Passivation of carbon steel using encapsulated oxygen
AssigneeThe Babcock & Wilcox Company
InventorsDonald T. Martin, Larry D. Paul, Neil N. Carpenter
Life of this patent
Estimating the term…
Abstract
A protective passive oxide layer is formed on the inner surfaces of metal heat pipes or tubes including their end caps, welds and accompanying hardware through the use of an oxygen encapsulation method. After cleaning the tube and its accompanying parts, the tube is reassembled and existing gases within the tube are removed thereby creating a vacuum inside the tube. The tube is then filled with pure oxygen and sealed. After the oxygen is sealed within the tube, the sealed tube is heated thereby forming a passive oxide layer, such as magnetite (Fe.sub.3 O.sub.4) on the inner surface of the tube.
Claims7
A method of forming a passive magnetite oxide layer on an inner surface of an iron base metal heat pipe for reducing corrosion and thereby reduce the amount of incondensible gas formation within the heat pipe, the method comprising the steps of:
- assembling end caps on an iron base metal tube, one of said end caps having a fill tube;
- removing existing gases from the iron base metal tube through the fill tube thereby creating a vacuum in the iron base metal tube;
- filling the iron base metal tube with oxygen gas through the fill tube;
- sealing the oxygen gas within the iron base metal tube;
- heating the sealed iron base metal tube to a temperature less than 1050.degree. F. to form a passive magnetite oxide layer on the inner surface of the iron base metal tube;
- and
- filling the iron base metal tube with a working fluid to make a heat pipe which has a passive magnetite oxide layer on an inner surface that reduces corrosion and an amount of incondensible gas formation therein.
Dependencies are inferred from the claim text.