NOV TYPE CH reset safety valve
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technical feature |
Core Customer Value (Core Value) |
Advantage quantification |
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Self/quick reset function |
Significantly improve the safety of operation and resume normal operation immediately after the overvoltage event |
Significant reduction in non-production time (NPT) caused by replacement of shear pin or blasting sheet |
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High wear resistance/corrosion resistant material |
It can maintain long life in harsh environment such as high abrasion and sulfur content |
Save long-term maintenance, spare parts procurement and replacement costs |
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High precision pressure relief setting |
Precisely protect downstream equipment to avoid overpressure damage or unnecessary pressure relief shutdown |
Improve system reliability and control accuracy |
Detailed working principle: automatic reset technology analysis (H2)
The NOV Type CH reset safety valve uses an advanced mechanical/hydraulic linkage design to achieve the "automatic reset" function without manual intervention, which makes it far more convenient than traditional one-time pressure relief devices.
Automatic reset mechanism: goodbye to the shear pin (H3)
The pressure relief mechanism of the Type CH valve is based on a balance between the system hydraulic pressure and the internal mechanical reset force.
Working principle: The hydraulic pressure in the system directly acts on the ball and valve seat mechanism 1. When the system pressure is lower than the set value, the ball remains in position to prevent fluid flow.
Pressure relief trigger: Once the pipeline pressure exceeds the preset value, the sphere begins to leave the valve seat (unseat), and the overpressure fluid is released through the outlet branch.
Reset action: After pressure relief, Type CH valve is self-resetting 1. The disc spring is configured inside the valve. Once the overpressure is eliminated, the disc spring mechanism can ensure that the valve quickly returns to seat and seal, and return to normal working state.
Buffer design: The early Retsco Titan Class "CH" valve (which is used) uses a pressure balance chamber (pressure balance chamber) to throttle fluid through the piston port to achieve hydraulic buffering, thus smoothing the opening motion of the piston.
Comparison with traditional pressure relief devices (H3)
Traditional shear pin (Shear Pin) or rupture disc (Rupture Disc) safety valves must manually replace damaged components after pressure relief, while the automatic reset feature of Type CH valve directly eliminates this pain point.
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Comparison of characteristics |
Resettable Relief Valve |
Shear pin/rupture disc (Shear Pin/Rupture Disc) |
Summary of client benefits |
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Status after decompression |
Automatic reset, resume operation immediately |
Replacement of shear pin or blasting cap is required and the system must be shut down |
Eliminate non-productive time (NPT) and achieve operational continuity |
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cost structure |
The initial investment is high, but it can be reused and the long-term cost is low |
The initial cost is low, but each activation requires replacement parts and labor costs |
Long-term operating costs are significantly reduced |
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tightness |
Although wear may occur, it can be restored through maintenance |
The shrapnel provides absolute sealing before it breaks |
It can be improved by combining detonators/safety valves in series |
Performance parameters and industry standards (H2)
Pressure class and bore range (H3)
NOV's line of pressure relief valves covers the most demanding pressure requirements in the oil and gas industry.
Type CH series related pressure range:
Titan C/B Series: Pressure ratings range from 400 psi to 5000 psi.
Titan RX Series: Pressure ratings range from 2,000 psi to 8,000 psi.
Anson™ high pressure valve (standard service): working pressure up to 20,000 psi (Fig 2002).
Anson™ high pressure valve (with sulfur service): working pressure up to 15,000 psi (Figure 2202).
Size range: The NOV high-pressure flow line equipment series includes fittings designed for 20,000 psi service. Figure 2202 shows that the hammering specifications typically cover 2 ", 3", and 4" sizes.
Material specification and adaptability to harsh working conditions (H3)
Type CH valves are manufactured from high-performance materials to ensure reliability in extreme pressure and corrosive fluids (e.g. in sulfur-containing H₂S environments).
Valve body material: usually made of forged steel, can be customized to meet API 6A specifications. High pressure valves require industrial grade materials with excellent tensile strength and yield strength, such as stainless steel, carbon steel or special alloys.
Sour Service (SAS):
For harsh environments containing sulfur (H₂S), NOV offers NACE MR0175-compliant valves such as the Fig 2202 Acid Gas Service Valve, which operates at pressures up to 15,000 psi. The NACE MR0175 standard imposes strict requirements on materials like high-nickel alloys and specialty stainless steels to prevent sulfide stress corrosion cracking in H₂S environments.
Valve internals/seals: For critical applications requiring higher temperature and corrosion resistance, special nickel alloys such as Inconel, Hastelloy, or Monel are used as valve internals. The selection of seals will depend on specific temperature and chemical compatibility requirements to meet customer needs across various operating fluids.
Manufacturing process and reliability assurance (H2)
The manufacturing process of high pressure valves focuses on improving the durability and reliability of products, especially under high wear and high pressure differential conditions.
Manufacturing basis: The main body of the valve is forged steel, which has better mechanical properties and internal structural integrity than cast parts, and can withstand high pressure.
Surface strengthening technology: In order to ensure the wear resistance of key valve internals such as valve seat and ball under high speed fluid scouring, the following surface treatment technology is often adopted:
Stellite (Stellite) cladding: Stellite is a cobalt based alloy known for its excellent wear resistance, corrosion resistance and high temperature stability.
Tungsten Carbide Coating: This advanced coating is produced through High-velocity Oxygen Fuel (HVOF) spraying technology, which deposits carbide particles onto sealing surfaces at high speeds. The process creates a robust coating with exceptional adhesion, hardness (up to 1400 HV), and low porosity. These properties significantly enhance valve erosion resistance and wear performance, effectively extending service life in high-erosive fluid environments.
Typical application scenario (H2)
The NOV Type CH reset safety valve is a core component of high pressure gas field services and is suitable for operations where safety and continuity are extremely high.
- Fracturing/Stimulation: In applications such as shale gas, high pressure fracturing pump trucks apply extremely high pressure to the flow line 1. The Type CH valve acts as the final safety barrier to protect the pump and flow line from sudden overpressure.
- Pressure Controlling Drilling (MPD): The Type CH valve is used in the pressure controlling drilling system to prevent wellbore accidents by precisely releasing pressure, and its rapid reset characteristics help reduce total non-production time (NPT) of drilling.
- Acidizing and cementing: These operations involve corrosive fluids and high pressure pumping, and valves need to withstand complex media, where Type CH's corrosion resistance plays a key role.
- Wellhead safety protection: used to protect Christmas tree, test separator and pipe hanger system from pressure transients during pumping or production to ensure the integrity of the entire system.
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