API Specification 6A is the recognized industry specification for wellhead and tree equipment that was formulated to provide for the availability of safer, dimensionally and functionally interchangeable wellhead and tree equipment. This specification includes detailed requirements for the manufacture of tubular suspension equipment, valves, and fittings used at the location of oil and gas wells to contain and control pressure and fluid flows.

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Specification 6A also serves as the reference source for the design of flanged end and outlet connections for use at 2,000- to 20,000-psi maximum rated working pressures and a family of gate valves for use over these same pressure ranges API Specification 6A is also specified as the base standard for manufacture of subsea equipment in accordance with API Specification 17D, 16C, and 16A. Aftermarket repair and remanufacturing of API 6A equipment is covered under API standard 6AR The guidelines for tooling are in API Technical Report 6RT

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Elements not addressed in API 6A include

• Advanced design analysis

• Research and development

• Supplier management

• Reliability

• Materials characterization

• Field maintenance and service

• Mandatory product qualification

 

API Specification 6A covers wellhead and tree equipment as follows:

Wellhead Equipment

• Casing and tubing heads (housings and adapters)

• Casing and tubing hangers (slip and mandrel type.

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Valves, Chokes, and Actuators

• Single completion valve

• Multiple completion valves

• Actuated valves Valves prepared for actuators

• Check valves

• Chokes

• Safety valves SSV/USV/boarding shutdown valve (BSDV) and actuators

• Actuators

• Backpressure valves​

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Plugs, Connectors, and Gaskets

• Integral, blind, and test flange

• Ring gaskets

• Threaded connectors

• Tees and crosses

• Bullplugs Valve-removal plugs  

• Top connectors

• Top connectors (nonstandard)

• Crossover connectors

• Other end connectors (OECs)

• Spools (adapter and spacer)