Industry Learnings on Burner Boom
Related Structures
Erick Dubis (Completions Engineer)
May 2011
Atwood Eagle King Post Structure Safety Issue DRIMS #5223563
Abstract
The following presentation shows how industry and internal learnings related
to burner boom installation have influenced positively in Woodside.
The events describe how a few changes to a design, though potentially
insignificant if looked in isolation, when combined could lead to exceeding the
design safety factors or structural failure.
The slides also describe how Woodside’s and contractors internal process
prevented an escalation of the event, and some improvements that have been
made to the processes since the events occurred.
King Post Structure Safety Issue DRIMS #5223563
Slide 2
Standard King Post Boom Rig-up
Water Nozzle
King post
Burner Head
Pedestal
King Post Structure Safety Issue DRIMS #5223563
Slide 3
Background
Background:
• Rig and testing contractors confirmed that the same 85ft burner booms have
been safely used before on the same rig.
• Certified documentation was provided on the king post structure that supports
the burner boom.
• Burner booms were safely installed.
• Investigation results from another operator, related to a burner boom
collapse, and an additional modification required to the decks, drove the team
to revisit burner boom and rig documentation.
• A quick verification of the structures suitability was conducted by an
engineering firm to asses the impact of the new required modifications.
• Some inconsistencies were found in the rig structures and the burner boom
weights.
King Post Structure Safety Issue DRIMS #5223563
Slide 4
Background
• A full investigation/verification by an external specialist was
conducted, this involved physical verification of the structures in
place against certified drawings.
• Calculations showed the structures were overstressed, not only for
the required modifications, but overstressed by the burner booms
already in place.
The investigation and calculations revealed:
• Inconsistencies with the rig drawings and physical structures.
• Inconsistencies with the testing contractors actual booms weights
and weights assumed in the existing drawings and calculations.
• Some structures were severely overstressed and close to failure.
King Post Structure Safety Issue DRIMS #5223563
Slide 5
Snowball Effect
Water Nozzle
Burner Head
Additional 300kg
Additional 400kg
Pedestal
1m higher
King Post Structure Safety Issue DRIMS #5223563
Slide 6
Consequence
One of the pedestals bent and
tore its bracing
King Post Structure Safety Issue DRIMS #5223563
Slide 7
Inadequate MOC Snowball Effect
Causes:
• Inadequate MOC in place for the additional weight on the boom:
• Improvements to the burner head and added approximately 400kg.
• New the water nozzle added 300kg.
• Inadequate MOC in place by for the structural changes:
• Burner boom pedestal was 1m higher than the certified drawings .
• Rig drawings had inconsistencies with actual structures regarding positioning and reenforcements.
• No standardized verification process.
An additional weight of ~ 700 kg and a taller pedestal created a bending
moment that pushed the structures close to failure.
King Post Structure Safety Issue DRIMS #5223563
Slide 8
Swiss Cheese Barrier Model
Rig Contractor
Testing Contractor
Woodside
Built in Safety Factors
King Post Structure Safety Issue DRIMS #5223563
Slide 9
Actions Taken
Actions taken for mitigation and prevention:
Mitigations
• Burner booms were placed in a safe position to avoid structure overload.
• Structures were strengthen to withstand the loads.
• Pedestal was repaired and extra bracing was placed.
Future Preventions
• Lesson learnt were captured.
• An independent structural study is now performed in Woodside as part of
the QA/QC process before installing the burner booms.
King Post Structure Safety Issue DRIMS #5223563
Slide 10
What was Prevented?
King Post Structure Safety Issue DRIMS #5223563
Slide 11