Chemical Cleaning

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The two major categories of chemical cleaning are pre-operational chemical cleaning—part of pre-commissioning or commissioning activities—and post-operational or maintenance chemical cleaning—part of regular shut down work.
Pre-operational chemical cleaning is performed to remove any foreign material remaining from the construction activities either on the pipe or system fabrication. Major considerations in the pre-operational phase include mill scale, corrosion products, weld scale, oil, grease, sand, dirt, temporary protective coatings, and other construction debris.
Post-operational cleaning is performed for a number of reasons, including reduced heat transfer, reduced flow, safety (e.g., H₂S, pyrophoric iron, LELs, ammonia, etc.), reduced surface area (e.g., catalyst), access to full inspection, and more. The type and frequency of post-operational cleaning varies with system design, operating requirements, and history of operation and fluid/water treatment.

To choose a proper chemical cleaning method, several factors should be considered, including: