The working principle of a butterfly valve is that the valve disc rotates around an axis perpendicular to the flow passage, and only needs to rotate 90° from fully open to fully closed. This structural difference brings systematic advantages:
Compact structure and light weight are the most prominent competitiveness of large - diameter butterfly valves. The weight of a DN1000 butterfly valve is usually only one - third to one - half of that of a gate valve of the same diameter, and the installation space height is only one - quarter to one - fifth of that of a gate valve. For scenarios such as buried pipelines, limited spaces in pumping stations, and pipe galleries, this difference is sufficient to determine the selectable range of valves.
Rapid opening and closing is another significant advantage. The 90° rotation can be completed within a few seconds, which is particularly suitable for accident conditions that require quick cut - off or process links that require frequent adjustment. In terms of cost, the manufacturing cost of large - diameter butterfly valves is much lower than that of gate valves of the same diameter. The larger the diameter, the more significant the price difference. The price of butterfly valves above DN1200 is usually only 40% - 60% of that of gate valves.
The sealing performance of butterfly valves has made remarkable progress in the past decade. The sealing of traditional center - line butterfly valves relies on the elastic extrusion of the rubber valve seat, which is prone to aging and failure under high - temperature and high - pressure conditions. The advent of triple - eccentric butterfly valves has completely changed this situation - the metal sealing surface adopts a conical geometric design. During the closing process, there is no sliding friction between the valve disc and the valve seat. The opening and closing torque is small, and the sealing specific pressure increases with the increase of the system pressure. The leakage rate of modern triple - eccentric metal - sealed butterfly valves can reach the ANSI Class VI (zero visible leakage) level, and in terms of temperature resistance, it can cover a wide temperature range from - 196°C to 600°C, applicable to everything from ultra - low - temperature liquefied natural gas to high - temperature steam.
Although the substitution of butterfly valves is the general trend, it is still necessary to clearly recognize the irreplaceable position of gate valves in some scenarios. In high - temperature and high - pressure steam pipelines, the wedge - shaped sealing structure of gate valves is still more reliable than that of butterfly valves of the same specification in terms of thermal expansion compensation and long - term high - temperature creep. In the transportation of media such as hydrogen and high - pressure natural gas that require absolute zero leakage, the wedging effect of the valve disc of the gate valve provides a more certain sealing specific pressure. In occasions that require frequent opening and closing and have extremely high requirements for the erosion and wear of the sealing surface, the sealing surface of the gate valve is parallel to the direction of medium flow, resulting in less erosion, while the butterfly valve is continuously eroded by the medium because the valve disc is always in the flow passage.
Another area where gate valves are retained is in working conditions with strict two - way equal - pressure sealing requirements. The sealing ability of some butterfly valves under reverse pressure difference is weaker than that under forward pressure, while the two - way sealing performance of gate valves is symmetrical.
The selection of large - diameter shut - off valves should not simply choose between butterfly valves and gate valves, but should be based on a multi - dimensional assessment of specific working conditions: By pressure level, butterfly valves are preferred in medium - low pressure (PN≤4.0MPa) scenarios, and the applicability of butterfly valves needs to be carefully evaluated in high - pressure (PN≥6.4MPa) scenarios; by operation frequency, butterfly valves have obvious advantages in frequently operated working conditions; by diameter, when DN≥300, the cost and installation advantages of butterfly valves begin to emerge, and when DN≥600, they have an overwhelming advantage; by medium cleanliness, gate valves are prone to jamming in media containing particles, and eccentric butterfly valves are more suitable; by sealing level, for working conditions that require Class VI zero - visible - leakage, triple - eccentric butterfly valves can be competent but the cost is high, and gate valves are still a conservative choice.
Butterfly valves are "eating into" the market share of gate valves in the field of large - diameter shut - off valves. The technical basis of this trend is the significant improvement of triple - eccentric metal - sealed butterfly valves in sealing grade, temperature - resistant range, and reliability. The economic basis is the systematic advantages of butterfly valves in terms of structural compactness, weight, and cost. The industrial basis is the rigid demand of large - diameter pipelines for quick operation and space saving. Gate valves will not disappear, but in more and more large - diameter scenarios, the balance of selection is tilting towards butterfly valves. For engineers, the core question has changed from "which is better, gate valves or butterfly valves" to "in the current working conditions, are the advantages of butterfly valves sufficient to cover their limitations?" The answer lies in the working condition table, not in habit.
