Low Concentrations Of H2S Research Articles

Gaseous hydrogen sulfide determination by discoloration of lead-stabilized PVC.

The discoloration of lead-stabilized PVC resulting from its interaction with H2S gas has been investigated as a potential H2S measurement technique. Color measurements of PVC samples exposed to controlled concentrations of H2S over a range of humidities and temperatures demonstrate that toxic H2S concentrations can be detected in less than five minutes. The technique is thus appropriate for industrial applications such as the pretesting of manhole atmospheres prior to entry. Exposure times of several hours are sufficient to detect the much lower H2S concentrations that may be present ambient air; for example, 15 hour exposures are needed for 10 +/- 3 ppb H2S, a level typical of certain oil field, swamp, and sewage treatment areas. The technique is inexpensive and can be performed by unskilled personnel.

Studies of the kinetics of nickel sulfidation in H2S-H2 mixtures in the temperature range 450–600°C

The reaction between pure nickel and H2S-H2 mixtures containing 1–65% H2S has been studied over the temperature range 450–600°C. The sulfidation of nickel in the temperature range 560–600°C has been found to follow a linear rate law at low concentrations of H2S and a parabolic rate law at higher concentrations (10% and 65% H2S); X-ray examination of the scale formed on the metal showed it to be almost entirely β-Ni3S2. On the basis of the kinetics and marker studies it can be concluded that the sulfide scale on nickel is formed by the outward transport of the metal and the inward transport of sulfur. In the temperature range 450–500°C the sulfidation of nickel follows a parabolic rate law. In mixtures containing 10% H2S the scale formed contains voids, the occurrence of which is connected with formation of Ni7S6. It has also been shown that the rate of transport through the Ni3S2 layer has an essential influence on the formation of a continuous layer of Ni7S6. Marker studies have shown that both nickel and sulfur appear to be mobile in β′-Ni3S2.

A routine method for measuring the efficiency of ferric oxide as an extractor of hydrogen sulphide from air

AbstractMeasurement of the absorptive efficiency of ferric oxide is made by passing a measured volume of air containing a known low concentration of H2S through the sample at a known constant velocity, and measuring the residual H2S which has not been extracted. This last measurement is carried out by passing the air through a paper impregnated with silver nitrate, and measuring the optical transmission density of the stain formed. Concentrations are calculated from the sulphide stain densities and the volumes of air passed through the papers. The calibration technique forms the basis of a method of measurement of trace amounts of H2S in the atmosphere, and is unaffected by the presence of SO2.

Stress Corrosion Crocking of Oil Country Tubular Goods★

Abstract Stress corrosion cracking as encountered in oil production is discussed as two problems: sulfide corrosion cracking and sweet corrosion cracking. Brief review of the literature is included. A new test method is given which uses a notched ring loaded to different percentages of yield deformation. Also includes simple polished beam specimen test methods. Tabular data is given on hardness, applied stress and time-to-failure obtained in a saturated H2S-brine system using J-55 and N-80 steels. Concludes that any steel will suffer sulfide corrosion cracking above given hardness limits and that these limits depend on applied stress. Tests to reproduce failures in sweet systems are reported. Conclusion is drawn that sweet cracking failures are sulfide cracking at low H2S concentrations and that time-to-failure is an inverse function of the H2S concentration. 3.2.2