The steam turbine EH oil system is a key control unit of modern thermal power generating units. The reliability of its hydraulic pressure measuring hose directly affects the safe operation of the unit. This article focuses on the fatigue life test data of the S100-AC-AC-0150 pressure measuring hose in a vibration environment, and combines the operating characteristics of the EH oil system with material mechanics analysis to reveal its performance and technical optimization path under extreme working conditions.

1. EH oil system operating environment and pressure measuring hose functional positioning

1.1 High pressure and vibration characteristics of EH oil system

The steam turbine EH oil system uses phosphate ester fire-resistant oil as the medium, and the working pressure is usually maintained at 14.5±0.5 MPa. The high-frequency pressure pulsation (up to 85 L/min flow fluctuation) generated by the operation of the core components of the system, such as high-pressure plunger pumps and overflow valves, is superimposed on the vibration of the turbine rotor (typical frequency range 5-50 Hz), forming a composite dynamic load environment. This working condition places strict requirements on the pressure resistance and fatigue resistance of the pressure measuring hose.

1.2 The key role of the S100-AC-AC-0150 pressure hose

The hose is connected between the hydraulic test point and the pressure sensor, and is responsible for transmitting the oil pressure signal in real time. Its failure may cause the control system to misjudge the oil pressure, thereby triggering the main pipe low pressure alarm (≤11.03 MPa joint start standby pump) or even trip protection (≤9.3 MPa joint trip turbine). Therefore, its fatigue life is directly related to the unit operation stability.

2. Analysis of the design characteristics of the S100-AC-AC-0150 pressure hose

2.1 Material selection and structural design

The inner lining of the S100-AC-AC-0150 pressure hose is made of fluororubber sealing material, which is resistant to chemical corrosion of fuel oil and has an operating temperature range of -20℃~150℃. Its reinforcement layer is a double-layer 316L stainless steel wire braided structure with a tensile strength of ≥2,000 MPa, ensuring a pressure safety factor of ≥4 times under 14.5 MPa working conditions. The outer sheath of the hose is oil-resistant chloroprene rubber, which is resistant to mechanical wear and ozone aging.

2.2 Structural optimization to improve anti-vibration performance

The minimum dynamic bending radius R=80 mm reduces the local stress concentration caused by vibration. The hose joint adopts a 24° cone + double ferrule sealing structure with an anti-loosening design. When the vibration acceleration is ≤5 g, the leakage rate is kept at <1 drop/minute. At the same time, a silicone vibration damping ring is added to the middle of the hose to attenuate the high-frequency vibration energy transmission.

3. Fatigue life test data and failure mechanism

In-depth analysis of the failure mechanism

Material fatigue cumulative damage: The alternating stress caused by vibration causes the initiation and expansion of microcracks in the steel wire braid layer;

Friction wear of the sealing interface: The high-frequency micro-displacement (≤50 μm) between the joint and the pipe body accelerates the wear of the sealing surface;

Thermo-mechanical coupling effect: The hardness of fluororubber decreases at a high temperature of 60°C (Shore A hardness from 75→65), and the deformation resistance is weakened.

In order to improve the fatigue life of the S100-AC-AC-0150 pressure measuring hose in a vibration environment, in addition to material upgrade and optimization, the damping design can be optimized and ultrasonic flaw detection can be used to screen the damage of the internal steel wire layer to further prevent the service life from being affected by vibration, providing key protection for the long-term safe operation of the EH oil system.

When looking for high-quality, reliable pressure measuring hoses, YOYIK is undoubtedly a choice worth considering. The company specializes in providing a variety of power equipment including steam turbine accessories, and has won wide acclaim for its high-quality products and services. For more information or inquiries, please contact the customer service below:

E-mail: sales@yoyik.com
Tel: +86-838-2226655
Whatsapp: +86-13618105229

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