1. Bruce Witwer, Dril-Quip Inc.
API Consideration for
Worst Cast Discharge
Bruce Witwer, Dril-Quip Inc.

2. Definitions

3. RATED ≠ EXTREME ≠ SURVIVAL
Definitions
Survival Loads
Watch circles
Storm events
Repeatable (probabilistic)
Worst Case Loads/Discharge (WCD)
Drive-off
Blowout/uncontrolled flow
One time event (stochastic)
Allowable stress scenarios (ref. API 17G/2RD)
Rated = .67 (σY)
Extreme = .80 (σY)
Survival = 1.00 (σY)
RATED ≠ EXTREME ≠ SURVIVAL
Where does WCD fit?

4. WCD - Example #1 Blowout/uncontrolled flow Casing hanger & seal
Pressure control (rated)
Lockdown load (beyond rated)
Current industry standards
API 17D/6A (group 4)
Cyclic loads (rated)
Cyclic thermal

5. WCD - Example #2 Blowout/uncontrolled flow Liner hanger & packer
Pressure control or containment
Lockdown load
Current industry standards
API 11D1
API 19 LH (pending)
Cyclic thermal
Inconsistent terms, failure modes

6. WCD - Example #3 Drive-off event Wellhead System Proposal
Pressure containment (rated)
Structural capacity (beyond rated)
Current industry standards
N/A
Proposal
Survival (ALS) event
API 17G & API 2RD
1.00 (σY)