staging Area. At this time, the Tuff Tank contained approximately 240 gallons of liquid (primarily water) in three layers; an oil layer at the top, an aqueous layer in the middle, and a layer with solids/sludge at the bottom. The liquid contained a collection of water from a crane wash tank, various skid pans, and sample bottles from the reactor area. Analysis of the water was performed, including screening for radionuclides. Approximately a month later, the Tuff Tank was transferred to a second staging area for sampling and liquid transfer to five new 55 gallon drums for storage. Four of the drums contained mostly aqueous material (No. 1114, 1115, 1116, and 1117) and a fifth drum contained mostly oil. Some oil/sludge carryover into the aqueous drums may have occurred. Local work practices call for leaving a 10% head space in all liquid waste containers. The drums were relo
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