Making Difficult HDD Intersect Bores Practical

Picture two large directional drilling rigs several thousand feet apart – usually on opposite sides of a body of water.

Each rig drills from its location, and the two pilot bores meet at a precisely-planned point in between. Successful horizontal directional drilling “intersects” always attract attention in the industry. Today they are not uncommon, but certainly can’t be called routine, and there aren’t many drilling contractors with the equipment, know-how and experience to undertake an intersect.

Several years ago, a driller discovered that a simple locking swivel could simplify intersects.

The story begins at North Houston Machine Inc., a company offering downhole products for multiple types of drilling operations, including horizontal directional drilling (HDD). In its product line is an HDD locking swivel.

“We designed the swivel to rotate freely to allow fluid to pass through, or to lock, stopping rotation,” said North Houston Machine (NHN) owner Mike Mannen. “With two rigs placed at each side of the bore, the swivel is used on the pull side or exit side to allow fluid to pass through and rotate freely. When it comes time to breakout the pipe, the swivel can be switched to the lock position.

“The benefit of being able to lock the swivel creates a safer and more efficient way to begin removing the pipe. And ‘free spooling’ helps eliminate unnecessary stress on the equipment which allows machinery and tools to last longer.”

Mannen said changing the swivel from “free spool” to “locked” is simple. There are four socket head cap screws to loosen, slide the locking ring over the mating hex, tighten the bolts, and the swivel will be in the “locked position”.


It’s not clear how long free spooling has been employed with intersects.

“We have been making locking pull swivels for over 15 years,” Mannen said. “A superintendent at Direct Horizontal Drilling told me they have been using them in “intersecting” applications for at least five years. Word has spread through the industry about the benefits of free spooling for intersects. Pull swivels are in our catalog, and we have featured it at trade shows. We have seen an increase in sales.”

Mannen said other companies also have locking swivels, but the locking/unlocking process in not as simple. NHM has two patents on its locking swivel design.

Established in 1979, North Houston Machine, Tomball, Texas, has a fully-equipped machine shop with precision weld and fabrication facilities and specializes in custom-design products such as rotary heads, swivels, side feed and conventional swivels for air, water or mud drilling, and designs and manufactures drill pipe and tool joints for water and seismic drilling. NHM’s patented breakout system requires no tongs or wrenches.


North Houston Machine, (281) 351-8108,


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