Valves are extensively used in petroleum and petrochemical facilities—wherever there are pipelines, valves are essential. The overall performance of valves is critically important for engineering installation, system commissioning, start-up, routine operation, and ultimately, the containment or loss of the circulating medium. In petrochemical and chemical facilities, piping materials typically account for 15% to 20% of total project investment, with valves making up more than 50% of the total piping cost. The volume of valve procurement is therefore substantial.
Once the process package for an industrial plant is finalized, the selection of valve specifications and types is typically carried out by the piping and instrumentation departments of the respective design institutes. Valves are generally classified into two categories: process valves and instrument valves. Process valves are usually manual or automated, while instrument valves are commonly pneumatic or electrically actuated.
Each type of valve has distinct purchasing considerations. As key supporting components for major equipment, valves must first comply with relevant industry standards. It is essential to clarify which standards apply within the intended field of use. Procurement decisions should also take into account the operating environment of the valve—such as the medium, pressure, and temperature—and thoroughly understand the valve type along with its characteristics and performance features.
Industries such as petrochemicals, power generation, and metallurgy require continuous, stable, long-term operation. Therefore, the valves used in these sectors must exhibit high reliability and a significant safety margin. Valve failures must not lead to major safety incidents or personal injuries. Valves should be capable of supporting long-term, uninterrupted operation, as sustained production directly impacts overall efficiency. Additionally, leakage must be minimized or eliminated to maintain clean, well-organized facilities and to support effective HSE (Health, Safety, and Environment) management.
Valves must meet the specific demands of the process in terms of medium, operating pressure, temperature, and intended function. This is the most fundamental principle of valve selection.
- If overpressure protection and discharge of excess medium are required, safety valves or relief valves should be used.
- If reverse flow of the medium must be prevented, check valves are necessary.
- Steam traps are essential for automatically removing condensate, air, and other non-condensable gases from steam lines and equipment, while also preventing steam loss. In addition, if the medium is corrosive, materials with high corrosion resistance should be selected.
After installation, valves should be clearly marked with direction indicators, opening positions, and signal indicators so operators can quickly and correctly respond to emergencies. The valve’s structure should be as simple as possible, allowing for convenient installation, inspection, and maintenance.
Valves with simpler structures and lower manufacturing costs should be selected when they meet all functional and process requirements. This helps reduce overall system costs, avoids unnecessary waste of materials, and lowers future installation and maintenance expenses.
Several aspects of after-sales service should be evaluated:
- The professionalism and standardization of the service
- The responsiveness and timeliness of issue resolution
- Service costs
- The technical competency of the service team
Clear communication with the supplier about the intended operating conditions is essential to ensure a smooth procurement process and to avoid unnecessary spending on overly high-end products.
One final point worth emphasizing is that transaction costs are often overlooked in China. Some decision-makers focus exclusively on preventing procurement-related corruption, without fully understanding the broader implications of transaction costs. As a result, bidding scopes are unnecessarily expanded, which significantly drives up overall procurement expenses.
Process valves are primarily used to isolate flow and prevent backflow. The following factors should be considered during procurement:
(1) Sealing performance and pressure resistance
(2) Connection type and size specifications
(3) Material requirements
(4) Special performance requirements, such as corrosion resistance, erosion resistance, high-temperature resistance, low-temperature resistance, and vacuum compatibility.
Instrument valves are used for flow regulation and diversion. When selecting these valves, attention should be given to the following factors:
(1) Electrical system requirements, including protection level, explosion-proof features, power supply, and voltage;
(2) Opening and closing times, as well as the frequency of operation;
(3) Expected service life;
(4) Local control capabilities;
(5) Sealing performance and pressure resistance;
(6) Connection type and size specifications;
(7) Material requirements;
(8) Special performance requirements, such as corrosion resistance, erosion resistance, high-temperature resistance, low-temperature resistance, and vacuum compatibility.
