Welds hydrogen attack

The amount of hydrogen partial pressure reduction depends upon the materials and the relative thickness of the cladding/ weld overlay and the base metal—the thicker the stainless barrier is relative to the base metal the better.32 Archakov and Grebeshkova33 mathematically considered how stainless steel corrosion barrier layers increase resistance of carbon and low alloy steels to high temperature hydrogen attack. 

A4. R. Chiba, K. Ohnishi, K. Ishii, and K. Maeda, Effect of Heat Treatment on the Resistance of C-0.5Mo Steel Base Metal and Its Welds to Hydrogen Attack, 1985 Proceeding, Refining Department, Volume 64, American Petroleum Institute, Washington, D.C., pp. 57-74. 

Report on the Effect of Stainless Steel Weld Overlay or Cladding on Hydrogen Attack of Underlying Steel, Materials Properties Council, New York, September 1984. 

High temperature hydrogen attack damage may occur in welds, weld HAZs, or base metal. Even within these specific areas, the degree of damage may vary widely. Consequently,... 

Heat-affected zones are more susceptible to hydrogen attack than the base or weld metal. 

Apparatus in which fluorine is to be handled at room temperature may be made from a number of metals. Platinum, copper, nickel, magnesium, monel metal, brass, steel, and German silver are all known to be satisfactory. Most of these become coated with a film of fluoride which prevents further corrosion. If the metal is in contact not only with fluorine but also with a liquid such as water or hydrogen fluoride, corrosion frequently becomes troublesome. Under such circumstances, platinum usually behaves in the most satisfactory manner. With the gas alone, brass needle valves may be used with success, but the packing is eventually ruined. Fabrication of apparatus is best accomplished by welding, brazing, or silver soldering. Solder made from lead and tin does not resist attack. 

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