NOTA SOBRE A SELEÇÃO DO AÇO PARA O SERVIÇO COM H2S
ON STEEL SELECTION TO WET H2S SERVICE
Alvisi, Paulo Pio
http://dx.doi.org/10.4322/tmm.00604002
Tecnol. Metal. Mater. Min., vol.6, n4, p.192-200, 2010
Resumo
Uma parcela importante dos vasos de pressão que compõe os equipamentos de uma refinaria de petróleo, incluindo cascos de trocadores de calor, faz contato com o H2S sob condições em que a fragilização de seu material construtivo (muito frequentemente o aço carbono) e de suas juntas soldadas, é esperada. Uma vez que a definição da "classe" do aço destinado à construção de vasos que em serviço deverão fazer contato com o H2S é dependente da agressividade ou da "capacidade hidrogenante" do meio (conforme norma Petrobras N-1706), são apresentados os mecanismos associados com a geração e a absorção do hidrogênio, fenômenos que têm início com a corrosão ao aço promovida pelo "H2S-úmido" ou ácido sulfídrico. São feitas, então, considerações relativas à agressividade dos ambientes tipicamente encontrados em refinarias contendo o ácido, e com as características metalúrgicas que acarretam um melhor desempenho do aço carbono e das juntas soldadas relativamente à nucleação de trincas por "Corrosão Sob Tensão por Sulfetos" (SSC), e as "Trincas Induzidas pelo Hidrogênio" (HIC) e suas variantes. Por fim, dois dos principais documentos que tratam do assunto são apresentados.
Palavras-chave
Aço resistente ao HIC, Trincamento induzido pelo hidrogênio, Ácido sulfídrico
Abstract
An important fraction of pressure vessels existing in a crude refinery makes contact with wet H2S under conditions in which it is possible the embritlement of its constructive steel and weldments. Once that steel definition destined to such kind of service is dependent of environment aggressiveness (in conformity with standard Petrobras N-1706), this work first shows the mechanism related with hydrogen generation and absorption and the consequent steel embritlement phenomenon that has begin with the corrosion due to wet H2S. Then it becomes possible to do comments about the aggressiveness of the environment typically found in refineries containing the acid as well as the metallurgical characteristics which cause a better performance of the carbon steel and of the weldements in crack nucleation caused by sulfide Stress Corrosion Cracking (SSC) and the Hydrogen Induced Cracking (HIC) and its derivates. Finally, two of the main documents about the subject are presented.
Keywords
HIC resistant steel, Hydrogen induced cracking, Sulphidric acid
Referências
1 PETROBRAS. Norma N-1706c. Projeto de vaso de pressão para o serviço com H2S. Rio de Janeiro, 2007.
2 SATO, N. Toward a more fundamental understanding of corrosion process. Corrosion, v. 45, n. 5, p. 354-368, 1989.
3 NAGUMO, M. Hydrogen entry into metals from liquid phase I: Basic electrochemical reactions. Corrosion Engineering, v. 55, n. 9, p. 511-33, 2006.
4 IYER, R. N. et al. Hydrogen sulfide effect on hydrogen entry into iron: a mechanistic study. Corrosion, v. 46, n. 6, p. 460-8, 1990.
5 VIEIRA, M. M. et al. Efeito do pH na corrosão e permeação de hidrogênio em aço carbono em presença de água ácida desaerada. In: COTEQ, 6.; CONBRASCORR, 22., 2002, Salvador, Bahia. Anais… São Paulo: ABENDE, 2002. Coteq 100.
6 BONNER, W. A.; BURNHAM, H. D. Air injection for prevention of hydrogen penetration of steel. Corrosion, v. 11, n. 10, p. 447-54, 1955.
7 HERTZBERG, R. W. Deformation and fracture mechanics of engineering materials. New York: John Willey & Sons, 1989.
8 AUBERT, L. Contribution of mechanism in the modeling of environment sensitive fracture. In: EUROCORR, 2005, Lisboa. Frankfurt: Dechema, 2002.
9 KAESCHE, H. The absorption of atomic hydrogen. etching bubbles: hydrogen-induced fracture In: ________. Metallic corrosion. Houston: NACE, 1981. p. 372-87.
10 AMERICAN PETROLEUM INSTITUTE – API. Research report on characterization and monitoring of cracking in wet H2S service. Washington, 1994. (Publication 939).
11 AMERICAN PETROLEUM INSTITUTE – API. RP 571. Damage mechanism affecting fixed equipment in the refining industry. Washington, 2003.
12 van GELDER, K.; KROESE, C. J. Effect of corrosion inhibitors for sour oil and gas transport on hydrogen uptake by pipelines steels. In: EUROPEAN SYMPOSIUM ON CORROSION INHIBITORS, 6., 1985, Ferrara, Itália. Proceedings... Annali dell Universita di Ferrara, Suppl. 8, p.1387-94, 1985.
13 ABAYRATHNA, D.; KANE, R. D. The role of environmental parameters on the severity of hydrogen charging in wet H2S environments. In: CORROSION96, 1996, Denver. Houston: Nace International,1996. paper 606.
14 NACE INTERNATIONAL. NACE TM 0284. Evaluation of pipeline and pressure vessel steels for resistance to hydrogeninduced cracking. Houston, 2003.
15 CARNEIRO, R. A.; RATNAPULI, R. C.; LINS, V. F. C. The influence of chemical composition and microstructure of API linepipe steels on hydrogen induced cracking and sulfide stress corrosion cracking. Materials Science & Engineering, v. 357, n. 1-2, p. 104-10, Sep. 2003.
16 NACE INTERNATIONAL. NACE IP 8X-194. Materials and fabrication practices for new pressure vessels used in wet H2S refinery service. Houston, 2006.
2 SATO, N. Toward a more fundamental understanding of corrosion process. Corrosion, v. 45, n. 5, p. 354-368, 1989.
3 NAGUMO, M. Hydrogen entry into metals from liquid phase I: Basic electrochemical reactions. Corrosion Engineering, v. 55, n. 9, p. 511-33, 2006.
4 IYER, R. N. et al. Hydrogen sulfide effect on hydrogen entry into iron: a mechanistic study. Corrosion, v. 46, n. 6, p. 460-8, 1990.
5 VIEIRA, M. M. et al. Efeito do pH na corrosão e permeação de hidrogênio em aço carbono em presença de água ácida desaerada. In: COTEQ, 6.; CONBRASCORR, 22., 2002, Salvador, Bahia. Anais… São Paulo: ABENDE, 2002. Coteq 100.
6 BONNER, W. A.; BURNHAM, H. D. Air injection for prevention of hydrogen penetration of steel. Corrosion, v. 11, n. 10, p. 447-54, 1955.
7 HERTZBERG, R. W. Deformation and fracture mechanics of engineering materials. New York: John Willey & Sons, 1989.
8 AUBERT, L. Contribution of mechanism in the modeling of environment sensitive fracture. In: EUROCORR, 2005, Lisboa. Frankfurt: Dechema, 2002.
9 KAESCHE, H. The absorption of atomic hydrogen. etching bubbles: hydrogen-induced fracture In: ________. Metallic corrosion. Houston: NACE, 1981. p. 372-87.
10 AMERICAN PETROLEUM INSTITUTE – API. Research report on characterization and monitoring of cracking in wet H2S service. Washington, 1994. (Publication 939).
11 AMERICAN PETROLEUM INSTITUTE – API. RP 571. Damage mechanism affecting fixed equipment in the refining industry. Washington, 2003.
12 van GELDER, K.; KROESE, C. J. Effect of corrosion inhibitors for sour oil and gas transport on hydrogen uptake by pipelines steels. In: EUROPEAN SYMPOSIUM ON CORROSION INHIBITORS, 6., 1985, Ferrara, Itália. Proceedings... Annali dell Universita di Ferrara, Suppl. 8, p.1387-94, 1985.
13 ABAYRATHNA, D.; KANE, R. D. The role of environmental parameters on the severity of hydrogen charging in wet H2S environments. In: CORROSION96, 1996, Denver. Houston: Nace International,1996. paper 606.
14 NACE INTERNATIONAL. NACE TM 0284. Evaluation of pipeline and pressure vessel steels for resistance to hydrogeninduced cracking. Houston, 2003.
15 CARNEIRO, R. A.; RATNAPULI, R. C.; LINS, V. F. C. The influence of chemical composition and microstructure of API linepipe steels on hydrogen induced cracking and sulfide stress corrosion cracking. Materials Science & Engineering, v. 357, n. 1-2, p. 104-10, Sep. 2003.
16 NACE INTERNATIONAL. NACE IP 8X-194. Materials and fabrication practices for new pressure vessels used in wet H2S refinery service. Houston, 2006.
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