BK-A 10" CRUDE RISER SECTIONAL REPLACEMENT USING COFFERDAM
Year
2023
Location
BUNGA KEKWA ALPHA (BK-A) AT PM3 SOUTHERN FIELD
Background
During routine maintenance in 2018, corrosion was identified on the 10-inch crude
riser at Bunga Kekwa Alpha (BK-A), located near the splash zone. A temporary
repair was completed in 2020, but the riser required a permanent restoration due
to the following critical conditions revealed by the 2018 In-Line Inspection (ILI):
• External wall loss ranging from 16% to 61%
• Only ~190 mm clearance between the riser and existing riser guard clamp
• Presence of a 4-inch piggybacked riser secured with piggyback clamps
• Repair located in wet splash-zone conditions
• Cutting line below Mean Sea Level (MSL), preventing conventional repair approaches
Due to these constraints, conventional diver-based repair and marine vessel support were not feasible.
• External wall loss ranging from 16% to 61%
• Only ~190 mm clearance between the riser and existing riser guard clamp
• Presence of a 4-inch piggybacked riser secured with piggyback clamps
• Repair located in wet splash-zone conditions
• Cutting line below Mean Sea Level (MSL), preventing conventional repair approaches
Due to these constraints, conventional diver-based repair and marine vessel support were not feasible.
Our Role
ECMS proposed a watertight cofferdam
solution, designed using Finite Element
Analysis (FEA) in accordance with
industry standards.
To address the restricted space and piggyback configuration, the cofferdam was built as a three-part assembly consisting of two rectangular sections and one clamp. Once installed, the cofferdam allowed the work area to be fully dewatered, creating
a dry and controlled environment for one- atmosphere welding.
To address the restricted space and piggyback configuration, the cofferdam was built as a three-part assembly consisting of two rectangular sections and one clamp. Once installed, the cofferdam allowed the work area to be fully dewatered, creating
a dry and controlled environment for one- atmosphere welding.
Outcome
✓ Safe execution below MSL
✓ Dry welding achieved despite splash-zone conditions
✓ Secure and stable installation within tight clearance
✓ Efficient installation and removal of the cofferdam
✓ Dry welding achieved despite splash-zone conditions
✓ Secure and stable installation within tight clearance
✓ Efficient installation and removal of the cofferdam