A large container vessel had a failed DN1000 exhaust-gas scrubber drain system. Irwin used Automet FAB to capture the as-built geometry, then renewed the failed GRE drain lines with temperature-matched lined carbon-steel spools and DN1000 duplex-stainless isolation valves.
The Problem
The vessel’s GRE drain lines from the scrubber outlets were heat-damaged and leaking. One GRE spool had begun pulling out of its bonded flange, turning the drain system into a repeat-risk item rather than a simple like-for-like pipe replacement.
The root operating issue was also addressed: the drain lines did not have isolation valves, which made it difficult to shut off hot, low-pH effluent during service.
What Irwin Did
Survey and modelling
- Surveyed the failed drain system onboard with Automet FAB.
- Created a 3D as-built digital twin of the installed arrangement.
- Prepared the replacement geometry before fabrication began.
Temperature-matched materials
- Used Halar-lined carbon steel for hotter sections.
- Used PE-lined carbon steel elsewhere in the drain system.
- Added four DN1000 duplex-stainless isolation valves.
The replacement spools were prefabricated ashore for bolt-in installation to the existing system. A riding team carried out the onboard renewal and re-supported the line scope by scope, with the work completed to the owner’s representative’s satisfaction.
Material Selection Guide
| Service temperature | Recommended Irwin approach | Reason |
|---|---|---|
| Up to 70 C | PE-lined carbon steel | Polyethylene lining gives corrosion and erosion resistance while the steel carrier takes the mechanical load. |
| 70-160 C | Halar-lined carbon steel | ECTFE lining is used for hotter scrubber drain sections above polyethylene’s working range. |
| Above 160 C | SMO254 or solid alloy | For the hottest sections, material selection shifts to suitable alloy construction rather than polymer lining. |
Why This Matters For Similar Vessels
For owners with recurring scrubber drain leaks, replacing the same material like for like may leave the underlying failure mode untouched. A better renewal strategy starts with the service conditions: temperature, effluent chemistry, mechanical loading, support arrangement and whether the line can be isolated.
For this vessel, Irwin matched the lining to the operating temperature, added isolation capability, and delivered a prefabricated bolt-in renewal that avoided a dockyard dependency for this scope.
FAQ
Can scrubber drain lines be renewed without drydocking?
For some scopes, yes. This DN1000 scrubber drain renewal was completed in service by a riding team using prefabricated bolt-in spools. Feasibility depends on access, isolation, support, class requirements and the specific line arrangement.
When should PE-lined carbon steel be used for scrubber drains?
PE-lined carbon steel is suitable for many wash-water and drain-line sections up to 70 C. Hotter sections may require Halar-lined carbon steel, SMO254 or another solid alloy solution.
Why replace GRE with lined carbon steel?
GRE provides corrosion resistance but can be vulnerable at bonded joints under mechanical load. Lined carbon steel uses steel for mechanical strength while the lining provides the corrosion barrier.
Why add isolation valves?
The source case noted that the drain lines lacked isolation valves. Adding isolation valves helped address operating control of the drain system, not only the visible failed spool.
What does Automet FAB add to this kind of job?
Automet FAB captures the as-built geometry so replacement spools can be prefabricated for the installed arrangement, reducing guesswork during onboard fitting.
Have a scrubber drain or GRE pipe failure?
Irwin can review the line arrangement, service temperature and repair window, then propose a prefabricated lined-steel renewal scope.