Non-Destructive Testing (NDT) for marine crane structures is a systematic "health check" regimen designed to ensure safe operation in extreme offshore environments. It encompasses a range of techniques, from basic visual inspection to advanced acoustic and electromagnetic methods, each with specific applications and advantages. Typical welding sequence of the crane foundation junction, installation of foundation upper part with adapting of plates; fillet weld inside; gouging outside; grinding gouged seam; 100% MT (magnetic particle testing); by negativ MT result, repeat step three-five；clean the tested surface; multi-pass welding outside ; 100% volumetric UT-ultrasonic testing.

The primary focus areas for NDT on marine cranes include:

• Structural connections: Bolts connecting the boom to the pedestal, slewing bearing connection bolts, luffing cylinder pins, and other critical pivot points.

• Load-bearing welds: Welds between boom main chords and lacing/webs, and welds connecting the pedestal to the deck.

• Major machinery components: Hoist drums, sheaves, and hooks.