Manufacturing standards and sealing mechanism of API globe valves

API globe valve is a type of valve that relies on the mechanical force applied by the valve stem to force the valve disc to tightly fit with the valve seat to achieve shut-off function. Its design and manufacturing mainly follow the specialized standards issued by the American Petroleum Institute.

This standard sets clear requirements for key indicators such as the minimum wall thickness of the API globe valve body, the minimum diameter of the valve stem, and the thickness of the sealing surface weld layer, ensuring that the valve can operate stably in high temperature, high pressure, and corrosive media environments for a long time. Unlike the flow form of gate valves, the flow channel of globe valves presents a curved direction. Although the fluid resistance is relatively high, its sealing performance is extremely outstanding, especially suitable for process nodes with strict limitations on leakage.

The valve disc and seat sealing surface of API globe valves are usually welded with cobalt based hard alloys of different hardness to form a wear-resistant sealing pair between hard alloys and hard alloys. This combination has excellent erosion resistance and high-temperature creep resistance. Even in high flow media containing solid particles, globe valves can still maintain a low leakage rate. In terms of pressure applicability, globe valves can cover a wide range from low-pressure steam systems to ultra-high pressure hydraulic pipelines, and their temperature resistance is sufficient to cope with harsh environments ranging from deep freezing conditions to high-temperature superheated steam.

The driving methods of API globe valves are flexible and diverse, which can be directly operated by handwheel or equipped with gearbox reduction mechanism to reduce operating torque. Electric or pneumatic actuators can also be installed for remote automatic control, and users can freely choose according to their actual needs and automation level on site. It should be emphasized that globe valves have clear requirements for the flow direction of the medium. The flow arrows cast on the valve body must be consistent with the flow direction of the medium in the pipeline, otherwise it will cause the valve disc to fail to open or close normally, and even damage the sealing surface too quickly.

It is precisely the structural principle of forced sealing and the perfect standard system that make API globe valves widely used in cutting and regulating applications in many industrial sectors such as refining, chemical, pharmaceutical, and power.