1. Structural Differences
Sealing Design
Boiler globe valves mostly use metal hard sealing structures (such as Cr13 stainless steel discs and valve seats), combined with bellows sealing technology to ensure long-term sealing under high-temperature and high-pressure steam;
Gas globe valves (such as J41N models) use nylon plastic soft sealing valve seats, which enhance the sealing adaptability to natural gas, liquefied gas and other media through elastic deformation, reducing the risk of combustible gas leakage.
Valve Body Form
Boiler valves are mainly right-angle forged valve bodies, which are suitable for high-pressure split forging processes (such as high-temperature and high-pressure main steam pipelines with DN≤200);
Gas valves are mostly straight-through cast valve bodies, which simplify the flow channel design to reduce pressure loss and are suitable for medium and low-pressure gas transmission pipelines.
2. Material selection
Valve body and key components
The valve body of boiler valves is generally made of cast steel (such as WCB, WC6), which can withstand temperatures above 450°C and has the ability to resist high-pressure steam corrosion;
The valve body of gas valves is mainly made of carbon steel, and some gas containing hydrogen sulfide needs to be upgraded to sulfur-resistant materials (such as LCC, LF2).
Sealing and anti-corrosion treatment
The valve stem surface of the boiler valve is hardened by high-frequency quenching (HRC≥50), and the nickel-based alloy surfacing process is used to enhance high-temperature wear resistance;
Gas valve internals are often nickel-plated or sprayed with PTFE coating to prevent impurities in the gas from eroding and corroding the sealing surface.
3. Specifications and Features
Pressure Level
The pressure range of boiler stop valves covers CL150~CL2500. Typical models such as J41H-16C can withstand 16MPa high-pressure steam. The nominal pressure of gas valves is generally PN16~PN40, which is suitable for medium and low pressure conditions of urban gas pipelines.
Diameter and connection method
The common diameter of boiler valves is DN25~DN200, mainly flange connection, and some high-pressure small-diameter models use socket welding; Gas valves can be expanded to DN300, with flange connection and threaded connection coexisting to meet the needs of different installation scenarios.
4. Functional adaptability
Boiler valves must have high-frequency fine-tuning capabilities (such as steam flow control during the startup phase), and the valve stem adopts a multi-thread fine-tooth design to improve adjustment accuracy;
Gas valves emphasize quick cut-off and anti-static design, and some models integrate static electricity output devices to avoid sparks during operation.
