Circulating Sub

Circulating Sub Circulating swage

Circulating Sub is also called Circulating Head,circulating swage.

SizeFrom 2-3/8“ to 20″
CertificateAPI, ISO9001 2015
Loading PortQingdao/Tianjin China
Lead Time15-25 days


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.

Circulating Sub Types

According to the request and actual needs, there are casing thread circulating sub, tubing thread circulating sub, union thread circulating sub.( casing thread circulation head, drill pipe thread circulation head, union thread circulation head.)

Circulating Sub Specification

SpecificationOD mm(inch)ID mm(inch)Thread Size
2-3/885.7(3 3/8)31.82A11×2″1502
2-7/8104.8(4 1/8)38.1(1 1/2)211×2″1502
3-1/2121(4 3/4)44.5(1 3/4)311×2″1502
5168.3(6 5/8)44.5(1 3/4)411×2″1502
5-1/2177.8(7)44.5(1 3/4)521×2″1502
7177.8(7)44.5(1 3/4)7 BCSG P×2″1502
9-5/8244.5(9-5/8)44.5(1 3/4)9-5/8 BCSG P×2″1502
13-3/8340.1(13-3/8)44.5(1 3/4)13-3/8 BCSG P×2″1502
18-5/8473(18-5/8)44.5(1 3/4)18-5/8 BCSG P×2″1502
20508(20)44.5(1 3/4)20 BCSG P×2″1502
  • 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.

 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.


Confirmation when order:

  1. Overall length and length of neck.
  2. Thread type of top end.
  3. Thread type of bottom end.


  1. Hammer union box sub * Casing thread pin
  2. Hammer union box sub * Drill pipe pin
  3. Drill pipe thread box * casing thread pin

When ordering,please list:

  1. Overall length and length of neck.
  2. Thread type of top end.
  3. Thread type of bottom end.

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