The mud pumps on the production deck of a platform in Cook Inlet Alaska were replaced with heavier models. To install the new mudpumps, major support structure below the deck crane needed to be cut, temporarily, so that the new mudpumps could be maneuvered into place. Hopper Engineering was asked to assist with three task:
- Verify that the existing deck structure is not compromised by the additional weight.
- Determine if the temporary truss chord removal below the crane is acceptable, and provide guidance regarding the crane de-rating during the installation.
- Assist with the connection design for reattaching the removed truss chords.
Using hand calculations and a math model of the topsides structure, it was found that the heavier mudpumps could be supported by the existing deck structure. The same math model was then used to determine the reduced crane rating and deck loads with the braces removed from the truss. A connection detail that would adequately transfer the loads was designed for reattaching the cut out truss chords.