Loading for Reel Design – Reel-Lay Vessel

A Reel Drum design from a structural design standpoint, what is the most critical design loading condition? 

What is the significant difference between a mobile and a permanent reel drum? 

What about the differences between designing a reel drum for flexible products and a rigid pipeline? 

There will be quite a few loading conditions to consider, such as:
1. Self-weight 
2. Transit load ( transportation )
3. Crushing load ( due to full products loading + spooling tension )
4. Any other loads?

Although we may account for all loading conditions, what about the loading concepts? 

Do you think loading concepts and loading conditions shall always be code compliance?