These are just a few of the Subs that Houston Downhole builds that have a specific function.
Houston Downhole builds various Test Subs. These are used at the rig site to perform hydrostatic tests on the well control equipment. They look like a short Wear Sub with the addition of a threaded port hole that is machined into the side. The connections on the test are the same as what is on the drill pipe. One end of the test sub is made up to the drill pipe and the other end is made up to a test fixture that is closed on one end. Fluid is pumped thru the threaded port until the desired pressure is reached.
We also build Integral Test Joints in 20ft and 30ft lengths. These tools have the same Body OD as the drill pipe. One end of the Test Joint matches the Tool Joint of the Drill Pipe and the other end matches the thread that’s on a test fixture. The Bottom Upset can be furnished with or without a weephole.
The Ported Sub also looks like a Wear Sub with exception of a hole thru the side. This hole is referred to as a Port Hole or Weep Hole. This Port Hole can be plugged or left open depending on whether the testing is being performed at the top of the drill string or on a test rack.
A Jetted Sub is used for clean outs, scale removal and other operations where a jetting operation is required. They are usually built with a Box thread up and a Solid Bull Nose down to run at the bottom of the string. If the jetting operation needs to be performed at the top of the string for any reason, they can be built Box up x Pin down as well.
A series of angled holes are drilled thru the side of the sub and carbide jets are installed. The pattern, angle and quantity of the holes is usually determined by the customer.