A high-pressure mud manifold connects the mud-pump discharge outlet to the swivel or top-drive inlet. It supports single-pump and dual-pump operation, pressure relief, mud filling, and other drilling circulation functions. A typical assembly includes high-pressure hoses, valve groups, hammer unions, standpipes, swivel joints, rotary hoses, pressure gauges, and matching steel pipework.
Gate-Valve Assembly
The gate-valve assembly is normally built around 4 in mud gate valves. Common arrangements use cast Y-type and T-type bodies connected by hammer unions or flanges. The valves are not ordinary wedge gate valves; they are rising-stem slab gate valves with resilient seats for reliable shutoff in abrasive mud service.
The seat seal is formed when the slab gate compresses the resilient seat. This self-energizing sealing action is suitable for drilling fluids containing sand or solids, gives relatively low operating torque, and makes seat replacement practical in field maintenance.
High-Pressure Hose and Rotary Hose
Because drilling mud must be pumped downhole through a moving swivel or top drive, a flexible rotary hose is required between the standpipe and the rotating equipment. Additional high-pressure hoses can also be used to speed up the connection between mud pumps and surface manifolds.
Oilfield high-pressure hoses are generally steel-wire reinforced rubber hoses. End connections may be vulcanized to the hose at the factory or mechanically attached by ferrule, slip, or swaged structures. Rotary hoses are commonly identified by inside diameter, working pressure, and length.
Typical nominal sizes include 2 in, 2-1/2 in, 3 in, and 4 in. Working pressures are selected according to the mud-pump pressure rating and the manifold design pressure. The complete manifold should always be pressure-rated as a system, not as individual components only.
