BOP regulator set point sensitivity according to API spec 16D

[ab899072]

Hello All,
I have a question on the interpretation of a section from API 16D Section 4.3.2.2

Annular BOP Control Manifold
The manifold components shall include a dedicated pressure regulator to reduce upstream manifold pressure to the power fluid
pressure level that meets the BOP manufacturer's recommendations. The regulator shall respond to pressure changes on the
downstream side with sensitivity sufficient to maintain the set pressure ± 150 psi.
The annular BOP pressure regulator shall be remotely controllable. Direct manual valve and regulator operability shall permit
closing the annular BOP and/or maintaining the set regulated pressure in the event of loss of the remote control capability​

So specifically the section in bold, to me the word maintain means to hold. So for example, the set pressure is 1.5ksi and then there is a demand on the downstream of the regulator.. the requirement to meet the ± 150 psi would not only depend on the regulator (flow rate capacity on outlet) but only depend on the system as a whole and how much (or little) it can supply an inlet. Would that be correct?
If so, I guess I'm having trouble how this section can govern a regulator when it also depends on the system as well and not just the regulator.

Or is the correct way of interrupting that is once the demand is met the set point shall return to the original set point within 150psi?



Does anyone have any input or familiar with this API or annular BOP?
Thank You for your time,
Adam

 

[BigInch]

I don't have experience with BOP design, however I can see no other way to interprete that, except as follows,
The rule is inclusive of the system and sets a requirement for how a properly designed regulator in that service must respond when installed in that system. For example, if the regulator is properly sized, it will allow enough flow through itself to prohibit the downstream portion of the system from not being deprived of inflow such that its pressure drops more than 150 psi below the regulator's set point. In that manner it is actually setting a performance criteria for the regulator completely independent of whatever system it happens to be in. It is the designer's responsibility to make sure the regulator he chooses and system he puts it in perform well together.

When in doubt about how codes should be interpreted, take the wholistic system viewpoint. No code wants a regulator or any individual device to perform well at the expense of the system in which it is installed.

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