1. Product Introduction
The FZ35-35 Ram Blowout Preventer (BOP) is a premium well control device engineered for medium to high-pressure oil and gas drilling operations, compliant with API Spec 16A and GB industrial standards. This model is specifically designed to match 35MPa (5076 psi) working pressure requirements, serving as a critical safety barrier to contain wellbore fluids and prevent blowout incidents. It is tailored for drilling contractors, oilfield maintenance teams, and well control service providers who demand reliable part interchangeability, actionable technical support, and compliance with global oilfield safety regulations.
Unlike generic BOPs, the FZ35-35 features a modular design with precision-machined components, ensuring seamless integration into existing well control systems. Its ram assemblies, sealing structures, and hydraulic actuation parts are standardized to simplify maintenance, reduce downtime, and lower operational costs—addressing the core pain points of on-site teams that need to respond quickly to equipment wear or failures.
2. Core Functions
2.1 Wellbore Containment
Equipped with interchangeable pipe rams and blind rams, the FZ35-35 can seal annular spaces around various pipe sizes (2 3/8" to 10 3/4") or fully close the wellbore. This dual capability ensures effective pressure control during drilling, tripping, casing running, and well intervention operations.
2.2 Dynamic Sealing Assurance
The integrated primary and secondary seal systems work in tandem to maintain leak-tight performance. The primary seals (door seals, ram shaft seals) handle routine pressure loads, while the secondary seal system allows for in-service grease injection (EM-09-1) to reinforce sealing integrity and extend component lifespan.
2.3 Reliable Hydraulic Actuation
The piston assembly and hydraulic cylinder components deliver consistent force to drive ram movement, ensuring rapid response to pressure anomalies. The design prioritizes durability, with wear-resistant seals and precision bearings that withstand cyclic actuation in harsh downhole fluid environments.
3. Structural Features
3.1 Modular Ram Assembly
Each ram assembly consists of ram blocks, high-performance rubber seals, retaining screws (GB70 M12×65), and holders—all engineered for easy disassembly and replacement. The rubber seals are made of oil-resistant, high-abrasion elastomers to tolerate extreme temperatures and fluid exposure.
3.2 Robust Sealing Structures
The side door seal structure (2FZ3535-15) and ram shaft seal assembly feature multi-layer sealing elements (O-rings, Y-rings, backup rings) to prevent fluid bypass. The locking shaft seal assembly, with wiper rings and thrust sleeves, adds an extra layer of security for high-pressure operations.
3.3 Durable Hinge Mechanism
The hinge structure incorporates needle bearings (GB290-64) and precision-machined pins, ensuring smooth side door operation even under high pressure. Corrosion-resistant materials and redundant O-rings (GB1235 series) minimize wear and extend service intervals.
3.4 Simplified Maintenance Design
Standardized fasteners (GB/T 70.1, GB/T 120) and modular components allow maintenance teams to replace worn parts without specialized tools. The clear part numbering system ensures accurate part identification, reducing the risk of misordering or incorrect installation.
4. Applicable Working Conditions
The FZ35-35 Ram BOP is optimized for the following operational scenarios, aligning with the needs of onshore and shallow offshore drilling projects:
Pressure & Temperature: Operates reliably at pressures up to 35MPa and ambient temperatures ranging from -20°C to 120°C (-4°F to 248°F), adaptable to temperate and subtropical oilfield regions.
Well Types: Compatible with vertical, deviated, and horizontal wells, handling crude oil, drilling mud, brine, and other common downhole fluids.
Operations: Ideal for rotary drilling, tripping, well completion, and emergency well control situations where rapid pressure containment is critical.
Environmental Resistance: Corrosion-resistant components and sealed structures ensure performance in humid, dusty, or coastal environments.
5. Maintenance & Care Recommendations
5.1 Routine Inspection (Every 500 Operational Hours)
Conduct visual inspections of all seals (O-rings, Y-rings, wiper rings) for wear, cracking, or swelling. Replace damaged parts with genuine components to maintain API Spec 16A compliance. Lubricate hinge pins and bearings with high-pressure grease, and verify torque on retaining screws and locking nuts per manufacturer specifications.
5.2 Preventive Maintenance (Every 2000 Operational Hours)
Disassemble the ram shaft seal assembly and replace dynamic seals (SKZF100.01 Y-rings, SKZF100.02 backup rings). Inspect ram blocks for surface deformation and grind or replace if the sealing surface is compromised. Test the secondary seal system by injecting EM-09-1 grease and conducting a static pressure test to ensure leak-tight performance.
5.3 Storage & Handling
When not in use, store the BOP in a clean, dry environment with temperature control. Cover fluid ports with protective caps to prevent contamination, and apply anti-corrosion oil to metal surfaces. Replace worn seals before long-term storage to avoid elastomer degradation.
Pipe Size | Pipe Ram Assembly Name(Qty) | |||||
Assembly (2) | Ram block(2) | Retaining Screw(4) | Holder(2) | Retracting screw (4) | Rubber(2) | |
5" | DFZ1310.01A-00 | DFZ1310.01A-03 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01A.01-00 |
4 1/2" | DFZ1310.01B-00 | DFZ1310.01B-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01B.01-00 |
3 1/2" | DFZ1310.01C-00 | DFZ1310.01C-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01C.01-00 |
7" | DFZ1310.01D-00 | DFZ1310.01D-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01D.01-00 |
blind | DFZ1310.01E-00 | DFZ1310.01E-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01E.01-00 |
9 5/8" | DFZ1310.01F-00 | DFZ1310.01F-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01F.01-00 |
2 7/8" | DFZ1310.01G-00 | DFZ1310.01G-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01G.01-00 |
5 1/2" | DFZ1310.01H-00 | DFZ1310.01H-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01H.01-00 |
2 3/8" | DFZ1310.01L-00 | DFZ1310.01L-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01L.01-00 |
10 3/4" | DFZ1310.01M-00 | DFZ1310.01M-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01M.01-00 |
4 3/4" | DFZ1310.01N-00 | DFZ1310.01N-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01N.01-00 |
5 3/4" | DFZ1310.01P-00 | DFZ1310.01P-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01P.01-00 |
4" | DFZ1310.01I-00 | DFZ1310.01I-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01I.01-00 |
7 5/8" | DFZ1310.01Q-00 | DFZ1310.01Q-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01Q.01-00 |
6 5/8" | DFZ1310.01R-00 | DFZ1310.01R-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01R.01-00 |
5 7/8" | DFZ1310.01S-00 | DFZ1310.01S-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01S.01-00 |
8 5/8" | DFZ1310.01T-00 | DFZ1310.01T-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01T.01-00 |
9 7/8" | DFZ1310.01U-00 | DFZ1310.01U-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01U.01-00 |
7 7/8 ― | DFZ1310.01V-00 | DFZ1310.01V-02 | GB70 M12×65 | DFZ1310.01A-02 | DFZ1310.01A-04 | DFZ1310.01V.01-00 |
Part list of Side Door Seal Structure
No. | Description | Part No./Model | Qty (Single) | Qty (Double) |
4 | Door Seal | 2FZ3535-15 | 2 | 4 |
Part list of Ram Shaft Seal Assembly
No. | Description | Part No./Model | Qty. (Single) | Qty. (Double) |
14-1 | Retainer ring | DFZ5414-33 | 2 | 4 |
14-2 | Wiper ring 100 | Q/ZB336-77 | 2 | 4 |
14-3 | Bushing | 2FZ5414B-07 | 2 | 4 |
14-4 | O-ring | 105×3.1 | 4 | 8 |
14-5 | Packing Bearing Ring | DFZ5414-31 | 4 | 8 |
14-6 | O-ring | 120×3.1 | 4 | 8 |
14-7 | Backup ring | SKZF100.02 | 8 | 16 |
14-8 | Y-ring | SKZF100.01 | 4 | 8 |
14-9 | Washer | DFZ5414-28 | 4 | 8 |
Secondary Seal System
No. | Description | P/N | Qty. (Single) | Qty. (Double) |
7-1 | Z1″ External hexagonal blocking | SFZ2835-38 | 2 | 4 |
7-2 | Cock | SFZ2835-37 | 2 | 4 |
7-3 | Secondary sealing grease | EM-09-1 | 2 | 4 |
7-4 | Z1/2″ Internal hexagonal plug screw with hole | SFZ2835-40 | 2 | 4 |
Parts list of Locking Shaft Seal Assembly
No. | Description | Part No./Model | Qty. (Single) | Qty. (Double) |
18-1 | Retainer Ring | GB/T893.1 95 | 2 | 4 |
18-2 | Thrust Shaft Sleeve | 2FZ3535-17A | 2 | 4 |
18-3 | W-ring | DFZ5414-25 | 6 | 12 |
18-4 | Back –up ring | DFZ5414-24 | 2 | 4 |
18-5 | Wiper Seat Retainer | DFZ5414-23 | 2 | 4 |
18-6 | Wiper Ring | DFZ5414-22 | 2 | 4 |
Parts list of Hinge structure
No. | Description | Part No./Model | Qty. (Single) | Qty. (Double) | |||
9-1 | Hinge Pin | 2FZ3535.11.01-08 | 4 | 8 | |||
9-2 | O Ring | GB1235 70×3.1 | 4 | 8 | |||
9-3 | O Ring | GB1235 55×3.1 | 12 | 24 | |||
9-4 a | Hinge Bracket | 2FZ3535.11-06 | 4 | 8 | |||
9-5a | Hinge（one） | 2FZ3535.11.01-00 | 2 | 4 | |||
9-6 | O Ring | GB1235 40×3.1 | 4 | 8 | |||
9-7 | Hydraulic Connection | 2FZ3535.11-04 | 4 | 8 | |||
9-8 | Spring | 2FZ3535.11-03 | 4 | 8 | |||
9-9 | Left Hinge Bracket | 2FZ3535.11.02-00 | 1 | 2 | |||
Right Hinge Bracket | 2FZ3535.12.01-00 | 1 | 2 | ||||
9-10a | Hinge（two） | 2FZ3535.11.07-00 | 2 | 4 | |||
9-11 | O Ring | GB1235 25×2.4 | 4 | 8 | |||
9-12 | Pin | GB/T 120 B12×50 | 8 | 16 | |||
9-13 | Screw | GB/T 70.1 M16×40 | 16 | 32 | |||
9-14 | Screw | GB/T 70.1 M20×65 | 16 | 32 | |||
9-15 | Pin | GB/T 120 B12×60 | 8 | 16 | |||
9-16 | Screw | GB70 M16×45 | 8 | 16 | |||
9-17 | O Ring | 30×3.1 | 4 | 8 | |||
9-18 | O Ring | 35×3.1 | 4 | 8 | |||
9-19 | Needle Bearing 941/30 | GB290-64 | 4 | 8 | |||
9-20 | Washer, Adjust | 2FZ3535.11-05 | 8 | 16 | |||
9-21 | Bearing 8107 | GB301-64 | 4 | 8 | |||
Parts list of Piston Assembly
No. | Description | Part No./Model | Qty.(Single) | Qty.(Double) |
17-1 | Piston | DFZ5414-14 | 2 | 4 |
17-2 | Piston Seal | DFZ5414-13 | 4 | 8 |
17-3 | O-ring | 95×3.1 | 2 | 4 |
17-4 | Screw | GB71 M8×16 | 2 | 4 |
17-5 | Locking nut | DFZ5414-44 | 2 | 4 |
No. | Description | FZ18-70 Part No./Model | Qty. (Single) | Qty. (Double) | |
1 | Body | 1 | 1 | ||
2 | Locating Pin | 2FZ3535-16 | 2 | 4 | |
3 | Ram Assembly | DFZ1310.01().00 | 2 | 4 | |
4 | Side Door Seal Structure | 2FZ3535-15 | 2 | 4 | |
5[a] | Left Door | 2FZ3535-02 | 2 | 4 | |
6 | O-ring | 250×5.7 | 4 | 8 | |
7 | Secondary Seal System | See 3.2.4 | - | - | |
8 | Door bolt | 2FZ3535-13 | 20 | 40 | |
9[a] | Hinge Assembly | See 3.2.7 | - | - | |
10 | O-ring | 50×3.1 | 2 | 4 | |
11 | Nozzle flange | SFZ2835-42 | 2 | 4 | |
12 | Screw | GB5782 M12×45 | 6 | 12 | |
13 | NPT 1" Plug | SFZ2835-41 | 2 | 4 | |
14 | Ram Shaft Seal Assembly | See 3.2.3 | -- | -- | |
15 | Ram shaft | 2FZ3535-05A | 2 | 4 | |
16 | Locking screw | 2FZ3535-10A | 2 | 4 | |
17 | Piston Assembly | See 3.2.8 | - | - | |
18 | Locking Shaft Seal Assembly | See 3.2.5 | - | - | |
19 | O-ring | 32×3.1 | 4 | 8 | |
20 | Hydraulic cylinder | 2FZ3535-04 | 2 | 4 | |
21 | Cylinder Bolt | 2FZ3535-07 | 12 | 24 | |
22 | Nut | DFZ5414-16 | 12 | 24 | |
23 | NPT 1/2" Plug | SFZ2835-39 | 2 | 4 | |
24 | Right Cylinder head | 2FZ3535-06A | 1 | 2 | |
Left Cylinder head | 2FZ3535-18A | 1 | 2 | ||
Spare Parts list for one year for FZ35-35
No. | Description | Part No./Model | Qty. (Single) | Qty. (Double) |
4 | Door seal | 2FZ3535-15 | 2 | 4 |
6 | O-ring | 250×5.7 | 4 | 8 |
7-3 | Secondary sealing grease | EM-09-1 | 2 | 4 |
9-2 | O-ring | 70×3.1 | 4 | 8 |
9-3 | O-ring | 55×3.1 | 12 | 24 |
9-6 | O-ring | 40×3.1 | 4 | 8 |
9-11 | O-ring | 25×2.4 | 4 | 8 |
9-17 | O-ring | 30×3.1 | 4 | 8 |
9-18 | O-ring | 35×3.1 | 4 | 8 |
10 | O-ring | 50×3.1 | 2 | 4 |
14-2 | Wiper ring 100 | Q/ZB336-77 | 2 | 4 |
14-4 | O-ring | 105×3.1 | 4 | 8 |
14-6 | O-ring | 120×3.1 | 4 | 8 |
14-8 | Y-ring | SKZF100.01 | 4 | 8 |
14-7 | Back up ring | SKZF100.02 | 8 | 16 |
17-2 | Piston Seal | DFZ5414-13 | 4 | 8 |
17-3 | O-ring | 95×3.1 | 2 | 4 |
18-3 | W-ring | DFZ5414-25 | 6 | 12 |
18-4 | Back –up ring | DFZ5414-24 | 2 | 4 |
18-6 | Wiper ring | DFZ5414-22 | 2 | 4 |
19 | O-ring | 32×3.1 | 4 | 8 |
6. Field Fault Repair Cases
Case 1: Ram Shaft Leakage During Tripping
Scenario: A drilling team operating an FZ35-35 BOP noticed hydraulic fluid leakage around the ram shaft during tripping operations. The leak worsened under well pressure, threatening operational safety.
Diagnosis: On-site inspection revealed worn Y-rings (SKZF100.01) and backup rings (SKZF100.02) in the ram shaft seal assembly. The damage was caused by prolonged exposure to high-pressure drilling mud and cyclic actuation beyond the recommended maintenance interval.
Solution: The team replaced the worn seals with genuine parts, re-lubricated the ram shaft, and conducted a 35MPa static pressure test. The leak was eliminated, and the BOP resumed normal operation within 2 hours—minimizing downtime and avoiding costly well control incidents.
Case 2: Side Door Seal Failure During Pressure Testing
Scenario: During a well pressure test, the side door seal (2FZ3535-15) of an FZ35-35 BOP failed, resulting in fluid leakage. The seal had been in service for 1800 hours without replacement.
Diagnosis: The seal had degraded due to exposure to high-temperature well fluids, losing elasticity and sealing capability. The secondary seal system was not activated in time to compensate for the primary seal failure.
Solution: The damaged door seal was replaced with a genuine 2FZ3535-15 component. The secondary seal system was then activated by injecting EM-09-1 grease, and a follow-up pressure test confirmed leak-tight performance. The team adjusted their maintenance schedule to inspect side door seals every 1000 hours to prevent recurrence.
7. Frequently Asked Questions (FAQs)
FAQ | Answer |
Can non-genuine seals be used for the FZ35-35 BOP? | No. Non-genuine seals do not meet API Spec 16A or GB standards, and may not withstand the FZ35-35’s pressure and temperature requirements. Using non-genuine parts increases the risk of seal failure, blowouts, and non-compliance with safety regulations. Always use genuine components (e.g., DFZ5414-13 piston seals, 2FZ3535-15 door seals). |
What is the difference between single and double quantities in the parts list? | “Single” quantity refers to parts needed for one FZ35-35 BOP unit, while “double” quantity is for two units (common in dual-BOP well control systems). For example, the door seal (2FZ3535-15) requires 2 pieces per single BOP and 4 pieces per double configuration. This ensures accurate procurement for both standard and redundant setups. |
How often should EM-09-1 secondary sealing grease be replenished? | EM-09-1 grease should be replenished every 500 operational hours, or whenever the secondary seal system is activated for leak repair. For wells with aggressive fluids (e.g., high-salinity brine), reduce the interval to 300 hours to maintain optimal sealing performance and extend primary seal lifespan. |
8. Procurement Guidance & Conclusion
The FZ35-35 Ram BOP is a critical investment in well control safety, and using genuine parts is essential to maintain its performance and compliance. When procuring parts, refer to the official part numbering system provided to ensure compatibility—this eliminates the risk of incorrect installations that could compromise well control integrity.
We offer a full range of genuine FZ35-35 parts, including ram assemblies, seals, hydraulic components, and hinge parts, all manufactured to meet API Spec 16A and GB standards. Our technical team provides on-demand support for part identification, maintenance guidance, and troubleshooting, helping you minimize downtime and maximize operational safety. Whether you need routine spare parts or emergency replacements, we are committed to supplying high-quality components that align with your drilling needs. Contact us today to discuss your procurement requirements and access personalized technical support.
By adhering to the maintenance recommendations and using genuine parts, you can ensure the FZ35-35 BOP delivers reliable performance in critical well control scenarios, protecting your team, equipment, and the environment.
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