Which Details in Valve Production Determine Service Life?

For buyers, the service life of valves is directly related to procurement costs and production safety. For valves of the same specification, the core difference in service life lies in production details. The following sorts out 6 key details to help you avoid procurement pitfalls and select durable valves.

 

 

The production process of valve blanks (valve bodies, bonnets and other core components) is the basis for determining their pressure resistance and corrosion resistance, and is also an easily overlooked point for buyers.

Casting Details: Strictly control the smelting composition to avoid loose material caused by impurities and prevent hidden defects such as shrinkage cavities and sand holes; annealing and normalizing are required after casting to eliminate internal stress. Buyers can request X-ray and ultrasonic flaw detection reports to rule out defective blanks.

Forging Details: Valves for high-pressure and high-temperature working conditions are mostly forged. It is necessary to control temperature, pressure and deformation, and perform tempering treatment after forging to avoid forging cracks and interlayers; otherwise, deformation and fracture are likely to occur under long-term pressure bearing.

 

 

The sealing performance of valves depends on precision machining, and even minor errors can lead to leakage and accelerated wear.

Sealing Surface Machining: It needs to go through multiple processes such as finish turning and grinding, with a surface roughness of less than Ra0.8μm; high-end valves can be overlay welded with hard alloy to improve wear resistance and corrosion resistance. Buyers should pay attention to the machining process and material.

Inner Cavity and Thread Machining: The inner cavity needs to be finish bored and polished to reduce medium erosion; threads adopt rolling process to improve precision and wear resistance, avoiding loose assembly and leakage.

 

 

Materials must be accurately matched with the medium, temperature and pressure; otherwise, no matter how precise the machining is, it will be useless. Many buyers neglect adaptation, leading to premature damage of valves.

Valve Body Material: Carbon steel is selected for general working conditions, 304/316L stainless steel or special alloy for corrosive working conditions, and heat-resistant steel for high-pressure and high-temperature working conditions to avoid material creep and corrosion.

Valve Stem and Sealing Components: The valve stem is made of high-strength and wear-resistant material, and the sealing components are adapted to the working conditions (flexible graphite for high temperature, polytetrafluoroethylene for corrosion) to prevent aging and leakage.

 

 

Improper assembly will lead to valve jamming and leakage, which are "congenital defects" that are difficult to repair. Details need to be focused on.

Precise Assembly: Align the actuator with the valve body, firmly connect the valve stem with the valve core, and properly compress the packing to avoid unsmooth opening and closing and accelerated wear.

Cleanliness Control: Clean and dry parts before assembly, and take dust-proof and impurity-proof measures throughout the process to prevent iron chips and dust from wearing the sealing surface and jamming the valve core.

 

 

High-quality valves must go through the whole-process inspection, while inferior valves often omit inspection. Buyers should pay attention to 3 types of core inspections:

Non-destructive Testing: Detect key parts such as blanks and welds to eliminate internal defects;

Pressure and Leakage Testing: Conduct water pressure and air tightness tests before leaving the factory to ensure no leakage under rated pressure;

Action Commissioning: Repeatedly commission the opening and closing actions to ensure flexibility, stability, no jamming or abnormal noise.

 

 

In outdoor, humid or corrosive environments, surface treatment can effectively prevent corrosion and rust, and extend the service life of valves.

Anti-corrosion Treatment: Paint or galvanize carbon steel valves to ensure no exposure on the surface and prevent rust; passivate and polish stainless steel valves to improve corrosion resistance;

Protection Details: Do a good job in protecting the flange surface and interface to avoid scratches and damage during transportation and storage, which will affect the sealing performance.

 

 

The service life of valves depends on the whole-process detail control. When purchasing, in addition to paying attention to specifications and prices, you should also ask about the manufacturer's production process, inspection process and material report to avoid low-price traps. Although high-quality valves have slightly higher procurement costs, they have longer service life and lower operation and maintenance costs, which are more cost-effective in the long run.