What is a gate valve? It is a shut-off device to open and close the flow of the fluid conveyed by a piping system (or a pipeline). A gate valve is a bi-directional valve, as the fluid may flow in either direction. The installation of this type of valve creates a modest pressure drop in the pipeline, lower than globe valves. Gate valves have forged bodies for bore sizes below 2 inches (API 602/BS 5352), and cast bodies for larger sizes (API 600, API 603, API 6D).
What is a gate valve? It is a shut-off device to open and close the flow of the fluid conveyed by a piping system (or a pipeline). A gate valve is a bi-directional valve, as the fluid may flow in either direction. The installation of this type of valve creates a modest pressure drop in the pipeline, lower than globe valves. Gate valves have forged bodies for bore sizes below 2 inches (API 602/BS 5352), and cast bodies for larger sizes (API 600, API 603, API 6D).
The main advantages of this type of valve are:
Easy to maintain and disassemble
Optimal as a shut off valve
Bidirectional
Low cost
Can be used with slurries and viscous liquids
Available in large sizes
Inherently fire-safe (when used with a metal sheet)
The disadvantages are:
Slow open and close time
Low-pressure limitations
Erosion of the seat and disk can occur
Poor throttling characteristics
Difficult to repair
GATE VALVE TYPES
CAST STEEL
This is the most common type, covered by the API 600 (carbon and alloy steel) and API 603 (stainless steel and higher grades) specifications. Cast steel gate valves are available in sizes above 2 inches, and up to 80 inches.
FORGED STEEL
Forged steel valves are used for small bore piping, generally below 2 inches in diameter. The API 602 and BS 5352 specifications cover this type of gate valves.
API 6D FOR PIPELINES (THROUGH-CONDUIT)
These are gate valves for pipelines and are available in two key designs, slab and expanding gate.
PRESSURE SEAL
Pressure seal gate valves are used for high-pressure applications. The most common types of valves for high-pressure application are the flexible wedge and the parallel slide pressure seal valve. They are generally available with cast or forged bodies, in dimensions from 2 to 24 inches and pressure rating from 600# to 4500#, with socket weld or butt weld, ends to ensure tight flanged joint connections (but flanged ends are also possible).
Post time: Oct-26-2019