Circulating Sub

Description

Circulating Sub (also called Circulating Head,circulating swage) The circulating sub is a specialized tool for circulating drilling fluid.

It is installed to the top of the drill pipe or tubing to form a connection with the mud system to permit circulation of the drilling mud to help properly locate the casing string.

Its top end connects to drill pipe via drill pipe thread, or connects to the hose, the bottom connects to casing joint via casing BTC (LTC/STC).Sometimes the cementing head can be replaced by lifting circulation head.

Features

• 1. Its upper end is drill pipe box or union, the nether end is casing pin. It is a crossover(X/O) with hollow inside.
• 2. Main body are made from heat treated alloy steel （AISI 4140/4145 alloy steel）. Connected with union by internal and external argon arc welding, high strength, resistance to high pressure, safety and reliability.

Applications

 The circulating sub is connected between wellhead pipe string and ground circulating system. When casing is running or finished running, the circulating sub is connected to make fluid circulation. According to the application, the circulating sub is connected between Kelly and casing or between casing and hose. The former is used for fluid circulation during connecting of casing. The later generally is used after connecting of casing.