SUBJECT: Design Specifications for Process Water
4. Installation and Material of Construction and Component Selection 1 General
3.4 Cleaning and passivation
Cleaning 1 — Cleaning medium shall be compatible with electro-polished tubing and finish. Cleaning is mandatory. Operate accord-ing to a written preapproved procedure. Record and log cleanaccord-ing dates and steps.
Passivation — Passivation is mandatory. Use a 15 to 20%
weight/weight nitric acid solution in water. Circulate at least 1 hour.
Operate according to a written preapproved procedure. Do not use fluorhydric acid for passivation. Record and log passivation dates and steps. Drain the system completely.
Rinsing — Fill the system with DI water. Circulate for 15 min, then flush each use point outlet and equipment connection until the pH of discharge water is balanced with the inlet pH. Record and log cleaning dates and steps.
3.5 Identification
The whole equipment (pump, tank, sensor, valves, heat exchangers, etc.) must be tagged with an engraved stainless steel tag. The tag number must follow the number of the P&I.
4. Installation and Material of Construction and Component Selection
wire filler where necessary, inert gas, automatic welding machines, and regular inspection and documentation help to ensure accept-able weld quality.
Final cleaning and passivation shall be performed for removing contamination and corrosion products and to reestablish the pas-sive corrosion resistant surface.
Plastic materials can be fused (welded) in some cases and also require smooth, uniform internal surfaces. Adhesives should be avoided due to the potential for voids and chemical reaction.
Mechanical methods of joining, such as flange fittings, shall be performed carefully to avoid the creation of offsets, gaps, pene-trations, and voids.
Control measures shall include good alignment, properly sized gaskets, appropriate spacing, uniform sealing force, and avoidance of threaded fittings.
4.2 Materials of construction
Materials of construction selected should be compatible with con-trol measures such as sanitizing, cleaning, and passivation.
Materials selected should be able to handle elevated operating, sanitization temperature, and chemicals or additives to be used to clean, control, or sanitize the system.
Materials should be capable of handling turbulent flow and elevated velocities without wear on the corrosive barrier impact such as the passivation-related chromium oxide surface of stainless steel.
The finish on metallic materials such as stainless steel, whether it is a refined mill finish, polished to specific grit, or an electro-polished treatment, should complement system design and provide satisfactory corrosion and microbial activity resistance.
Auxiliary equipment and fittings that require seals, gaskets, diaphragms, filter media, and membranes should exclude mate-rials that permit the possibility of extractable, shedding, and microbial activity.
Insulating materials exposed to stainless steel surfaces should be free of chlorides to avoid the phenomenon of stress corrosion cracking that can lead to system contamination and the destruction of tanks and critical system components.
SOP No. Val. 200.80 Effective date: mm/dd/yyyy
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Specifications are important to ensure proper selection of materials and serve as a reference for system qualification and maintenance.
Information such as mill reports for stainless steel and reports of composition, ratings, and material handling capabilities for non-metallic substances should be reviewed for suitability and retained for reference.
Component (auxiliary equipment) selection should be made with the assurance that it does not create a source for contamination intrusion.
Heat exchangers should be double tube sheet or concentric tube design.
Heat exchangers should include differential pressure monitoring or utilize a heat transfer medium of equal or better quality to avoid problems if leaks develop.
Pumps should be of sanitary design with seals that prevent con-tamination of the water.
Valves should have smooth internal surfaces with the seat and closing device exposed to the flushing action of water, such as occurs in diaphragm valves.
Valves with pocket areas or closing devices (e.g., ball, plug, gate, and globe) that move into and out of flow area should be avoided.
4.3 Sanitization
Microbial control in water systems should be achieved primarily through sanitization practices. Systems should be sanitized using either thermal or chemical means. In-line ultraviolet light at a wavelength of 254 mm can also be used to sanitize water in the system continuously.
Thermal approaches to system sanitization shall include periodically or continuously circulating hot water and the use of steam.
These techniques are limited to systems that are compatible with the higher temperatures needed to achieve sanitization, such as stainless steel and some polymer formulations. Although thermal methods control biofilm development, they are not effective in removing established biofilms.
Chemical methods, where compatible, shall be used on a wider variety of construction materials. These methods typically employ oxidizing agents such as halogenated compounds, hydrogen peroxide, ozone,
SOP No. Val. 200.80 Effective date: mm/dd/yyyy
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or peracetic acid. Halogenated compounds are effective sanitizers but are difficult to flush from the system and tend to leave biofilms intact. Compounds such as hydrogen peroxide, ozone, and peracetic acid oxidize bacteria and biofilms by forming reactive peroxides and free radicals (notably hydroxyl radicals). The short half-life of these compounds, particularly ozone, may require that they be added continuously during the sanitization process. Hydrogen peroxide and ozone rapidly degrade to water and oxygen; peracetic acid degrades to acetic acid in the presence of ultraviolet light.
Ultraviolet light impacts the development of biofilms by reducing the rate of new microbial colonization in the system; however, it is only partially effective against planktonic microorganisms. Alone, ultraviolet light is not an effective tool because it does not eliminate existing biofilm. However, when coupled with conventional thermal or chem-ical sanitization technologies, it is most effective and can prolong the interval between system sanitizations. The use of ultraviolet light also facilitates the degradation of hydrogen peroxide ozone.
Sanitization steps should be validated to demonstrate the capability of reducing and holding microbial contamination at acceptable levels.
Validation of thermal methods should include a heat distribution study to demonstrate that sanitization temperatures are achieved throughout the system.
Validation of chemical methods should demonstrate adequate chemical concentrations throughout the system. In addition, when the sanitization process is completed, effective removal of chemical residues must be demonstrated.
The frequency of sanitization derived from the trend analysis of the microbiological data should be used as the alert mechanism for maintenance. The frequency of sanitization should be estab-lished such that the system operates in a state of microbiological control and does not exceed alert levels.
REASONS FOR REVISION
Effective date: mm/dd/yyyy
First time issued for your company, affiliates, and contract manu-facturers
SOP No. Val. 200.80 Effective date: mm/dd/yyyy
Approved by: