The barrier is a system, not a stack
API RP 53 is the API recommended practice for blowout prevention equipment systems for drilling wells, the industry reference for BOP configuration, testing, and maintenance. Well control rests on barriers, and on wells with subsea BOP stacks the federal rules require two independent barriers, including one mechanical barrier, in each annular flow path. The stack is only as good as the seals, the hydraulic system, and the people who operate it. A BOP that has never been function tested is a sculpture, and the testing schedule is what turns it into a control.
The test numbers that are actually in the rules
Federal rules for OCS drilling operations under 30 CFR 250 Subpart D are specific about frequency. The diverter sealing element and diverter valves must be pressure-tested to a minimum of 200 psi, with subsequent tests within 7 days after the previous test. Capping stacks must have all pressure-containing critical components function tested on a quarterly frequency, not to exceed 104 days between tests. Posted BOP pressures must consider the surface pressure at which the formation at the shoe would break down, the rated working pressure of the BOP stack, and 70 percent of casing burst.
Drills make the reaction automatic
Crews drill well control responses so the reaction to a kick is muscle memory: shut in, verify, report. Test records and drill records are the evidence an auditor looks for, because a program that cannot show dates cannot show compliance. The drill log is also the operations log, because it shows which crews actually ran the sequence, how long it took, and where it broke down. A drill that takes too long on the choke line is a training gap found at zero cost, before the real kick finds it at full cost.
BOP discipline belongs with the other life-critical routines on location: H2S monitoring, critical lifts, and job safety analysis. If test dates and drill times are filled in after the fact, an operations audit will show which barriers are proven and which are assumed.