Chemical Cleaning as a Maintenance Tool

This paper will attempt to outline how chemical cleaning provides apractical method of removing fouling products which interfere with heattransfer or with flow rates. It will discuss how the selection of the proper solvent and technique for asuccessful and economic cleaning application depends on a number of factors, such as the nature of the deposit, the metals in the equipment to be cleaned, the solvents available, temperatures and safe operating practices. The relationship of time and frequency of cleaning to cost will be outlined, as well as the factors which should be considered in the total cost whenevaluating chemical cleaning as a maintenance tool. The author will also discuss recent developments in new solvents andtechniques, such as EDTA formulations, foam cleaning, organic solvents, vapourcleaning and one-stage copper solvents. Chemical cleaning provides a practical method of removing fouling productswhich interfere with heat transfer or with flow rates. In the case of newpiping or other new equipment, the chemical removal of mill scale and oils andpreservatives is frequently necessary. This is especially true in the case oflubricating oil systems, oxygen systems and high-pressure boilers. The successful and economic application of solvent cleaning depends upon anumber of factors; namely, the deposits, the metals in the equipment to becleaned, the solvents available and safe operating practices. The removal ofany type of deposit with solvents is dependent upon the nature of thatdeposit. In solvent cleaning, the deposits, for purposes of identification, aredivided into one of three broad classes - namely, inorganic deposits, organic deposits,or mixtures of inorganic and organic deposits. The inorganic deposits (Table I) consist of a comparatively small number ofspecific chemical compounds (Table II). They may be designated by chemical ormineral name, and by chemical formulae.