Tubing Head API 6A Wellhead Components For Tubing Suspension & Annular Sealing

The tubing head is a wellhead component installed on top of the casing head that serves as the interface between the casing string and the production tubing. It is also commonly referred to as a tubing spool. It consists of a flanged body housing with a flanged top connection, a flanged bottom connection, and two side outlets. The top flange is equipped with lockdown screws used to securely fix the tubing hanger in position.-

The tubing head is installed above the casing head and below the Christmas tree. Its primary functions are:

Suspending the tubing string within the well

Sealing the annular space between the tubing and the production casing

Providing a transitional connection between the casing head and the Christmas tree

Our tubing heads are designed and manufactured in strict accordance with API Spec 6A (Specification for Wellhead and Christmas Tree Equipment) and NACE MR0175/ISO 15156 for sour service applications. The main pressure-containing parts and flanges are forged from modified alloy steel, with special heat treatment applied to ensure optimal performance in H₂S environments. The standard design features a straight-bore bowl with a 45° landing shoulder that supports the tubing hanger while preventing damage to sealing areas from drilling tools.

We can manufacture tubing heads with standard structures that include tubing hangers installed on the body housing cone. The tubing hanger can be tapped with back-pressure valve (BPV) threads upon customer request.

Key Functions of a Tubing Head

1. Suspending the Tubing String

The tubing head securely holds the tubing hanger, ensuring that the entire tubing string is properly suspended within the wellbore. This is critical for maintaining well integrity during both production and intervention operations.

2. Providing Annular Sealing

Sealing components within the tubing head prevent fluid or gas leaks between the tubing and casing annulus, controlling well pressure and preventing cross-flow between different zones.

3. Connecting to the Christmas Tree

The tubing head provides the mounting interface for the Christmas tree, which controls production flow and pressure. The flanged top connection allows for easy tree installation and removal.

4. Facilitating Well Maintenance and Intervention

The design of the tubing head provides access to the wellbore for workover operations, tubing replacement, and other well intervention activities without requiring removal of the casing head.

5. Providing Side Outlet Access

The two side outlets on the tubing head body serve multiple purposes, including dynamic liquid level measurement, casing gas venting, hot washing operations, and chemical injection lines.

Components of a Tubing Head

Technical Specifications

Our tubing heads are available across a wide range of configurations to suit virtually any well condition or regulatory requirement.

Notes on Specifications:

 Working Pressure (2,000 – 20,000 psi): Standard options include 2,000psi, 3,000psi, 5,000psi, 10,000psi, and 15,000psi. Higher ratings up to 20,000psi are available for HPHT applications. Higher working pressures require thicker flanges, heavier wall sections, and more robust sealing systems.

 Material Class (AA to FF): Defines the material properties and corrosion resistance requirements based on the service environment. Class AA is suitable for general non-corrosive service, while Class FF provides the highest level of corrosion resistance for severe sour service with high H₂S and CO₂ concentrations.

 Product Specification Level (PSL 1 to PSL 4): Higher PSL levels impose additional requirements for material chemistry, hardness control, nondestructive examination (NDE), and documentation. PSL 4 is typically required for critical offshore and HPHT applications and includes 100% NDE of all pressure containing parts.

 Performance Requirement (PR1 to PR2): PR2 certification requires more rigorous testing than PR1, including cyclic pressure and temperature testing, to validate the performance of seals and connections under simulated service conditions.

 Temperature Class (L, P, R, S, T, U): Indicates the minimum and maximum service temperatures the equipment can withstand. Class L is rated for -46°C to 82°C while Class U extends to 121°C.

Installation Procedure

Proper installation of the tubing head is critical for long-term well integrity and safe operation. Follow these steps:

Step 1 – Preparation

Verify compatibility of the tubing head with existing wellhead components.

Inspect all sealing surfaces, flange faces, and threads for damage, debris, or corrosion.

Ensure all required seals, gaskets, lockdown screws, and accessories are available.

Step 2 – Positioning

Lower the tubing head onto the casing head or casing spool.

Align the flange bolt holes and install stud bolts and nuts.

Use approved ring gaskets (type R, RX, or BX depending on pressure rating) between flanges.

Tighten flange bolts to the specified torque values in a crosspattern sequence to ensure even gasket compression.

Step 3 – Installing the Tubing Hanger

Run the tubing string into the well to the required depth.

Land the tubing hanger into the tubing head bowl, seating it on the 45° landing shoulder.

Engage the lockdown screws to secure the hanger in place and prevent vertical movement during pressure reversals.

Step 4 – Pressure Testing

Install test plugs or adapters as required.

Pressure test the tubing head seals, including the annular seal and the tubing hanger seal.

Typical test pressure is 1.5× the rated working pressure for shell testing and 1.1× for seat/seal testing.

Record all test results for well records and regulatory compliance.

Step 5 – Final Assembly

Remove test plugs and install the Christmas tree on the tubing head top flange.

Connect side outlets to choke and kill lines, annulus access lines, or chemical injection systems as required.

Perform final systemlevel pressure test of the complete wellhead assembly.

Why Choose Sunrise for Tubing Heads

As a specialized trading company with strong API-certified manufacturing partnerships, Sunrise offers:

Full API 6A compliance – Equipment is designed, manufactured, tested, and marked in accordance with API Spec 6A. PSL 1 through PSL 4 available.

NACE MR0175 sour service compliance – Materials selected and heat-treated per NACE MR0175/ISO 15156 requirements for H₂S environments.

Wide range of options – Pressure ratings from 2,000 psi to 20,000 psi, bore sizes from 7-1/16″ to 13-5/8″.

Material class flexibility – From Class AA (noncorrosive) to Class FF (severe sour service).

Complete documentation – Mill test reports, NDE reports, pressure test records, and API compliance certification included with every shipment.

Custom manufacturing – Tubing hanger threads, side outlet configurations, and special materials available on request.

Global logistics support – Export documentation, sea/air freight, and delivery to remote drilling locations worldwide.

Contact Sunrise to order the right tubing head for your well completion program. We provide the correct pressure rating, bore size, material class, and PSL level for your specific well conditions — with full API 6A compliance, NACE MR0175 sour service capability, and ontime delivery.