wettedpart

A wetted part is any portion of a device that has direct contact with the process fluid during normal operation. In equipment such as pumps, valves, sensors, and meters, wetted parts include interior surfaces, seats, gaskets, seals, and any components that may come into contact with the liquid. Exterior housings and noncontact components are generally not considered wetted parts unless they are immersed.

Materials and finishes for wetted parts are chosen for chemical compatibility, corrosion resistance, and cleanability. Common materials include stainless steels such as 304 and 316, nickel and cobalt alloys, titanium, and approved plastics. Elastomeric seals and gaskets may also be wetted parts if they contact the process fluid, requiring careful selection to avoid swelling, leaching, or incompatibility. Surface finish is important to minimize contamination and facilitate cleaning; sanitary designs favor smooth, crevice-free interiors to improve cleanability and reduce biofilm or residue buildup.

Hygiene and regulatory considerations are prominent in pharmaceutical, biotech, and food processing industries. Wetted parts often must meet sanitary design standards and material compliance requirements (for example, USP Class VI materials, 3-A Sanitary Standards, and FDA cGMP) and are designed for CIP (clean-in-place) and SIP (sterilize-in-place) with validated cleaning and sanitization processes.

Design and maintenance implications include specifying compatible materials, choosing appropriate coatings, and planning for inspection, replacement, and routine sanitization. Wetted parts are subject to testing such as hydrostatic or leak tests and, where applicable, extraction or leachables assessments to ensure product safety and process integrity.