Hydrogen Blistering Problems

Hydrogen blistering problems are well known. The basic cause of hydrogen blistering is the trapping of atomic hydrogen in the interstices between grains of metal or at inclusions or laminations where 

In hydrocracking systems corrosion by aqueous effluents increases with the mathematical product of the nitrogen and sulfur contents of the water, which can be expressed as an equivalent content of ammonium sulfide. Total water volume, as well as fluid velocity, are also factors determining corrosion rates. Various parameters involved in corrosion in such systems and effect of pH, sulfide content, and cyanide content as competition between the formation of a protective iron sulfide film and its dissolution as soluble ferrocyanide. 

This type of corrosion is becoming more common as hydrogen treatment processes proliferate. It is noteworthy that corrosion occurs at basic pH values, where it would be expected that iron and its alloys would be protected. A blue deposit of the ferro and ferrocyanides of iron in fouled or corroded equipment is often evidence of this sort of corrosion. 

Both overall attack and hydrogen blistering may be effectively reduced by the use of proper filmforming amines. These amines are similar to be used for other refinery corrosion prevention services. It is very important that the proper inhibitor be used, as determined by preliminary laboratory and plant evalnation. This is because overall attack may be reduced, while blistering or hydrogen embrittlement may not if an improper inhibitor is used. 

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Water washing of the overhead systems of debutanizers and depropanizers is indicated only if serious fouling problems occur. Normally, these streams are quite dry and should be kept that way to minimize corrosion and hydrogen blistering problems. With proper water washing of the compressed wet-gas stream, water washing of the overhead vapor streams of the debutanizer and depropanizer towers becomes unnecessary. 

The simultaneous irradiation with hydrogenic and helium ions can also present a serious blistering problem because of synergistic effects. Although there is a paucity of data, a D-T fusion environment is highly conducive to such synergistic effects. 

Recontact drum over condensation Stripper inefficiency Stripper turndown problems Cyanides cause hydrogen blistering... 

Hydrogenic ion-induced blistering has been observed, but by itself will not likely present a problem to the first wall at elevated reactor operating temperatures. The effects of blistering at high primary fluxes such as those found at beam dumps and components of neutral beam injectors, divertor throats and bombardment plates, are not known. 

Blistering has been couched traditionally in the context of materials performance in a fusion environment, and, as such, has been considered a problem in the longterm sense. There exists, however, some indication that blistering-like phenomena may occur when hydrogen discharge cleaning techniques are used to condition the plasma containment chamber walls of existing devices. (See Sect. 5.6.2.)... 

One consequence of reducing the rate of corrosion of steel in an acid is also to reduce the production of hydrogen, which has been reported as the cause of explosions in phosphoric acid systems. The presence of hydrogen may also induce the formation of blisters at inclusions in the metal and can also produce grooving on vertical surfaces. Anodic protection has been found to significantly stifle the formation of hydrogen, therefore minimizing such problems. 

Hydrogen sulfide is a particularly troublesome problem. The dissolved gas attacks steel only slowly when first exposed, due to the formation of a protective layer of iron sulfide. The iron sulfide film affords only temporary protection, however, because it becomes permeable to hydrogen sulfide, and the corrosion rate increases with time, producing blistering, high metal loss, and possibly hydrogen embrittlement. 

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