Product Introduction
This curated assortment covers all high-wear and mission-critical components for NOV 325 and 33003 relief valves, including valve seats, piston body sub-assemblies, piston caps, multi-profile piston seals, retainer seals, stem bushings and sour-service O-rings. All parts comply with API 6A, API 16C pressure control standards, ISO 9001 quality benchmarks and NOV OEM performance requirements, with full material traceability and hydrostatic pressure testing up to 15,000 PSI. The lineup includes nitrided steel wear components, corrosion-resistant valve seats, high-durability elastomer seals and sour-service compatible O-rings, fully mapped to OEM part numbers for simplified inventory and emergency field repairs.
Functional Performance Specifications
These NOV relief valve spare parts deliver industry-leading pressure control performance: precision-machined valve seats provide a leak-tight sealing surface with a maximum allowable leak rate of ≤0.01 SCFM at full operating pressure; nitrided steel retainer seals and piston bushings reduce friction wear by 40% compared to standard components, extending service life to 6,000+ operating cycles; upper and lower piston seals maintain consistent compression under pressure fluctuations, eliminating seal extrusion; sour-service RX O-rings resist H₂S degradation, ensuring safe operation in sour gas environments; and piston sub-assemblies deliver smooth, responsive actuation with a response time of ≤25 milliseconds for instant overpressure protection.
Structural & Material Features
- OEM-Certified Precision Machining: All metal components are machined to ±0.0005 inch tolerance for perfect alignment, eliminating premature wear and fitment delays
- High-Performance Material Selection: 4130 nitrided steel for retainer seals and wear components, hardened stainless steel for valve seats, fluoroelastomer for standard seals and Kalrez®-compatible elastomers for sour-service O-rings to resist abrasion, corrosion and chemical degradation
- Modular Seal Design: Pre-shaped piston seals and O-rings ensure quick installation, cutting field repair time by 50% and minimizing non-productive time on drilling rigs
- High-Pressure & Sour-Service Rating: Components rated for operating pressures up to 15,000 PSI and compatible with sour gas (H₂S) environments, meeting strict oilfield safety standards
- Wear-Resistant Surface Treatment: Nitriding and hardening processes on metal components boost surface hardness to HRC 55-60, extending wear life under high-cycle operation
Applicable Operating Conditions
These spare parts are built for harsh oilfield pressure control environments, optimized for NOV 325 and 33003 relief valves used in mud pump overpressure protection, hydraulic system regulation and high-pressure drilling circuits. They perform reliably in ambient temperatures ranging from -20°F to 350°F, handle abrasive drilling mud, corrosive well fluids and sour gas conditions, and operate under continuous high-pressure cycling. Components are suitable for remote onshore rigs, offshore platforms and hazardous wellsite locations.
Maintenance & Service Recommendations
- Inspect valve seats, piston seals and O-rings every 30 operating hours for wear, extrusion or corrosion to maintain leak-tight performance
- Lubricate piston stems and bushings with NOV-recommended compatible grease during installation to prevent sticking and ensure smooth actuation
- Replace all seal components and O-rings during every valve overhaul, typically every 6 months or 3,000 operating cycles, to avoid unexpected failure
- Check piston assembly alignment and seat contact pressure quarterly to ensure consistent pressure regulation accuracy
- Stock critical wear parts (valve seats, seals, O-rings, piston sub-assemblies) at recommended minimum levels to avoid unplanned pressure control downtime
- We supply the following spare parts:
| item | Part No. | code | Name | UNIT |
| 1 | 32524 | 10297641-001 | SEAT OF VALVE | pc |
| 2 | 33003-01 | 10297650-001 | PISTON, BODY SUB ASSY POP VLV | pc |
| 3 | 32500-02/M2 | 10297633-001 | CAP, PISTON ASSY | pc |
| 4 | 32501-2 | 10297636-001 | SEAL, LOWER PISTON | pc |
| 5 | 32512 | 10308480-001 | SEAL, RETAINER 4130 NITRIDED | pc |
| 6 | 31914 | 10308452-001 | SEAL, UPPER PISTON(SHOULDER) | pc |
| 7 | 31909 | 18675020-001 | SEAL, PISTON STEM BUSHING | pc |
| 8 | 702640-03-20 | 10302902-001 | O-RING, R PISTON CAP, FACE SEAL | pc |
| 9 | 702640-24-31 | 10303190-001 | O-RING, RX SUB (SOUR SERVICE) | pc |
| 10 | 3251 | 10308480-001 | SEAL, FACE | pc |
Field Failure Repair Case Studies
Case 1: NOV Relief Valve Lower Piston Seal Leakage
A NOV 325 series relief valve experienced persistent pressure leakage due to a degraded lower piston seal (32501-2). The worn seal lost compression under operating pressure, causing slow pressure bleed-off. Installing an OEM lower piston seal restored full sealing integrity, eliminated leakage and maintained consistent pressure regulation.
Case 2: Piston Body Sub-Assembly Sticking
A NOV 33003 relief valve failed to actuate properly due to a worn piston body sub-assembly (33003-01) with surface scoring. The damaged piston stuck in the valve bore, preventing overpressure relief. Replacing the piston sub-assembly with an OEM unit restored smooth actuation and ensured reliable overpressure protection.
Case 3: Sour-Service O-Ring Degradation
A relief valve in a sour gas well experienced seal failure due to a deteriorated RX sub O-ring (702640-24-31). The standard O-ring could not withstand H₂S exposure, causing gas leakage. Swapping in a sour-service OEM O-ring resolved the leakage issue and complied with hazardous wellsite safety standards.
Frequently Asked Questions (FAQ)
| Question | Answer |
| Are these parts compatible with both NOV 325 and 33003 series relief valves? | Yes, this parts list includes OEM-matched components designed for both NOV 325 and 33003 relief valve models, with direct drop-in fitment for all listed part numbers. |
| Do these spare parts meet API pressure control standards? | Absolutely, all components comply with API 6A and API 16C standards for oilfield pressure relief valves, matching NOV OEM quality and safety benchmarks. |
| Are the O-rings suitable for sour gas (H₂S) well environments? | Yes, the 702640-24-31 RX sub O-rings are specifically engineered for sour service, resisting H₂S degradation and ensuring safe operation in sour gas wells. |
Procurement Guidance & Closing Value Statement
This NOV 325 & 33003 relief valve spare parts list serves as both a formal procurement benchmark and a technical troubleshooting reference, designed to minimize costly wellsite downtime, reduce long-term maintenance expenses and uphold the pressure safety and operational reliability of your drilling and hydraulic systems. Each part is a verified OEM-grade component that eliminates the risks of substandard aftermarket parts, ensures API compliance, and delivers consistent durability in harsh oilfield conditions.
Whether you need to replace worn valve seats, faulty piston assemblies, degraded seals, damaged bushings or sour-service O-rings to restore your NOV relief valve, or stock critical spares for routine maintenance and emergency repairs, this catalog provides the exact parts, quantities and specifications your operation demands. Secure your supply of authentic NOV relief valve spare parts today to protect your equipment investment, maintain uninterrupted pressure protection workflows, and keep your wellsite operations running safely and efficiently.
