Can anbody suggest material specification & manufacturer for carbon steel plates resistant to hydrogen blistering?:)

Rrajesh Hydorgen blistering is a low temperature form of hydrogen attack on steel. This occurs even at ambient temperature if moisture and hydrogen in gaseous form (for ex: syn gas from olden days coal gasification plant) is in service in the equipment Moisture with hydorgen, in the system, with even low hydrogen partial pressures penetrate steel lattice to form local blisters (atomic hydrogen combines with carbon atoms to form methane which develops high pressures in steel lattice - which appears as local blisters). Normal plate manufacturing C.S plates - i.e, Killed steel (Si or Al added) improves resistance to hydrogen penetration at low temperature. This will do for most applications. Second alternative is to protect the internal surface exposed by epoxy painting which will be impervious to low temp hydrogen entry. This phenomenon (low temp hydrogen blistering at ambient temperature at low pressures) is different from high temperture hydrogen attack i.e., when same hydrogen penetrates steel lattice at high temperature (where basic mechanism is decarburization of steel). This requrires higher partial pressure of hydrogen at higher temperatures. Trust this helps you. C.V.Srinivasan Nishi Engineers Pvt Ltd India June 14,2007 E-mail: nishi@vsl.com >Can anbody suggest material specification & manufacturer for >carbon steel plates resistant to hydrogen blistering?:)

Vitt Hydorgen penetration in steel can be in general classified into four: First low temperature related called hydrogen blistering, Second also low temp related (HIC or low temperature related hydrogen embrittlement), Third: High temperature and High pressure effect related called decarburization of steel at high temp /high partial pressure -specially for Carbon steel), Fourth high temperature related HIC or SCC for materials with high hardness but subjected to high partial pressrue of hydrogen and hgih temperature with high tensile strength. First effect : At low temp, atomic (nascent) hydrogen enters and when it combines with carbon atom it forms molecular hydrogen to form CH4(methane). Methane develops pressures of the order of 6000 PSIG (internal) and molecular hydrogen with carbon becomes methane. This develops as blisters. This is one form of hydrogen effect on steel. For this to occur, moisture is the predominent mode for nascent (atomic) hydrogen to diffuse into steel lattice. Many olden days coal gasification syn gas producing plants with carbon steel vessels have experienced low temperature related "hydrogen blistering" - which is nothing but methane (molecular hydrogen combining with carbon atoms) trying to come out develops high pressures and so called localized blisters. A second effect : Another effect of hydrogen is also low temperature hydrogen brittlement - you may call HIC at low temperature. This happens for materials having high tensile strength - like studs and bolts . Third effect :At high temperature, the same phenonmenon occurs especially for carbon steel material subjected to high pressures of hydrogen and at high temperature. This is called high temperature hydrogen attack - resulting in decarburization - especially for carbon steel. Nelson curve limit was developed by G.A. Nelson - for different materials based on this observed phenomenon in refineries. This is where Nelson curve limit for choice of MOC and partial pressure and effect of temperature is referred to all for the last 40-50 years. The Fourth effect is similar to the low temperature hydrogen assisted embrittlement but occurs at high temperature. This is referred to HIC or high temperature related hydrogen embrittlement ( you can call again as HIC or a form of SCC) with diffusion of atomic hydrogen at hard zones of weld or materials with high tensility. This occurs mostly at tube to tube sheet weld areas in high pressure and high temperature heat exchangers or weld zones of socket welds or TI or PI areas where effective stress relieving is not completed during PWHT after welding. This can happen for C.S, low alloy steel, turbine blades, turbine and compressor discs etc. Trust this helps you C.V.Srinivasan Nishi Engineers Pvt Ltd India E-mail: nishi@vsnl.com June 15, 2007 >I suggest you also NACE standard TM 0284-2003 "Evaluation of >Pipeline and Pressure Vessel Steels for Resistance to HIC". >I think that at low pressure the hydrogen will recombine to >give H2 and not CH4 that will form at higher temperature and >decarburize the material. > >hope this help > >regards > >Vitt