API blowout preventer (and other drill-through equipment) specifications have not been comprehensive and have been lacking in detail. This situation is being corrected in a new publication which is reviewed in this paper. The publication covers annular and ram blowout preventers, drilling spools, adapters and hubs for clamp connections. It will include dimensional, pressure, and temperature requirements; performance, process control and design and material requirements. New hub dimensions will be discussed. Welding, marking, and purchasing guidelines will be included. Much of the material is to be patterned after or taken from the new API Specification For Wellhead and Christmas Tree Equipment, and is tailored to be used in conjunction with API's new Specification for Quality Programs. The publication represents an amalgamation and documentation of current industry practices. Equipment and assemblies not covered in the first edition are under study and will be incorporated into future revisions.

This new document is intended to serve as a basic purchase and manufacturing specification, facilitating communication between manufacturers and users. It should significantly reduce misunderstanding and shorten communications regarding ordering and manufacture of drill-through equipment. The result should be improvement in the fitness of equipment for intended service and a corresponding improvement in safety and reliability.

As the oil and gas industry has moved into more severe environments, particularly offshore in cold climates, and has come under growing regulatory requirements, the need for a comprehensive consensus specification for drill-through equipment has become accentuated. This new publication will satisfy that need.


The API Committee on Drill Through Equipment, API Committee 16, was formed in September, 1984.determined by the API Executive Committee on Standardization of Oilfield Equipment and Materials included the development and maintenance of API bulletins, recommended practices and specifications for standardization of that equipment used in the drilling of oil and gas wells which is commonly known as "drill through equipment". This equipment includes ram type blowout preventers, annular type blowout preventers, drilling spools, adapters, and valves used in choke and kill manifolds. Also included are drilling chokes, other components associated with drilling choke and kill manifolds for both surface and subsea applications, hydraulic closing units used to operate both surface and subsea blowout preventer stacks, and drilling risers and associated equipment used with subsea blowout preventer systems. In order to adequately handle the many kinds of equipment and the many variations in requirements for this equipment, Committee 16 was divided into four subcommittees. These subcommittees became:

  • Subcommittee l6A - Drill Through Equipment

  • Subcommittee l6B - Marine Drilling Riser Systems

  • Subcommittee l6C - BOP Closing Systems

  • Subcommittee l6D - Choke and Kill Systems

Each of these subcommittees has been instructed to develop performance-type rather than "how-to" specifications. They are to develop specifications that can become unequivocally accepted throughout the world for equipment that is safe in intended use, as well as functionally interchangeable. Further they are to develop specifications that can be met by competent manufacturers using commonly accepted and readily available techniques and technology.

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