Meritus Technology

Deepwater Structure Fabrication

Deepwater structures are unforgiving. Fatigue life is calculated, not estimated; weld quality is the design assumption everything else rests on; and once the structure is installed, inspection and repair are measured in vessel days.

Meritus sources deepwater and subsea structural scopes from Chinese fabricators, with weld quality and NDT coverage treated as the controlling deliverable rather than a percentage sampled at the end.

Capabilities

Scope we cover

Tension leg platform and spar hull sections; semi-submersible hull and column structures; jacket structures, piles and appurtenances; subsea structures including manifold frames, protection structures and foundations; mooring components and connectors; riser support and guide structures.

Weld quality and fatigue

For fatigue-governed structures the weld profile matters as much as the weld soundness. We review welding procedures against the fatigue design assumptions, verify NDT coverage against the specified extent rather than the shop's habit, and check that any repair welds are recorded, re-inspected and reported — repairs are where fatigue life quietly disappears.

Materials and coatings

Material substitution is the most common and most consequential shortcut in heavy structural work. We verify heat numbers against mill certificates and confirm impact and through-thickness properties where the design calls for them. Coating systems are inspected for surface preparation and DFT, not just final appearance. Every order runs through the same quality chain: shop pre-qualification, material traceability against mill certificates, in-process and final inspection, and a documentation pack released before shipment.

Failure modes we inspect for

Repair welds ground flush and unrecorded — the single most consequential omission in fatigue-governed structures. NDT coverage sampled at the shop's customary rate rather than the specified extent. Through-thickness properties assumed rather than tested where the design calls for Z-grade material. And coating applied over a surface preparation standard that was signed off but not achieved.

How an order runs

Enquiry and specification review; shop shortlisting against the actual scope rather than a general vendor list; quotation with the inspection plan priced in, not added later; kick-off with agreed hold and witness points; in-process inspection at those points; final inspection, document pack release and shipment; arrival support if anything is queried. On deepwater scopes we agree the NDT extent and the repair-recording protocol before the first production weld, since retrofitting either is not possible.

Standards and certifications referenced

Frequently asked questions

Why is weld quality more critical on deepwater structures?

Because fatigue governs the design. The structure is sized on an assumed weld class, and a weld that is sound but has a poor profile can still fall short of the assumed fatigue life — with inspection and repair costed in vessel days once installed.

What structures does this cover?

TLP and spar hull sections, semi-submersible hulls and columns, jackets and piles, subsea manifold frames and protection structures, mooring components and connectors, and riser support structures.

How is material substitution prevented?

Heat-number verification against mill certificates, PMI on the delivered material, and confirmation of impact and through-thickness properties where the design specifies them.

Are repair welds acceptable?

Recorded, re-inspected and reported ones, yes. Unrecorded ones are the problem — which is why the repair protocol is agreed before production starts.

Related products and technical insights

Request a Quote

Contact Meritus Technology's ISO 9001:2015 certified procurement desk in Shanghai for deepwater structure fabrication — supplier verification, QA/QC, and global shipping. Request a quote or contact us.