1. Product Introduction
The FZ35-21 Ram Blowout Preventer (BOP) is a critical pressure control device designed for onshore and offshore oil and gas drilling operations, specifically engineered to manage wellbore pressure and prevent blowouts during drilling, tripping, and well completion processes. As a core component of the well control system, this ram BOP is compatible with multiple pipe sizes and features interchangeable ram assemblies, enabling flexible adaptation to diverse drilling scenarios. It adheres to industry standards for pressure-bearing capacity and sealing performance, ensuring reliable operation in high-pressure, high-temperature (HPHT) drilling environments.
This manual provides a comprehensive overview of the FZ35-21 Ram BOP’s parts configuration, functional principles, structural characteristics, application conditions, maintenance protocols, and troubleshooting solutions. It serves as an authoritative reference for drilling engineers, maintenance technicians, and procurement personnel, facilitating accurate parts identification, standardized maintenance, and efficient fault resolution—while also offering clear procurement guidelines for genuine replacement parts to ensure equipment integrity and operational safety.
2. Core Purpose
The primary function of the FZ35-21 Ram BOP is to seal the wellbore and control well pressure in emergency and routine operations. Its key objectives include: isolating the wellbore from the drilling rig to prevent formation fluid (oil, gas, water) from gushing out; accommodating different pipe sizes through interchangeable ram assemblies (including pipe rams, blind rams, and variable diameter rams) to seal around drill pipes or fully close the wellbore when needed; and working in conjunction with other well control equipment (such as annular BOPs and choke manifolds) to form a complete pressure control system. For target users—including oilfield operation companies, drilling contractors, and maintenance service providers—this device addresses the core needs of ensuring drilling safety, reducing downtime due to equipment failure, and simplifying parts replacement and maintenance workflows.
3. Functional Description
3.1 Main Functions
The FZ35-21 Ram BOP achieves pressure control and wellbore sealing through hydraulic actuation of ram assemblies. Key functions include:
Pipe Sealing: When drill pipes of specified sizes are run in the well, pipe rams move horizontally under hydraulic pressure to clamp the pipe, forming a reliable seal between the ram packers and the pipe outer wall, preventing formation fluid leakage.
Blind Sealing: Blind rams are used when no pipe is present in the well, fully closing the wellbore to isolate the formation and prevent blowouts in emergency situations.
Variable Diameter Adaptation: The variable diameter ram assembly supports pipe size switching between 4 1/2" and 5 1/2", eliminating the need for frequent ram replacement and improving operational efficiency.
Secondary Sealing: The integrated secondary seal system provides auxiliary sealing and grease injection capabilities, enhancing sealing reliability and allowing for on-site sealing maintenance without disassembling the main equipment.
3.2 Auxiliary Functions
In addition to core sealing functions, the FZ35-21 Ram BOP is equipped with multiple auxiliary structures to ensure stable operation: shaft seal assemblies (ram shaft and locking shaft) prevent hydraulic fluid leakage and external contamination; side door seal structures ensure sealing between the BOP body and side doors; and hinge structures facilitate easy opening and closing of side doors for ram replacement and internal maintenance.
4. Structural Characteristics
4.1 Overall Structural Design
The FZ35-21 Ram BOP adopts a split-type body structure, consisting of a main body, left/right side doors, hydraulic cylinders, ram assemblies, locking mechanisms, and sealing systems. This modular design simplifies disassembly, assembly, and maintenance—technicians can quickly open the side doors via hinge structures to replace ram blocks, seals, or other wearing parts, reducing maintenance time.
4.2 Key Component Features
Ram Assemblies: Interchangeable pipe rams, blind rams, and variable diameter rams are available, with standardized part numbers for easy identification and replacement. Each ram assembly is equipped with high-wear-resistance packers and seals to ensure long-term sealing performance under high pressure.
Hydraulic Actuation System: Composed of hydraulic cylinders, pistons, and piston seals, the system provides stable and reliable driving force for ram movement. The piston seal adopts a dual-sealing structure (Y-ring + backup ring) to prevent hydraulic fluid leakage and improve pressure resistance.
Sealing Systems: Multiple sealing structures (side door seals, ram shaft seals, locking shaft seals, secondary seals) form a multi-layer protection system. Seals are made of high-temperature and high-pressure resistant materials, compatible with drilling fluids and formation fluids to avoid seal failure due to corrosion or aging.
Locking Mechanism: The locking shaft and locking screw ensure that the ram assemblies remain in the sealed position when the hydraulic system is depressurized, preventing accidental movement and enhancing operational safety.
4.3 Material Advantages
Key structural components (body, ram blocks, hydraulic cylinders) are made of high-strength alloy steel,经过 heat treatment to improve tensile strength and impact resistance, meeting the requirements of HPHT drilling environments. Sealing components are made of nitrile rubber or fluororubber, featuring excellent wear resistance, corrosion resistance, and temperature adaptability, ensuring long service life in harsh working conditions.
5. Application Conditions
The FZ35-21 Ram BOP is suitable for onshore and offshore oil and gas drilling operations, and its specific application conditions are as follows:
Pressure Range: Designed for working pressures up to 35 MPa (5075 psi), compatible with medium to high-pressure well drilling scenarios.
Pipe Size Compatibility: Supports pipe sizes including 2 7/8", 3 1/2", 4 1/2", 5", 5 1/2", 7", 9 5/8", and blind sealing, covering most common drill pipe specifications in oil and gas drilling.
Environmental Adaptability: Suitable for ambient temperatures ranging from -20°C to 80°C, adaptable to cold, hot, and humid onshore and offshore environments (with additional protection measures for extreme cold or corrosive marine environments).
Working Medium: Compatible with common drilling fluids (water-based, oil-based) and formation fluids, ensuring no damage to internal components or seal failure.
6. Maintenance and Maintenance Recommendations
6.1 Routine Maintenance (Daily/Weekly)
Inspect the overall sealing performance of the BOP, focusing on side door seals, ram shaft seals, and hydraulic cylinder seals for leakage. If leakage is found, replace the corresponding seals immediately.
Check the hydraulic system pressure to ensure it is within the specified range (35 MPa), and inspect hydraulic pipelines for damage or blockage.
Clean the surface of the BOP and internal components (especially ram blocks and packers) to remove drilling fluid residues and debris, avoiding wear on sealing surfaces.
Lubricate hinge structures, locking screws, and other moving parts with appropriate lubricants to ensure flexible operation.
6.2 Periodic Maintenance (Monthly/Quarterly)
Disassemble and inspect ram assemblies, replace worn ram blocks, packers, or seals, and verify that the part numbers of replacement parts match the original specifications (refer to the parts lists below for details).
Inspect the wear condition of hydraulic cylinder pistons and piston seals, and replace them if there is excessive wear or deformation.
Test the secondary seal system, inject EM-09-1 secondary sealing grease, and check the grease injection effect to ensure auxiliary sealing reliability.
Inspect the locking mechanism, including locking shafts and retaining rings, for wear or loosening, and tighten or replace parts as needed.
6.3 Long-Term Storage Maintenance
If the BOP is not in use for more than 6 months, clean all internal and external components, apply anti-rust oil to metal surfaces, and store in a dry, ventilated environment away from direct sunlight and corrosive substances. Sealing components should be removed and stored separately in a cool, dry place to avoid aging. Before reuse, conduct a comprehensive inspection and pressure test to ensure operational reliability.
6.4 Maintenance Notes
All replacement parts must be genuine products with matching part numbers to avoid equipment failure caused by incompatible or inferior parts.
Maintenance operations must be performed after depressurizing the hydraulic system and isolating the wellbore to ensure operator safety.
Record maintenance details (including parts replaced, maintenance date, and inspection results) to establish a complete maintenance history for traceability.
7. On-Site Fault Repair Cases
Case 1: Ram Sealing Failure
Fault Phenomenon: During drilling operation, formation fluid leaks from the ram sealing area when using the 5 1/2" pipe ram.
Inspection and Diagnosis: Disassembled the ram assembly and found that the packer (Part No.: 2FZ3535ASL. 02E.01-00) was severely worn and had cracks, leading to poor sealing.
Repair Solution: Replaced the worn packer with a genuine part of the same model, cleaned the ram block sealing surface, reassembled the ram assembly, and conducted a pressure test.
Result: Sealing performance was restored, and no leakage occurred during subsequent operations.
Preventive Measure: Shorten the inspection cycle of ram packers for wells with high formation pressure, and replace worn parts in a timely manner.
Case 2: Hydraulic Fluid Leakage from Ram Shaft
Fault Phenomenon: Hydraulic fluid leaked continuously from the ram shaft connection during hydraulic actuation of the BOP.
Inspection and Diagnosis: Checked the ram shaft seal assembly and found that the Y-ring (Part No.: SKZF100.01) and backup ring (Part No.: SKZF100.02) were aged and deformed, losing their sealing effect.
Repair Solution: Replaced the Y-ring and backup ring with new genuine parts, applied appropriate lubricant to the seal installation surface, and reassembled the seal assembly.
Result: Leakage was completely eliminated, and the hydraulic system pressure remained stable.
Preventive Measure: Regularly inspect the ram shaft seal assembly, especially in high-temperature working environments, and replace seals every 3 months.
Case 3: Side Door Seal Damage
Fault Phenomenon: After opening and closing the side door for ram replacement, drilling fluid leaked from the side door gap.
Inspection and Diagnosis: Inspected the side door seal (Part No.: 2S78.03.08) and found that the seal was scratched and deformed due to improper installation.
Repair Solution: Replaced the side door seal with a new part, cleaned the side door and body sealing surfaces, and ensured correct installation (avoiding over-tightening of side door bolts to prevent seal damage).
Result: Side door sealing was restored, and no leakage occurred.
Preventive Measure: Standardize the side door disassembly and assembly process, and inspect the seal for damage before installation.
Case 4: Variable Diameter Ram Assembly Jamming
Fault Phenomenon: The variable diameter ram assembly (4 1/2"-5 1/2") failed to move smoothly during pipe size switching, leading to inability to seal.
Inspection and Diagnosis: Disassembled the ram assembly and found that the front seal (Part No.: VBR3535SB.02.00) was stuck due to debris accumulation, and the ram body was slightly worn.
Repair Solution: Cleaned the ram body and front seal, removed debris, replaced the worn front seal, and lubricated the ram body sliding surface.
Result: The variable diameter ram assembly moved smoothly, and size switching and sealing functions were restored.
Preventive Measure: Strengthen routine cleaning of the variable diameter ram assembly, and avoid debris entering the ram sliding area.
8. FAQ (Frequently Asked Questions)
No. | Question | Answer |
1 | What should I do if the ram BOP cannot achieve effective sealing after ram replacement? | First, verify that the ram assembly part number matches the pipe size (refer to the pipe ram assembly parts list). Then check if the ram block and packer are worn or improperly installed, and ensure the sealing surface is clean and free of debris. If the problem persists, replace the packer or ram block with genuine parts and conduct a pressure test. |
2 | How often should the secondary sealing grease (EM-09-1) be replenished? | It is recommended to replenish the secondary sealing grease every month during routine maintenance. If the BOP is used in high-pressure or high-leakage scenarios, the replenishment cycle can be shortened to 2 weeks. After replenishment, test the secondary seal to ensure it functions properly. |
3 | What are the key points for selecting replacement seals for the ram shaft and locking shaft? | Replacement seals must match the original part numbers (e.g., Y-ring SKZF100.01, backup ring SKZF100.02) to ensure compatibility with the shaft diameter and working pressure. Additionally, select seals made of materials suitable for the working medium (drilling fluid, formation fluid) to avoid corrosion or aging. |
4 | Why does the hydraulic cylinder fail to drive the ram assembly to move? | Common reasons include insufficient hydraulic system pressure, blocked hydraulic pipelines, worn piston seals (leading to internal leakage), or jamming of the ram assembly due to debris. Inspect and troubleshoot in sequence: check hydraulic pressure, unblock pipelines, replace piston seals, and clean the ram assembly. |
5 | Can the FZ35-21 Ram BOP be used in offshore corrosive environments? | Yes, but additional anti-corrosion measures are required: apply marine-grade anti-corrosion paint to the BOP surface, use corrosion-resistant materials for exposed sealing components, and increase the frequency of routine cleaning and maintenance to prevent corrosion of metal components and seal damage. |
FZ35-21 Ram BOP
Pipe Size | Pipe Ram Assembly Name(Qty) | ||||||
Ram Assembly (2) | Ram Block(2) | Screw (4) | Holder(2) | Screw(4) | Packer(2) | ||
2 7/8" | 2S78.01B.00 | 2FZ3535ASL. 02A-02 | 2FZ3535ASL. 02A-03 | 2S78.01B.01 | 2FZ3535ASL. 02A-05 | 2FZ3535ASL. 02A.01-00 | |
3 1/2" | 2S78.01C.00 | 2FZ3535ASL. 02B-02 | 2FZ3535ASL. 02A-03 | 2S78.01B.01 | 2FZ3535ASL. 02A-05 | 2FZ3535ASL. 02B.01-00 | |
4 1/2" | 2S78.01D.00 | 2FZ3535ASL. 02C-02 | 2FZ3535ASL. 02A-03 | 2S78.01B.01 | 2FZ3535ASL. 02A-05 | 2FZ3535ASL. 02C.01-00 | |
5" | 2S78.01E.00 | 2FZ3535ASL. 02D-02 | 2FZ3535ASL. 02A-03 | 2S78.01B.01 | 2FZ3535ASL. 02A-05 | 2FZ3535ASL. 02D.01-00 | |
5 1/2" | 2S78.01G.00 | 2FZ3535ASL. 02E-02 | 2FZ3535ASL. 02A-03 | 2S78.01B.01 | 2FZ3535ASL. 02A-05 | 2FZ3535ASL. 02E.01-00 | |
7" | 2S78.01H.00 | 2FZ3535ASL. 02F-02 | 2FZ3535ASL. 02A-03 | 2S78.01B.01 | 2FZ3535ASL. 02A-05 | 2FZ3535ASL. 02F.01-00 | |
9 5/8" | 2S78.01I.00 | 2FZ3535ASL. 02G-02 | 2FZ3535ASL. 02A-03 | 2S78.01B.01 | 2FZ3535ASL. 02A-05 | 2FZ3535ASL. 02G.01-00 | |
Blind | 2S78.01J.00 | 2FZ3535ASL. 02H-02 | 2FZ3535ASL. 02A-03 | 2S78.01B.01 | 2FZ3535ASL. 02A-05 | 2FZ3535ASL. 02H.01-00 | |
Parts of HF pipe ram
Pipe size | Pipe Ram Assembly Name(Qty) | ||||
Ram Assembly | Ram Block(2) | Front Seal(2) | Top Seal(2) | ||
5 1/2" | SKF15-339-03.00 | 2S78.01F.01-01 | SKF15-339-03.01.00 | 2S78.01A.03.00 | |
Blind | 2S78.01A.00 | 2S78.01A.01 | 2S78.01A.02 | 2S78.01A.03.00 | |
Parts list of variable diameter ram assembly
Name (Qty.) P/N | Front Seal(2) | Top Seal(2) | Ram body(2) | Screw(2) |
4 1/2"-5 1/2" SKF15-339-04.00 | VBR3535SB.02.00 | VBR3535SLA.03.00 | SKF15-339-04.01.00 | GB/T70.1 M12×100 |
Part list of Side Door Seal Structure
No. | Description | Part No./Model | Qty(Single) | Qty(Double) |
27 | Side Door Seal | 2S78.03.08 | 2 | 4 |
Part list of Ram Shaft Seal Assembly
No. | Description | P/N | Qty. (Single) | Qty. (Double) |
24-1 | Retainer ring | DFZ5414-33A | 2 | 4 |
24-2 | Wiper 100 | Q/ZB336-77 | 2 | 4 |
24-3 | Wiper ring holder | 2FZ5414B-07 | 2 | 4 |
24-4 | Y-ring for shaft seal of Ram | SKZF100.01 | 2 | 4 |
24-5 | Backup ring | SKZF100.02 | 4 | 8 |
24-6 | Packing Bearing Ring | 2S78.03.02 | 2 | 4 |
24-7 | O-ring | GB/T3452.1 120×3.1 | 4 | 8 |
24-8 | O-ring | GB/T3452.1 105×3.1 | 4 | 8 |
24-9 | Yx-seal ring | JB/ZQ 4265 | 2 | 4 |
Parts list of Secondary Seal System
No. | Description | P/N | Qty. (Single) | Qty. (Double) |
23-1 | Z1″ External hexagonal blocking | SFZ2835-38 | 2 | 4 |
23-2 | Cock | SFZ2835-37 | 2 | 4 |
23-3 | Secondary sealing grease | EM-09-1 | 2 | 4 |
23-4 | Z1/2″ Internal hexagonal plug screw with hole | SFZ2835-40 | 2 | 4 |
Parts list of Locking Shaft Seal Assembly
No. | Description | P/N | Qty. (Single) | Qty. (Double) |
15-1 | Retainer Ring | GB893.1 95 | 2 | 4 |
15-2 | Thrust Shaft Sleeve | SFZ1310-21 | 2 | 4 |
15-3 | Lip ring cover | 2FZ1870DBYS.03-23 | 2 | 4 |
15-4 | Lip ring | 2FZ1870DBYS.03.22-00 | 2 | 4 |
15-5 | Wiper Seat Retainer | SFZ1310-22 | 2 | 4 |
15-6 | Wiper Ring | SFZ1310-23 | 2 | 4 |
Parts list of Hinge structure
No. | Description | Part No./Model | Qty. (Single) | Qty. (Double) |
7 a | Hinge Block | 2S78.07 | 4 | 8 |
5 | Locating Pin | GB118 A16×80 | 8 | 16 |
6 | Screw | GB/T70.1 M16×90 | 16 | 32 |
4 | O Ring | 43.7×3.55 | 8 | 16 |
No. | Description | Part No./Model | Qty. (Single) | Qty. (Double) | |||
1 | Body | 1 | 1 | ||||
2 | Ram Assembly | 2 | 4 | ||||
3 | Door bolt | 2S78.05 | 8 | 16 | |||
4 | O-ring | 43.7×3.55 | 8 | 16 | |||
5 | Taper pin | GB/T118 A16×80 | 8 | 16 | |||
6 | Screw | GB70.1 M16×90 | 16 | 32 | |||
7a | Hinge Block | 2S78.07 | 4 | 8 | |||
8 | O-ring | 31.5×3.55 | 4 | 8 | |||
9 | Plug NPT 1" | 2S48.11 | 2 | 4 | |||
10 | Screw | GB/T5782 M12×40 | 8 | 16 | |||
11 | Nozzle flange | 2S48.10 | 2 | 4 | |||
12 | O-ring | 38.7×3.55 | 2 | 4 | |||
13 | Right Cylinder head | 2S78.03.06 | 1 | 2 | |||
Left Cylinder head | 2S78.04.02 | 1 | 2 | ||||
14 | O-ring | 236×5.3 | 4 | 8 | |||
15 | Locking Shaft Seal Assembly | See 3.2.6 | -- | -- | |||
16 | Hydraulic cylinder | 2S78.03.03 | 2 | 4 | |||
17 | Screw | GB/T71 M8×16 | 2 | 4 | |||
18 | Locking nut | 2FZ2870.03.17 | 2 | 4 | |||
19 | Piston | 2FZ2870.03.07 | 2 | 4 | |||
20 | O-ring, Piston | 90×3.55 | 2 | 4 | |||
21 | Piston Seal | DFZ5414-13 | 4 | 8 | |||
22 | Right Door | 2S78.03.01 | 1 | 2 | |||
Left Door | 2S78.04.01 | 1 | 2 | ||||
23 | Secondary Seal System | See 3.2.5 | -- | -- | |||
24 | Ram Shaft Seal Assembly | See 3.2.4 | -- | -- | |||
25 | Locating Pin | 2FZ1870DBYS-08 | 2 | 4 | |||
26 | Ram shaft | 2S78.03.04 | 2 | 4 | |||
27 | Side Door Seal | 2S78.03.08 | 2 | 4 | |||
28 | O-ring | 28×3.55 | 4 | 8 | |||
29 | Locking screw | 2S78.03.07 | 4 | 8 | |||
30 | Plug NPT1/2" | SFZ2835-39 | 2 | 4 | |||
31 | Cylinder Bolt | 2S78.03.05 | 12 | 24 | |||
32 | Cap Nut | 2FZ3570DA.02-03 | 12 | 24 | |||
Spare Parts list
No. | Description | Single Ram BOP Part No./Model | Double Ram BOP Part No./Model | Qty. (Single) | Qty. (Double) | ||||
4 | O-ring | 43.7×3.55 | 8 | 16 | |||||
8 | O-ring | 31.5×3.55 | 4 | 8 | |||||
12 | O-ring | 38.7×3.55 | 2 | 4 | |||||
14 | O-ring | 236×5.3 | 4 | 8 | |||||
15-3 | Lip ring cover | 2FZ1870DBYS.03-23 | 2 | 4 | |||||
15-4 | Lip ring | 2FZ1870DBYS.03.22-00 | 2 | 4 | |||||
15-6 | Wiper ring | SFZ1310-23 | 2 | 4 | |||||
20 | O-ring,Piston | 90×3.55 | 2 | 4 | |||||
21 | Piston seal | DFZ5414-13 | 4 | 8 | |||||
23-3 | Secondary sealing grease | EM-09-1 | 2 | 4 | |||||
24-4 | Y-ring | SKZF100.01 | 2 | 4 | |||||
24-5 | Backup ring | SKZF100.02 | 4 | 8 | |||||
24-7 | O-ring | GB/T3452.1 120×3.1 | 4 | 8 | |||||
24-8 | O-ring | GB/T3452.1 105×3.1 | 4 | 8 | |||||
24-9 | Yx seal ring | JB/ZQ 4265 | 2 | 4 | |||||
27 | O-ring | 2S78.03.08 | 2 | 4 | |||||
28 | O-ring | 28×3.55 | 4 | 8 | |||||
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