🔍 Key Concepts

• Lightweight survey / lightweight changes for a drilling unit and how they affect allowable variable deck loads • How setback and cantilever pipe rack loads count against the total allowable variable load or hook load envelope • Using the unit’s load chart / hook load vs. setback load curves to find the remaining capacity

💭 Think About

• How would adding 450 kips in setback and 200 kips in the cantilever pipe rack reduce the available capacity for hook load compared with the baseline condition? • If the unit has a maximum combined variable load in this operating condition, what portion of that total has already been ‘used up’ by the given setback and pipe rack loads? • Look at the typical shape of a hook‑load / setback interaction curve: is the remaining hook capacity small, moderate, or still close to the maximum, given the stated weights?

✅ Before You Answer

• Confirm what the maximum allowable hook load is in the relevant condition before these additional weights are applied (from the load chart / stability manual). • Check whether the 450 kips and 200 kips are already included in or added to the variable deck load used to derive the hook‑load limit. • Verify that the final hook load stays within both the structural limits (derrick / cantilever ratings) and stability limits (GM, leg reactions) specified for that operating case.