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Hydrogen Attack, Detection, Assessment and Evaluation

R. Kot
Senior Engineer, Intico,
84 Churchill Road North,
Dry Creek, S.A. 5094
Australia.
Contact

Abstract

1. INTRODUCTION

2. DETECTION AND QUANTIFICATION OF HYDROGEN DAMAGE

Fig 7: Mechanical properties of carbon-1/2Mo steel as a function of exposure time [3].

3. ESTIMATION OR REMAINING LIFE OF A HYDROGEN-DAMAGED PLANT

4. CONCLUSIONS

  1. Hydrogen attack is caused by exposure of steel to a hydrogen environment. The severity of the damage depends on the time of exposure, temperature, hydrogen partial pressure, stress level, steel composition and structure.
  2. To avoid/prevent hydrogen attack, steels with elements forming stable carbides should be used. A heat treatment should be carefully applied to avoid producing structures with low resistance to hydrogen attack (martensite, bainite). Proper inspection and quality control systems are necessary during the manufacturing process of hydrogen and hydrocarbon handling equipment.
  3. Hydrogen undamaged and damaged samples of steel used in plant equipment should be available for the hydrogen attack testing purposes.
  4. Recommended methods for detection of hydrogen damage are AUBT - Advanced Ultrasonic Backscatter Techniques, methods based on TOFD, thickness mapping, backscatter and velocity ratio and in-situ metallography - replicas. Results of methods like AUBT can be used for estimation of life of hydrogen attacked equipment.
  5. Non-destructive methods based on ultrasonics are able to quantify the hydrogen attack and estimate mechanical properties of hydrogen-damaged steels. The results of such tests can be used in life assessment calculations.

5. REFERENCES

  1. Alvorado G, "Methods for Detection, characterisation and Quantification of High Temperature Hydrogen Attack", Inspectioneering Journal, Vol. 1, Issue 5, November/December, 1995.
  2. API 941, "Steels for Hydrogen Service at Elevated Temperatures and Pressures in Petroleum Refineries and Petrochemical Plants", American National Standard ANSI/API, Publ. 941-1990.
  3. Birring A.S., Barlett, Kavano M.K., "Ultrasonic Detection of Hydrogen Attack in Steels", Corrosion-Vol.45, No.3, national Association of Corrosion Engineers, 1989.
  4. Das A.K., "Metallurgy of Failure Analysis". Tata McGraw-Hill Publishing Company Limited, New Delhi, 1996.
  5. Inoue N., Ebara R., Yamada Y., Yamada T., Shindo S., "Non-destructive Evaluation of Remaining life of Hydrogen attacked 1/2 Mo Steel for Long Term Used Chemical Plants", Proceedings of Ninth International Conference on Pressure Vessel Technology, ICPVT-9, Sydney Australia, 9-14 April, 2000.
  6. Intico Reports.
  7. Proceedings of an International Conference, "Effect of Hydrogen Behaviour of Materials", Jackson Lake, Moran, Wyoming, September 7-11, 1975.
  8. Timborn N., Verkooijen J., "Hot Hydrogen Attack: a Novel Approach for Reliable Detection and Monitoring", www.ndt.net, 1998.
  9. Turnbull A., Proceedings of a conference held at The National Physical Laboratory Teddington, "Hydrogen Transport and Cracking in Metals", UK, 13-14 April 1994. The University Press, Cambridge, 1995.
  10. Wang W.D., United States Patent No. 5,404,754, April 11, 1995.

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