CLASSIFICATIONAPI classification of example arrangements for blowout preventer equipment is based on working pressure ratings.
Stack Arrangements shown belows. For API Classes 2M, 3M, 5M, 10M and 15M. Arrangements other than those illustrated may be equally adequate in meeting well requirements and promoting safety and efficiency.
STACK COMPONENT CODESA= annular type blowout preventer.
G= rotating head.
R=single ram type preventer with one set of rams, either blank or for pipe, as operator prefers.
Rd = double ram type preventer with two sets of rams, positioned according to operator’s choice.
Rt = triple ram type preventer with three sets of rams, positioned according to operator’s choice.
S =drilling spool with side outlet connections for choke and kill lines.
M = 1000 psi rated working pressure.
- Components are listed reading upward from the uppermost piece of permanent wellhead equipment, or from the bottom of the preventer stack.
- A blowout preventer stack may be fully identified by a very simple designation, such as:
5M -13 5/ 8 - SRRAThis preventer stack would be rated 5000 psi working pressure, would have throughbore of 13 5 /8 inches, and would be arranged as in Fig. C.5
RAM LOCKSRam type preventers should be equipped with extension hand wheels hydraulic locks.
SPARE PARTSThe following recommended minimum blowout preventer spare parts approved for the service intended should be available at each rig:
- A complete set of drill pipe rams and ram rubbers for each size drill pipe being used,
- A complete set of bonnet or door seals for each size and type of ram preventer being used,
- Plastic packing for blow out preventer secondary seals,
- Ring gaskets to fit flange connections, and
- Appropriate spare parts for annular preventers, when used.
- When storing blowout preventer metal parts and related equipment, they should be coated with a protective coating to prevent rust.
- While choke and kill lines may be connected to side outlets of the blowout preventers, many operators prefer that these lines be connected to a drilling spool installed below at least one preventer capable of closing on pipe.
- Utilisation of the BOP side outlet reduces the number of stack connections by eliminating the drilling spool and shortens the overall height.
- The reasons for using a drilling spool are to localise possible erosion in the less expensive spool and to allow additional space between rams to facilitate stripping operations.
Drilling spools should meet the following minimum specifications:
- Have side outlets no smaller than 2" nominal diameter and be flanged, studded, or clamped for API Class 2M, 3M, and 5M. API Class 10M and 15M installations should have a minimum of two side outlets, one 3" and one 2" nominal diameter.
- Have a vertical bore diameter at least equal to the maximum bore of the uppermost casinghead.
- Have a working pressure rating equal to the rated working pressure of the attached blowout preventer.