Stress corrosion cracking amines

Certain environments containing nitrate, cyanide, carbonate, amines, ammonia or strong caustic, due to the risk of stress corrosion cracking. Temperature is an important factor in assessment of each cracking environment ... 

Richert, J. P., Bagdasarian, A. J. and Shargay, C. A., Stress corrosion cracking of carbon steel in amine systems. Materials Performance, 27, 9-18 (1988)... 

Certain internal chemical treatments employed also need strict control to avoid risks of adverse chemical reaction and resultant corrosion. In particular, nitrogen-containing chemicals such as hydrazine and amines require effective monitoring to limit the concentration of ammonia release into steam because the presence of ammonia may, under certain conditions, cause stress corrosion cracking of copper and brasses. 

H. U. Schutt. Reducing stress corrosion cracking in treating gases with alkanol amines. Patent US 4959177,1990. 

Cladding or overlays are sometimes applied to carbon and low-alloy steel to avoid stress corrosion cracking problems. For example, carbon steel clad with Type 304L SS is often used in severe amine services. 

Stress-corrosion cracking of copper-zinc alloys can occur in environments other than ammoniacal solutions (Ref 114, 147, 151, 152). Included are nitrogen-bearing compounds such as amines and aniline, as well as sulfates, nitrates, nitrites, acetates, formates, and tartrates. These environments can produce tarnish films of Cu20 similar to the films formed in ammoniacal solutions. Both the rate of formation and... 

Richert, J. P., A. J. Bagdasarian, and C.A. Shargay, "Stress Corrosion Cracking of Carbon Steel in Amine Systems, Paper 187, NACE "Corrosion 1987 Meeting, San Francisco, Calif., March 9-13, 1987, also Oil Gas J., June 5, 1989, p. 45. 

Another possible adverse effect of inhibition is an increased rate of corrosion of a metal in the system other than the one for which the inhibitor was selected to protect. For example, some amines protect steel admirably but will severely attack copper and brass. Nitrites may attack lead and lead alloys such as solder. In some cases, the inhibitor may react in the system to produce a harmful product. An illustration of this is the reduction of nitrite inhibitors to form ammonia that causes stress corrosion cracking of copper and brass. The only way to avoid these problems is to know the metallic components of a system and be thoroughly familiar with the properties of the inhibitor to be used (Nasr-El-Din et al. 2002). 

NH4OH (plus O2). A complex ion, Cu(NH3) +, forms. Substituted NH3 compounds (amines) are also corrosive. These compounds are those that cause stress-corrosion cracking of susceptible copper alloys. 

Stress corrosion cracking of brass commonly occurs when brass is subjected to an applied or residual tensional stress or while in contact with a trace of ammonia or amine in the presence of moisture and oxygen. The risk of stress corrosion cracking in brasses is greatest in industrial and urban atmospheres, characterized by high contents of sulfur dioxide and ammonia. The stress corrosion susceptibility is markedly lower in marine atmospheres. The relative resistance to stress corrosion cracking of the brasses is as follows ... 

An ammonia-rich gas stream was once accidentally charged to a gas plant. Shortly thereafter, leaks appeared in many of the tubes of the distillation towers reflux condensers. The admiralty tubes (a copper alloy in the condensers) were cracked by the ammonia environment. Admiralty may also experience stress-corrosion cracking when exposed to concentrated amines. 

To a lesser extent, the above warning applies to all amine systems. The presence of carboxylic acids produced from heat-stable salts, overloaded amine, and cyanides accelerates the process of hydrogen-assisted stress-corrosion cracking. 

Hay, M. G., Baron, J. J., and Moffat, T. A., 1996, Elastomer Induced Crevice Cmrosirm and Stress Corrosion Cracking of Stainless Steel Heat Exchanger Plates in Sour Amine Service, paper presented at Corrosion 96, The NACE International Aimual Conference and Exposition, Paper No. 389, Denver, CO, March 24-29. 

SwRL 1989, An Investigation of Amine-Induced Stress Corrosion Cracking of Steels in Natural Gas Treatment Plants, Final Report SwRI Project No. 06-1202, prepared by the Southwest Research Institute, San Antonio, TX. 

Stress corrosion cracking of carbon steel by aqueous amine solutions, which are used to remove hydrogen sulfide and carbon dioxide from refinery and petrochemical plant streams, has been a recurring problem for number of years. 

This section deals with the corrosion behavior of duplex stainless steel, some high austenitic stainless steels, and a nickel-based alloy in 28% HCl acidizing solutions, either in inhibited or uninhibited conditions, at 130 °C. Weight loss, crevice corrosion, and stress corrosion cracking tests were carried out for 6 and 24 hours, with amine-based commercial corrosion inhibitors, originally formulated for carbon steel. 

Stress corrosion is cracking that develops in sensitive aHoys under tensile stress which is either internally imposed or is a residual after forming, in environments such as the presence of amines and moist ammonia. The crack path can be either intercrystaHine or transcrystaHine, depending on aHoy and environment. Not aH aHoys are susceptible to stress corrosion (31). 

Only certain specific environments appear to produce stress corrosion of copper alloys, notably ammonia or ammonium compounds or related compounds such as amines. Mercury or solutions of mercury salts (which cause deposition of mercury) or other molten metals will also cause cracking, but the mechanism is undoubtedly differentCracks produced by mercury are always intercrystalline, but ammonia may produce cracks that are transcrystalline or intercrystalline, or a mixture of both, according to circumstances. As an illustration of this, Edmundsfound that mercury would not produce cracking in a stressed single crystal of brass, but ammonia did. 

The chemical resistance of ECTFE is outstanding. It is resistant to most of the common corrosive chemicals encountered in industry. Included in this list of chemicals are strong mineral and oxidizing acids, alkalies, metal etchants, liquid oxygen, and practically all organic solvents except hot amines (aniline, dimethylamine, etc.). No known solvent dissolves or stress cracks ECTFE at temperatures up to 250°F (120°C). 

Amine color and solids concentration Inadequate filtering Corrosive amine Regenerator feed temp>erature too high High velocities Stress cracking... 

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