Steel boiler

In appHcations as hard surface cleaners of stainless steel boilers and process equipment, glycoHc acid and formic acid mixtures are particularly advantageous because of effective removal of operational and preoperational deposits, absence of chlorides, low corrosion, freedom from organic Hon precipitations, economy, and volatile decomposition products. Ammoniated glycoHc acid Hi mixture with citric acid shows exceUent dissolution of the oxides and salts and the corrosion rates are low. 

Cast iron sectional boilers Steel boilers Electrode boilers Steam generators Vertical shell boilers Horizontal shell boilers Watertube boilers Waste heat boilers Fluid bed boilers... 

Galvanising baths are generally constructed from special mild steel boiler plate having very small amounts of trace elements so that they are not rapidly attacked by molten zinc but they can be made of ceramic materials and heated from the top or by immersion heaters. 

Morpholine is still the standard by which other amines are compared for pH control, and AMP has commonly been employed to control carbon steel boiler tube erosion-corrosion problems in European gas-cooled reactor stations. 

A 213 Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger... 

A 249 Welded Austenitic Steel Boiler, Superheater, Heat-Exchanger, and Condenser Tubes... 

The materials of construction vary considerably with different boiler designs. Conventional drum boilers generally use carbon steel boiler tubes and stainless steel superheater tubes. 

In the retort method of processing, the cans are placed in large iron or steel boilers, known as retorts, which can be securely closed by means of bolts. In these retorts the cads are subjected to the action of steam under pressure and in this way high temperatures can be secured. The length of time the cans remain in the retorts and the temperatures employed depend upon the nature of the product and the size of the cans. 

Carbon steel boiler plate rimmed, semi-killed or killed. 30-35 50-60 BS. 1501-151 Grade 26B A42 C2 PN A36-205 DIN 17155 Hll Fe 42-1 UNI 5869 SIS 1430 ASTM A285 Grade C... 

With the increase in cost of refractories, acid proof bricks, special quality mild steel, boiler tubes, alloy steels, etc., an innovative process is emerging in the manufacture of sulfuric acid and sulfonating agents. 

Traces of O2, even if not damaging to the steel boiler directly, are nevertheless effective in causing attack of the condenser system, especially if CO2 or NH3 is also present in the condensate. Such corrosion is sufficient to return small amounts of copper salts to the boiler followed by deposition of metallic copper. Although the condensers may not be damaged appreciably by such corrosion, the question remains whether pitting of the boiler is initiated by copper contamination of boiler waters. 

The previously feared caustic embrittlement of steel boilers has practically vanished after the introduction of high purity, i.e. deionised water [60]. Low carbon steels are sufficient for those sections of the steam boiler which come into contact with liquid water less than 330 °C. For the hot side of turbines a steel with 12% Cr is recommended. The remaining sections of the steam boiler system consist of carbon steel or low alloyed steel [22]. Steam boiler operation in the super heater section (500-600 °C) affects the diffusion of hydrogen in the steel, and will thereby be dec-arburised [14]. The methane that is formed caimot escape from the iron, stresses are formed and the formation of cracks and blisters occurs. A remedy was found by adding 0.5% Mo and 1% Cr, whose carbides at boiler temperature do not transform into methane [14, 61]. The limit of the use of these steels is portrayed in Figure 7. 

In contrast to cathodic protection, anodic protection is relatively new. The feasibility of anodic protection was first demonstrated in 1954 and tested on a small-scale stainless steel boiler designed to handle sulfuric acid [23]. Anodic protection refers to the corrosion protection achieved by maintaining an active-passive metal or alloy in its passive state by applying an external anodic current. The basic principle for this type of protection is explained by the behavior shown in Fig. 5.40. 

In contrast to cathodic protection, anodic protection is relatively new. Edeleanu first demonstrated the feasibihty of anodic protection in 1954 and tested it on small-scale stainless steel boilers used for sulfimc acid solutions. This was probably the first industrial apphcation, although other experimental work had been carried out elsewhere. This technique was developed using electrode kinetics principles and is somewhat difficult to describe without introducing advanced concepts of electrochemical theory. Simply, anodic protection is based on the formation of a protective film on metals by externally applied anodic currents. Anodic protection possesses unique advantages. For example, the applied current is usually equal to the corrosion rate of the protected system. Thus, anodic protection not only protects but also offers a direct means for monitoring the corrosion rate of a system. As an... 

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