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Austenitic stainless steels, caustic

Virtuallv evety alloy system has its specific environment conditions which will prodiice stress-corrosion cracking, and the time of exposure required to produce failure will vary from minutes to years. Typical examples include cracking of cold-formed brass in ammonia environments, cracking of austenitic stainless steels in the presence of chlorides, cracking of Monel in hydrofluosihcic acid, and caustic embrittlement cracking of steel in caustic solutions. [Pg.2418]

Austenitic stainless steel Chlorides Hot concentrated caustic Hydrogen sulfide... [Pg.206]

Austenitic stainless steels will exhibit stress-corrosion cracking in hot aqueous chloride solutions, in acid chloride containing solutions at room temperature, in hot caustic solutions and in high-temperature high-pressure oxygenated water. [Pg.1214]

The behaviour of austenitic stainless steels in caustic solutions has received less attention than cracking in chloride environments. Transgranular cracking has been reported for low-carbon (< 0.05%) steels in caustic solutions, whereas higher carbon content alloys cracked intergranularly. Wilson and Aspen showed that resistance to cracking was not decreased by sensitisation heat treatments. Type 316 stainless steel has been shown to be more susceptible to cracking in caustic than type 304. ... [Pg.1215]

This form of SCC affects both carbon steels and austenitic stainless steels (300 series) that are under stress. It is particularly associated with the inducement of boiler waterside metal-surface fractures (cracking) under localized deposits containing high concentrations of sodium hydroxide (caustic soda). [Pg.255]

The greatest problems with austenitic stainless steel piping usually arise when the unit is off stream rather than when it is operating. Such problems must be anticipated. The use of stainless steels requires that the necessary steps be taken to avoid them. Chlorides and caustics can cause any austenitic stainless steel pipe to crack trans-granularly under some conditions. Plain chromium stainless steels do not crack in chloride solutions, but they usually pit badly enough to be only moderately satisfactory. [Pg.290]

W.L. Williams, Chloride and caustic stress corrosion of austenitic stainless steel in hot water and steam. Corrosion 13 (1957) 539t—545t. [Pg.441]

Production of a corrosive product (aqueous sodium hydroxide). Caustic stress corrosion cracking risks arise at around 120°C on stainless steel (Phenix superheater and resuperheater material is an austenitic stainless steel). [Pg.101]

Since austenitic stainless steels are susceptible to pitting and intergranular corrosion in the presence of chloride ions, other materials were examined for caustic service [43-47]. These include Fe-Cr alloys, which are resistant to SCC. However, these alloys are brittle and suffer from 475°C embrittlement and sigma embrittlement. A popular alloy that was examined for the caustic evaporator service was E-Brite-26-1, containing 26% Fe and 1 % Mo, which exhibited performance characteristics comparable to that of... [Pg.1340]

For steam heating coils, austenitic stainless steel, e.g. AISI 316, is recommended in preference to mild steel. It is better practice to have a larger surface area of heating coil at a lower temperature than vice versa, as a means of avoiding stress cracking at elevated temperatures. The temperatures above which 304 and 316 type stainless steel are susceptible to stress corrosion in caustic liquors vary with concentration between 115 and 240°C. L.P. steam should therefore be used. [Pg.54]

Figure 5-6. Intergranular stress corrosion crack on austenitic stainless steel in caustic solution at 200 °C a) Optical microscopy on metallographic section b) SEM of crack faces. Figure 5-6. Intergranular stress corrosion crack on austenitic stainless steel in caustic solution at 200 °C a) Optical microscopy on metallographic section b) SEM of crack faces.
Figure 5-22. Mixed cracking of an austenitic stainless steel in deaerated caustic solution at 200 °C (SEM examination) a) thick oxide layer on the free surfaces, b-c) no visible traces of dissolution on the crack faces. Figure 5-22. Mixed cracking of an austenitic stainless steel in deaerated caustic solution at 200 °C (SEM examination) a) thick oxide layer on the free surfaces, b-c) no visible traces of dissolution on the crack faces.
For such reasons, the dissolved solids content of the water must be kept as close as possible to zero. A large fraction of the water is continuously cleaned up in a bypass circuit containing ion exchange (demineralizer) beds. At start-up, 100 percent of the water may be passed through the cleanup beds. Chlorides and caustic are the most undesirable salts because they are known to cause SCC of the austenitic stainless steels. Dissolved oxygen may be reduced by the methods described previously to a few parts per billion. [Pg.298]

Sodium hydroxide is widely used in refinery and petrochemical plant operations to neutralize acid constituents. At ambient temperature and under dry conditions, NaOH can be handled in carbon steel equipment. Carbon steel is also satisfactory for aqueous caustic solutions below 50-80 °C, depending on concentration. For caustic service above these temperatures, but below 95 °C, carbon steel can also be used if it has been post-weld heat treated to avoid SCC at welds. Austenitic stainless steels, such... [Pg.11]

Caustic see of carbon steel occurs at temperatures above 50 to 80 °C (120 to 180 °F), depending on caustic concentration. Welded carbon steel components that are exposed to caustic solutions above these temperatures should be post-weld heat treated at 620 °C (115 °F) for 1 h per 25 mm (1 in.) of metal thickness. Caustic SCC of austenitic stainless steels occurs between 105 and 205 °C (220 and 400 °F), depending on caustic concentration. [Pg.23]

Susceptibility of austenitic stainless steels to this form of corrosion usually becomes a problem when the caustic concentration exceeds approximately 25% and temperatures are above 100 °C (212 °F). Because welding is involved in most fabrications, the weld joint becomes the focus of attention because of potential stress-raising effects and because of high residual shrinkage stresses. Cracking occurs most often in the weld HAZ. [Pg.447]

Ferritic stainless steels in general are less resistant than the austenitics and are subject to caustic cracking. Cupronickel tubes are occasionally used for low- to medium-concentration caustic at mild temperatures and with restrictions on fluid velocity. These alloys are also resistant to hot 70% NaOH, but only in the complete absence of oxidants. Monel has a number of applications, but its use can be restricted by the slow development of color due to copper contamination. It is a frequent choice for processing equipment in the salt-recovery section of the diaphragm-cell process (Sections 9.3.2.S and 9.3.2.6). [Pg.950]


See other pages where Austenitic stainless steels, caustic is mentioned: [Pg.1214]    [Pg.219]    [Pg.251]    [Pg.179]    [Pg.246]    [Pg.250]    [Pg.267]    [Pg.381]    [Pg.382]    [Pg.1026]    [Pg.17]    [Pg.1247]    [Pg.39]    [Pg.218]    [Pg.218]    [Pg.414]    [Pg.410]    [Pg.206]    [Pg.23]    [Pg.213]    [Pg.509]    [Pg.121]    [Pg.950]    [Pg.89]   


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