IACS UR Z23

IACS Unified Requirement Z23 is the Hull Survey for New Construction standard, the requirement that defines how classification surveyors witness and verify hull fabrication during shipbuilding. It applies to bulk carriers and oil tankers and covers Tier II functional items from the IMO Goal-Based Standards (resolution MSC.287(87)), including the survey of welded joints, alignment, and the performance standard for protective coatings (PSPC) in dedicated seawater ballast tanks and double-side skin spaces. Z23 sets the survey plan, the surveyor’s attendance points, and the records required, so that a newbuilding’s hull is verified against the Common Structural Rules and class rules before delivery.