Steel, hydrogen diffusion

By indirect embrittlement (reaction by-product, atomic hydrogen diffusing into the lattice of the steel)... 

In permeation measurements the first signs of hydrogen diffusing through 1 mm steel membranes can be observed in a few minutes. The practical measurement of diffusion parameters tends to be rather unreproducibie. 

If the acid contains certain impurities such as arsenic, the arsenic raises the overvoltage for the hydrogen evolution reaction. Consequently, the amount of atomic hydrogen diffusing into the steel, and the brittleness, increase. 

Hydrogen diffusivity as a function of temperature. The effective diffusivity data of X52 and X65 pipeline steels obtained under gaseous hydrogen charging conditions are compared with the compiled results for the literature. (After Alefeld, G. and Volkl, J. Hydrogen in Metals I—Basic Properties, Springer, New York, 1978.)... 

Variable-hardness pipe, with the harder material in the interior, softer toward the exterior, so that any hydrogen that diffused into the interior steel rapidly diffuses outward and escapes... 

Pipelines represent the primary option for the most efficient transportation mode in a hydrogen energy environment. Pipeline is the most economical option for transportation however, the embrittlement of steels and diffusion losses represents a technical challenge. Sensor technologies for continued integrity management of such a pipeline network will be critical in the development of the hydrogen economy. 

We solved the transient hydrogen diffusion initial/boundary-value problem coupled with the large strain elastoplastic boundary value problem for a pipe of an outer diameter 40.64 cm, wall thickness h = 9.52 mm, and with an axial crack of depth 0.2/i on the inner wall-surface. We obtained the solutions under hydrogen gas pressure of 15 MPa, material properties for an X70/80 type steel, and... 

Only vessels for small units are completley made of corrosion- resistant material. This protection method is to expensive for large vessels. They can be more economically protected by a liner of corrosion-resistant material containing Mo, Cr, Ni and V. Multilayer vessels require corrosion-resistant steel only for the innner layer. They are often equipped with venting channels, so-called Bosch-holes to ensure that for example hydrogen diffusing through the inner layer is drained and could be analysed. 

Similar measurements were also performed on stainless steel. The nitride layer was attacked by the hydrogen discharge and therefore no quantitative data on the hydrogen diffusion could be obtained192,194a). This system also requires further investigation. 

The sheet of porous stainless steel with Re-carbon deposited film divided membrane reactor onto two equal parts. Cyclohexane vapors were fed to the surface of membrane with Re-carbon film (reaction part of membrane reactor) in argon flow from the thermostated bubler. The second part of reactor was flowed by argon and used for the removal of hydrogen, diffused through a membrane catalyst from the reaction zone. The products of reaction were benzene and hydrogen. 

Four appendixes are included. Appendix A contains standard materials selection used by many refiners and contractors in petroleum processing equipment. Appendix B contains a rules of thumb overview of refinery materials of construction. Appendix C contains background information on hydrogen diffusion through vessel walls, and Appendix D contains a standard specification for steel line pipe. 

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