Water Storage

RAW WATER STORAGE
Raw water is generally stored in FRP or HDPE Tanks with a closed Lid and Vent. The tank shall have a Lid of minimum 50mm dia for easy cleaning and inspection.

STORAGE OF TREATED WATER
Treated water shall be stored in Metallic tank made out of SS316 quality material. SS 304 quality material are susceptible to corrosion when exposed to chlorides hence SS 316 which contains Molybdenum should be considered which reduces corrosion and where welding is required.

FRP
Fiberglass Reinforced Plastic tanks are sometimes used as storage vessels. This material is acceptable for non-microsusceptible raw materials, such as certain acids or caustics, but is not appropriate for product contact where bioburden is a concern. the porus nature of the material's surface make these vessels very difficult to clean, and microbial growth will be a problem in anything but bacteriostatic media.

SURFACE FINISH
Product contact surfaces should have an interior surface finish of 15 - 25 u-inch Ra. Where micro-susceptibility is a concern or the product is particularly difficult to clean, the vessel may be electropolished after the mechanical polish has been completed. All interior welds should be ground smooth and successively polished and electropolished (where specified) to the same finish as the adjoining surfaces.

Mechanical polishingshould be performed with multiple passes using appropriate abrasive material. each polishing pass uses an abrasive with a finar grit than the previous pass and be performed at a 90degree angle from the previous pass. Each polishing operation should completely remove the polishing marks from the polishing operation. Surfaces in contact with products shall be free from visible scratches, burrs, flash, folds, nicks, inclusions, crevices and other defects.

Surface finish should be measured by a profilometer, after a successively built up mechanical polish is completed, but prior to electropolishing.