API 16C Flexible Choke and Kill Hose for Well Control Systems

Description

Goldenman API 16C Flexible Choke and Kill Hose is designed to transport high-pressure drilling fluid, kill fluid and well-control media between the BOP stack, choke and kill manifold and associated high-pressure piping.

The flexible construction accommodates relative movement, installation misalignment, vibration and changing equipment positions where rigid piping alone is not practical.

Available configurations cover nominal inside diameters from 2 to 4 inches and rated working pressures from 5,000 to 20,000 psi. Depending on the selected size and pressure class, minimum burst pressure is rated up to 45,000 psi.

Goldenman supplies API-certified flexible choke and kill lines with project-specific lengths, end connections, pressure testing and inspection documentation.

Product Highlights

• Manufactured to applicable API Spec 16C requirements
• API-certified flexible choke and kill line
• Nominal inside diameters from 2 to 4 inches
• Working pressures from 5,000 to 20,000 psi
• Test pressures up to 30,000 psi
• Minimum burst pressures up to 45,000 psi
• Minimum bend radius from 900 to 1,200 mm
• High-pressure flanged end configurations
• Custom hose length and connection options
• High-pressure, abrasion-resistant internal construction
• External thermal, flame and mechanical protection
• Configurations for land and offshore well-control systems
• Pressure-test and traceability documentation
• Replacement hose dimensional matching support
• Third-party inspection available

What Is an API 16C Flexible Choke and Kill Line?

An API 16C flexible choke and kill line is a high-pressure hose assembly installed in a drilling well-control system.

It provides a flexible pressure-containing path between equipment such as:

• BOP stack side outlets
• Choke line outlets
• Kill line outlets
• Choke manifold
• Kill manifold
• Rigid high-pressure piping
• Mud-gas separator routing
• Well-control pumping equipment

A choke line carries flow from the well toward the choke manifold, where pressure and flow are controlled.

A kill line provides a path for pumping drilling fluid or kill fluid into the well during approved well-control operations.

Although the hose construction may be similar, the final assembly must be configured according to its exact position, flow direction, pressure rating and end connections.

Main Applications

The flexible hose can be configured for:

• Choke lines between the BOP stack and choke manifold
• Kill lines between the BOP stack and kill manifold
• High-pressure well-control circulation
• Controlled well influx circulation
• Kill-fluid pumping
• Pressure bleed-off and relief routing
• Land drilling-rig BOP systems
• Offshore drilling systems
• Semi-submersible drilling units
• Jack-up drilling rigs
• Rig movement and alignment compensation
• Replacement of existing flexible choke and kill lines

It should not be used as a rotary drilling hose or hydraulic BOP control hose unless the assembly is separately designed, certified and documented for that service.

General Technical Specifications

Parameter	Available Specification
Product name	Flexible Choke and Kill Hose
Applicable standard	API Spec 16C, applicable current edition
API product category	Flexible Choke and Kill Line
Nominal inside diameter	2–4 in
Working pressure	35–138 MPa / 5,000–20,000 psi
Test pressure	70–207 MPa / 10,000–30,000 psi
Minimum burst pressure	105–310 MPa / 15,000–45,000 psi
Minimum bend radius	900–1,200 mm
Main service	Drilling well-control flowlines
Main media	Drilling fluid, kill fluid, and specified well fluids
End connections	Flanged or project-specific
Hose length	According to the approved project specification
Installation	Land, offshore, or project-specific
Sour-service option	Available according to service conditions
Fire and thermal protection	According to the approved hose construction
Certification	API certificate
Inspection	Factory and third-party inspection as specified

Final hose length, flange specification, temperature class, FSL, end-fitting dimensions and service conditions must be confirmed in the approved product datasheet.

Complete Size and Pressure Specifications

5,000 psi Flexible Hose

Nominal ID	Working Pressure	Test Pressure	Minimum Burst Pressure	Minimum Bend Radius
2 in / 50.8 mm	35 MPa / 5,000 psi	70 MPa / 10,000 psi	105 MPa / 15,000 psi	900 mm
2-1/2 in / 64 mm	35 MPa / 5,000 psi	70 MPa / 10,000 psi	105 MPa / 15,000 psi	1,000 mm
3 in / 76.2 mm	35 MPa / 5,000 psi	70 MPa / 10,000 psi	105 MPa / 15,000 psi	1,000 mm
3-1/2 in / 89 mm	35 MPa / 5,000 psi	70 MPa / 10,000 psi	105 MPa / 15,000 psi	1,100 mm
4 in / 101.6 mm	35 MPa / 5,000 psi	70 MPa / 10,000 psi	105 MPa / 15,000 psi	1,200 mm

10,000 psi Flexible Hose

Nominal ID	Working Pressure	Test Pressure	Minimum Burst Pressure	Minimum Bend Radius
2 in / 50.8 mm	70 MPa / 10,000 psi	105 MPa / 15,000 psi	157.5 MPa / 22,500 psi	1,000 mm
2-1/2 in / 63.5 mm	70 MPa / 10,000 psi	105 MPa / 15,000 psi	157.5 MPa / 22,500 psi	1,100 mm
3 in / 76.2 mm	70 MPa / 10,000 psi	105 MPa / 15,000 psi	157.5 MPa / 22,500 psi	1,150 mm

15,000 psi Flexible Hose

Nominal ID	Working Pressure	Test Pressure	Minimum Burst Pressure	Minimum Bend Radius
2 in / 50.8 mm	105 MPa / 15,000 psi	157.5 MPa / 22,500 psi	236.25 MPa / 33,750 psi	1,000 mm
2-1/2 in / 63.5 mm	105 MPa / 15,000 psi	157.5 MPa / 22,500 psi	236.25 MPa / 33,750 psi	1,150 mm
3 in / 76.2 mm	105 MPa / 15,000 psi	157.5 MPa / 22,500 psi	236.25 MPa / 33,750 psi	1,200 mm

20,000 psi Flexible Hose

Nominal ID	Working Pressure	Test Pressure	Minimum Burst Pressure	Minimum Bend Radius
2 in / 50.8 mm	138 MPa / 20,000 psi	207 MPa / 30,000 psi	310 MPa / 45,000 psi	900 mm
2-1/2 in / 64 mm	138 MPa / 20,000 psi	207 MPa / 30,000 psi	310 MPa / 45,000 psi	1,100 mm
3 in / 76.2 mm	138 MPa / 20,000 psi	207 MPa / 30,000 psi	310 MPa / 45,000 psi	1,200 mm

Not every inside diameter is available in every pressure class. Final availability and dimensions must be confirmed through the approved manufacturing datasheet.

API 16C Hose vs API 7K Rotary Drilling Hose

These two hose types perform different functions and should not be treated as interchangeable.

Comparison	API 16C Choke and Kill Hose	API 7K Rotary Drilling Hose
Main application	Drilling well-control system	Drilling-fluid circulation system
Typical installation	BOP stack to choke or kill the manifold	Standpipe to swivel or top drive
Main flow function	Choke, kill or well-control flow	Continuous drilling mud or cement circulation
Typical operating condition	Well control pressure and possible well fluid exposure	Mud-pump discharge circulation
API product category	Flexible Choke and Kill Line	High-Pressure Mud and Cement Hose
Selection basis	BOP pressure, well-control layout and fluid conditions	Mud-pump pressure, flow rate and rig movement
Direct interchangeability	No	No

A hose marked or certified for one application should not be installed in the other service without a complete technical and certification review.

Hose Construction and Protection

The exact internal construction depends on pressure class, bore and approved design, but a high-pressure flexible choke and kill line normally includes several functional layers.

Inner Fluid Tube

The inner tube provides the primary contact surface for the transported medium.

It should be selected for:

• Drilling fluid
• Kill fluid
• Hydrocarbon exposure
• Gas content
• Abrasive solids
• Chemical additives
• Operating temperature
• H₂S conditions

Pressure Reinforcement

Multiple high-strength reinforcement layers contain internal pressure and transfer mechanical loads through the hose assembly.

The reinforcement must remain protected from:

• Excessive bending
• Crushing
• Torsion
• Impact damage
• Corrosion
• External abrasion
• Incorrect clamping

External Cover

The external cover protects the reinforcement from weather, abrasion, flame exposure and normal rig-site mechanical damage.

External protection does not make the hose resistant to unlimited fire exposure or severe crushing.

End Fittings

End fittings transfer pressure and mechanical loads between the flexible hose body and connected equipment.

The pressure rating of the complete hose is limited by the lowest-rated component, including:

• Hose body
• End fittings
• Flanges
• Hubs
• Adapters
• Bolting
• Ring gaskets
• Connected valves or piping

How to Select the Correct Choke and Kill Hose

1. Confirm the Required Working Pressure

The hose rating should be selected from:

• BOP stack rated working pressure
• Maximum anticipated wellhead pressure
• Maximum choke-line pressure
• Maximum kill-pump pressure
• Well-controlled circulation pressure
• Pressure-test requirements
• End-user design margin

Normal drilling pressure alone is not sufficient for hose selection.

A hose should not be selected solely because its pressure rating matches the BOP nameplate. The connected manifold, valves, adapters and end fittings must also have compatible ratings.

2. Select the Correct Inside Diameter

The hose bore affects:

• Maximum flow capacity
• Pressure loss
• Fluid velocity
• Erosion
• Solids transport
• Gas-liquid flow behavior
• Well-control response

An undersized hose can increase flow velocity, pressure loss, and erosion.

A larger hose may reduce velocity but increase weight, bend radius, end-fitting size, and installation requirements.

The purchaser should provide the expected flow rate, drilling-fluid properties, gas content, and solids concentration.

3. Confirm the Hose Length

The hose should accommodate:

• Distance between connection points
• Rig and BOP movement
• Installation tolerances
• Equipment vibration
• Required bend radius
• Safe routing
• Maintenance access
• Connection orientation

The required length should be measured along the planned hose routing, not only as a straight-line distance.

An excessively short hose may be tensioned or bent below its minimum radius. An excessively long hose may sag, rub against equipment or create unnecessary movement.

4. Maintain the Minimum Bend Radius

Each size and pressure class has a specified minimum bend radius.

Installing the hose below the minimum radius can cause:

• Internal tube deformation
• Reinforcement damage
• Reduced flow area
• Increased local stress
• End-fitting fatigue
• Premature leakage
• Reduced pressure capacity

The bend radius must be maintained during installation, operation, transportation, and storage.

5. Confirm End Connections

The order specification should define:

• End connection at side A
• End connection at side B
• Flange or hub type
• Nominal size
• Working-pressure class
• Ring-gasket specification
• Bolt-hole orientation
• Face-to-face length
• End-fitting angular orientation
• Required adapters

The expression “hose with flange” is not sufficient for production.

6. Define the Service Medium

Provide details of:

• Water-based drilling mud
• Oil-based or synthetic-based mud
• Kill fluid
• Hydrocarbon exposure
• Gas content
• Sand or solids concentration
• H₂S and CO₂
• Chemical additives
• Operating temperature

The hose inner tube, seals and metallic fittings must be compatible with the actual service.

Sour-Service and Temperature Selection

For sour or corrosive service, the purchaser should provide:

• H₂S concentration or partial pressure
• CO₂ concentration
• Chloride content
• Working pressure
• Operating temperature
• Drilling-fluid chemistry
• Produced-fluid composition
• Applicable NACE MR0175/ISO 15156 requirements

The review should cover:

• Metallic end fittings
• Flanges or hubs
• Welded components
• Bolting
• Inner tube
• Elastomeric seals
• Reinforcement protection
• Hardness restrictions
• Required documentation

A standard hose assembly should not automatically be considered suitable for H₂S service.

Replacement Hose Compatibility

A replacement flexible choke or kill hose should not be ordered using only its size and pressure rating.

For accurate replacement, provide:

• Existing manufacturer
• Hose model
• Serial number
• API identification
• FSL, where applicable
• Nominal inside diameter
• Working pressure
• Overall hose length
• End-to-end length
• End connection at both sides
• Flange or hub specification
• Ring-gasket numbers
• End-fitting orientation
• Minimum bend radius
• Operating temperature
• Service medium
• Existing product photographs
• Hose assembly drawing

Two hoses described as “3-inch 15,000 psi API 16C hose” may still have different end fittings, dimensions, FSLs and service qualifications.

Hose Installation Requirements

Correct installation is critical to hose performance and service life.

The hose should be installed without:

• Axial tension
• Torsional twisting
• Crushing
• Kinking
• Bending below the minimum radius
• Contact with sharp steel edges
• Unsupported excessive weight
• Rubbing against moving equipment
• Exposure to hot exhaust surfaces
• Incorrect flange alignment

The hose should be supported in a manner that does not locally compress the body.

Flanges should align naturally. The hose should not be twisted or forced into position to correct piping misalignment.

Inspection and Service-Life Management

A high-pressure flexible line should be inspected before installation and at defined service intervals.

Inspection should include:

• External cover condition
• Cuts, cracks and abrasion
• Bulges or local deformation
• Kinking
• Flattened areas
• Corrosion at end fittings
• Flange and ring-groove condition
• Leakage
• Hose movement and support
• Product marking and traceability
• Exposure to fire, impact or overpressure

The hose should be removed from service when it has experienced conditions outside its approved limits or shows evidence of structural damage.

Service-life decisions should consider operating history rather than calendar age alone.

Manufacturing and Quality Control

Goldenman manufacturing and inspection controls may include:

• Raw-material verification
• Reinforcement-material inspection
• Inner-tube inspection
• End-fitting material verification
• Heat-number traceability
• Flange and connection dimensional inspection
• Hose bore verification
• Overall length inspection
• End-fitting orientation inspection
• Hose assembly inspection
• Proof-pressure testing
• Pressure-holding test
• External leakage inspection
• Bend and dimensional verification
• Product marking inspection
• Coating and preservation inspection
• Final documentation review

Qualification or destructive testing is performed according to the applicable product design, API requirements, and agreed FSL.

Factory Acceptance and Documentation

The agreed factory acceptance scope may include:

• Approved datasheet review
• Hose assembly drawing verification
• Material traceability review
• Overall dimensional inspection
• End-connection verification
• Ring-groove inspection
• End-fitting orientation check
• Proof-pressure test
• Pressure-holding test
• Leakage inspection
• Product marking check
• Documentation review
• Packing inspection

Customer or third-party witness requirements should be stated before production.

Available Documentation

The project documentation package can include:

• API certificate
• Certificate of Conformity
• Approved hose datasheet
• Hose assembly drawing
• Material certificates for metallic fittings
• Dimensional inspection report
• End-connection inspection report
• Proof-pressure test report
• Pressure-holding record
• Product traceability record
• Applicable qualification-test documentation
• Installation and inspection instructions
• Operation and maintenance guidance
• Recommended spare gasket list
• Packing list
• Third-party inspection report

Frequently Asked Questions

What is the difference between an API 16C choke and kill hose and an API 7K rotary drilling hose?

An API 16C hose is part of the drilling well-control system. It normally connects the BOP stack with the choke or kill manifold and may be exposed to well-control pressure, gas and well fluids.

An API 7K rotary hose is part of the drilling-fluid circulating system. It normally connects the standpipe to the swivel or top drive and carries mud or cement pumped toward the drillstring.

The two hose types have different application standards, installation positions, qualification requirements and service risks. They should not be treated as interchangeable.

What is the difference between a flexible choke line and a flexible kill line?

A choke line carries flow away from the well toward the choke manifold, where backpressure and flow are controlled.

A kill line provides a path for pumping drilling fluid or kill fluid into the well.

A flexible hose may be manufactured using a similar pressure-containing design for either application, but the length, connections, flow direction and system interfaces must match its exact location.

Can a 20,000 psi hose replace a 15,000 psi hose?

A higher pressure rating alone does not confirm replacement compatibility.

The bore, length, end fittings, flange dimensions, ring grooves, FSL, minimum bend radius, temperature rating and service medium must also match.

A higher-rated hose may also be heavier, less flexible and require a larger installation envelope.

How should the minimum bend radius be measured?

The minimum bend radius is measured to the centerline of the curved hose section unless the approved manufacturer’s drawing specifies otherwise.

The hose should maintain at least the stated radius throughout installation and operation. The bend should also begin at a suitable distance from the end fitting rather than directly at the coupling.

Can the hose be used to correct severe piping misalignment?

No. The hose can accommodate normal equipment movement and installation variation, but it should not be twisted, stretched or sharply bent to correct an incorrectly positioned manifold or BOP outlet.

Excessive misalignment should be corrected through piping, adapters or equipment positioning.

What information is required to manufacture a replacement API 16C hose?

Provide the hose size, pressure rating, length, both end connections, flange or hub details, ring-gasket numbers, fitting orientation, service medium, temperature and existing FSL.

The existing hose nameplate, API marking, drawing and clear photographs should also be supplied.

Why can two hoses with the same size and pressure have different minimum bend radii?

Minimum bend radius depends on the reinforcement design, pressure class, hose construction and outside diameter.

Higher pressure does not always produce the same radius relationship across every size. The approved datasheet for the exact hose must be followed.

What can cause premature failure of a choke and kill hose?

Common causes include:

• Bending below the minimum radius
• Hose twisting
• Axial tension
• Incorrect support
• External abrasion
• Mechanical impact
• Pressure above the rating
• Chemical incompatibility
• Excessive temperature
• Corroded end fittings
• Incorrect flange alignment
• Continued use after fire or severe damage

What is FSL and why must it be confirmed?

FSL means Flexible Specification Level and defines the applicable design, verification, testing and documentation level for an API 16C flexible line.

The required FSL should be identified by the project specification and confirmed on the manufacturer’s API certificate and product documentation.

Information Required for Quotation

Please provide:

• Choke-line or kill-line application
• Required API 16C FSL
• Nominal inside diameter
• Rated working pressure
• Required hose length
• End-to-end length definition
• End connection at side A
• End connection at side B
• Flange or hub specification
• Ring-gasket numbers
• End-fitting orientation
• Maximum operating pressure
• Required test pressure
• Maximum flow rate
• Drilling-fluid or kill-fluid type
• Solids and gas content
• Operating temperature
• Minimum ambient temperature
• H₂S and CO₂ conditions
• Applicable NACE requirements
• BOP stack connection
• Manifold connection
• API certificate requirement
• Qualification and test-document requirements
• Third-party inspection requirements
• Quantity
• Destination country
• Required delivery schedule

For replacement hoses, also provide the existing nameplate, serial number, API marking, dimensional drawing and product photographs.

Request a Technical Quotation

Goldenman supplies API 16C flexible choke and kill hoses for land and offshore drilling well-control systems.

Available configurations include 2–4 inch inside diameters, working-pressure ratings from 5,000 to 20,000 psi and project-specific flanged connections.

Send your hose size, pressure, length, end connections, service conditions and required FSL to:

Email: info@goldenman.com

Goldenman will review the BOP and manifold interfaces and prepare the appropriate hose datasheet, connection drawing, inspection package and commercial quotation.