top of page
WhatsApp Image 2026-06-03 at 10.20.51 (8).jpeg

Scrubber repairs

A PART OF GREEN SHIFT GROUP

WPQR 131 vs WPQR 141: know the difference, get the result

EN ISO 15614-1 
Welding Procedure Qualification Record 
Developed for scrubber repairs

​​

Improved Scrubber Repair Solutions

Exhaust Gas Cleaning Systems (EGCS), commonly referred to as scrubbers, operate in one of the most aggressive environments onboard a vessel. Continuous exposure to acidic wash water, elevated temperatures, thermal cycling, vibration, and corrosive exhaust gases places significant demands on both the scrubber structure and repair methods used throughout its operational life.


Traditional repair approaches often prioritize artistry quality alone, without fully considering long-term corrosion performance, material compatibility, heat input, and onboard execution efficiency. As a result, repairs may introduce new corrosion mechanisms, unnecessary downtime, or reduced service life.


GSG FSQ has developed an improved scrubber repair methodology that balances structural integrity, corrosion resistance, operational efficiency, and documented quality. By utilizing qualified welding procedures, matching filler materials, controlled heat input, and repair techniques specifically developed for marine scrubber applications, repairs can be executed faster while improving long-term performance.

Our approach is based on practical experience gained from onboard repairs, shipyard projects, and offshore installations. Every repair is supported by approved welding procedures, certified welders, full traceability, and comprehensive documentation to satisfy shipowners, classification societies, insurers, and technical managers.


The objective is simple: reduce downtime, improve repair durability, and deliver a technically sound solution that performs under real operating conditions, not only in laboratory testing.

​

The comparison below evaluates WPQR 131 (MIG/MAG) and WPQR 141 (TIG) welding procedures under identical EN ISO 15614-1 test conditions for marine and offshore scrubber applications. The data demonstrates significant operational differences in welding speed, productivity, heat input, corrosion performance, and onboard scrubber repairs.

image.png
image.png

WPQR 131:
MIG/MAG (Process 131)

  • Standard: EN ISO 15614-1

  • Manufacturer: GSG FSQ

  • Test Object: Butt weld

  • Welding Process: 131 (MIG/MAG)

  • Filler Metal: MT-254 (SMO 1.4547)

  • Shielding Gas: Ar

  • Position: PB

  • Thickness: 1.0 mm

  • Result: Approved

  • Acceptance: Meets requirements

  • Macro: Meets requirements

  • Micro: Meets requirements

  • Full Penetration: Approved

  • Welding Speed: 540 mm/min

  • Number of Passes: 1 Pass

  • Completion: Completed in one weld

WPQR 14:
TIG (Process 141)

  • Standard: EN ISO 15614-1

  • Manufacturer: GSG FSQ

  • Test Object: Butt weld

  • Welding Process: 141 (TIG)

  • Filler Metal: Inconel 625

  • Electrode: Wolfram (WL20)

  • Position: PB

  • Thickness: 1.0 mm

  • Result: Approved

  • Acceptance: Meets requirements

  • Micro: Meets requirements

  • Welding Speed: 115 mm/min

  • Number of Passes: 2 Passes Required

  • Time Impact: Welding time doubled

  • Process Note: Two passes required to achieve equivalent weld

Screenshot 2026-05-29 at 04.20.27.png

Advantages & Disadvantages

WPQR 131: Advantages

​

  • Perfect for scrubber repairs

  • Stable process and easy repeatability

  • Approved WPQR with EN ISO 15614-1 qualification

  • Matching filler material (SMO)

  • Ideal for retrofit and onboard execution

  • Lower heat input

  • Higher operational productivity

  • Better corrosion performance

WPQR 141: Disadvantages

​

  • Slower process

  • Higher heat input

  • Longer process execution

  • Requires higher finishing competence

  • Increased operational cost

  • Lower productivity

  • Dissimilar filler material

Filler material: correct match vs TIG compromise

Screenshot 2026-06-03 at 10.57.43.png

Key Technical Conclusions

  • Process 131 provides substantially higher production efficiency compared to TIG process 141.

  • One-pass welding significantly reduces execution time during onboard scrubber repairs.

  • Lower heat input reduces thermal stress and distortion risk.

  • Matching SMO filler material provides improved corrosion compatibility in aggressive marine environments.

  • TIG process 141 may provide improved visual appearance, but at the expense of productivity, heat input, and operational cost.

  • Process 131 is highly suitable for retrofit projects and onboard repair work where execution time and operational efficiency are critical.

Inspection of scrubber installation (Issue of damage report and recommended SoW)  

We recommend starting with a scrubber inspection to establish the full repair scope and proper planning to avoid unnecessary vessel delays and, where possible, to carry out the repairs outside of dry docking. Documentation required if available: 

​

  • Scrubber type / Installation year

  • Scrubber tower material specification

  • Previous repair history (if any)

  • Drawing of scrubber tower with clearly marked damage area

  • Fabrication drawings, if available (normally not available onboard)

  • Pictures from inside the scrubber tower showing the damaged area

  • Dimensions of damaged area including:

  • Length / Width / Estimated depth/thickness reduction

  • Pictures from outside the damaged area

  • Close-up pictures of cracks, corrosion, delamination, erosion, or burn-through

  • General overview pictures of complete scrubber tower condition

  • Thickness measurements / UT readings around damaged area

  • Any previous inspection or class reports related to the damage

  • Material grade information if known

  • General arrangement drawing of scrubber tower

  • Marked-up damage location drawing

  • Internal and external photographs

bottom of page