Project Overview

When a subsea client identified severe corrosion on the locking ring mechanism of their dive bell manway doors, the component quickly became a critical-path repair. The locking ring grooves on the outside diameter of the bell manways required precision in-situ machining to restore a true diameter and controlled geometry, allowing the integration of new brass wear plates to ensure long-term reliability and safe offshore operations.

Operating within the confined internal architecture of the dive bell presented significant technical challenges — demanding an innovative onsite machining solution delivered within a tight project schedule.

The Challenge

• Highly corroded locking ring grooves requiring full re-machining to a known datum diameter

• Extremely restricted working envelope inside the dive bell structure

• Limited radial clearance for machining equipment and tooling

• Requirement to drill and tap 200 M5 holes on an outer radius with difficult access

• Need to verify dimensional compliance offshore with limited measurement space

• Project classified as critical path for vessel readiness

Our Onsite Machining Solution

Our team deployed one of our standard flange facing machines, adapted specifically for the scope with:

• Bespoke designed tool holders and special form tooling to generate the new groove profile

• Detailed 3D CAD modelling of the dive bell architecture prior to mobilisation to guarantee machine and tooling fit

• A full mock-up machining trial to validate tooling clearances, machining strategy and measurement methods

• Design and manufacture of a precision drill jig that located directly within the machined groove — ensuring hole pitch accuracy and squareness despite tight access

This approach enabled controlled subsea equipment machining onsite, eliminating the need for costly removal or workshop repair.

Execution & Results

• Locking ring grooves successfully re-machined back to true diameter and specified profile

• 200 M5 holes drilled and tapped holes completed accurately using the custom jig

• Brass wear plates installed to improve durability of the mechanism

• Work completed safely, on schedule and within critical project timelines

• Enabled the client to return their dive system to operational readiness without delay

Client Feedback

“Only positive feedback from your team that carried out the work scope. Great bunch of lads — very meticulous and great communications throughout. Top job!!”
Diving Technical Supervisor

Significance
This case demonstrates the firm’s mastery of in‑situ machining within constrained subsea environments, and confirms its capacity to deliver precise, high‑integrity solutions under time pressure. By integrating Flange Facing  technology with custom tooling and rigorous pre‑planning, the team has set a benchmark for future dive chamber repairs and underscored its position as a trusted partner in subsea sector engineering projects.