Better way to mount a ramming tool

Mar 31, 2016

In-line ramming tool cradle maximizes energy transfer in pipe ramming extraction technique

Pipe ramming tools from HammerHead Trenchless Equipment can now be locked inside a wide range of ready-made extraction cradles manufactured by the company. The extraction cradles, sometimes referred to as “canoes,” enable horizontal direction drilling (HDD) contractors to orient a ramming tool 180 degrees to extract stuck pipe or tooling, assist in product pullback and remove  washover casing at the end of the HDD job. Extraction cradles also give pipeline installers the most effective means to slick bore and install cathodic protection (CP) pipe.

Unlike fabricated offset mounts that lose a significant portion of ramming energy laterally, an extraction cradle is mounted directly in line with the pipe or tooling. This alignment transfers impact force from the ramming tool to the pipe or HDD tooling with maximum efficiency. Compared to other mounting methods, using an extraction cradle means more work gets done, while eliminating time and labor – hours, sometimes days – of fabricating a mounting system. Alan Goodman, a Global Sales Manager for HammerHead Trenchless Equipment, said the ready-made extraction cradles are reusable and highly versatile. A single cradle can also accommodate a range of both pipe and hammer sizes.

“For instance our 36-inch extraction cradle can mount to 36-inch casing on one end and a 30-inch casing on the other end,” Goodman said. “Then it can be modified further to address other casing sizes by using standard pipe reducers. This means the same cradles can be used with our 26-inch, 24- or 20-inch hammers.”

Slick boring pipeline

One of the most exciting uses of the extraction cradle is in a trenchless pipeline installation method called “slick boring,” an effective, safe method of installing pipeline products, which are routinely protected by a coating supplemented with cathodic protection (CP). A CP system protects a wide variety of metallic structures from corrosion in various environments unless it is compromised.

To install a coated-lined pipe with a pipe ramming tool, a slick bore contractor simply drives a sacrificial, standard casing as a “dummy” into the ground with conventional pipe ramming technique. The contractor removes the ramming tool to place it in the extraction cradle, which has been mounted at the other end of the pipe.

The contractor welds the new coated-lined pipe to the dummy casing that was initially rammed into place. As the hammer locked inside of the cradle extracts the dummy casing from the ground, the dummy casing pulls the coated-lined pipe into place. Slick-boring method limits stress or damage to the pipe or its coating, since they are never subjected to direct impacts from the hammer. The dummy casing, which takes the brunt of the impact force as the casing cuts and drives the casing forward, can often be reused for additional slick boring jobs.

HDD completion insurance

Having an extraction cradle and hammer on hand during challenging HDD operations helps to assure the contractor of completion. “Stuck pipe or tooling is an urgent situation,” Goodman said. “Since there is little fabrication or welding needed, the contractor begins efforts to save the bore, pipe, or tool string as quickly as possible.”

Minutes make the difference in such cases, Goodman said. “There’s no 100 percent guarantee that ramming a stuck pipe or drill stem will save a job. While it’s definitely the best technique available for getting them moving again, the chances of saving the bore hole and freeing pipe or tooling go down with the length of time they remain in the ground. If the contractor doesn’t have a standby extraction cradle and hammer, HammerHead Trenchless Equipment will rush one of each to the site immediately upon getting the call for help. We can also have a technician there on site with them.”

Removing washover casing

HDD contractors drive washover casing to reach more favorable drilling conditions, isolate drilling operations from the formation, protect circulation, and ensure maximum recovery of fluids. Pipe ramming tools mounted in extraction cradles are an effective means of extracting the washover casings at the end of the job.

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