How to Purchase Valves

2025-06-12 08:04:30

When selecting valves in daily operations, the following steps are generally adopted:  

01 Clarify the Valve's Purpose  

When choosing different types of valves, the first step is to clarify the role of the valve in the equipment or pipeline.  

Then, determine the working conditions of the valve in the pipeline, including:  

- The type of medium pipeline it serves (e.g., water, gas, oil);  

- The pipeline pressure where the valve is installed (stable pressure, fluctuating pressure, high-pressure system, or vacuumsystem);  

- Internal system temperature and ambient temperature. Factors such as valve material and sealing material determine the minimum and maximum service temperatures of the valve.  

Ensure the selected valve correctly matches the technical requirements of the on-site pipeline, with its pressure rating, temperature tolerance, and compatible medium aligning with the on-site operating conditions.  

02 Identify the Valve Category  

There are numerous valve categories in the market. A basic understanding of these categories is essential when selecting valves, including common types such as:  

- On-off valves, regulating valves, safety valves, hydraulic control valves, special-purpose valves, etc.  

03 Determine the Valve Type  

Based on the valve's purpose and operating conditions, select the specific type, such as:  

- Gate valve, globe valve, ball valve, butterfly valve, plug valve, angle seat valve, pressure reducing valve, steam trap, plunger valve, control valve, safety valve, diaphragm valve, pinch valve, sludge Drain Valve, breather valve, flame arrester, throttle valve, etc.  

04 Define Specific Valve Parameters  

This step is critical. Determine the specific parameters of the valve to be installed in the pipeline to meet on-site requirements, primarily including:  

- Nominal pressure (PN) and nominal diameter (DN), which must match the pipeline specifications.  

In general, the standard system applied in process pipeline design forms the basis for other pipeline components. For example:  

- If JB-series standard flanges are used, the matching valves must also comply with JB standards; otherwise, installation will be impossible.  

- After determining the pipeline's pressure class, the valve's nominal pressure is set accordingly (e.g., on-off valves should have a nominal pressure higher than the pipeline's pressure class).  

- The valve's nominal diameter must align with the supporting pipeline flanges or connectors.  

05 Specify the Valve Material  

The valve material (valve body, components, and sealing surface) is determined by the process pipeline's medium, working pressure, and temperature. Examples include:  

- Brass valves, cast iron valves, stainless steel valves, carbon steel valves, forged steel valves, alloy steel valves, lined valves, etc.  

06 Determine Geometric Parameters  

Once the valve material and model are confirmed, define the geometric parameters based on the nominal diameter, such as:  

- Structural length of the valve;  

- Flange connection type and dimensions;  

- Height during valve opening/closing;  

- Dimensions of connecting bolt holes;  

- Overall external dimensions of the valve.  

Through the above selection steps, the appropriate valves for on-site pipelines can be determined, followed by procurement and installation. For novices, valve selection knowledge may seem overwhelming, and the fear of errors can hinder confident decision-making. In such cases, consulting professional valve manufacturers is recommended.