Cleaning chemicals

Use chemical cleaning, in situ where possible. Avoid any abrasive mechanical cleaning. Replacement may be the most practical alternative. 

When establishing a cleaning procedure, plant management must consider 

Many different cleaning agents are available for specific uses. The best choice for a given situation depends on 

Industries such as those dealing with food, pharmaceuticals, or personal care products are regulated by the FDA or the USDA. These agencies may also regulate cleaning compounds and their concentrations. 

With all the problems encountered in the handling and disposal of cleaning agents, it is advantageous to minimize their consumption. Several methods may be used to reduce the use of cleaning chemicals. 

The external fouhng of furnace mbes depends on the nature of the fuel. Oil-burning furnaces usually have significantly more deposit formation and corrosion problems than coal-burning types, while natural-gas-buming furnaces have very few problems. 

Chemical cleaning is the use of chemicals to dissolve or loosen deposits from process equipment and piping. It offers several advantages over mechanical cleaning, including more uniform removal, no 

The primary disadvantages of chemical cleaning are the possibility of excessive equipment corrosion and solvent disposal. Chemical cleaning solvents must be assessed in a corrosion test program before their field acceptance. Chemical cleaning is performed by a contractor who specializes in this work. Some cleaning procedures are protected by patents. 

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Ingots of EGS are evaluated for resistivity, crystal perfection, and mechanical and physical properties, such as she and mass. The iagots are sHced iato wafers usiag at least 10 machining and polishing procedures. These wafers are sHced sequentially from the iugot, and evaluated for the correct surface orientation, thickness, taper, and bow. As a final procedure, the wafers are chemically cleaned to remove surface contaminants prior to use. 

The possible remedial and preventive actions are hot soaks and drains during cooldown to help remove soluble deposited material, chemical cleaning to remove corrosion products and reduce the pressure drop (see Metal surface treatments), and reduced corrosion product transport into OTSG using amines other than ammonia in feedwater (14). 

Sulfamic acid has a unique combination of properties that makes it particularly well suited for scale removal and chemical cleaning operations, the main commercial appHcations. Sulfamic acid is also used in sulfation reactions, pH adjustment, preparation of synthetic sweeteners (qv), and a variety of chemical processing appHcations. Salts of sulfamic acid are used in electroplating (qv) and electroforrning operations as well as for manufacturing flame retardants (qv) and weed and hnish killers (see Herbicides). 

In Japan, sulfamic acid is produced and suppHed in crystal form. It is packaged in 25-kg net weight paper bags and in 600-kg, 700-kg, and 750-kg resinous dexible containers. The tmddoad price (fob Japan) is 1—2/kg. Three principal uses of sulfamic acid are in chemical cleaning, as sulfonation reagent, and for use in synthetic sweetener. 

Stress Corrosion Crocking. Stress corrosion cracking occurs from the combined action of corrosion and stress. The corrosion may be initiated by improper chemical cleaning, high dissolved oxygen levels, pH excursions in the boiler water, the presence of free hydroxide, and high levels of chlorides. Stresses are either residual in the metal or caused by thermal excursions. Rapid startup or shutdown can cause or further aggravate stresses. Tube failures occur near stressed areas such as welds, supports, or cold worked areas. 

Because of its functionaUty and environmental acceptabiUty, citric acid and its salts (primarily sodium and potassium) are used in many industrial appbcations for cbelation, buffering, pH adjustment, and derivatization. These uses include laundry detergents, shampoos, cosmetics, enhanced oil recovery, and chemical cleaning. 

Chemical cleaning implies the removal of material from the surface of the specimen by dissolution in an appropriate chemical agent. Solvents such as acetone, carbon tetrachloride, and alcohol are used to remove oil, grease, or resin and are usually apphed prior to other methods of cleaning. Various chemicals are chosen for appheation to specific materials some of these treatments in general use are outlined in the NACE standard. 

Chemical cleaning was suggested. A tannin-citric acid process was tested and produced good results. 

Chemical cleaning was considered since small-diameter pipe had been plugged in dead-leg regions. At the time of writing, no decision had been made concerning cleaning. 

Figure 5.17 As in Fig. 5.16 but after a brief chemical cleaning. The coating is more easily visible, and small depressions are visible beneath the coating blisters. (Magnification 7.5x.)... 

The dezincification was caused by underdeposit corrosion. The fact that the brass was not an inhibited grade was a major contributing factor. Chemical cleaning had not been done since this exchanger was installed. No chemical treatment was used on either external or internal surfaces. 

Maintenance and production records, along with the used lean and rich glycol analyses, can be very helpful to the troubleshooter. A history of filter element, carbon, tower packing, and firetube changeouts can sometimes be very revealing. The frequency of pump repairs and chemical cleaning jobs is also beneficial. With this type of knowledge, the troubleshooter can quickly eliminate and prevent costly problems. 

Check continuity zero and adjust Calibrate as required Chemical Cleaning Activation Passivation Rinse... 

Clean-out of the lubrication system, including chemical cleaning and passivation, where required. 

Chemical Cleaning Methods Possible Possible Possible... 

VOCs are released during chemical cleaning of bonding surfaces. The extract system is designed on the basis of the steady-state concentration determined for maximum source strength and considering the mechanical extract ventilation only and no air-exchange with the assembly hail. Ehis concentration must be kept below the threshold concentration (TVL) which is set to 300 mg/kg in this example. 

The problem is to evaluate cross-contamination of the assembly hall by VOCs from the chemical cleaning and bonding process in the treatment hall. 

Self-cleaning An air-cleaning device that has the ability to be mechanically or chemically cleaned. 

The first use of new plant, or start-up after a shutdown, poses corrosion hazards additional to those encountered in normal operation. New plant such as boilers requires special water treatment, involving boil-out, passivation and possible chemical cleaning. Actual requirements depend on the boiler type, the proposed service, the quality of water available during commissioning and the internal condition of the boiler. The condition of the boiler depends on for how long and in what conditions it has been stored. The presence of any salts, dirt or rust is harmful. An adherent, protective layer of magnetite in normal operation... 

The materials selection procedure should take into account the commissioning requirements of all parts of the plant in order not to include any materials that cannot safely be degreased or chemically cleaned. 

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