YONGJIA TONGBALL Valve Co., Ltd. (TONGBALL) recently completed a test on its hard sealed ball valve components: 500°C thermal shock testing. The test simulated temperature cycling scenarios that valves may encounter in actual service, validating product reliability under extreme temperature fluctuations.
What is Thermal Shock Testing?
Thermal shock testing involves heating components to a set high temperature and then rapidly cooling them, repeated multiple times, to assess the material's ability to withstand thermal stress.
In industries such as petrochemical, coal chemical, and high-temperature flue gas treatment, valves often experience rapid temperature changes during equipment start/stop or media switching. Such conditions impose higher demands on coating-to-substrate bond strength and material thermal shock resistance.
Test Method and Results
The test was conducted as follows:
Heating: Ball and seat assemblies were placed in a 500°C furnace and held until temperature uniformity
Quenching: Quickly removed and immersed in ambient temperature water
Cycling: Repeated the above steps multiple times
Inspection: After each cycle, coating appearance, adhesion, and air tightness were checked
Results:
No coating spalling or cracks
Sealing performance unaffected – zero leakage maintained
Technical Basis
The successful completion of this test is supported by:
Substrate matching: High-temperature alloys or heat-resistant stainless steel with thermal expansion coefficients compatible with coatings
Coating process: HVOF or plasma spray, bond strength ≥70MPa, porosity <1%
Precision machining: Sealing surface roughness Ra≤0.1μm, minimizing stress concentration
"Many valves perform well under sustained high temperatures but fail when temperatures change rapidly."
—— TONGBALL Technical Director
"The 500°C thermal shock test validates reliability under such conditions."
Applicable Services
Hard sealing components that have passed this test are suitable for:
Coal chemical black water/grey water systems (large temperature fluctuations, solid particles)
FCC units (frequent switching between high-temperature regenerator and reactor)
High-temperature flue gas desulfurization (rapid flue gas temperature changes)
Hot oil / molten salt systems (thermal shock during start/stop cycles)
Summary
Test item: 500°C → ambient quench, multiple cycles
Pass criteria: No coating spalling or cracks, zero leakage
Technical enablers: Substrate matching + HVOF coating + ultra-precision machining
Application value: Suitable for severe service with dramatic temperature fluctuations
YONGJIA TONGBALL Valve uses testing standards that exceed industry requirements to ensure product reliability under real service conditions.
