Loadout
This article covers introduction to loadout analysis.
Table of contents
What is Loadout?
- A pre-service, post-fabrication operation.
- Transferring of fabricated structure on to a cargo barge for transporting to its final location of installation.
Methods of Loadout
- By skidding—push-pull strand jacks (skidding by pull-push method using cable strand jacks, used to pull on to the transport barge).
- Using trailers—a mobile train of self-powered skid, with continuous support of pneumatic tires, roll on to the transport barge.
- By lifting.
Importance of a Loadout analysis
- Loadout is a crucial part of installation sequence.
- In terms of project schedule and progress, loadout is considered a milestone achieved.
- Analysis captures the worst possible loadout scenarios such as, but not limited to, the following: [a] Sinking of support, [b] Partial loss of support and [c] Total loss of support.
- Analysis confirms the supports that need to be continually supported—at all times, supports that can be allowed for scenarios of support loss temporarily. This helps fabrication and installation teams to orient the structure such that, support loss conditions are in check, and in ensuring a safe loadout operation.
Computer model and Loads
Jacket model in a four-point Loadout analysis.
Computer model and (pre-service) loads are similar to that of a lift model, except that there are no slings modeled. In addition, rigging loads (loads of installation equipment, viz., slings, shackles, and other temporary items) are captured in the total loadout weight.
Analysis
Four point support as an example (worst loadout case):
- Base case: All supported.
- Loss, partial loss or sinking of support at each support one at a time (never considered simultaneously—one case per support).
Other loadout cases can either be studied as per the design basis, or based on client-specific requirements dictated in a given project.
For an in-depth and critical loadout analysis, Gap element analysis is commonly used, for greater control and accuracy of a loadout sequence.
Negative reaction (or tension) indicates that the support is ineffective, and therefore, the structure needs to be reanalyzed without that support—provided the equilibrium can still be achieved.
Discussion
This article does not cover many aspects and variables involved in a typical detailed design. However, the author is of the opinion that it provides a general guideline in understanding and performing a loadout analysis. Readers are welcome to suggest errors, omissions and obvious inclusions—if any—in this article. You may write to the author here.
Disclaimer: Please be aware that the author bears no responsibility with regards to the content and use of this article.