API 6A Surface Christmas Tree for Well Production Control

Description

Goldenman API 6A Christmas Tree equipment is designed to control oil and gas flow at the wellhead during production, shut-in, testing, stimulation, and fluid-injection operations.

Available pressure ratings range from 2,000 to 10,000 psi, with PSL 1–4, PR1–PR2, material classes AA–EE and PU temperature classification from −29°C to 121°C.

Each Christmas tree is configured according to the well pressure, produced medium, H₂S or CO₂ exposure, tubing-head connection, required valve arrangement, choke type, actuation method, and project documentation requirements.

Goldenman supplies API-certified Christmas tree equipment for oil wells, gas wells, well-testing systems, and surface production facilities.

Product Highlights

• Manufactured to applicable API Spec 6A requirements
• Working pressure from 2,000 to 10,000 psi
• Product Specification Levels from PSL 1 to PSL 4
• Performance Requirements PR1 and PR2
• Material classes from AA to EE
• PU temperature ranges from −29°C to 121°C
• Configurations for oil, natural gas, and specified well fluids
• Manual or actuated valve options
• Fixed or adjustable choke options were required
• Sour-service configurations are available according to project conditions
• Custom flange, outlet, and valve arrangements
• API certificate and inspection documentation available
• Third-party inspection and customer witness support

What Is an Oilfield Christmas Tree?

An oilfield Christmas tree is an assembly of pressure-containing valves, fittings, outlets, and control components installed above the tubing head or tubing head adapter.

Its primary function is to control the flow of oil, gas, and other well fluids between the production tubing and the surface production system.

Depending on the well design and operating procedure, a Christmas tree can support:

• Normal oil or gas production
• Well shut-in and pressure isolation
• Production-rate control
• Pressure monitoring
• Well testing
• Chemical or fluid injection
• Acidizing and stimulation
• Pressure bleed-off
• Access to the production tubing
• Emergency well-control procedures

The Christmas tree is part of the complete wellhead system, but it is not the same as the casing head or tubing head. The casing and tubing heads support and seal the casing and tubing strings, while the Christmas tree controls flow above the production tubing.

Typical Christmas Tree Components

The exact tree configuration varies according to the well program. A typical surface Christmas tree may include:

• Lower master valve
• Upper master valve
• Production wing valve
• Kill the wing valve
• Swab valve
• Production choke
• Tree cap or top connector
• Pressure gauges
• Gauge valves
• Tees or crosses
• Tubing head adapter
• Outlet flanges or connectors
• Manual, hydraulic, or pneumatic actuators

Not every project requires the same components. The final bill of materials and flow-path arrangement should be approved through the general arrangement drawing before production.

Main Applications

Goldenman API 6A Christmas Tree equipment can be configured for:

• Onshore oil production wells
• Natural gas production wells
• Sour oil and gas wells
• Well-testing operations
• Workover and completion projects
• Acid-fracturing operations
• Well stimulation
• Fluid or chemical injection
• Artificial-lift wellhead systems
• Production-well upgrades
• Replacement of existing wellhead tree assemblies

For stimulation, acidizing, or high-pressure well-testing service, the working pressure, fluid compatibility, erosion risk, and temporary flow path must be reviewed separately from normal production conditions.

Technical Specifications

Parameter	Available Specification
Product name	Surface Christmas Tree
Applicable standard	API Spec 6A
Additional standard	SY/T 5127-2002, which was contractually required
Working pressure	2,000–10,000 psi
Temperature class	PU
Operating temperature	−29°C to 121°C
Material class	AA, BB, CC, DD, EE
Product Specification Level	PSL 1, PSL 2, PSL 3, PSL 4
Performance Requirement	PR1, PR2
Working media	Oil, natural gas, and specified well fluids
Main components	Gate valves, chokes, tees/crosses, adapters, and gauges
Valve operation	Manual or actuated as specified
Choke configuration	Fixed or adjustable as specified
Connection size	Project-specific
Nominal bore	Project-specific
Tree arrangement	Single-wing, dual-wing, or custom configuration
Sour-service option	Available according to specified service conditions
Certification	Applicable API certificate
Inspection	Factory and third-party inspection as specified

The pressure rating, bore size, material class, temperature class, PSL, and PR must be selected as one complete technical specification. These ratings should not be chosen independently.

Available Pressure Ratings

Christmas tree pressure ratings can be configured within the page-listed range of:

• 2,000 psi
• 3,000 psi
• 5,000 psi
• 10,000 psi

The selected pressure rating should be equal to or greater than the maximum anticipated wellhead pressure under the defined operating and test conditions.

Selection should consider:

• Maximum shut-in wellhead pressure
• Normal production pressure
• Well-test pressure
• Stimulation and acidizing pressure
• Injection pressure
• Temperature effects
• Pressure surges
• Future production changes
• End-user design margin

A 10,000 psi tree should not be selected automatically when a lower rating meets the approved well design. Higher pressure ratings can affect dimensions, weight, valve cost, actuator requirements, and replacement-part availability.

How to Select the Correct Christmas Tree Configuration

1. Confirm the Well Type and Operating Function

The purchaser should identify whether the tree is intended for:

• Oil production
• Gas production
• Injection service
• Well testing
• Acidizing or stimulation
• Artificial lift
• Workover service
• Replacement of an existing tree

The required flow paths and valve arrangement depend on the operating function.

2. Determine the Required Pressure Rating

Provide the normal operating pressure, maximum anticipated wellhead pressure, and required test pressure.

For wells that will undergo acid fracturing, injection, or high-pressure testing, the temporary operation pressure must also be included.

3. Confirm Nominal Bore and Connections

The tree must match the tubing head adapter, production tubing, and surface flowline.

Required information includes:

• Tree nominal bore
• Lower connection
• Upper connection
• Production-wing outlet
• Kill-wing outlet
• Flange or hub type
• Ring-gasket specification
• Face-to-face dimensions
• Existing wellhead interface

For replacement projects, the model name alone is not sufficient to confirm interchangeability.

4. Select the Valve Arrangement

A common tree may use two master valves, one or two wing valves, and a swab valve. However, the exact arrangement depends on the well-control philosophy and end-user specification.

Buyers should confirm:

• Single-wing or dual-wing design
• Number of master valves
• Production-wing arrangement
• Kill-wing arrangement
• Swab-valve requirement
• Valve size and pressure rating
• Manual or actuated operation
• Fail-safe requirements

5. Select the Choke Type

The production outlet may require:

• Fixed choke
• Positive choke
• Adjustable choke
• Needle-type choke
• Actuated choke

The selection depends on expected flow rate, pressure drop, erosion conditions, production-control requirements, and operating frequency.

6. Confirm the Well Fluid and Corrosive Conditions

The purchaser should provide:

• Oil and gas composition
• H₂S concentration
• CO₂ concentration
• Chloride content
• Water cut
• Sand production
• Chemical-treatment fluids
• Acidizing-fluid composition
• Operating temperature

This information affects material class, trim, elastomers, sealing materials, bolting, and corrosion-control requirements.

Material Class and Source-Service Selection

The original page lists API 6A material classes from AA through EE. The correct material class must be selected according to the produced medium and the well environment.

For H₂S-containing or otherwise corrosive service, it is not sufficient to specify only “sour service.” The purchaser should provide actual fluid composition and partial-pressure data where required.

The technical review should consider:

• H₂S exposure
• CO₂ exposure
• Chloride concentration
• Operating pressure
• Operating temperature
• Material hardness limits
• Valve trim material
• Seal and elastomer compatibility
• Bolting requirements
• Applicable NACE MR0175/ISO 15156 requirements

Not every AA–EE material configuration is suitable for every H₂S well. The material class and component materials must be confirmed against the actual service conditions.

Selecting PSL 1–4

The Product Specification Level defines the required level of material control, manufacturing control, traceability, inspection, testing, and documentation.

Selection is normally influenced by:

• Well criticality
• Pressure rating
• Sour-service conditions
• Operating environment
• Regulatory requirements
• End-user specifications
• Consequences of equipment failure
• Required material traceability
• Required inspection records

PSL should not be selected only as a commercial upgrade. The purchaser and manufacturer should determine the appropriate level based on the well conditions and project specification.

Higher PSL requirements may increase:

• Material qualification requirements
• Traceability
• Nondestructive examination
• Documentation
• Manufacturing lead time
• Inspection cost

Selecting PR1 or PR2

The Performance Requirement level defines the required product validation and performance-verification scope.

PR2 is generally selected when the project requires a more demanding validation level than PR1. However, PR2 should not be added automatically without reviewing the equipment type, operating conditions, and end-user requirements.

The purchase specification should clearly identify:

• Required PR level
• Applicable valves and components
• Validation requirements
• Functional testing
• Pressure-cycle requirements
• Documentation requirements

Manual and Actuated Valve Options

Christmas tree valves may be manually operated or equipped with hydraulic or pneumatic actuators.

Manual valves are often appropriate when:

• Local operation is acceptable
• Operating frequency is low
• Remote shutdown is not required
• The well is easily accessible

Actuated valves may be required when:

• A remote control is needed
• Emergency shutdown is required
• The site is unmanned
• Rapid isolation is necessary
• The valve is part of a safety system
• Integration with a control panel is required

For actuated valves, the quotation should define the actuator type, operating pressure, fail position, control-panel interface, and emergency shutdown logic.

Procurement Considerations

Complete Scope of Supply

A quotation described only as “one Christmas tree” may not define all included components.

The purchaser should confirm whether the quotation includes:

• Complete valve assembly
• Tubing head adapter
• Production choke
• Pressure gauges
• Companion flanges
• Ring gaskets
• Studs and nuts
• Actuators
• Control panel
• Spare seals
• Installation tools
• Documentation
• Export packing

Comparing quotations without matching the complete supply boundary can produce misleading price differences.

Existing Wellhead Compatibility

For replacement projects, confirm:

• Existing manufacturer and model
• Tubing head connection
• Nominal bore
• Pressure rating
• Flange or hub type
• Ring-gasket number
• Outlet orientation
• Overall height
• Available installation space
• Flowline connection
• Actuator clearance

A replacement tree may require an adapter or dimensional modification even when the nominal pressure and bore are the same.

Sand and Erosion Risk

High sand production or a large pressure drop across the choke can accelerate erosion.

The manufacturer should be informed of:

• Expected sand content
• Production flow rate
• Pressure differential
• Choke operating position
• Well-testing duration
• Required trim material
• Inspection and replacement strategy

API Certification and Quality Control

Goldenman supplies Christmas tree equipment with applicable API 6A certification according to the agreed product scope.

Manufacturing and inspection controls may include:

• Material certificate verification
• Heat-number traceability
• Dimensional inspection
• Hardness testing
• Visual inspection
• Ultrasonic testing is required
• Magnetic-particle or liquid-penetrant examination
• Weld and overlay inspection, where applicable
• Valve assembly inspection
• Hydrostatic shell testing
• Seat and sealing testing
• Functional operation testing
• Actuator testing where applicable
• Product marking verification
• Coating inspection
• Final documentation review

The exact inspection and testing scope is determined by the equipment type, PSL, PR, purchase specification, and approved quality plan.

Documentation Available

The project documentation package can include:

• API certificate
• Certificate of Conformity
• General arrangement drawing
• Approved datasheet
• Material certificates
• Heat-treatment records
• NDE reports
• Hardness reports
• Dimensional inspection report
• Hydrostatic test report
• Seat and function test records
• Coating inspection report
• Operation and maintenance manual
• Spare-parts list
• Packing list
• Third-party inspection report

Document requirements and approval points should be defined before production.

Frequently Asked Questions

How should the pressure rating of an API 6A Christmas tree be selected?

The pressure rating should be based on the maximum anticipated wellhead pressure, shut-in pressure, test pressure, and any temporary stimulation or injection pressure.

Normal production pressure alone is not sufficient. The selected tree rating must also match the pressure ratings of the tubing head, adapters, valves, chokes, and connected flowline equipment.

What is the difference between a wellhead and a Christmas tree?

The wellhead supports and seals the casing and tubing strings and provides the structural and pressure-containing interface at the top of the well.

The Christmas tree is installed above the tubing head or tubing head adapter and uses valves, outlets, and chokes to control production flow and well access. A complete surface system may include both, but they perform different functions.

How should PSL 1, PSL 2, PSL 3 or PSL 4 be selected?

PSL selection depends on well criticality, pressure, service environment, material traceability, inspection requirements, and end-user specifications.

Higher PSL does not simply mean a stronger tree. It generally means more extensive manufacturing controls, verification, traceability, examination, and documentation.

When is PR2 required instead of PR1?

PR2 may be specified when the project or end user requires a higher level of performance validation. Selection should be based on the applicable equipment, operating conditions, and contractual specification rather than on using PR2 as a general marketing upgrade.

Which material class should be used for an H₂S well?

Material selection cannot be based on the presence of H₂S alone. The manufacturer needs the H₂S and CO₂ levels, pressure, temperature, chloride content and other fluid information.

The material class, valve trim, bolting, seals, and hardness controls should then be matched to the actual sour-service conditions and applicable NACE MR0175/ISO 15156 requirements.

Can the same Christmas tree be used for production and acid-fracturing operations?

It may be possible when the tree pressure rating, materials, seals, valves, and flow path are suitable for the acidizing fluid, pumping pressure and erosion conditions.

The stimulation conditions must be reviewed separately. A production tree should not automatically be assumed suitable for high-pressure acid-fracturing service.

What information is needed to replace an existing Christmas tree?

Provide the existing tree nameplate, manufacturer, pressure rating, bore size, lower connection, outlet connections, ring-gasket numbers, overall dimensions, valve arrangement and clear photographs.

General arrangement drawings and tubing-head interface drawings are strongly recommended.

What should be included in a Christmas tree factory acceptance test?

The FAT scope may include document review, material traceability, dimensional inspection, valve operation, hydrostatic shell testing, seat testing, functional testing, actuator testing and product-marking verification.

The final FAT procedure should be agreed before production and aligned with the selected PSL, PR, and project inspection plan.

Can manual and hydraulic valves be used on the same tree?

Yes, when permitted by the approved design. For example, some valves may be manually operated while a master or wing valve is hydraulically actuated for remote shutdown.

The required fail position, actuator pressure, control logic, and emergency shutdown interface must be specified.

Information Required for Quotation

Please provide:

• Well type: oil, gas, injection or testing
• Maximum anticipated wellhead pressure
• Normal operating pressure
• Required pressure rating
• Operating and test temperature
• Nominal bore
• Lower connection
• Upper connection
• Production-wing outlet
• Kill-wing outlet
• Valve arrangement
• Manual or actuated valves
• Required choke type
• H₂S and CO₂ content
• Chloride concentration
• Sand-production conditions
• Material class
• Temperature class
• Required PSL
• Required PR
• Applicable NACE requirements
• Required API certificate
• Third-party inspection requirements
• Required documentation
• Quantity
• Destination country
• Delivery schedule

For replacement equipment, also provide the existing nameplate, general arrangement drawing, and connection dimensions.

Request a Technical Quotation

Goldenman supplies API 6A Christmas tree equipment for oil production, natural gas production, well testing, injection, and stimulation applications.

Send your pressure rating, bore size, connection details, valve arrangement, fluid composition, material class, PSL, PR, and inspection requirements to:

Email: info@goldenman.com

Goldenman will review the well conditions and prepare a Christmas tree configuration, technical datasheet, and commercial quotation for your project.