16D Subsea
accumulators.
Subsea accumulators and special-purpose circuits, following the remaining worked examples in API 16D Annex D. The same engine, the same report, and the same real-gas nitrogen as the 16D check, extended for water depth.
For: offshore drilling contractors and operators with subsea stacks.
Illustration: 15 gal bottle at 70 °F, 1,000 psi surface precharge plus seawater head, 5,000 psi supply plus control-fluid head, minimum 1,500 psi above ambient. Nitrogen uses an approximate compressibility fit here; the module uses the Span et al. reference equation of state.
The 16D check, taken to the seabed.
Subsea stacks put the accumulators under thousands of feet of seawater. Precharge has to rise with water depth, the nitrogen works at higher pressure, and every bottle delivers less usable fluid than it would on deck. The subsea module follows the remaining API 16D Annex D worked examples to size those circuits properly.
- Subsea accumulator banksSized for water depth, with precharge corrected for seawater head.
- Special-purpose circuitsThe remaining Annex D worked examples, each sized as its own circuit.
- Real-gas nitrogen at depthThe same reference equation of state as the 16D check, where the ideal-gas shortcut is furthest off.
- Same engine, same reportBottle options compared side by side, with pass/fail and the margin on every check.
Sizing subsea accumulators?
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