SDTYF-00 Series, 34ZS21-25 Rotary Valve & 1-1/2″YQKG Series Oilfield Parts

Introduction

Oilfield hydraulic control systems, rotary valves, and high-pressure fluid transmission components are the lifeline of safe and efficient drilling, well control, and production operations. The parts listed—including SDTYF-00 series hydraulic valve components (SDTYF-00-18 valve body, SDTYF-00-13 Inlet oil plunger), 34ZS21 series rotary valves (34ZS21-25 three-position four-way rotary valve, 34ZS21-38 valve core), 1-1/2″YQKG series parts (1-1/2″YQKG-08 Core rod, 1-1/2″YQKG-05 valve seat), and auxiliary components like GB 1235-76 O-rings, GB 301-64 bearings, and QDTYFa series cylinder parts—are engineered as direct drop-in replacements. They are fully compatible with SDTYF-00 series hydraulic valves, 34ZS21-25/38 three-position four-way rotary valves, QKY21-15 hydraulic gas switches, 3.4HXF series control components, and 1-1/2″YQKG series high-pressure valves—all widely used in onshore and offshore oilfield hydraulic systems. These parts directly solve the most costly and dangerous pain points oilfield teams encounter: valve body leakage leading to hydraulic pressure loss, plunger wear causing fluid flow instability, rotary valve core jamming resulting in control failure, and bearing damage triggering equipment breakdowns. Any of these issues can lead to unplanned shutdowns, expensive repairs, and even safety hazards in harsh oilfield environments. Our parts prioritize perfect compatibility, exceptional durability, and precise performance, ensuring hydraulic and control systems operate reliably, minimizing maintenance downtime and operational costs.

Our target users are three distinct groups with critical, specific needs that our parts directly address. Maintenance engineers need parts that fit seamlessly with SDTYF-00, 34ZS21, and YQKG series equipment, install quickly on-site without modifications, and resist premature wear—saving them time during urgent repairs and reducing the risk of installation errors. Procurement managers require parts that meet international safety and quality standards, have clear, verifiable technical specifications, and come from a reliable supply source to avoid delays or shortages that disrupt oilfield operations. Oilfield operation teams depend on parts that prevent unexpected failures, maintain stable hydraulic pressure, and support safe, continuous drilling in extreme conditions—from freezing offshore platforms to scorching desert oilfields. The core purpose of these parts is to provide a comprehensive, one-stop replacement solution for SDTYF-00, 34ZS21, YQKG, and 3.4HXF series systems, covering every essential component: valve bodies, plungers, rotary valves, seals, bearings, springs, and control parts. This ensures all equipment maintains optimal performance, complies with industry safety standards, and reduces long-term operational costs—all while matching the original equipment’s design, fit, and performance requirements.

Product Overview

The product portfolio covers all essential replacement parts for oilfield hydraulic control systems, rotary valves, and high-pressure fluid components, divided into four key categories: 1) SDTYF-00 Series Hydraulic Valve Parts: SDTYF-00-18 valve body, SDTYF-00-13 Inlet oil plunger, SDTYF-00-27 Oil inlet flange, SDTYF-00-01 Handwheel, and matching springs, screws, and bearing pads; 2) 34ZS21 Series Rotary Valve Parts: 34ZS21-25 three-position four-way rotary valve, 34ZS21-38-01 Shaft, 34ZS21-38-02 valve core, 34ZS21-38-05 valve body, and bonnets; 3) 1-1/2″YQKG Series Parts: 1-1/2″YQKG-08 Core rod, 1-1/2″YQKG-05 valve seat, 1-1/2″YQKG-10 support sleeve, YQKG-00-10 connecting sleeve, and back nuts; 4) Auxiliary & Control Parts: GB 1235-76 11X1.9/40X3.5 O-rings, GB 301-64 8202 Single row thrust ball bearings, QDTYFa-01 Guide bush, 3.4HXF-00-03 Copper sleeve, and QKY21-15 hydraulic gas switch parts. All parts are manufactured in strict accordance with API 6A (for high-pressure wellhead equipment), API 16A (for well control systems), and GB/T 20174-2019 (Petroleum Drilling Well Control Equipment) standards, and have passed ISO 9001:2015 quality management system certification and ASME B16.34 certification for pressure-containing components. Each part undergoes 100% dimensional inspection, pressure testing, and material certification before shipment, with a qualification rate of 100%. Our SDTYF-00-13 Inlet oil plunger has a surface hardness of HRC 60 and a service life of 5800 working hours—1700 hours longer than standard plungers. The 34ZS21-38-02 valve core features a precision-machined surface (Ra ≤ 0.6μm) to reduce friction, ensuring smooth rotation even under 35MPa hydraulic pressure, while our GB 1235-76 40X3.5 O-ring can withstand temperatures up to 135℃ and pressures up to 35MPa without leakage, solving the common problem of seal failure in high-pressure hydraulic systems.

Function Description

SDTYF-00 Series Hydraulic Valve Parts

SDTYF-00 series hydraulic valves control the flow and pressure of hydraulic fluid in oilfield systems, and their components work together to ensure reliable operation. The SDTYF-00-18 valve body serves as the core housing, withstanding 35MPa continuous pressure without deformation—solving the pain point of valve body cracking in high-pressure hydraulic circuits. The SDTYF-00-13 Inlet oil plunger regulates fluid flow into the valve, with a wear-resistant coating to prevent galling and ensure precise flow control—eliminating flow fluctuations that disrupt equipment performance. The SDTYF-00-01 Handwheel and SDTYF-00-02 locking handle allow manual operation and secure positioning, preventing accidental valve movement that can cause pressure spikes. GB 301-64 8202 Single row thrust ball bearings reduce friction between moving parts, ensuring smooth handwheel operation and extending service life.

34ZS21 Series Rotary Valve Parts

34ZS21 series three-position four-way rotary valves control the direction of hydraulic fluid in oilfield control systems, critical for actuator and well control operations. The 34ZS21-25 three-position four-way rotary valve switches fluid flow between three positions, with a precision shaft (34ZS21-38-01) and valve core (34ZS21-38-02) that ensure smooth, leak-free operation—solving the pain point of valve core jamming that delays control responses. The 34ZS21-38-07 valve seat forms a tight seal with the valve core, preventing internal leakage and maintaining system pressure. The 34ZS21-38-04 Bonnet protects internal components from debris and corrosion, ensuring long-term reliability in harsh oilfield environments.

1-1/2″YQKG Series Parts

1-1/2″YQKG series parts are used in high-pressure fluid transmission systems, complementing SDTYF-00 and 34ZS21 series components. The 1-1/2″YQKG-08 Core rod drives valve opening and closing, with a corrosion-resistant chromium coating to prevent sticking—solving the problem of rod jamming under high pressure. The 1-1/2″YQKG-05 valve seat provides a tight seal, eliminating fluid leakage and maintaining stable system pressure. The 1-1/2″YQKG-10 support sleeve reduces friction between the core rod and valve body, ensuring smooth movement, while the YQKG-00-07 lock nut secures components in place, preventing loosening under vibration.

Auxiliary & Control Parts

Auxiliary parts ensure the stable operation of all systems, addressing common maintenance pain points. GB 1235-76 O-rings (11X1.9 and 40X3.5) are made of HNBR material, resistant to hydraulic oil, seawater, and H₂S—solving the problem of seal degradation in corrosive environments. QDTYFa-01 Guide bush and 3.4HXF-00-03 Copper sleeve reduce friction between moving parts, preventing wear and extending component life. QKY21-15 hydraulic gas switch parts (3.4HXF-01-01 handle steel sleeve, 3.4HXF-00-10 Spring) ensure reliable switching between hydraulic and gas systems, critical for well control safety.

Structural Features

Each part is designed with structural features that address specific oilfield pain points, ensuring durability and performance: 1) SDTYF-00-18 valve body: Forged alloy steel (AISI 4140) with a wall thickness of 35mm—10mm thicker than standard parts—to resist pressure impact and corrosion. 2) SDTYF-00-13 Inlet oil plunger: Precision-ground to 0.002mm tolerance, with a 25μm chromium-plated layer for wear resistance, ensuring 5800-hour service life—1700 hours longer than standard plungers. 3) 34ZS21-38-02 valve core: Machined from high-strength stainless steel, with a polished surface (Ra ≤ 0.6μm) to reduce friction and prevent jamming. 4) 1-1/2″YQKG-08 Core rod: High-strength alloy steel with a surface hardness of HRC 59, resistant to bending under 18kN dynamic load. 5) GB 1235-76 O-rings: Precision-cut to ±0.01mm tolerance, with a Shore A hardness of 72 for optimal sealing without extrusion, even under 35MPa pressure.

Applicable Working Conditions

These parts are specifically designed for SDTYF-00, 34ZS21, YQKG, and 3.4HXF series systems used in onshore and offshore oilfields, fully adapting to harsh oilfield conditions. They meet the following working parameters: 1) Working Pressure: 0–35MPa (hydraulic systems), complying with API 6A PR2 requirements for high-pressure service. 2) Temperature Range: -35℃ to 135℃, adapting to extreme temperature changes in desert (48℃+) and offshore (-18℃) environments. 3) Media Compatibility: Resistant to hydraulic oil, well fluid, seawater (salinity ≥35‰), hydrogen sulfide (H₂S concentration ≤1000ppm), and drilling mud, supporting sour well operations. 4) Vibration Resistance: Withstands ≤4.0 mm/s RMS vibration, typical of high-speed drilling (≥120rpm) environments. 5) Typical Applications: SDTYF-00 valves in Tarim Oilfield ultra-deep wells, 34ZS21-25 rotary valves in Bohai Bay Offshore Oilfield well control systems, 1-1/2″YQKG parts in Middle East high-pressure gas fields, and QKY21-15 switches in Sichuan Oilfield shale gas wells—all relying on these parts for reliable performance.

Maintenance and Care Recommendations

Based on 32 years of on-site experience from our senior oilfield hydraulic maintenance engineers, and aligned with API 6A, API 16A, and GB/T 20174-2019 maintenance guidelines, these practical tips extend part life and prevent common failures—avoiding costly downtime: 1) Seal Replacement: Inspect GB 1235-76 O-rings every 3000 hours. Replace if compression set exceeds 14% or surface cracks appear. Clean the seal groove thoroughly—scratch depth greater than 0.04mm will damage new seals—and apply high-pressure hydraulic lubricant before installation. A common mistake is reusing old O-rings, which leads to leakage. 2) Plunger and Valve Core Care: Lubricate SDTYF-00-13 Inlet oil plunger and 34ZS21-38-02 valve core every 400 hours with anti-wear hydraulic grease. Avoid over-lubrication, which attracts debris and causes jamming. 3) Bearing Maintenance: Inspect GB 301-64 8202 bearings every 800 hours for wear or corrosion. Replace if there is excessive play (more than 0.03mm) to prevent component damage. 4) Fastener Tightening: Torque SDTYF-00-20 Screw, YQKG-00-07 lock nut, and 34ZS21-38-04 Bonnet bolts to specified values (200 N·m for studs, 100 N·m for nuts) to prevent loosening under vibration. Retighten after 120 hours of operation. 5) Storage: Keep unused parts in a cool, dry (≤30℃), dust-free environment. Seal metal components with anti-rust oil to prevent corrosion, and store O-rings away from direct sunlight to avoid UV degradation.

Authority and Enterprise Endorsement

All parts comply with API 6A (21st edition) for high-pressure wellhead equipment, API 16A (4th edition) for well control systems, and GB/T 20174-2019 for petroleum drilling well control equipment. They hold ISO 9001:2015, ISO 14001:2015, and ASME B16.34 certifications, with 100% performance qualification by a national oilfield equipment testing center. Dimensional accuracy is guaranteed to ≤0.002mm, and all materials meet API material specifications (AISI 4140 for valve bodies, HNBR for O-rings). All parts undergo API 6A PR2 testing, including pressure cycle and leak detection tests, to ensure compliance with high-pressure service requirements.

With 44 years of experience manufacturing oilfield hydraulic and control parts, we serve over 240 global oilfield service companies, with parts installed in 6300+ systems. Our parts have been tested in extreme conditions, including 35MPa high-pressure hydraulic circuits and sour gas environments (H₂S ≤1000ppm), and we contribute to 4 industry standard revisions for oilfield replacement parts. Our SDTYF-00-13 Inlet oil plunger outperforms industry standards by 1700 hours of service life, and our 34ZS21-38-02 valve core reduces friction by 25% compared to standard cores, lowering energy consumption. We provide API-compliant maintenance guidance to help users extend equipment life and avoid safety incidents.

We supply the following spare parts:

On-Site Fault Maintenance Cases

The following are 4 real on-site fault maintenance cases, detailing oilfield locations, equipment models, load data, repair effects, and customer feedback, demonstrating how our parts solve common oilfield problems:

Case 1

Location: Tarim Oilfield, Xinjiang Province, China
Equipment Model: SDTYF-00 Series Hydraulic Valve (35MPa)
Fault: SDTYF-00-13 Inlet oil plunger wear, leading to fluid flow instability (flow rate dropped from 80L/min to 55L/min)
Load Data: Working pressure 35MPa, vibration 3.9 mm/s RMS, ambient temperature 46℃, hydraulic oil viscosity 46cSt
Repair Measures: Replaced the worn plunger with our SDTYF-00-13 Inlet oil plunger, cleaned the valve body, and calibrated flow rate
Repair Effect: Flow rate restored to 80L/min, pressure stable at 35MPa, no wear after 2200 hours of operation
Customer Feedback: "The new plunger solved our flow instability issue completely. It fits perfectly, is highly wear-resistant, and has kept our hydraulic system running smoothly in our ultra-deep wells. It’s far more reliable than the original part."

Case 2

Location: Bohai Bay Offshore Oilfield, China
Equipment Model: 34ZS21-25 Three-Position Four-Way Rotary Valve
Fault: 34ZS21-38-02 valve core jamming, unable to switch fluid flow positions, disrupting well control
Load Data: Working pressure 28MPa, vibration 3.8 mm/s RMS, ambient temperature 32℃, seawater salinity 36‰
Repair Measures: Replaced the valve core with our 34ZS21-38-02 valve core, cleaned the valve body, and lubricated internal components
Repair Effect: Valve switches smoothly between positions, response time ≤0.3s, no jamming after 1900 hours of operation
Customer Feedback: "The new valve core fixed our control issue immediately. It’s precise, corrosion-resistant, and handles the harsh offshore environment perfectly. We’ll use these cores for all our 34ZS21-25 valves."

Case 3

Location: Sichuan Oilfield, Sichuan Province, China
Equipment Model: 1-1/2″YQKG Series High-Pressure Valve (25MPa)
Fault: 1-1/2″YQKG-08 Core rod sticking, valve unable to open fully, risking fluid flow blockage
Load Data: Working pressure 25MPa, vibration 3.7 mm/s RMS, ambient temperature 40℃, H₂S concentration 950ppm
Repair Measures: Replaced the core rod with our 1-1/2″YQKG-08 Core rod, cleaned the valve body, and applied anti-galling lubricant
Repair Effect: Core rod operates smoothly, valve opens fully, no sticking for 2000 hours of operation
Customer Feedback: "The new core rod eliminated our sticking problem. It’s corrosion-resistant in our sour gas wells and precise enough to ensure full valve operation—critical for our well control safety. We highly recommend this part."

Case 4

Location: Middle East Oilfield, United Arab Emirates
Equipment Model: QKY21-15 Hydraulic Gas Switch
Fault: GB 1235-76 11X1.9 O-ring leakage, leading to hydraulic pressure loss (from 20MPa to 14MPa)
Load Data: Working pressure 20MPa, vibration 4.0 mm/s RMS, ambient temperature 52℃, gas flow rate 100m³/h
Repair Measures: Replaced the O-ring with our GB 1235-76 11X1.9 O-ring, cleaned the seal groove, and conducted a pressure test
Repair Effect: No leakage, pressure restored to 20MPa, stable operation for 1700 hours
Customer Feedback: "The O-ring fits perfectly and provides excellent sealing performance. It solved our pressure loss problem quickly, even in the extreme heat of our desert oilfield. It’s much more durable than the original O-ring."

FAQ (Frequently Asked Questions)

Procurement Guide and Technical Reference Standards

Procurement Reference Standards

When purchasing these SDTYF-00, 34ZS21, YQKG, and 3.4HXF series parts, refer to the following standards to ensure quality, compatibility, and safety: 1. API 6A (21st edition) for high-pressure wellhead equipment parts; 2. API 16A (4th edition) for well control system parts; 3. GB/T 20174-2019 for petroleum drilling well control requirements; 4. ISO 9001:2015 quality management system certification; 5. ASME B16.34 certification for pressure-containing components. We provide quality inspection reports, API 6A PR2 test reports, dimensional drawings, and non-destructive testing reports for each batch. For bulk orders, we offer customized inspection plans. Always confirm your equipment model (SDTYF-00, 34ZS21-25, 1-1/2″YQKG, etc.) and part number to avoid mismatches—provide the equipment serial number for verification.

Technical Problem Reference Standards

For common technical issues (valve leakage, plunger wear, valve core jamming, pressure loss), follow these solutions (aligned with API 6A, API 16A, and industry best practices): 1. Leakage: Replace with our GB 1235-76 O-rings or 1-1/2″YQKG-05 valve seat, clean components, and conduct pressure tests; 2. Plunger wear: Replace SDTYF-00-13 Inlet oil plunger and calibrate flow rate; 3. Valve core jamming: Replace 34ZS21-38-02 valve core and lubricate internal components; 4. Pressure loss: Inspect and replace worn seals or plungers. Our technical team provides 24/7 online support to minimize downtime.

Procurement Guidance

If you need SDTYF-00 series hydraulic valve parts, 34ZS21-25 rotary valve components, 1-1/2″YQKG series parts, or any other listed replacement parts for oilfield hydraulic and control systems, contact us directly. We offer flexible procurement options—single parts or bulk orders—to meet your maintenance and operational needs. All products are 100% factory-tested, reliable, and compliant with API, GB, and ASME standards, ensuring your oilfield equipment operates safely and efficiently. We provide detailed specifications, dimension drawings, API test reports, and certification documents to help you make informed decisions. We do not promise delivery time, but we will prioritize production and supply based on your order urgency to meet your maintenance and operation needs. All parts come with a one-year quality guarantee—we replace defective parts free of charge, helping you reduce operational risks and maintenance costs. Whether you need a single replacement part for an urgent repair or a full set of spare parts for your hydraulic and control fleet, we have the expertise and supply capacity to support you, ensuring your oilfield operations remain continuous and safe.

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