API 16C Choke and Kill Manifold for Drilling Well Control

Goldenman API 16C Choke and Kill Manifold systems are designed to control wellhead pressure, divert well fluids and provide a controlled pumping path during drilling well-control operations.

Available configurations cover working pressures from 3,000 to 15,000 psi and nominal bore sizes from 2-1/16 to 4-1/16 inches. Systems can be supplied with manual or hydraulically operated well-control chokes, gate valves, pressure-monitoring components and a remote hydraulic control panel.

Each manifold is configured according to the BOP stack pressure rating, required flow paths, well-control procedure, drilling-fluid properties, sour-service conditions, temperature, connection type and project inspection requirements.

Goldenman supplies API-certified choke and kill manifold equipment for onshore, offshore, balanced and underbalanced drilling applications.

Product Highlights

• Manufactured to applicable API Spec 16C requirements
• API-certified choke and kill manifold equipment
• Working pressure from 3,000 to 15,000 psi
• Nominal bore from 2-1/16 to 4-1/16 inches
• Manual and hydraulic well-control choke options
• Remote hydraulic choke control available
• Multiple valve and flow-path arrangements
• Configurations for onshore and offshore drilling
• Sour-service material options according to project conditions
• High-pressure flanged or hub connections
• Pressure-monitoring and bleed-off arrangements
• Skid-mounted system options
• Factory pressure and functional testing
• Third-party inspection and documentation support

What Is a Choke and Kill Manifold?

A choke and kill manifold is a high-pressure piping and valve system connected to the BOP stack during drilling operations.

The choke manifold provides a controlled flow path for well fluids leaving the well. By directing flow through a well-control choke, the operator can regulate backpressure while circulating out an influx or carrying out other well-control procedures.

The kill manifold provides a controlled path for pumping drilling fluid or kill fluid into the well through the BOP stack or designated kill line.

Although the choke and kill systems are closely related, they perform different functions:

The final manifold arrangement must follow the approved well-control philosophy and rig piping layout.

Main Functions

Goldenman choke and kill manifold systems can support:

• Controlled circulation of a well influx
• Regulation of casing or annular pressure
• Maintenance of required bottom-hole pressure
• Controlled bleed-off of well pressure
• Diversion of well fluids to the mud-gas separator, flare line or other approved outlet
• Pumping of kill fluid into the well
• Replacement of contaminated drilling fluid
• BOP stack pressure relief through an approved flow path
• Balanced drilling operations
• Underbalanced drilling operations
• Offshore and land-rig well-control systems

The manifold should only be operated according to the approved well-control procedure and site safety requirements.

Technical Specifications

The final pressure rating, nominal bore, connection, material, temperature rating and valve arrangement must be selected as one complete system specification.

Available Pressure and Bore Configurations

Common project pressure ratings within the available range may include:

• 3,000 psi
• 5,000 psi
• 10,000 psi
• 15,000 psi

Available nominal bore sizes range from:

• 2-1/16 in
• Intermediate project-specific sizes
• Up to 4-1/16 in

The exact bore and pressure combination must be confirmed through the approved datasheet and general arrangement drawing.

Larger bore does not automatically mean a better manifold. Increasing bore size may affect:

• Flow capacity
• Pressure loss
• Valve and choke dimensions
• Total manifold weight
• Skid size
• Required connection rating
• Replacement-part cost
• Maintenance access

Typical System Components

Depending on the approved flow diagram, a choke and kill manifold package may include:

• Manual well-control choke
• Hydraulically operated well-control choke
• High-pressure gate valves
• Check valves where required
• Tees and crosses
• Spacer or adapter components
• Pressure gauges
• Pressure transmitters
• Gauge isolation valves
• Buffer or distribution chambers
• Rigid choke and kill lines
• High-pressure flexible lines
• Flanged or hub connectors
• Remote hydraulic control panel
• Control hoses and fittings
• Skid and structural support
• Drain and bleed-off connections
• Companion flanges, studs and ring gaskets

The quotation should identify exactly which components are included. A manifold price cannot be compared accurately without matching the complete scope of supply.

How to Select the Correct Manifold

1. Confirm the Required Working Pressure

The manifold pressure rating should be selected from:

• BOP stack rated working pressure
• Maximum anticipated wellhead pressure
• Maximum casing pressure
• Well-control circulation pressure
• Pump pressure
• Kill operation pressure
• Applicable design margin
• End-user and regulatory requirements

The choke manifold is part of the pressure-control system and should not be selected using only normal drilling pressure.

All pressure-containing components in the selected flow path must have compatible ratings.

2. Select the Required Nominal Bore

Bore selection affects flow capacity, erosion velocity and pressure loss.

The purchaser should provide:

• Expected maximum flow rate
• Drilling-fluid density
• Mud viscosity
• Gas-liquid ratio
• Expected solids content
• Required outlet routing
• Planned well-control procedure
• Maximum allowable pressure loss

A bore selected only by copying the BOP connection size may not provide the required manifold performance.

3. Define the Required Flow Paths

The manifold piping layout should clearly show:

• BOP inlet connections
• Main choke line inlet
• Kill line inlet
• Manual choke flow path
• Hydraulic choke flow path
• Bypass path
• Mud-gas separator outlet
• Flare or vent outlet
• Mud tank return outlet
• Bleed-off and drain points
• Test connections

The final arrangement should allow the required valve-isolation and flow-diversion operations without creating an unintended trapped-pressure section.

4. Select Manual or Hydraulic Choke Control

A manual choke may be appropriate when:

• Local operation is acceptable
• Adjustment frequency is limited
• The operator can safely access the manifold
• Remote pressure control is not required

A hydraulically operated choke may be selected when:

• Remote adjustment is required
• Well pressure changes rapidly
• The operator must remain in a protected location
• The system is integrated with a choke control panel
• Offshore or critical well-control operations require remote control

Some systems use both manual and hydraulic choke branches to provide operating flexibility and redundancy.

5. Confirm Connections and Interfaces

The manifold must match:

• BOP choke and kill outlets
• Choke and kill line connections
• Mud-gas separator inlet
• Flare or vent line
• Standpipe or pump connection
• Rig piping specification
• Existing flange or hub system
• Ring-gasket specification
• Available installation space

For replacement projects, pressure rating and nominal bore alone are not enough to confirm interchangeability.

Choke Selection and Erosion Control

The well-control choke is one of the most critical components in the manifold.

Choke selection should consider:

• Maximum differential pressure
• Expected flow rate
• Gas fraction
• Mud density
• Solids concentration
• Sand content
• Operating temperature
• Required adjustment accuracy
• Expected operating duration
• Manual or hydraulic actuation

High differential pressure, gas expansion and abrasive solids can produce severe localized erosion.

To reduce premature wear, the technical review may include:

• Suitable choke type
• Replaceable trim
• Erosion-resistant trim material
• Controlled operating position
• Appropriate bore size
• Flow-velocity review
• Downstream piping arrangement
• Inspection and replacement plan

A choke selected only by pressure rating may not provide acceptable service life in abrasive well-control flow.

Sour-Service and Material Selection

For H₂S or corrosive well conditions, the buyer should provide:

• H₂S concentration or partial pressure
• CO₂ concentration
• Chloride content
• Operating pressure
• Operating temperature
• Drilling-fluid chemistry
• Produced-water conditions
• Required NACE MR0175/ISO 15156 compliance
• End-user material specification

The complete pressure-containing system should be reviewed, including:

• Manifold blocks and piping
• Valve bodies and bonnets
• Choke body and trim
• Stems and internal parts
• Bolting
• Seals and elastomers
• Welds and overlay
• Connection components

A general statement such as “sour service required” is not sufficient for final material selection.

Replacement Manifold Compatibility

When replacing an existing choke or kill manifold, provide:

• Existing manufacturer and model
• Pressure rating
• Nominal bore
• BOP inlet connection
• Outlet connections
• Flange or hub type
• Ring-gasket numbers
• Flow diagram
• Valve arrangement
• Choke type
• Overall dimensions
• Skid mounting dimensions
• Inlet and outlet center heights
• Control-panel interface
• Available installation space
• Existing photographs and nameplates

Two manifolds with the same pressure rating and bore may still have different dimensions, valve orientation, connection locations and operating logic.

API Certification and Quality Control

Goldenman supplies choke and kill manifold equipment with applicable API 16C certification according to the agreed order scope.

Manufacturing and inspection controls may include:

• Material certificate review
• Heat-number traceability
• Chemical and mechanical property verification
• Dimensional inspection
• Hardness testing
• Welding procedure control
• Welder qualification verification
• Weld inspection
• Ultrasonic testing where required
• Magnetic-particle or liquid-penetrant examination
• Pressure-containing component inspection
• Valve assembly inspection
• Choke assembly inspection
• Hydrostatic body testing
• Seat and sealing testing
• Functional valve operation
• Hydraulic choke operation testing
• Control-panel function testing
• Pressure-gauge verification
• Product marking inspection
• Coating and preservation inspection
• Final documentation review

The final inspection and testing scope should follow the applicable API requirements, approved inspection and test plan and purchase order.

Factory Acceptance Test

The agreed factory acceptance test may include:

• Verification of approved drawings
• Bill of materials review
• Material traceability review
• Dimensional inspection
• Connection and ring-groove inspection
• Valve opening and closing test
• Choke adjustment test
• Hydraulic actuator test
• Control-panel function test
• Hydrostatic body test
• Seat or sealing test
• Pressure-gauge verification
• Flow-path and valve-position confirmation
• Product marking check
• Coating inspection
• Documentation review

Witness and hold points should be defined before production when the customer or third-party inspection agency will attend the test.

Available Documentation

The project documentation package can include:

• API certificate
• Certificate of Conformity
• Approved datasheet
• General arrangement drawing
• Piping and instrumentation diagram
• Bill of materials
• Material certificates
• Welding procedure records
• Welder qualification records
• Heat-treatment records
• NDE reports
• Hardness reports
• Dimensional inspection report
• Hydrostatic test report
• Seat and functional test records
• Control-panel test report
• Gauge calibration certificates
• Coating inspection report
• Operation and maintenance manual
• Recommended spare-parts list
• Packing list
• Third-party inspection report

Documentation requirements should be agreed before production to avoid missing project records at final delivery.

Frequently Asked Questions

What is the operational difference between a choke manifold and a kill manifold?

The choke manifold receives flow leaving the well and regulates backpressure through a controlled choke path.

The kill manifold provides a high-pressure path for pumping drilling fluid or kill fluid into the well.

Their flow directions, valve arrangements and operating procedures are different, even when both systems are supplied on one skid or as one project package.

Can the choke manifold have a lower pressure rating than the BOP stack?

The manifold rating must be selected through the approved well-control design and must be compatible with the maximum pressure that can be applied to the selected flow path.

Using a manifold with a lower rating than connected well-control equipment requires a formally engineered pressure-limitation strategy. It should never be assumed acceptable only because normal operating pressure is lower.

How should the bore size be selected for a choke manifold?

The bore should be selected from the required flow rate, fluid properties, gas content, solids concentration, allowable erosion velocity and acceptable pressure loss.

Selecting the same bore as the BOP outlet without reviewing flow performance may result in excessive pressure loss or erosion.

When is a hydraulically operated choke preferred over a manual choke?

A hydraulic choke is generally preferred when remote operation, rapid adjustment or operation from a protected control station is required.

It is particularly valuable during changing well conditions, high-pressure operations and offshore applications. Many manifold systems retain a manual choke branch for backup or alternative operation.

What causes rapid choke and manifold erosion?

Common causes include:

• High differential pressure
• High flow velocity
• Abrasive drilling solids
• Sand production
• Gas expansion
• Incorrect choke sizing
• Operating continuously near a damaging choke position
• Poor downstream flow geometry

The choke type, trim material, bore and piping arrangement should be reviewed together.

Can an existing choke manifold be replaced using only pressure and bore specifications?

No. The connection types, ring grooves, valve layout, choke configuration, inlet and outlet locations, skid dimensions and control system must also be confirmed.

A detailed general arrangement drawing and flow diagram are strongly recommended for replacement projects.

What should be checked when ordering a manifold for H₂S service?

The manufacturer needs the actual H₂S and CO₂ conditions, temperature, pressure, chloride content and drilling-fluid chemistry.

The review must include pressure-containing materials, choke trim, valve internals, bolting, seals, elastomers, welds and applicable NACE requirements.

What is normally included in a choke manifold factory acceptance test?

A typical FAT may include document review, material traceability, dimensional inspection, valve and choke operation, hydrostatic testing, seat or sealing tests, control-panel testing and product-marking verification.

The exact test pressure, procedure, acceptance criteria and witness points should be agreed before production.

What spare parts should be ordered with a choke and kill manifold?

The recommended package depends on the manifold design, but commonly considered items include:

• Choke trim and wear components
• Valve stem and seat components
• Gate and seal kits
• Packing and elastomer kits
• Actuator seal kits
• Control hoses and fittings
• Pressure gauges
• Ring gaskets
• Studs and nuts
• Hydraulic control components

Spare-part quantities should reflect the number of wells, operating duration and availability of local inventory.

Information Required for Quotation

Please provide:

• Required working pressure
• Nominal bore
• BOP stack pressure rating
• BOP choke and kill outlet connections
• Maximum anticipated wellhead pressure
• Expected flow rate
• Drilling-fluid density and viscosity
• Gas and solids content
• Required flow-path arrangement
• Manual or hydraulic choke requirement
• Number and type of choke branches
• Valve quantity and operation method
• Inlet and outlet connections
• Mud-gas separator connection
• Flare or vent connection
• Skid dimensional limitations
• Operating temperature
• H₂S and CO₂ conditions
• Applicable NACE requirements
• API certificate requirement
• Third-party inspection requirement
• Required FAT scope
• Documentation requirements
• Recommended spare-parts requirement
• Destination country
• Delivery schedule

For replacement manifolds, also provide the existing nameplate, flow diagram, general arrangement drawing and site photographs.

Request a Technical Quotation

Goldenman supplies API 16C choke and kill manifolds for drilling rigs, well-control systems, offshore projects and replacement installations.

Available configurations cover working pressures from 3,000 to 15,000 psi and nominal bore sizes from 2-1/16 to 4-1/16 inches.

Send your pressure rating, bore size, BOP connection, flow diagram, choke type, service conditions and inspection requirements to:

Email: info@goldenman.com

Goldenman will review the well-control requirements and prepare the manifold configuration, technical datasheet and commercial quotation for your project.