In the manufacturing of critical ball valve components, advanced processing equipment and process parameters alone are not sufficient to guarantee final product reliability. Every ball, seat, and stem must pass through multiple layers of rigorous inspection — from raw material incoming to finished product outbound. YONGJIA TONGBALL Valve Co., Ltd. (TONGBALL) has established a full-process precision inspection system that exceeds industry standards, using data to uphold the commitment to "zero leakage" quality.
Gate 1: Raw Material Incoming Inspection – Eliminating Defects at the Source
All special alloys, ceramic powders, and coating materials must pass the following before entering production:
✅ Spectroscopic composition analysis: Using handheld XRF or direct-reading spectrometer to verify material grade and composition meet specifications (e.g., Hastelloy C276, Monel 400)
✅ Hardness testing: Rockwell/Vickers hardness tester multi-point inspection to ensure mechanical properties meet requirements
✅ Metallographic sampling: Microstructure examination for critical batches to exclude segregation, inclusions, and other internal defects
✅ Dimensional and surface preliminary inspection: Outer diameter, roundness, surface cracks, etc., of bar and tube stock
Only raw materials that 100% pass incoming inspection proceed to the next process.
Gate 2: In-Process Quality Control – Real-Time Monitoring During Machining
During precision machining, TONGBALL implements a first-article inspection + patrol inspection + final inspection three-tier quality control system:
First-article inspection: The first piece processed for each batch on each machine undergoes full dimensional inspection using a CMM. Mass production proceeds only after approval.
Patrol inspection: Quality inspectors perform regular sampling of work-in-process, focusing on key characteristics such as ball sphericity, sealing surface roughness, and stem concentricity.
Final inspection: After each batch is completed, final dimensional and visual inspection is performed according to AQL sampling standards.
Internal control standards for key precision indicators are far stricter than industry norms:
Ball sphericity: ≤0.005 mm (industry typical ≤0.025 mm)
Sealing surface roughness: Ra ≤0.1 μm (mirror finish)
Stem straightness: ≤0.01 mm/m
Gate 3: Coating and Heat Treatment Inspection – Verification of Enhanced Layer Quality
For HVOF coatings, PVD coatings, hardfacing layers, and heat-treated workpieces, TONGBALL performs specialized inspections:
✅ Coating thickness: Using eddy current or metallographic cross-section method to ensure uniform thickness within design range (0.2-0.5 mm)
✅ Coating bond strength: Tensile testing per ASTM C633, requiring ≥70 MPa
✅ Coating porosity: Evaluation under metallographic microscope, requiring <1% and no through-pores
✅ Coating hardness: Multi-point micro Vickers hardness testing, variation ≤5%
✅ Heat treatment effectiveness: Through hardness gradient or microstructure inspection to ensure residual stress relief and required mechanical properties
Gate 4: Ultimate Sealing Performance Test – Simulating Real Service Conditions
Every matched hard-seated ball and seat pair must pass high-pressure gas seal test and low-pressure gas seal test:
✅ High-pressure gas seal test: Holding pressure with nitrogen or air at 1.1 times rated pressure for ≥15 seconds, leak rate ≤0.1 cc/min per API 598
✅ Low-pressure gas seal test: Same holding pressure test at 0.6 MPa to verify low-pressure start-up sealing
✅ Helium mass spectrometry leak detection: For demanding applications such as LNG and vacuum, using helium mass spectrometer with sensitivity down to 10⁻⁶ Pa·m³/s, far superior to bubble method
TONGBALL's first-pass assembly yield for metal-sealed components consistently stays at ≥99.11% (based on 12 consecutive months of data), meaning very low rework rates and stable delivery quality.
Gate 5: Final Inspection and Outbound Release – The Last Line of Defense
Before finished products enter inventory, each piece must pass:
Visual and marking inspection: No dents or scratches, traceability code clearly readable
Key dimension re-inspection: Sampling or 100% inspection to ensure no deformation before/after transport
Cleanliness inspection: No oil, burrs, or metal chips
Documentation check: Material certificate, inspection report, and certificate of conformity complete
Only products that pass all items are released for delivery to customers.
Full Traceability – Every Product Has an "ID Card"
TONGBALL has established a full lifecycle traceability system. All information — from raw material heat number, processing equipment, operator, inspection data to finished product outbound — is recorded. Customers can query key inspection data using the traceability code on the product.
"Inspection is not the end point; it is a commitment to our customers."
—— Quality Manager, TONGBALL
"Every unit of cost we put into inspection reduces ten units of downtime risk for our customers. Exceeding industry standards is our dedication to 'zero leakage'."
Summary: TONGBALL Full-Process Precision Inspection System
Five gates: Raw material → In-process → Coating/heat treatment → Sealing test → Final inspection
Core equipment: Spectrometer, CMM, roughness tester, roundness tester, helium mass spectrometer, hardness tester, metallographic microscope
Key indicators: Ball sphericity ≤0.005 mm, roughness Ra ≤0.1 μm, coating bond strength ≥70 MPa, seal leakage ≤10⁻⁶ Pa·m³/s
Traceability: Every product traceable to complete records of raw material, process, and inspection
With the dual guarantee of precision manufacturing + full-process inspection, YONGJIA TONGBALL Valve continuously supplies stable, reliable, zero-leakage ball valve core components to global customers. Choosing TONGBALL means choosing verifiable quality.
