API RP 945-2003 pdf free download

API RP 945-2003 pdf free download.Avoiding Environmental Cracking in Amine Units.
1 Scope This recommended practice discusses environmental cracking problems of carbon steel equipment in amine units. Stress corrosion cracking of stainless steels in amine units is beyond the scope of this document although there have been isolated reports of such problems. This practice does provide guidelines for carbon steel construction materials including their fabrication, inspection, and repair to help assure safe and reliable operation. The steels referred to in this document are deÞned by the ASTM designation system, or are equivalent materials contained in other recognized codes or standards. Welded construction is considered the primary method of fab- ricating and joining amine unit equipment. See 3.1 and 3.2 for the deÞnitions of weld and weldment. This document is based on current engineering practices and insights from recent industry experience. Older amine units may not conform exactly to the information contained in this recommended practice, but this does not imply that such units are operating in an unsafe or unreliable manner. No two amine units are alike, and the need to modify a speciÞc facility depends on its operating, inspection, and maintenance history. Each user company is responsible for safe and reli- able unit operation. 2 References 2.1 REFERENCED PUBLICATIONS The following publications are referenced by number in this recommended practice. 1. H. W. Schmidt et al., ÒStress Corrosion Cracking in Alkaline Solutions,Ó Corrosion, 1951, Volume 7, No. 9, p. 295. 2. G. L. Garwood, ÒWhat to Do About Amine Stress Cor- rosion,Ó Oil and Gas Journal, July 27, 1953, Volume 52, p. 334. 3. P. G. Hughes, ÒStress Corrosion Cracking in an MEA Unit,Ó Proceedings of the 1982 U.K. National Corrosion Conference, Institute of Corrosion Science and Technol- ogy, Birmingham, England, 1982, p. 87. 4. H. I. McHenry et al., ÒFailure Analysis of an Amine Absorber Pressure Vessel,Ó Materials Performance, 1987. Volume 26, No.
K. F. Butwell, ÒHow to Maintain Effective MEA Solutions,Ó Hydrocarbon Processing , 1982, Volume 61, No. 3, p. 108. J. C. Dingman et al., ÒMinimize Corrosion in MEA Units,Ó Hydrocarbon Processing , 1966, Volume 45, No. 9, p. 285. R. A. Feagan et al., ÒExperience with Amine Units,Ó Petro- leum Refiner , 1954, Volume 33, No. 6, p. 167. R. J. Hafsten et al., ÒAPI Survey Shows Few Amine Corro- sion Problems,Ó Petroleum Refiner , 1958, Volume 37, No. 11, p. 281. G. D. Hall, ÒDesign and Operating Tips for Ethanolamine Gas Scrubbing Systems,Ó Chemical Engineering Progress , 1983, Volume 62, No. 8, p. 71. A. L. Kohl and F. C. Riesenfeld, Gas Purification (4th ed.), Gulf Publishing, Houston, 1985. N. R Liebenmann, ÒAmine Appearance Signals Condition of System,Ó Oil & Gas Journal , May 23, 1980, Volume 78, p. 115. A. J. MacNab and R. S. Treseder, ÒMaterials Requirements for a Gas Treating Process,Ó Materials Protection and Perfor- mance , 1971, Volume 10, No. 1, p. 21. A. J. R. Rees, ÒProblems with Pressure Vessels in Sour Gas Service (Case Histories),Ó Materials Performance , 1977, Vol- ume 16, No. 7, p. 29. F. C. Riesenfeld and C.L. Blohm, ÒCorrosion Resistance of Alloys in Amine Gas Treating Systems,Ó Petroleum Refiner , 1951, Volume 30, No. 10, p. 107. W. R. Schmeal et al., ÒCorrosion in Amine/Sour Gas Treat- ing Contactors,Ó Chemical Engineering Progress , March, 1978. M. K. Seubert and G. D. Wallace, ÒCorrosion in DGA Treating PlantsÓ (paper 159), Corrosion/85, NACE Interna- tional, Houston, 1985.
4.2.2 Environmental Cracking Problems with environmental cracking occur when carbon steels are in regions of high hardness, high residual stress, or both. In particular, areas of high hardness in and adjacent to welds have been problematic. Cracks have also been reported in areas where high hardness levels were not detectable with standard Þeld hardnessÐmeasurement equipment. The crack- ing of weld-repaired areas has also caused serious problems when excessively hard zones or regions of high residual stresses have not been eliminated by the repair procedure. In some instances, cracking has occurred in base metal at sites of internal arc strikes, or opposite external welds for vessel attachments, such as ladders. Four different cracking mechanisms have been identiÞed in carbon steel components in amine units: a. SulÞde stress cracking (SSC). b. Hydrogen-induced cracking (HIC) associated with hydro- gen blistering. c. Stress-oriented hydrogen-induced cracking (SOHIC). d. Alkaline stress corrosion cracking (ASCC).