FH 18 – 35 API 16A Annular BOP

The Goldenman FH18-35 Annular Blowout Preventer is a compact, hydraulically operated well-control device with a 180 mm (7-1/16 in) bore and a rated working pressure of 35 MPa (5,000 psi).

Its annular packing element is designed to form a pressure seal around drill pipe, tubing, casing, drill collars and other approved tubular profiles. Subject to the selected packing unit and approved operating procedure, the BOP can also provide open-bore sealing and controlled stripping capability.

The compact bolted-cover structure has an overall reference size of 745 × 788 mm and a reference weight of 1,444 kg, making the FH18-35 suitable for drilling and workover installations where BOP stack height and available space are important.

Goldenman supplies the FH18-35 with an API certificate, factory pressure testing, functional inspection and project-specific documentation.

Product Highlights

• API-certified Annular BOP
• Model FH18-35
• 180 mm / 7-1/16 in nominal bore
• 35 MPa / 5,000 psi rated working pressure
• 70 MPa / 10,000 psi shell test pressure
• Recommended hydraulic operating pressure of 8.4–10.5 MPa
• 15 L hydraulic fluid required to open
• 20 L hydraulic fluid required to close
• Compact bolted-cover construction
• Reference dimensions of 745 × 788 mm
• Reference weight of 1,444 kg
• Working temperature range from −29°C to 121°C
• Replacement packing elements and seal kits available
• H₂S-service configuration available according to project requirements
• Third-party inspection and FAT support

What Is the FH18-35 Annular BOP?

The FH18-35 is an annular-type blowout preventer installed as part of a drilling or workover BOP stack.

Hydraulic pressure moves an internal piston, compressing the reinforced elastomeric packing element inward toward the center of the bore. This allows the BOP to form a seal around different tubular outside diameters without changing fixed-size ram blocks.

Depending on the approved packing-element capability, it may seal around:

• Drill pipe
• Tubing
• Casing
• Drill collars
• Kelly or approved drilling profiles
• Wireline or small-diameter tools
• Tool joints under approved operating conditions
• An open bore when no tubular is present

The Annular BOP provides flexible sealing across multiple tubular sizes, but it does not replace the dedicated pipe ram, blind ram or shear ram functions required in a complete BOP stack.

Main Applications

The FH18-35 Annular BOP can be used for:

• Onshore oil and gas drilling
• Workover and well-servicing operations
• Compact BOP stack assemblies
• Pressure control around drill pipe and tubing
• Well shut-in
• Open-bore isolation
• Controlled stripping operations
• Snubbing and pressure-control systems
• Replacement of an existing 7-1/16 in Annular BOP
• New API well-control equipment packages

Final suitability depends on the tubular profile, maximum well pressure, service temperature, drilling-fluid chemistry and approved well-control procedure.

FH18-35 Technical Specifications

The final connection type, control-port size, material class, elastomer compound and overall configuration must be confirmed in the approved manufacturing datasheet.

Compact Bolted-Cover Design

The FH18-35 uses a compact bolted-cover configuration intended to reduce installation height while retaining access to the piston and packing-element assemblies.

This design can be advantageous when:

• BOP stack height is limited
• Rig substructure clearance is restricted
• Equipment weight must be controlled
• Maintenance access is required
• The BOP will replace an existing compact unit
• A 7-1/16 in, 5,000 psi pressure-control package is required

Stack compatibility must still be checked against the exact top and bottom connections, hydraulic port locations and maintenance-clearance requirements.

How the FH18-35 Annular BOP Works

The FH18-35 is operated by hydraulic control pressure.

During closure:

1. Hydraulic fluid enters the closing circuit.
2. The operating piston moves within the BOP body.
3. Piston movement compresses the annular packing element.
4. The packing element deforms inward toward the bore.
5. The elastomer forms a pressure seal around the tubular or approved open-bore condition.

During opening:

1. Hydraulic pressure is directed to the opening circuit.
2. The piston retracts.
3. Compression on the packing element is released.
4. The packing element returns toward its open position.
5. The bore becomes available for tubular movement.

The recommended hydraulic operating pressure is 8.4–10.5 MPa, but the actual closing pressure should follow the operating manual and well conditions.

Excessive hydraulic closing pressure should be avoided because it can increase packing-element wear and tubular contact force.

Matching the FH18-35 to the BOP Control System

The FH18-35 requires approximately:

• 15 L to open
• 20 L to close

These values are important when selecting or verifying the BOP control unit.

The control-system review should include:

• FH18-35 closing volume
• FH18-35 opening volume
• Ram BOP operating volumes
• Hydraulic connector and valve functions
• Total number of controlled functions
• Accumulator usable-fluid volume
• Hydraulic operating pressure
• Required closing time
• Emergency operating reserve
• Simultaneous-operation requirements

The nominal accumulator volume alone does not represent the amount of hydraulic fluid available to operate the BOP stack.

The usable volume must be calculated at the applicable precharge, operating and minimum system pressures.

How to Select the Correct FH18-35 Configuration

Confirm the BOP Stack Bore

The 7-1/16 in bore must match the wellhead and other stack components, including:

• Ram BOP
• Drilling spool
• Adapter spool
• Wellhead equipment
• Hydraulic connector
• Riser or pressure-control equipment

The maximum tubular and tool-joint OD must also pass safely through the bore.

Confirm the Required Pressure Rating

The 5,000 psi rating should be checked against:

• Maximum anticipated surface pressure
• Shut-in pressure
• BOP stack design pressure
• Well-control test pressure
• Workover pressure
• End-user design requirements

Every pressure-containing component in the stack must have a compatible pressure rating.

Confirm the Largest Tubular Profile

Provide the largest OD expected to pass through or be sealed by the BOP, including:

• Drill pipe tool joints
• Drill collars
• Casing couplings
• Tubing couplings
• Workover tools
• Completion assemblies
• Wireline pressure-control components

Selection should not be based only on the nominal drill pipe or tubing body size.

Confirm Top and Bottom Connections

The approved order specification should identify:

• Top connection type
• Bottom connection type
• Pressure rating
• Flange, studded or hub configuration
• Ring-gasket specification
• Stud size and quantity
• Connection face and groove details
• Required overall height

For replacement equipment, the existing BOP stack drawing should be supplied.

Confirm Service Conditions

Provide:

• Minimum and maximum temperature
• Water-based, oil-based or synthetic-based mud
• Hydrocarbon exposure
• H₂S and CO₂ conditions
• Chloride content
• Drilling-fluid additives
• Stripping requirement
• Expected pressure cycles
• Storage conditions

These factors affect packing-element and dynamic-seal selection.

Packing Element Selection

The packing element is the primary pressure-sealing component of the FH18-35.

It must be matched to:

• FH18-35 BOP design
• 180 mm bore
• 5,000 psi pressure rating
• Tubular OD range
• Tool-joint profile
• Operating temperature
• Drilling-fluid type
• Oil and chemical exposure
• H₂S conditions
• Planned stripping operations

A replacement packing element should not be ordered only as a “7-1/16 in Annular BOP rubber.”

For accurate matching, provide:

• BOP manufacturer
• Model FH18-35
• Serial number
• Existing packing-element part number
• Packing-element dimensions
• Existing elastomer identification
• Service temperature
• Mud and chemical conditions
• Product photographs

Packing elements from different Annular BOP body designs should not be assumed interchangeable.

Open-Bore Sealing and Stripping

The ability to close on an open bore or strip tubulars through a closed packing element must be confirmed for the exact packing unit and operating procedure.

For stripping operations, the operator must control:

• Hydraulic closing pressure
• Tubular OD
• Tool-joint OD and profile
• Well pressure
• Pipe movement speed
• Packing-element lubrication
• Tubular surface condition
• Packing-element wear
• Control-system response

The objective is to maintain the required pressure seal without applying unnecessary compression to the packing element.

Tool joints should not be pulled through the packing unit unless the equipment configuration and approved procedure specifically permit it.

H₂S and Sour-Service Configuration

The original FH-series product data identifies service with crude oil, natural gas and drilling fluid containing H₂S.

However, final sour-service suitability must be confirmed from the actual operating conditions.

The buyer should provide:

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

The review should include:

• Pressure-containing body material
• Bolting
• Piston and internal metallic components
• Packing-element compound
• Dynamic seals
• Hardness limitations
• Material traceability
• Required inspection documentation

A standard packing element should not automatically be assumed suitable for every H₂S environment.

Replacement Compatibility

An FH18-35 replacement should not be ordered using only the 7-1/16 in bore and 5,000 psi pressure rating.

Confirm:

• Existing manufacturer
• Existing model
• Serial number
• Top connection
• Bottom connection
• Ring-gasket specifications
• Overall diameter and height
• Hydraulic port size
• Hydraulic port location
• Opening and closing volume
• Packing-element part number
• Existing control unit
• Required maintenance clearance
• BOP stack drawing

Two Annular BOPs with the same bore and pressure rating may still have different dimensions, control volumes and packing-element designs.

Common Procurement Mistakes

Selecting Only by Bore and Pressure

A “7-1/16 in, 5,000 psi Annular BOP” description does not define the connections, operating volume, dimensions, elastomers or control-system compatibility.

Ignoring Tool-Joint OD

The tool joint may be substantially larger than the drill pipe body and must be considered when checking bore clearance and stripping capability.

Ordering the Packing Element by Bore Size Alone

Packing-element design and dimensions vary between BOP models and manufacturers.

Failing to Check Control-Unit Capacity

The accumulator system must provide enough usable hydraulic fluid for the complete BOP stack, not only the FH18-35.

Treating H₂S Compatibility as a General Option

Sour-service materials and elastomers must be selected from actual pressure, temperature and fluid-composition data.

Manufacturing and Quality Control

Goldenman quality-control procedures for the FH18-35 may include:

• Material certificate verification
• Heat-number traceability
• Chemical and mechanical property review
• Heat-treatment record verification
• Body dimensional inspection
• Bore inspection
• Connection and ring-groove inspection
• Hardness testing
• Ultrasonic examination where required
• Magnetic-particle or liquid-penetrant examination
• Piston and sealing-surface inspection
• Packing-element identification
• Hydraulic opening and closing test
• Shell hydrostatic test
• Packing-element sealing test
• Pressure-holding test
• External leakage inspection
• Product marking verification
• Coating and preservation inspection
• Final documentation review

The final quality plan and inspection scope are confirmed according to API requirements and the purchase order.

Factory Acceptance Test

The agreed FH18-35 FAT may include:

• Approved drawing review
• Bill of materials verification
• Material traceability review
• Dimensional inspection
• Bore and connection inspection
• Hydraulic opening test
• Hydraulic closing test
• Operating-volume verification
• Shell pressure test
• Packing-element sealing test
• Pressure-holding test
• External leakage inspection
• Functional cycling
• Product marking inspection
• Coating inspection
• Documentation review

Customer or third-party witness and hold points should be agreed before production.

Available Documentation

The project documentation package can include:

• API certificate
• Certificate of Conformity
• Approved FH18-35 datasheet
• General arrangement drawing
• Material certificates
• Heat-treatment records
• NDE reports
• Hardness report
• Dimensional inspection report
• Connection inspection record
• Shell pressure-test report
• Packing-element sealing test report
• Hydraulic functional test report
• Packing-element identification
• Operation and maintenance manual
• Recommended spare-parts list
• Packing list
• Third-party inspection report

Frequently Asked Questions

Can the FH18-35 seal around different drill pipe and tubing sizes?

Yes. The annular packing element is designed to deform around a range of approved tubular outside diameters.

The exact minimum and maximum sealing diameters must be confirmed from the selected packing element and manufacturer’s operating data.

Can the FH18-35 close on an open wellbore?

Open-bore sealing may be available with the approved packing-element configuration.

It must be confirmed for the exact BOP and should only be performed according to the operation manual and approved well-control procedure.

Can a drill pipe tool joint pass through the FH18-35 while it is closed?

Controlled stripping may be possible when the tool-joint profile, packing-element design and operating procedure permit it.

The maximum tool-joint OD, shape, well pressure and required hydraulic closing pressure must be reviewed before operation.

Is the recommended 1,200–1,500 psi hydraulic pressure the same as the BOP well-pressure rating?

No.

The 1,200–1,500 psi value refers to the recommended hydraulic control pressure used to operate the BOP piston. The 5,000 psi rating refers to the wellbore pressure the BOP is designed to contain.

These are separate pressure systems.

How should the BOP control unit be sized for the FH18-35?

The FH18-35 requires approximately 20 L to close and 15 L to open.

Control-unit sizing must also include every other BOP and hydraulic function in the stack, accumulator usable volume, operating-pressure range and required emergency reserve.

Can the same packing element be used for water-based mud, oil-based mud and H₂S service?

Not automatically.

The packing-element compound must be selected for the actual temperature, hydrocarbon exposure, drilling-fluid chemistry and H₂S conditions.

What information is required to order a replacement FH18-35 packing element?

Provide the BOP manufacturer, model, serial number, part number, packing-element dimensions, operating temperature, drilling-fluid type and H₂S requirements.

Photographs of the existing element and markings are recommended.

Can another 7-1/16 in, 5,000 psi Annular BOP directly replace the FH18-35?

Not without dimensional verification.

Top and bottom connections, overall height, outside diameter, hydraulic ports, operating volumes and packing-element design must all be compared.

What documents should be supplied with an API FH18-35 Annular BOP?

The agreed package may include the API certificate, material certificates, NDE reports, dimensional inspection, shell test report, sealing test report, functional test records and Certificate of Conformity.

Information Required for Quotation

Please provide:

• Required model: FH18-35
• Required quantity
• Top connection
• Bottom connection
• Ring-gasket specifications
• Maximum anticipated well pressure
• Maximum tubular OD
• Maximum tool-joint OD
• Open-bore sealing requirement
• Stripping requirement
• Operating temperature
• Drilling-fluid type
• H₂S and CO₂ conditions
• Applicable NACE requirements
• Required packing-element compound
• Existing BOP stack configuration
• BOP control-unit model
• Required spare packing elements
• Required seal kits
• API certificate requirements
• FAT requirements
• Third-party inspection requirements
• Destination country
• Required delivery schedule

For replacement equipment, also provide the existing nameplate, general arrangement drawing, connection details and hydraulic port locations.

Request an FH18-35 Technical Quotation

Goldenman supplies API-certified FH18-35 Annular BOPs, replacement packing elements and seal kits for drilling and workover well-control systems.

Send your connection details, maximum tubular OD, well pressure, drilling-fluid conditions, BOP stack drawing and inspection requirements to:

Email: info@goldenman.com

Goldenman will review the installation and prepare the FH18-35 technical datasheet, packing-element configuration and commercial quotation.