At Zhengmao Valve, quality control starts from incoming raw materials and continues through every stage of production. Each valve is manufactured under defined process requirements and fully tested before shipment. Pressure resistance, dimensional accuracy, and sealing performance are all checked to ensure the product meets relevant international standards for industrial pipeline use.
Internationally Recognized Quality Management System
Our manufacturing facility is designed to meet the stringent technical requirements of global engineering projects and procurement systems. We strictly comply with international standards to ensure systematic, repeatable, and fully auditable production:
Quality & Safety Systems: Certified under ISO 9001 (Quality Management), ISO 14001 (Environmental Management), and ISO 45001 (Occupational Health & Safety).
Manufacturing License: TS A1 Special Equipment Manufacturing License (highest pressure rating qualification), fully aligned with API-compliant manufacturing procedures.
Global Market Access: All products are designed and manufactured in accordance with CE (Pressure Equipment Directive 2014/68/EU) requirements, ensuring compliance with European and international regulatory frameworks.
Rigorous Incoming Material Inspection (IMI)
To reduce metallurgical risks and prevent premature field failures, 100% of incoming materials (forgings, castings, bars, and sealing components) are strictly inspected:
Chemical Composition Verification: Optical emission spectrometry and Positive Material Identification (PMI) are used to verify alloy elements (Cr, Ni, Mo, etc.) against ASME Section II requirements.
Mechanical Property Testing: Each batch undergoes destructive testing, including tensile strength, yield strength, and Charpy V-notch impact testing, to confirm structural integrity.
Non-Destructive Testing (NDT): High-pressure and critical-service castings undergo Radiographic Testing (RT) or Ultrasonic Testing (UT) as required. Machined surfaces are inspected using Magnetic Particle (MT) or Dye Penetrant (PT) testing.
Mill Test Certificate (MTC) Verification: No material is released to production without a valid EN 10204 3.1 Mill Test Certificate from approved steel mills. Each batch is traceable through an internal tracking system linked to its heat number.
In-Process Quality Control (IPQC)
During machining, fabrication, and pre-assembly, strict dimensional and tolerance controls are enforced directly on the shop floor to eliminate deviations:
CNC Precision Machining
Critical sealing surfaces, valve stems, and stuffing box dimensions are processed on high-precision CNC machines and verified using digital micrometers and Coordinate Measuring Machines (CMM).
Geometric Tolerance Control
Wall thickness (ASME B16.34), face-to-face dimensions (ASME B16.10), and flange finishes (ASME B16.5) are strictly controlled to ensure 100% installation compatibility.
In-Line Cleaning Process
All components are thoroughly cleaned before assembly to remove chips, cutting fluids, and grease, preventing seat contamination.
Advanced Performance Testing Capabilities
Every industrial valve is 100% individually tested before shipment. We do not use sampling inspection.
Shell Strength Testing: Conducted at 1.5 times the rated design pressure using water with corrosion inhibitors, in accordance with API 598 or ISO 5208 requirements.
High & Low Pressure Seat Testing:
• Hydrostatic Seat Test: 1.1 times design pressure to verify sealing performance.
• Pneumatic Low-Pressure Seat Test: 6 bar (80 psi) air or nitrogen test to detect micro-leakage, achieving API 598 or ISO 5208 Class A (zero visible leakage).
Functional & Torque Testing: Manual and actuated valves (pneumatic, electric, or hydraulic) undergo multi-cycle operation testing to verify breakaway torque, running torque, and limit switch accuracy.
Fugitive Emission Testing: For chemical and gas applications, testing is available in accordance with ISO 15848-1 or API 622/641 standards to ensure stem sealing integrity.
Specialized Testing Facilities & Equipment
Our dedicated testing center simulates real pipeline operating conditions to validate product performance before mass delivery:
Hydrostatic Test Rigs
Automated high-pressure systems capable of testing large-diameter and high-pressure valves.
Cryogenic Chambers
Liquid nitrogen testing down to -196°C (-320°F) for LNG service valves, in compliance with BS 6364.
High-Temperature Furnaces
Thermal testing up to +550°C (+1022°F) to evaluate expansion tolerance, structural stability, and graphite packing performance.
Final Pre-Shipment Inspection (FQC) & Packaging
Before packaging, final inspections ensure full compliance and project readiness:
Visual & Marking Inspection: Verification of surface quality, coating thickness (measured in microns), and nameplate data in accordance with MSS-SP-25 (Heat No., Size, Rating, Material Grade).
Quantity & Accessories Check: Confirmation that flanges, bolts, limit switches, solenoids, and actuators match project requirements.
Export-Ready Packaging: After testing, valves are fully dried. Flange faces are coated with anti-rust grease and fitted with protective covers. Large valves are securely packed in fumigated steel-reinforced wooden crates (IPPC ISPM 15 compliant) with moisture-absorbing desiccants for ocean transport protection.
Traceability Dossier & Quality Documentation
Each shipment includes a fully traceable quality dossier to support engineering approval, project audits, and asset management:
Material Test Certificates (MTC)
EN 10204 3.1 certificates including chemical composition and mechanical test results.
Pressure Test Reports
Detailed records of shell and seat test pressure, holding time, test medium, and leakage results (zero leakage).
Non-Destructive Testing Reports
RT, UT, MT, or PT reports issued by certified inspectors when required.
Certificates of Compliance
API, CE, and ISO certificates valid for the manufacturing year.