Equipment chemical cleaning procedures

The incidents related to failures in proper vessel and piping cleaning are common. However, in today s world there are API guidelines and a CSB Safety Bulletin Removal of Hazardous Material from Piping Systems available which can be very helpful to review equipment chemical cleaning procedures such as ... 

As a general rule, use these limits not more than 10 ppm, not more than 0.001 of the dose of any product will appear in the maximum daily dose of another product, and no physical or chemical residue will be visible on the equipment after cleaning procedures have been performed. 

Gleaning. Fouling films are removed from the membrane surface by chemical and mechanical methods. Chemicals and procedures vary with the process, membrane type, system configuration, and materials of constmction. The equipment manufacturer recommends cleaning methods for specific apphcations. A system is considered clean when it has returned to >75% of its original water flux. 

AH volatile organic solvents are toxic to some degree. Excessive vapor inhalation of the volatile chloriaated solveats, and the central nervous system depression that results, is the greatest hazard for iadustrial use of these solvents. Proper protective equipment and operating procedures permit safe use of solvents such as methylene chloride, 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene ia both cold and hot metal-cleaning operations. The toxicity of a solvent cannot be predicted from its chlorine content or chemical stmcture. For example, 1,1,1-trichloroethane is one of the least toxic metal-cleaning solvents and has a recommended threshold limit value (TLV) of 350 ppm. However, the 1,1,2-trichloroethane isomer is one of the more toxic chloriaated hydrocarboas, with a TLV of only 10 ppm. 

The personal security of our citizens also benefits directly from science and technology. Our police forces are equipped with light, strong bulletproof vests made of modem synthetic materials, and fire rescue personnel wear protective clothing made from temperature-resistant polymers. The smoke detectors and carbon monoxide detectors in our homes are based on chemical processes that detect dangerous substances. Personal security is enhanced in the broadest sense by water purification and by the chemical testing procedures that assure us of clean water and food. 

The approach of forming a team of specialists to evaluate a proposal to chemically clean refinery equipment is a concept that will be discussed in Chapter 10. This approach is excellent for developing Mechanical Integrity procedures of critical operations. 

Shortening units are constructed of carbon steel. The water phase in margarine is corrosive, and sanitation procedures require that all of the equipment used to manufacture it must be chemically cleaned. Margarine processing units contain chromium-plated commercially pure nickel heat transfer tubes and stainless steel for all product-contacted metal surfaces. 

As far as chemical variables are concerned, especially in case of trace determinations, all the steps of sample collection, treatment in the field and storage must be carefully considered in order to maintain sample integrity before analysis. In this respect the selection of appropriate equipment and non-contaminant materials, as well as the application of efficient cleaning procedures, are of paramount importance. For the most critical applications clean chemistry laboratories (equipped with Class 100 laminar flow cabins) must be available in the field or on board. 

Cleaning of multiple-use equipment should be validated. The manufacturer should determine the degree of effectiveness of the cleaning procedure for each excipient or intermediate chemical used in that particular piece of equipment. The amount of validation data required is dependent on the types of materials being made in the multiple-use equipment and the impact of trace contaminants on drug safety and performance. Validation data should verify that the cleaning process has removed residues to an acceptable level. 

Moreover, some of the gases have chemical properties (corrosive, highly toxic, self-igniting) that require the use of special equipment on the compressed gas containers (i.e. remotely controlled, pneumatically operated cylinder valves, flow restrictors, metal-to-metal seal between cylinder valve and process lines). Containers for electronic gases are subject to special cleaning procedures to remove particles, organic impurities, deposits and corrosion products from their inner surface. Depending on the chemical properties of the respective product and the speciflc demands in the respective field of application, apart from the usual steel containers also inside polished containers of steel, stainless steel or aluminium are used. 

Cleaning procedures for refinery/petrochemical equipment will continue to emphasize less toxic chemicals, high-pressure water blasting (with water recovery), and considerations for the disposal of the waste materials. Continued use of analytical methods (such as FTIR) may reduce the time necessary to develop an appropriate cleaning sequence. 

While chemical cleaning solvents usually are applied by pumping solvents through process equipment or power boilers, several other methods of applying them have been used. These include foams, "vapor phase" solvents, and special methods for cleaning pipelines. Because of the literature available, only foam cleaning and pipeline cleaning procedures will be reviewed. 

The single-crystal samples used in this work typically have an area of about 1 cm with a thickness of 1 mm. They are polished on both sides by standard metallurgical techniques to provide a surface smooth on the micron scale. The crystal can be heated resistively and the temperature of the sample is measured by a chromel-alumel thermocouple which is spot-welded to the crystal edge. In the case of iron crystals, bulk impurities such as sulfur and carbon are common, and before the sample is mounted in the UHV equipment, the crystal must be heated to about 873 K in a hydrogen furnace to help deplete the bulk of the sulfur. The cleaning procedure is continued in UHV where a combination of argon ion sputtering and chemical treatment is used. 

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. 

Use chemical interaction matrices to identify potential incompatibilities between combinations of materials (not just binary reactions) and interactions with cleaning solvents, heat transfer fluids and other utilities, equipment lubricants, scrubbing media, materials of construction, etc. Implement management of change procedures for changes in design, operation, equipment and chemistry. 

Chemical reaction due to Develop written procedures to clean and equipment not being verify reactor readiness properly cleaned/ drained. jn piement checklist verification from previous run. Possi- bility of unwanted reac- cleaning solvent tion or insufficient desired reaction. CCPS G-15 CCPS G-22 CCPS G-29... 

The first essential step in the design of a fume control system and selection of gas-cleaning equipment is the characterization of the fume emission source. Design procedures which can be used for new and existing industrial plants follow. The characterization of fume emission sources includes parameters such as plume flow rates (mVs), plume geometry (m), source heat flux (J/s), physical and chemical characteristics of particulates, fume loadings (mg/m ), etc. 

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