Answer
The Condition Assessment Scheme (CAS) is a mandatory verification framework introduced under MARPOL Annex I (Regulation 20 and 21).
Objective: It was originally designed to detect structural weaknesses in single-hull oil tankers and to determine if category 2 and 3 single-hull tankers could be permitted to operate beyond their phase-out dates. Today, it serves as a stringent, formal regime to ensure the structural integrity of aging oil tankers.
Applicability: It applies to oil tankers of 15 years of age or more.
Key Features:
It does not replace the enhanced survey programme (ESP) but runs in parallel, requiring a much higher level of stringency, documentation, and verification.
The survey includes extensive thickness measurements, close-up visual inspections, and structural assessments.
Issuance: Upon successful completion, the flag administration (or a recognized organization like a Classification Society acting on its behalf) issues a Statement of Compliance (SoC), valid for a maximum of 5 years, subject to intermediate verification.