Refresher courses must be redone periodically to keep a certificate valid. Typically 3 days.
Refresher and Updating Training for engineers renews the mandatory certificates and updates knowledge of machinery, regulation and safety practice. It is the engine-side equivalent of the deck revalidation route.
Part of renewing an engineer certificate of competency.
An engineer certificate of competency due for renewal.

Approvals and durations as published by DG Shipping, and the duration can differ between institutes. Fees and batch dates are set by the institute.