JT100 MACH 1DIRECTIONAL DRILL

stopimg title="drillpipe_1" style="padding-right: 20px;" align="left" alt="drillpipe_1" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/drillpipe_1stopimg4The Ditch Witch organization manufactures the most durable drill pipe in the underground construction industry. But even the most dependable pipe depends on you to use it properly. Yes, it's solid steel and manufactured with the utmost precision, but one false move—exceeding the pipe's bend radius, clamping on the body of the pipe, insufficient thread lubrication—and you can quickly ruin not only an individual pipe but also an entire drill string.

Pipe isn't cheap, as experienced horizontal directional drilling (HDD) professionals know well, nor is the downtime associated with replacing it, so it definitely pays to follow instructions in the operator's manual to the letter. Most HDD operators have learned how to execute a successful bore by making mistakes along the way. Sometimes experience is the best teacher, but by taking the following tips to heart, maybe you can avoid learning the hard way.

Before The Bore.

Proper drill pipe care starts long before you reach the jobsite. First, select a pipe designed for your drilling rig, keeping in mind that:

•  Simply selecting a tool joint that will function in the grippers is not enough. The tool joint must be designed to match the rig's output torque or it won't tighten correctly.
•  The outside diameter of the pipe greatly influences its steering characteristics. Too-large or too-small pipe bodies will not properly match the thrust and may create steering problems.

The bore should be thoroughly planned before unloading the rig. Take into consideration what buried hazards or obstacles exist on the jobsite (where and how deep they are), the size and type of material to be installed, the bend radius of the material and how deep it must be placed, your setup position and entry angle, and if the job allows entry and exit pits.

You'll want to use the lowest possible entry angle to minimize the bending necessary to drill horizontally at the proper depth; entry and exit pits help prevent sharp bends at these points, and allow the cutting tool to start without skidding and bending the pipe.

If you are using brand new pipe, perform the following preconditioning procedure three times for each pipe before first use:

      1. Hand-lubricate the entire surface of threads and shoulders of both ends of the pipe with the recommended copper-base tool-joint compound.
      2. Join the pipe and tighten the joint.
      3. Break the joint.

Failure to follow this procedure could result in fused joints and pipe damage. And remember to precondition new saver subs the same way you do new pipe.

During The Bore.

Both the drill pipe and the material to be installed have bend radius limits that you must know and never exceed. The maximum bend radius allowed for your Ditch Witch drill pipe is shown in a chart in your operator's manual. The product to be installed often has a bend radius different than the drill pipe, so the pilot bore should be planned for whichever has the greater bend radius.

How you make up and break apart tool joints greatly affects the life of your drill string. Before connecting drill pipe, lubricate the threads and shoulders of male joints with a copper-base tool-joint compound. This prevents rust and reduces wear on shoulders and threads. When necessary, clean the threads with high-pressure water and detergent. (Do NOT use gasoline or other petroleum-based solvents, as this will prevent the tool-joint compound from sticking to the joints and reduce thread life.)

Connecting and disconnecting joints should always be performed slowly and deliberately. Always carefully align the male and female ends of pipe before screwing them together. Poor alignment can damage the threads and destroy the usefulness of the joint.

stopimg title="drillpipe_2" style="padding-left: 20px;" align="right" alt="drillpipe_2" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/drillpipe_2stopimg4Carefully time the rotation with the carriage travel speed. This will help prevent thread crossing, galling, and shoulder swelling. Tapered threads don't fully engage until the last 1/16 of an inch, so make sure the shoulder faces are touching and then tighten the joint with full machine torque.

Never rush the job by letting the ground finish making up the joint. This will not provide sufficient torque to make a good connection.

Of all the joints in a drill string, those just behind the drill bit take the highest stress. The lead pipe is in the ground longer, and gets more shockloads and rotation cycles. Use a transition sub between the tool and the first drill pipe to absorb shock.

Never use machine torque to make or break joints away from the machine. To break threaded joints away from the machine, first shut down the engine and then use a breakout wrench to perform the task. Clamp onto the drill pipe only in the designated areas; even small cuts in the pipe can quickly lead to fatigue during bending rotation. With a Ditch Witch EZ Connect tool, you don't have to break apart tight threads on downhole tools.

During the drill operation, never rotate the drill pipe without pushing or pulling, as this will increase stress damage at every bend. Likewise, don't push a full length of pipe in the drill frame without rotating, as this can cause pipe to buckle. Drill in half the pipe before pushing without rotation.

When guiding the bore, never exceed the bend radius for your pipe. Bending pipe more sharply than recommended will damage the pipe and cause failure. All steering corrections should be made as gradually as possible. Overcorrecting will cause "snaking," which can damage pipe and make drilling and pullback more difficult. It is important to begin straightening out of each correction as early as possible.

Excessive changes in pitch—the up or down angle of the bit and lead pipe—can bend the pipe just like oversteering does. In your operator's manual, the bend limits for Ditch Witch pipe are shown in a chart that provides the total deflection allowable in pitch or steering without damaging the pipe.

Because each pipe comes in contact with the saver sub, check it regularly for wear and replace it when it is worn, or it will damage the drill pipe. And always replace bits and backreamers as soon as they become worn, because dull tools put more strain on the drill string.

During Pullback.

Stresses on the product during pullback are transferred to the backreamer and drill pipe. When pulling in the product, be advised of the following:

• Do not pull the backreamer faster than it can cut.    
• Never backream without good fluid flow. The right mixture and flow reduce torque, thrust and pullback forces.
•  Use the smallest backreamer practical for pullback. If you need a large borehole, make more than one pass, each with a progressively larger reamer.

After The Bore.

When buying replacement pipe, always replace the entire string with pipe from the same manufacturer. The HDD industry has no established industry standard for threads, so not all threads are made equally. Parts from different manufacturers may appear to assemble, but this does not mean the joint was made up correctly.

stopimg title="drillpipe_3" style="padding-right: 20px;" align="left" alt="drillpipe_3" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/drillpipe_3stopimg4Thread tolerances vary widely among manufacturers. And worn threads, of course, do not match any other threads. Mixing new and worn threads increases contact pressure and accelerates thread wear. Also, the bend radii of different brands of pipe may be different, which will cause accelerated and uneven wear on all pipe in the string.

Whenever you replace all of your drill pipe, replace the saver sub on the carriage, too. Putting new pipe through an old saver sub transfers damage from the sub to every new pipe in the string.

Because the lead drill pipe is in the ground longer, it is subjected to higher shock loads and experiences more wear. To help spread this wear evenly over all pipe, move the lead pipe to the last position in the rack after each job.

Drill Pipe Best Practices.

By making every effort to maximize the life of your drill pipe, you can help ensure the overall success of your HDD operations. Here's an abbreviated checklist to refer to when planning your next bore:

• Set up unit correctly. 
• Securely anchor drilling unit.    
• Break in threads on new pipe.    
• Make up and break out tool joints correctly.    
• Assemble and disassemble tool joints at moderate speed.    
• Keep the rotation speed and thrust speed synchronized. 
• Apply proper torque to all tool joints.    
• Avoid over-bending, over-steering and over-correcting.    
• Keep threads clean and lubricated.    
• Use correct drilling fluid for soil conditions and use plenty of it.    
• Refer to your operator's manual for complete drill pipe care, maintenance and operation.

stopimg title="keepCool_img1" style="padding-right: 20px;" align="left" style="BORDER-BOTTOM: 0px solid; BORDER-LEFT: 0px solid; WIDTH: 260px; PADDING-RIGHT: 10px; HEIGHT: 195px; BORDER-TOP: 0px solid; align: left" alt="keepCool_img1" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/1_KeepCool_260x195(1).jpg" border="0" />Catastrophic tornadoes and floods have grabbed recent headlines, but each year one weather phenomenon kills more people than tornadoes, floods, hurricanes, and lightning combined: heat.

According to the National Oceanic and Atmospheric Administration (NOAA), an average of more than 1,500 people in the U.S. die each year from excessive heat—yet it is the most preventable of weather-related deaths.

If you work in construction, summer is one of your busiest times of the year because it’s typically the driest season and offers the most hours of daylight. But the sun providing all that productive daylight can be the biggest jobsite hazard you face all year. No matter how tough you are or how used to the heat you think you are, excessive heat can bring down anyone who doesn’t take the necessary precautions.

The following information applies to anyone who is employed in an outdoor profession—construction workers in particular—but also applies to those who work in hot factories and anyone who spends time outdoors exercising, gardening, or laboring in any capacity during the summer months. (This is general information. More specific information can be found in the sources cited below.)

Know Your Chemistry

Our bodies dissipate heat by varying the rate and depth of blood circulation, and by expelling water through the skin and sweat glands. When we reach the danger zone, when our blood is heated above 98.6 degrees, we begin to pant—we’re literally “working like a dog.”

Sweating alone does little to cool the body, unless the sweat is removed by evaporation. But high relative humidity inhibits evaporation. When you’re checking the forecast for tomorrow, pay close attention to the heat index: the combination of relative humidity and air temperature. For example, if the air temperature is 96° F and the relative humidity is 65 percent, the heat index is 121° F. This is the heat your body really feels.

Heat disorders involve a reduction or collapse of our bodies’ ability to shed heat by circulatory changes and sweating, or a chemical (salt) imbalance caused by too much sweating. When heat gain exceeds the level the body can remove, or when the body cannot compensate for fluids and salt lost through perspiration, the temperature of the body's inner core begins to rise, bringing on various degrees of heat-related illnesses.

stopimg title="keepCool_img2" style="padding-left: 20px;" align="right" style="BORDER-BOTTOM: 0px solid; BORDER-LEFT: 0px solid; WIDTH: 260px; PADDING-RIGHT: 10px; HEIGHT: 195px; BORDER-TOP: 0px solid; align: right" alt="keepCool_img2" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/2_KeepCool_260x195.jpg" border="0" />Ranking Heat Disorders

The severity of heat disorders is relative to a person’s age, weight, fitness, medical condition, and degree of acclimatization to the heat. For example, heat cramps in a 17-year-old may translate as heat exhaustion in someone who is 40, and heat stroke in a person over 60. Common heat disorders include:

• Sunburn. Along with being painful and irritating, sunburn can significantly retard the skin’s ability to shed excess heat. The best solution for sunburn is prevention, by applying sunscreen throughout the day.
• Heat cramps. Symptoms are painful spasms, usually in the muscles of the legs and abdomen, often preceded by profuse sweating.
• Heat rash. Also known as prickly heat, heat rash can occur in hot, humid environments where sweat is not easily removed from the surface of the skin by evaporation. Serious heat rash can be so uncomfortable that it inhibits sleep and impedes a worker’s performance.
• Heat exhaustion. Symptoms include heavy sweating, weakness, headache, fainting, vomiting, and skin that is cold, pale and clammy. It is possible to have a normal temperature with heat exhaustion.
• Heat stroke or sunstroke. This is the most serious health problem for workers in hot environments. Heat stroke occurs when sweating stops and the body can no longer rid itself of excess heat. Symptoms include an excessively high body temperature (106° F or higher); mental confusion or delirium; convulsions; hot, dry skin; strong and rapid pulse; and possible unconsciousness. Make no mistake: heat stroke can be fatal, and victims need immediate medical attention.

Prevention: The Best Solution

The number one method of avoiding heat disorders: avoiding heat. But for construction workers in the summer, this is simply not possible. So, here are some tips for staying cool and staying alive, beginning with the most obvious:

• Drink plenty of fluids. Your body needs water to keep cool. Drink water even if you don't feel thirsty. Proper hydration actually begins the day before a long, strenuous day in the sun. Before increasing your fluid consumption, consult a physician if you (1) have epilepsy or heart, kidney, or liver disease; (2) are on a fluid-restrictive diet; or (3) have a problem with fluid retention.
• Do not drink alcoholic beverages. Alcohol dehydrates your body. Enough said.
• Limit caffeine intake.
• Do not take salt tablets unless specified by a physician.
• Put less fuel on your inner fires. Foods that are heavy in protein increase metabolic heat production and also increase water loss.
• Dress as lightly as possible. You need protective clothing, of course, but consider light-colored fabrics, such as cotton, that breathe.
• When possible, take longer breaks than normal in a cool, shaded area. A rested worker is a more productive worker.
• Know the symptoms of heat illnesses. Use a buddy system to keep tabs on your fellow workers.
• Acclimate yourself to the heat. You can “get used to” the heat, to some degree. Workers, especially those who follow the advice above, can eventually develop some degree of tolerance. However, new employees and workers returning from an absence of two weeks or more should have a five-day period of acclimatization: 50 percent of the normal workload and time exposure the first day, gradually building up to 100 percent on the fifth day.

stopimg title="keepCool_img3" style="padding-left: 20px;" align="right" style="BORDER-BOTTOM: 0px solid; BORDER-LEFT: 0px solid; WIDTH: 260px; PADDING-LEFT: 10px; HEIGHT: 195px; BORDER-TOP: 0px solid; align: left" alt="keepCool_img3" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/3_KeepCool_260x195.jpg" border="0" />Supervisor Obligations

There are precautions every employer should take when temperatures are high and the job involves physical work.

• Understand the signs of heat stress and permit workers to interrupt their work if they are extremely uncomfortable.
• Provide training about the hazards leading to heat stress and how to prevent them.
• If possible, schedule the heaviest workload for the coolest part of the day: early morning or late evening, when the sun is less intense.
• Make sure your workers have easy access to cool water—a minimum of one quart of water per hour, per worker.
• Schedule frequent rest periods with water breaks in shaded or air- conditioned areas.
• Routinely check on workers who are at risk of heat stress due to protective clothing and high temperature. Pay close attention to those who are at risk because of age and physical condition (including obesity and diabetes).

When A Fellow Worker Is Ill From The Heat

• Call a supervisor for help. If the supervisor is not available, call 911.
• Have someone stay with the worker until help arrives.
• Move the worker to a cooler/shaded area.
• Remove outer clothing.
• Fan and mist the worker with water; apply ice (ice bags or ice towels).
• Provide cool drinking water, if the worker is able to drink.

For more information about preventing and treating heat-related illness, consult these articles:

• “Heat Wave: A Major Summer Killer,” [http://www.noaawatch.gov/themes/heat.php] by the NOAA
• “Protecting Workers From Heat Stress,” [http://www.osha.gov/Publications/osha3154.pdf] by OSHA
• “Protecting Workers In Hot Environments,” [http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=FACT_SHEETS&p_id=167] by OSHA

Sources for this article:

• National Oceanic and Atmospheric Association (noaawatch.gov)
• Occupational and Safety Health Administration (osha.gov)

stopimg title="19a" style="padding-right: 20px;" align="left" alt="19a" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/19astopimg4Take the time to winterize your equipment this year. A few minutes spent could save you time and money in the months to come. The amount of winter care your equipment needs depends both on the climate and how it is used. Check your service manual guidelines, and keep the following tips in mind:

1. Check coolant. Provide protection by using the recommended antifreeze/water mixture for the lowest temperature expected during operations.

2. Change the oil and filter before cold weather arrives. In addition, use lubricants recommended for low temperature applications.

3. Maintain the battery. Remove cables, clean cable ends and posts, and clean and tighten terminals on the cranking motor. And remember never to charge a frozen battery.

4. Check tire inflation. Tires inflated in a warm shop will be under-inflated when used in cold temperatures.

5. Give hydraulic components time to warm up before beginning work. If you’re running diesel equipment, be sure to idle the engine a few minutes before shutting down to properly lubricate internal components. Your local Ditch Witch^® service technicians can help you make the most of your cold-weather equipment productivity, and can suggest winterizing techniques that are perfectly suited to your operation.

stopimg style="padding-right: 20px;" align="left" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/boca1.jpg" alt="boca1" title="boca1" />Boca Enterprises, Hagerhill, Kentucky, has developed a reputation for completing difficult horizontal directional drilling (HDD) projects, often jobs that other contractors declined to attempt.

Boca owner Kirby Bowling recognized when he started his underground utility construction business in 1996 that the rocky soils of the rugged hill country of eastern Kentucky would be challenging, and that he should be prepared to excavate and bore in hard, rocky soil conditions.

"We do every kind of underground utility construction," said Bowling. "Gas, water, sewer, telephone, and cable television. In 2009, we did a lot of gas, but with stimulus money becoming available, we are doing more water and sewer in 2010."

As the company's business grew, Bowling began looking for a directional drilling machine that was relatively compact and could tackle the tough conditions his crews encountered on almost every job. He wanted an economical unit that could drill in rock without needing a mud motor and the high volumes of drilling fluids. Ideally the same machine also could operate in "normal" soil conditions.

stopimg style="padding-left: 20px;" align="right" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/boca2.jpg" alt="boca2" title="boca2" />The solution was a Ditch Witch® JT2720 All Terrain (AT) machine Bowling purchased in 2001, and it has been the company's workhorse ever since.

The 27,000-pound pullback drill unit is equipped with the Ditch Witch organization's exclusive dual-pipe All Terrain drilling technology. The inner rod drives a rock bit while the outer pipe steers the downhole drilling tool for drilling pilot holes, and also provides rotary torque during backreaming. The mechanical drilling system delivers maximum downhole horsepower and operates on low volumes of drilling fluid. In addition to rock drilling, AT equipment is productive in almost every type of soil.

As Boca Enterprises grew, a new, larger, more powerful, rack-and-pinion JT4020 AT unit was added in 2009.

A recent project demonstrates the versatility of the All Terrain system.

An extension of water service in Knott County, Kentucky, required one segment of pipe to cross Carr Creek Lake near Hindman. The crossing would be 1,050 feet under the lake, which reached water depths of 45 feet, with the bore path being 20 to 25 feet below the floor of the lake.

Primary contractor G &W Construction, Morehead, Kentucky, selected Boca Enterprises to make the HDD crossing.

stopimg style="padding-right: 20px;" align="left" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/boca3.jpg" alt="boca3" title="boca3" />To complicate the installation, surface features required the entry of the bore to be on the side of a mountain where a setup position for the drill unit was constructed. From the position of the entry point, the entry angle of the pilot hole was at a 50-percent downward grade, which then had to level off to proceed under the lake to the exit point on the opposite side.

The larger JT4020 AT was used on the project because its greater power provides the capabilities to pull longer runs of larger-diameter pipe than the smaller model.

The 1,000-plus-foot pilot bore was drilled with a 6.5-inch-diameter Sandvik Rotary Tools roller cone bit offered by the Ditch Witch organization. Subsurface conditions included sandstone and some limestone. Progress of the bore under the lake was tracked from a pontoon boat with a Ditch Witch Electronics 752 Tracker. A remote antenna was attached to the receiver to extend the antenna below the surface of the water and get closer to the beacon's signal.

The pilot hole was enlarged with 12- and 16-inch roller cone backreamers, and the length of 12-inch HDPE pipe was pulled back behind the 16-inch backreaming pass.

The JT4020 AT has 40,000 pounds of pullback, 5,000 foot-pounds of spindle torque, and spindle speeds to 250 rpm.

The JT2720 AT produces 27,000 pounds of pullback, 3,200 foot-pounds of spindle torque, and spindle speeds to 225 rpm.

Each of the self-contained models is mounted on tracks.

All Terrain technology enables both machines to drill in rock and other difficult conditions that are beyond the capabilities of other machines of comparable size and power ratings.

stopimg style="padding-left: 20px;" align="right" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/boca4.jpg" alt="boca4" title="boca4" />Bowling said that during its first years of operation, Boca Enterprises served primarily as a specialist subcontractor, but has reached the point that it now bids jobs as the primary contractor. Over the years, the amount of directional drilling on projects has increased, and today about 80 percent of pipe and cable the company installs is with HDD.

Ditch Witch® equipment is manufactured by The Charles Machine Works, Inc., Perry, Oklahoma, a leading producer of underground construction equipment including trenchers, vibratory plows, horizontal directional drilling equipment, compact excavators, skid-steer loaders, excavator tool carriers, vacuum excavators, and related products.

stopimg style="padding-right: 20px;" align="left" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/SlantBeaconHousing.jpg" alt="SlantBeaconHousing" title="SlantBeaconHousing" />Ditch Witch® downhole tools are engineered to be the most flexible in the industry. We believe this comes from their patented technology, their 50-year history of providing underground construction solutions, and the fact that Ditch Witch downhole tools are manufactured specifically for the drills with the same name on them. Simply put: they get the job done because they just fit better. All of these factors combined make them the longest-lasting, most ruggedly built tools in the horizontal directional drilling industry. Whether your project includes extreme soil conditions or the challenge of managing the spoils of long bores, here are several reasons why Ditch Witch downhole tools should be a vital part of your next drilling project.

stopimg style="padding-left: 20px;" align="right" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/TalonBit.jpg" alt="TalonBit" title="TalonBit" />1. Ditch Witch beacon housings are several inches longer than most competitive housings, and the deflection angle on our bits is less aggressive by design. These two features combine to create exceptionally smooth steering, making steering corrections easier and lessening the chance of oversteering.

2. Aftermarket bits tend to be dramatically thicker, with carbide applied more generously. At first this may seem like a desirable feature. But Ditch Witch bits are engineered from the highest quality steel—so less steel is required to produce a bit of the same strength. And carbide is applied efficiently—only on the cutting edge, where it counts. The result is a more nimble bit that responds easily to steering corrections while still holding up the rigors encountered downhole. Compare this with heavier, bulky aftermarket bits, which some operators have described as trying to "push a brick with teeth" through the ground.

stopimg style="padding-right: 20px;" align="left" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/Tracker.jpg" alt="Tracker" title="Tracker" />3. Some aftermarket manufacturers offer only bottom-load beacon housings. All Ditch Witch beacon housings are sideload by design. Our engineers know that the side of the housing (perpendicular to the steering) is the optimal location for the opening. Since most horizontal directional drilling steering is up and down rather than side-to-side, the majority of stresses encountered downhole are on the top and bottom of the housing. Placing the beacon opening at the highest stress point on the housing is not optimal. The tendency is for the housing to flex, causing the beacon door to come off, and the beacon to be lost. Ditch Witch sideload housings strategically place the beacon opening at their lowest stress point, protecting your electronics investment.

stopimg style="padding-left: 20px;" align="right" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/TransitionSub.jpg" alt="TransitionSub" title="TransitionSub" />4. If your tracking electronics don't seem accurate, the problem could be your aftermarket housing. Because of the design of aftermarket bottom-load housings, it is almost impossible to place a Ditch Witch beacon in one so that the roll angle is properly clocked. Ditch Witch beacon housings and beacons are designed to work together to give you the most accurate locate on the market.

5. The beacon window on Ditch Witch housings is twice the size of the competitor's—so you get a stronger beacon signal, longer battery life, and a more productive bore. Additionally, the location of the beacon window on aftermarket housings causes inaccurate depth and right-to-left readings—up to eight inches off in some documented field reports.

stopimg style="padding-right: 20px;" align="left" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/Beacon.jpg" alt="Beacon" title="Beacon" />6. The design of many aftermarket housings allows high-pressure fluid to cut into the beacon compartment, damaging the beacon. Ditch Witch housings utilize the drilling fluid flow to cool and protect sensitive electronics from the rigors experienced downhole.

7. Only Ditch Witch beacon housings come equipped with an exclusive Beacon Buddy feature that works two ways to protect your electronics: It not only accommodates a check valve to prevent nozzles from plugging; it also maintains fluid flow to prevent overheating if nozzles do become plugged.

8. The diameter of the ports and jets on competitive beacon housing are significantly smaller than that of Ditch Witch housings. When drilling fluid flow increases, the smaller diameter ports cannot handle the flow, increasing back-pressure all the way to the fluid pump and causing premature failure of pump seals and cups. The larger the pump capacity, the larger the problem. Other effects of this back-pressure include lugging of the engine, hydraulic overheating, and O-ring failure.

stopimg style="padding-left: 20px;" align="right" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/Connector.jpg" alt="Connector" title="Connector" />9. The Ditch Witch organization uses the same propriety thread pattern on its saver subs, drill pipe, beacon housings, backreamers, connectors, and transition subs. This ensures the truest, tightest connection possible all the way through the drill string . . . for ultimate worry-free performance downhole. Other manufacturers try to match our thread pattern, but their connections aren't true, causing galling and cross-threading.

10. The pins on the competitive drill pipe do not match that of Ditch Witch drill pipe. This means that competitive pipe will not fully torque with Ditch Witch pipe at the shoulder and nose, nor will it bottom out in the box end. The types of failure this causes include mushrooming and splitting of the box end.

stopimg style="padding-right: 20px;" align="left" src="/uploadedImages/Left_Nav/Press_Room/Job_Related_List/41a.jpg" alt="41a" title="41a" />A long iron tube with threads on the end—how complicated can a piece of drill pipe be? The pipe itself isn’t, but selecting the right kind of drill pipe for your rig and the working conditions can be.

First and foremost, select a pipe designed for your horizontal directional drilling (HDD) unit. Simply selecting a tool joint that will function in the grippers is not enough. The tool joint must be designed to match the rig’s output torque or it will be improperly tightened. Also, the outside diameter of the pipe greatly influences the steering characteristics of the pipe. Too-large or too-small pipe bodies will not be properly matched to the thrust and may create steering problems.

Here are some other important considerations:

Is the pipe lined?
Lining was originally developed to deal with the corrosion caused by the drilling fluids available 15 years ago. Today’s fluids are less corrosive, but lining is still beneficial to the driller. It reduces the size of the cavity that fluid must fill every time a pipe is added to the drill string (lining reduces drilling fluid volume by as much as 65%). This reduces the amount of time required to pressure up a drill string and start drilling again. It also reduces the amount of mud spilled on the ground when pipes are removed from the drill string during pullback operations.

Will the welds hold?
Manufacturing practices play a big role in how a pipe performs. Forging can be used to produce a pipe with no weld seams, or to reinforce a friction weld. However, there is a limited amount of material that can be gathered to form the tool joint each time a pipe is heated. To gather large amounts of material on the end of a drill pipe usually requires several heating and forging cycles, which makes it difficult to produce a robust tool joint. Welding tool joints to a pipe body can produce a good pipe if the weld joint is properly designed. However, weld zones need to be structurally reinforced by stiffening the pipe in the weld zone. Increasing pipe diameter at the weld zone is the most effective method of reducing the working stress on the weld, and helps avoid failures in the weld or the heat-affected zone next to the weld. Pipe designs with unexpanded weld zones almost always fail prematurely in the weld zone, regardless of welding technique.

Is the pipe clean?
The heat associated with forging can cause “scale” to build inside the pipe. Scale is a hard, black layer of brittle iron oxide that is difficult to remove, but tends to pop loose when the pipe is bent. If a pipe is not aggressively cleaned after forging, the scale can come loose and plug the cutting tools, reducing mud flow into the bore. This can cause tracking beacons to overheat and possibly fail.

Do the thread patterns match?
When buying replacement pipe, always replace the entire string with pipe from the same manufacturer. The HDD industry has no established industry standard for threads, so not all threads are made equally. Parts from different manufacturers may appear to assemble, but this doesn’t mean the joint was made up correctly. Thread tolerances also vary widely among manufacturers. And worn threads, of course, do not match any other threads. Mixing new and worn threads increases contact pressure and accelerates thread wear. Also, bend radii of the pipe may be different, which will cause accelerated and uneven wear on all pipes in the string.

Published in the Fall 2007 issue of The Underground.