Before production starts, the valve is carefully designed based on the customer’s requirements. Engineers review all technical details, select suitable materials, and make sure everything is ready for the next step.

All materials are strictly tested before production. A German spectrometer is used to check chemical composition. Impact tests ensure the material has enough strength. Dye penetrant testing is used to find invisible surface cracks. If required by the customer, magnetic particle testing and ultrasonic testing can also be carried out to guarantee material quality.

After material inspection, the forged pieces are turned on lathes to remove the surface layer and prepare for further processing. Each valve body then goes through two rounds of shot blasting to clean the surface and improve coating adhesion.

Naishi is equipped with CNC 4-axis machining centers, CNC vertical lathes, and a variety of CNC lathes, enabling a wide range of precision machining operations. All our operators possess extensive experience and technical expertise, guaranteeing exceptional accuracy and consistent quality throughout the manufacturing process. This commitment ensures we meet the highest industry standards and customer requirements.

Naishi certified welders have years of experience and follow strict international standards ASME and ISO to ensure weld quality and structural integrity. We offer various welding methods including manual welding, submerged arc welding (SAW), plasma welding, and fully automated welding. Torque wrenches are used during central bolt assembly to ensure even force distribution and precise alignment of the valve body.

Every valve produced by Naishi undergoes both gas pressure and hydrostatic (liquid) pressure testing to ensure sealing performance and pressure resistance. Weld seams are inspected using dye penetrant testing (PT), and wall thickness is verified with ultrasonic thickness gauges to ensure product integrity and compliance with specifications.

We also support third-party inspections upon request, and welding records or WPS (Welding Procedure Specifications) can be provided according to customer requirements.

All valve surfaces are coated with high-quality industrial paint to protect against corrosion and extend service life. The process includes sandblasting for surface preparation, followed by primer and top coat application based on customer requirements or international standards. Naishi offers various coating options such as epoxy and polyurethane, with thickness and finish strictly controlled. Color marking can also be customized as needed.

For export products, we use specially designed wooden crates that meet international shipping standards. To prevent corrosion in humid environments, anti-rust oil is applied to the interior surfaces of the valve bodies before packing. Smaller valves are packed in moisture-resistant wooden boxes to ensure protection during transportation. Our packaging ensures that every product reaches the customer in perfect condition.