Comparative study of methods for determining the diffusible hydrogen content in welds

Summary

This paper presents a comparative study on the glycerine, mercury and gas chromatography methods for determining the diffusible hydrogen content in welded joints. The effects of the variables of time and temperature for hydrogen collection are also considered. AWS type E9018‐M electrodes were wetted, then dried at different temperatures for different times in order to obtain a wide range of diffusible hydrogen contents. The results showed that the collection time may be reduced when the sampling temperature is increased. The gas chromatography and mercury methods give similar results, much higher than those obtained with the glycerine method, without the need to use liquid nitrogen for preparation of test specimens. The gas chromatography method presents less scatter of results and a shorter sample collection time due to the increased sampling temperature. The use of equations found in the literature for comparison of the results obtained by the different methods is also discussed.