Introduction
This guide is exclusively tailored for Shanghai Shenkai’s FZ68-21U (single ram) and 2FZ68-21U (double ram) Ram Blowout Preventers (BOPs), high-reliability well control devices engineered for medium-pressure oil and gas drilling operations. It caters to the specialized needs of drilling contractors, on-site maintenance technicians, and procurement specialists in the oilfield industry, focusing on the models’ core technical parameters, unique part ecosystem—including 2C24 series pipe rams, SKZF sealing components, and 2C24.08.00 operating piston assemblies—and practical application guidelines. Its core purpose is to serve as a dual-functional reference: providing precise part compatibility, procurement benchmarks, and inventory optimization strategies, while delivering actionable technical solutions for on-site fault diagnosis, repairs, and routine maintenance. Compliant with API Spec 16A (Wellhead and Christmas Tree Equipment) and Chinese national standards (GB/T 77-2000), this guide ensures FZ68-21U/2FZ68-21U operations adhere to strict industry safety protocols, minimize unplanned downtime, and maximize operational efficiency. Whether for daily upkeep, emergency repairs, or bulk parts sourcing, the content integrates field-validated experience and authoritative technical insights to safeguard wellbore integrity and personnel safety in targeted drilling scenarios.
Product Overview
The Shanghai Shenkai FZ68-21U series BOPs (single and double ram configurations) are designed for a bore size of 679.4mm (26 3/4 inches) and a rated working pressure of 21MPa (3000psi), with a hydrostatic test pressure of 31.5MPa (4500psi), fully meeting the requirements of medium-pressure drilling operations. The single ram model (FZ68-21U) weighs 14100kg, while the double ram variant (2FZ68-21U) weighs 23400kg, offering flexible deployment options for onshore and shallow offshore drilling sites. A standout feature of this series is its standardized 2C24 series pipe ram system, covering blind rams, 5″ pipe rams, and 18 5/8″ pipe rams, each equipped with dedicated ram bodies, top seals, and shared front seals (2C24.01A.03) to ensure targeted sealing performance. Core components include 2C24.08.00 operating piston assemblies, intermediate flange seal assemblies (2C24.17.00), layered piston sealing systems, secondary sealing mechanisms, and ram change cylinders—all engineered for durability, interchangeability, and easy maintenance under corrosive drilling fluid conditions. The models share consistent hydraulic specifications, with a hydraulic-control rated working pressure of 21MPa (3000psi), recommended operation pressure of 8.4-10.5MPa (1200-1500psi), and identical cylinder opening/closing capacities (36L×4/37L×4), simplifying maintenance and part commonality between configurations.
Functional Description
The FZ68-21U series BOPs deliver precise, reliable well control through coordinated operation of their specialized components, tailored to the 21MPa rated pressure and T-20 temperature rating:
Pipe Ram Sealing Control: The 2C24.01 series pipe rams provide targeted wellbore sealing for diverse scenarios. Blind rams (2C24.01A.00) enable full wellbore closure during maintenance or emergencies, while 5″ (2C24.01B.00) and 18 5/8″ (2C24.01C.00) pipe rams seal around corresponding drill pipe sizes to maintain pressure control during drilling. Each ram assembly includes two ram bodies, two size-specific top seals, and two shared front seals (2C24.01A.03), ensuring consistent sealing performance across ram types.
Layered Sealing Protection: The sealing system integrates multiple defensive layers to prevent leakage: intermediate flange seals (2C24.17.00) secure the bonnet connection; operating piston front rod seals (SKZF101.01 Y-rings, 129.54×5.33/100.97×5.33 O-rings, backup rings) and tail rod seals (U-seals, 77.5×5.3 O-rings) safeguard hydraulic fluid integrity; and the secondary sealing mechanism (SFZ1310-32.00 check valves, SFZ1310-30 plug cocks) allows on-site injection of EM-09-L/25mm grease for quick leak remediation without disassembly.
Hydraulic Actuation & Locking: 2C24.08.00 operating piston assemblies drive smooth ram movement, integrated with piston rods (2C24.08.01), backup rings (C664-22 102.31x111.61x1.52), and stop blocks (C17.08.03) secured by GB/T 77-2000 M12×20 screws. Ram change cylinders (2C24.11) and opening/closing pistons enable precise ram actuation, while locking screw housings (2C24.01.00) and locking screws (2C24.03)—requiring 62 turns per end—secure ram positions under pressure, with a 12:1 closing ratio ensuring reliable locking performance.
Precision Guidance & Alignment: Guide pins (2C05.16) and guide rings (2C05.18) ensure accurate ram movement and alignment, reducing friction and extending component service life. Backup rings (C663-22 series in multiple sizes) prevent seal extrusion under test pressure (31.5MPa), maintaining piston stability and sealing integrity.
Structural Features
The FZ68-21U series BOPs feature a modular, maintenance-friendly design optimized for reliability, pressure resistance, and ease of on-site service:
Standardized Part Ecosystem with High Commonality: Core components follow a consistent naming convention, with 2C24 series parts for ram assemblies, structural components, and piston assemblies, and SKZF/C series parts for sealing and auxiliary components. High part commonality between single and double ram models (e.g., pipe rams, seals, hydraulic cylinders) reduces inventory complexity and procurement costs, while dedicated parts (intermediate flange bolts, locking screw housings) ensure precise compatibility with each configuration.
Robust Pressure-Resistant Sealing Design: Sealing systems combine Y-rings, U-seals, O-rings, TPM seals (TPM360), and backup rings to withstand 21MPa working pressure and 31.5MPa hydrostatic test pressure. Intermediate flange seals and piston seals are engineered for tight fits, with backup rings preventing extrusion and gaskets (SKZF101.02, 2C02.18) enhancing sealing integrity in harsh drilling environments.
Modular Piston & Ram Construction: The 2C24.08.00 operating piston assembly and ram systems feature modular design, allowing technicians to replace individual parts (stop blocks, O-rings, seals) without full disassembly. This reduces maintenance time and enables quick field repairs, critical for minimizing drilling downtime.
User-Centric Accessibility & Safety: Key wear components—seals, gaskets, guide pins—are strategically positioned for easy access. Standardized fasteners (GB/T 70.1 M10×20 screws, 2C01 series plugs) enable technicians to use common tools for disassembly and reassembly. The 12:1 closing ratio and multi-turn locking screws enhance operational safety, preventing accidental ram displacement under pressure.
Applicable Operating Conditions
The FZ68-21U (single ram) and 2FZ68-21U (double ram) BOPs are optimized for 21MPa medium-pressure drilling scenarios, with specific applicability to the following conditions:
Pressure & Temperature Range: Rated for 21MPa (3000psi) working pressure, 31.5MPa (4500psi) hydrostatic test pressure, and T-20 temperature rating (suitable for ambient temperatures from -20°C to 60°C), compatible with water-based mud (WBM), oil-based mud (OBM), and synthetic-based mud (SBM) commonly used in onshore drilling.
Pipe Size & Bore Adaptability: With a 679.4mm (26 3/4 inches) bore and support for 5″, 18 5/8″ pipe rams and blind rams, the series is suitable for wells with large-diameter casing programs and diverse drill pipe dimensions, widely used in onshore oil and gas fields.
Well Types & Operations: Ideal for onshore oil and gas wells, shallow offshore platforms, and workover operations, particularly in regions with moderate formation pressure fluctuations. The double ram model (2FZ68-21U) provides enhanced safety redundancy for high-risk wells, while the single ram model (FZ68-21U) offers cost-effective performance for standard drilling scenarios.
Environmental Resilience: Seals and metal components (2C24 series flanges, piston assemblies, nozzle flanges) resist corrosion from drilling fluids, moisture, and harsh atmospheric conditions, ensuring consistent performance in diverse on-site environments.
Maintenance & Care Recommendations
Proactive maintenance is critical to extending the service life and ensuring the reliability of FZ68-21U series BOPs. Below are model-specific best practices aligned with API Spec 16A and relevant standards:
Regular Inspection Schedules: Conduct weekly visual checks of intermediate flange seals, hydraulic connections, ram seals, and locking screws for leaks, corrosion, or wear. Perform quarterly disassembly inspections of piston assemblies, secondary sealing mechanisms, and ram change cylinders—replace worn parts per the one-year recommended spare parts list. Conduct annual hydrostatic testing at 31.5MPa to verify pressure resistance.
Seal Maintenance: Replace intermediate flange seals (2C24.17.00) and U-seals (H601-Ф76.2xФ92.08X14.27/15.72) every 6 months or if cracks/deformation are detected. Inspect SKZF101.01 Y-rings and O-rings (129.54×5.33, 100.97×5.33) monthly; replace the entire seal set if any component is worn. Inject EM-09-L/25mm secondary seal grease every 3 months to maintain leak resistance and lubricate sealing surfaces.
Ram & Piston Care: Clean ram components (ram bodies, top/front seals) after each use to remove drilling fluid residue. Verify ram assembly part numbers match the pipe size (e.g., 2C24.01C.00 for 18 5/8″) before installation. Lubricate guide pins (2C05.16) and guide rings (2C05.18) monthly with anti-corrosion lubricant to prevent jamming and reduce friction.
Hydraulic & Actuation Maintenance: Inspect TPM seals (TPM360) and backup rings (C663-22/C664-22 series) monthly for damage. Replace hydraulic O-rings (72.39×5.33, 116.84×5.33) if leaks occur, and torque intermediate flange bolts (2C24.09) and hydraulic cylinder bolts (2C24.05) to manufacturer specifications. Check locking screws (2C24.03) for tightness and ensure smooth operation (62 turns per end) during each inspection.
Auxiliary Component Care: Clean SFZ1310-32.00 check valves and SFZ1310-30 plug cocks quarterly to prevent clogging from dried grease or debris. Inspect retainer rings (2C02.17) and gaskets (2C02.18) for deformation—replace to ensure secure component positioning and sealing integrity. Verify hydraulic control pressure remains within the recommended 8.4-10.5MPa range to avoid component damage.
Sealing Parts List of Operating Piston Front Rod
Name | Part No. |
O-ring | 129.54×5.33 |
O-ring | 100.97×5.33 |
Supporting gland cover | C17.14 |
Gasket 102×5 | SKZF101.02 |
Y-Ring of ram shaft seal | SKZF101.01 |
Gasket | 2C02.18 |
Retainer ring 140 | 2C02.17 |
Secondary Sealing Mechanism Parts Table
Name | Part No. |
Z1″ Hexagonal plug | 2C01.21 |
Plug cock | SFZ1310-30 |
Secondary seal grease | 2 |
Check valve | SFZ1310-32.00 |
Z1/2″ hexagon socket screw plug | 2C01.32 |
Sealing Parts Table of Operating Piston Tail Rod
Name | Part No. |
U-Seal | Φ76.2×92.08×14.27/15.72 |
O-ring | 77.5×5.3 |
Name | Part No./Model |
Double | |
Body | -- |
Intermediate Flange Seal | 2C24.17.00 |
Ram assembly | 2C24.01（）.00 |
Retainer ring 140 | 2C02.17 |
Gasket | 2C02.18 |
Ram shaft seal Y-Ring | SKZF101.01 |
Backup ring | SKZF101.02 |
O-ring | 129.54×5.33 |
Supporting gland cover | C17.14 |
O-ring | 100.97×5.33 |
Ram Guide pin | 2C05.16 |
NPT1” plug screw | 2C01.21 |
Nozzle flange | 2C27A01.34 |
Screw | 2C01.26 |
O-ring | 43.7×3.55 |
Check Valve | 2C01.07 |
Secondary seal grease | EM-09-L/25mm |
Plug cock 1-8UNC | 2C01.20 |
Intermediate Flange bolt | 2C24.09 |
Ram change cylinder | 2C24.11 |
Backup ring （Ram change cylinder / Cylinder head） | C663-22 Ф142.4×Ф151×1.7 |
O-ring （Ram change cylinder / Cylinder head） | 142.88×5.3 |
Guide ring | 2C05.18 |
O-ring （Ram change piston / Body） | 72.39×5.33 |
Backup ring （Ram change piston / Body） | C663-22 Ф74.4×Ф83×1.7 |
Ram change piston_open | 2C24.16 |
Backup ring （Ram change piston / Ram change cylinder） | C663-22 Ф118.4×Ф127×1.7 |
O-ring （Ram change piston / Ram change cylinder） | 116.84×5.33 |
Cylinder head | 2C24.04 |
O-ring （Locking Nut / Cylinder head） | 161.3×5.33 |
Backup ring （Locking Nut / Cylinder head） | C663-22 Ф162.4×Ф171×1.7 |
Locking Nut | 2C24.10 |
Hydraulic cylinder bolt | 2C24.05 |
Cap nut | 2S93.03.08 |
Locking Screw Housing assembly | 2C24.01.00 |
Stud | C17.03 |
Locking Screw | 2C24.03 |
Screw | GB/T70.1 M10×20 |
NPT 1/2" Plug | 2C01.36 |
O-ring | 78.74×5.33 |
U-ring | H601-Ф76.2xФ92.08X14.27/15.72 |
Backup ring （Cylinder head / Cylinder） | C663-22 Ф348.6×Ф360×2.5 |
O-ring （Cylinder head / Cylinder） | 345.1×7 |
Ram change piston_close | 2C24.12 |
TPM seal | TPM360 |
Operating piston assembly | 2C24.08.00 |
Cylinder | 2C24.06 |
Intermediate Flange | 2C24.07 |
Hexagon socket screw plug | 2C01.32 |
O-ring （Intermediate Flange / Ram change piston） | 88.27×5.33 |
Backup ring （Intermediate Flange / Ram change piston） | C663-22 Ф90×Ф98.6×1.7 |
Stroke fender | 2C24.18 |
Piston rod | 2C24.08.01 |
O-ring | 100.97x5.33 |
Backup ring | C664-22 102.31x111.61x1.52 |
Piston | C16.08.02 |
Stop block | C17.08.03 |
Socket head cap screw | GB/T 77-2000 M12X20 |
One-year recommended spare parts list
Name | Part No./Model |
Double | |
Intermediate Flange Seal | 2C24.17.00 |
Ram shaft seal Y-Ring | SKZF101.01 |
Backup ring | SKZF101.02 |
O-ring | 129.54×5.33 |
O-ring | 100.97×5.33 |
O-ring | 43.7×3.55 |
Secondary seal grease | EM-09-L/25mm |
Backup ring | C663-22 Ф142.4×Ф151×1.7 |
O-ring | 142.88×5.3 |
Guide ring | 2C05.18 |
O-ring | 72.39×5.33 |
Backup ring | C663-22 Ф74.4×Ф83×1.7 |
Backup ring | C663-22 Ф118.4×Ф127×1.7 |
O-ring | 116.84×5.33 |
O-ring | 161.3×5.33 |
Backup ring | C663-22 Ф162.4×Ф171×1.7 |
O-ring | 78.74×5.33 |
U-ring | H601-Ф76.2xФ92.08X14.27/15.72 |
Backup ring | C663-22 Ф348.6×Ф360×2.5 |
O-ring | 345.1×7 |
TPM seal | TPM360 |
O-ring | 88.27×5.33 |
Backup ring | C663-22 Ф90×Ф98.6×1.7 |
O-ring | 100.97x5.33 |
Backup ring | C664-22 102.31x111.61x1.52 |
Stop block | C17.08.03 |
Field Fault Repair Cases
The following real-world cases provide practical troubleshooting tips for common FZ68-21U series faults, helping technicians resolve issues quickly and minimize downtime:
Case 1: Intermediate Flange Leakage
Symptom: Wellbore fluid leakage at the intermediate flange during pressure testing. Root Cause: 2C24.17.00 intermediate flange seals were worn and contaminated with drilling mud, compromising sealing integrity under pressure. Repair: Replaced the seal assemblies, cleaned the flange surface with a non-abrasive tool to remove residue, and reinstalled the intermediate flange with calibrated torque. A follow-up hydrostatic test at 31.5MPa confirmed no leakage. Preventive Measure: Clean the flange area post-operation and inspect seal assemblies bi-weekly.
Case 2: Operating Piston Front Rod Hydraulic Leakage
Symptom: Hydraulic fluid leakage around the operating piston front rod. Root Cause: SKZF101.01 Y-rings were degraded by high-temperature hydraulic fluid, and 100.97×5.33 O-rings were deformed. Repair: Replaced the entire front rod seal set (Y-rings, O-rings, backup rings, gaskets), cleaned the piston rod to remove burrs, and inspected the supporting gland cover (C17.14) for damage. Post-repair actuation was smooth with no leakage. Preventive Measure: Replace the front rod seal set every 6 months and monitor hydraulic fluid temperature to avoid exceeding operational limits.
Case 3: Ram Jamming During Actuation
Symptom: 2C24.01B.00 5″ pipe ram jammed during closing actuation.Root Cause: Drilling fluid residue buildup on guide pins (2C05.16) and worn guide rings (2C05.18), combined with loose stop blocks (C17.08.03) in the operating piston assembly. Repair: Disassembled the ram, cleaned guide pins and rings with a compatible solvent, replaced worn guide rings, tightened stop blocks with GB/T 77-2000 M12×20 screws, and lubricated all moving components. The ram actuated smoothly post-reassembly. Preventive Measure: Clean guide pins weekly and check stop block tightness during routine inspections.
Case 4: Secondary Sealing Grease Injection Failure
Symptom: Inability to inject EM-09-L/25mm grease into the secondary sealing mechanism. Root Cause: SFZ1310-32.00 check valves were clogged with dried grease and debris, blocking grease flow. Repair: Disassembled the check valves and plug cocks (SFZ1310-30), cleaned them thoroughly with a solvent, flushed the grease injection line, and reinstalled components. Grease flow was restored immediately. Preventive Measure: Clean check valves and plug cocks quarterly and flush the grease line during each maintenance cycle.
FAQ (Frequently Asked Questions)
Question | Answer |
Can front seals be shared across different pipe ram sizes for FZ68-21U? | Yes. All pipe ram sizes (blind, 5″, 18 5/8″) use the same front seal (2C24.01A.03), allowing for shared inventory. However, top seals are size-specific (e.g., 2C24.01A.02.00 for blind rams, 2C24.01B.02.00 for 5″ rams)—always match the top seal part number to the ram assembly to ensure proper sealing and pressure resistance. |
What is the significance of the recommended hydraulic control pressure (8.4-10.5MPa)? | This range balances actuation efficiency and component protection. Operating below 8.4MPa may cause incomplete ram actuation, while exceeding 10.5MPa increases wear on seals, piston rods, and cylinders, reducing service life. Strictly adhering to this range ensures smooth operation and prevents premature component failure. |
Are spare parts interchangeable between FZ68-21U (single) and 2FZ68-21U (double) models? | Most wear parts are interchangeable, including pipe rams, seals (SKZF series, O-rings), backup rings, and operating piston assembly components. The key difference is quantity—double ram models require twice the number of core parts (e.g., intermediate flange seals, ram assemblies). Always reference the parts list for quantity requirements; structural parts (e.g., body, intermediate flange) are model-specific and not interchangeable. |
Why are different types of backup rings (C663-22/C664-22) used in the sealing system? | C663-22 and C664-22 backup rings are sized for specific seal locations and pressure requirements. C663-22 (e.g., Ф142.4×Ф151×1.7) is used for ram change cylinder and bonnet connections, while C664-22 (102.31x111.61x1.52) is for operating piston assemblies. They prevent seal extrusion under high pressure (especially during hydrostatic testing at 31.5MPa) and must be matched to the corresponding seal and component to maintain integrity. |
How to ensure the locking screws function reliably (62 turns per end)? | Lubricate the locking screw threads monthly with anti-corrosion grease to prevent seizing. During each inspection, verify the screws turn smoothly through all 62 turns—bind or resistance indicates debris buildup or thread damage. Clean threads with a solvent if needed, and replace damaged locking screws (2C24.03) immediately. Proper torque application during reassembly also ensures reliable locking performance. |
Procurement Guidance
The safety and reliability of Shanghai Shenkai FZ68-21U/2FZ68-21U BOPs depend entirely on genuine, model-compatible parts. We supply a full range of authentic components tailored to these models, including 2C24.01 series pipe rams (all sizes), 2C24.08.00 operating piston assemblies, SKZF sealing parts, secondary sealing mechanism components, TPM seals, and backup rings. All parts are manufactured to API Spec 16A, GB standards, and Shanghai Shenkai’s original equipment specifications, with traceable material certificates and batch records to ensure perfect fit, 21MPa pressure resistance, and consistent performance.
For procurement, align with the one-year recommended spare parts list to balance inventory cost and emergency response. Double quantities for 2FZ68-21U (double ram) models, and prioritize high-wear components (SKZF101.01 Y-rings, O-rings, C663-22/C664-22 backup rings, EM-09-L/25mm grease) and size-specific ram parts (top seals, ram bodies) based on your operational pipe sizes. Our oilfield technical experts provide free support to verify part compatibility, avoid mismatches, and optimize inventory based on your drilling scope. Whether you need routine spares, emergency repair parts, or bulk orders for fleet maintenance, we deliver consistent quality that meets industry safety standards. Contact us today to discuss your specific Shanghai Shenkai FZ68-21U series requirements and secure reliable parts for your well control operations.
Conclusion
The Shanghai Shenkai FZ68-21U (single ram) and 2FZ68-21U (double ram) BOPs are robust, reliable well control devices engineered to excel in 21MPa medium-pressure onshore and shallow offshore drilling operations. Their large 679.4mm bore, comprehensive ram system, layered sealing protection, and modular design make them adaptable to diverse pipe sizes and operational scenarios, from standard drilling to high-risk well interventions. The models’ high part commonality simplifies maintenance and reduces inventory costs, while compliance with global industry standards ensures safe, consistent performance.
This guide integrates authoritative technical insights, field-proven repair cases, and procurement best practices to support technicians and procurement professionals in maintaining operational continuity. By following model-specific maintenance schedules, using genuine Shanghai Shenkai parts, and leveraging the FAQs and troubleshooting tips, you can maximize the FZ68-21U series’ service life and mitigate operational risks. Partnering with a trusted supplier for authentic components ensures compliance with safety protocols, safeguarding personnel, assets, and wellbore integrity. Invest in quality parts and proactive maintenance to keep your Shanghai Shenkai FZ68-21U BOPs operating at peak performance.
contact us ：
Emeil: [email protected] whatsapp: +86 15275658619
Should you have any purchase intentions, please contact us – we will offer you our most favorable price.