The image of the rotatastic drive with his team looking on, perplexed, flashed before Jamal’s eyes. Located about thirty meters from the city of Kuala Lumpur, a kelly bar gives way again: the drill is at a standstill. His last-minute choice of a friction-type bar, a layer admittedly in terms of component costs, was the greatest compromise in the cold sand and gravely cobble. Two more days wasted. One more expense policy cross check in the amount of a crane rental required to lift stuck tool. And a very pissed project manager.
If you ever hovered over a rotary drill rig, yes, this thing have happened before. The steel can be assembled on the work site only using proper rig and centerlocking Kelly bars. However, practitioners drop back into the price and availability trap and this is the point right when they look for the Kelly bar. All need to be the same in a driller and they cite regions, consumables, rig rates and formation thickness, which does not apply to a kelly bar. A Kelly bar mismatch in a drilling rig impairs productivity.
The article provides detailed information about the Kelly bar and how the device operates, including the various types available and the selection of the right one in conjunction with the ongoing maintenance support. The module provides a practical five-step selection guide, goes through the specifications that have been left out by most leading suppliers and gives ways that can help you to increase the component service duration. Whether you are an end user doing the first purchase or someone with several bars to manage, this article lets you make some educated choices.
What Is a Kelly Bar on a Drill Rig?
This is a mechanism for transferring the power generated by the rotary drilling machine to the drill tools. It comprises the wire lines or drillpipes used in addition to the boring device; principally, it is the mechanical junction of the rig’s rotary motor and the auger, drilling bucket or casing tube installed at the bore bottom.
The name is derived from a type of section – square or hexagonal – which was used during the early days of oil drilling, called a kelly. Indeed, the modern foundation drilling kelly bars are telescopic tubes which, when deepening a borehole, are pulled out. They fine-tune the total stroke according to the depth of the hole, as well as enable a Kelly bar piling rig with a hammer drive. The Kelly bar hybrid drilling system is one with multifunctional operating systems, which means it can drill a borehole from 15m to 100m and even more and retain its column and torque.
This is an outline of how the power is concentrated. There are a few shafts which are responsible for turning the Kelly boxes, which are situated at the top of the bar. Meanwhile, transmission segments that are turnable and located outside the walls of the shafts pass the turn-through the bar via the center to the attachment at the end. Similarly, the load from the rig operator movement mechanism also forces downward the same shaft and the attached tool against the rock.
A Kelly bar must meet three important criteria. It is essential that mechanical power is transmitted without losses. It is equally important that crowd pressure is applied without the deformation of the bar. Last, but not least, the Kelly bar must be capable of multiple cycles a day of extension and retraction in all materials possible. It holds true that when any of the above-mentioned functions is lacking the drilling activity is immediately stopped.
Need help matching a Kelly bar to your rig? Our engineering team can review your rig model and soil conditions to recommend the right specification. Contact us for a technical consultation.
Kelly Bar Types for Drill Rigs
There are differences in the operation of all types of Kelly bars. These differences in operation are in terms of the types of soils the extension best fits with the amount of torque that is being applied how high the bar is able to operate and the time of operation that the bar is installed.
Friction Kelly Bar
There are differences in the operation of all types of Kelly bars. These differences in operation are in terms of the types of soils the extension best fits with the amount of torque that is being applied, how high the bar is able to operate, and the time of operation that the bar is installed.
The arrangement is lighter and simpler than comprising connections in such aspects and the depth is higher because the absence of a locking mechanism reduces the weight as well as the mechanical design of the construction. For friction, Kelly bars performance positively corresponds to the bore nature of the soils, that is, when you talk about clay, silt, loose sand, and non-cohesive soils, where the mechanical energy applied during drilling is quite low and the standard crowd forces are taken into consideration.
One of the setbacks of the friction-type Kelly bar is that it lacks torque ratios. Especially when the subsurface is hard rock or has compaction or has boulders, the bars possess a tendency to slip under strain. That motion erodes the drive elements and shafts, complicates transmission processes and brings about premature damage. Also, others have percentage lower outputs which leave variation in the extent of stability that could be a concern due to possible changes in the direction to the borehole, especially in aggressive type of formations.
Interlocking Kelly Bar
An interlocking Kelly pin utilizes mechanical locks that are activated to join telescopic elements when they are operated. Top drive keys with dovelocked or recessed grooves come into play with the application of torque, forming a continuous section capable of withstanding buckling and turning moments with minimum losses.
This structure is particularly effective in hard soils, dense sand and gravel, rebars, and finally, even in rocks. Sliding is avoided because of the mechanical interfaces under excessive torque, which improves the horizontal stiffness for keeping vertical straighter holes, and may contribute to higher bending deformations without any well section falling off.
Unlike bar interlocked bars, the more bars within the same section of plain bars lead to higher production costs although using them is lighter, exemplifying the terms in friction and locking them together through the bars requires a more complex process of normal incidence than friction welding and other non-premachinable fastening types.
Typical interlocking rotary drilling rig kelly bar specifications consist of three to six sections, depths of up to 90 meters (although there are custom-sized bars that can be made longer), and various torque ratings between 140 and 500 kN m. It is typical that, for the most difficult foundation applications, the over-balanced bars are used.
Want to know the difference between Friction and Interlocking Kelly Bar? Please read our comparison guide about Friction and Interlocking Kelly Bar.
Full-Lock and Multi-Lock Kelly Bar
The full lock or multilock Kelly bar is a heavy duty alternative to the interlocking bar. It fixes all expanding sections in an order at any time to one firm steel column. This way there is almost no loss of torque and no flexibility when there is a load.
Bars are made using special materials; their reinforcing bars are installed up to 4 times more often than in plastic concrete in bedrock, granite, basalt, and hard pebble. The construction of such restraints consists of employing high-strength steel, increased wall thickness and the reinforcing keys. The permissible values of the operating torque are up to 500 kNm for the largest diameters.
Hybrid and Combination Kelly Bar
There are hybrid designs available from some manufacturers that bring a combined effect of friction and lodging features. The that these bars are self-adjusting bars and may have manual adjustments during installation with respect to the nature of the particular in-situ materials. They are used in formations that continuously change from depth, that is, in mixed formations consisting of soft and hard layers.
Casing Kelly Bar
A casing kelly bar is a design of a kelly whose blank allows drilling of the hole and construction of casing simultaneously. This type of kelly is used in any boreholes in alluvial soils or in boreholes in water-bearing strata to prevent the collapse of holes. Casing pipes are put through the hollow center, while drilling, the rotation is transmitted through the kelly bar to the rotary head.
Short Kelly Bar
| Feature | Friction Kelly Bar | Interlocking Kelly Bar | Full-Lock Kelly Bar |
|---|---|---|---|
| Torque transfer | Surface friction | Mechanical locks | Full-section rigid lock |
| Best for | Soft to medium soils | Hard soils, rock, gravel | Bedrock, boulders, extreme load |
| Max depth | Up to 60 m (standard) | Up to 90–130 m | Up to 90–120 m |
| Torque range | 120–360 kN·m | 140–500 kN·m | 280–500+ kN·m |
| Weight | Lighter | Heavier | Heaviest |
| Cost | Lower | Higher | Highest |
| Maintenance | Simpler | More involved | Intensive |
If you choose a Kelly Bar based on your needs, you can learn about it through our article about How to Choose a Kelly Bar.
Kelly Bar Specifications for Rotary Drill Rigs
The selection of the drill rig Kelly bar will depend on carefully looking at the specification sheets. It is these criteria that are important in Kelly bar selections.
Outer Diameter and Section Count
For example, an index chart may briefly describe what the outer diameter is which is very important to everyone generally, particularly when it comes to torque capability, drilling rigs, sections, etc. The common diameters would vary from approximately 299 millimeters to 630 millimeters. Such diameters are particularly suitable for mini-drill rigs and short boreholes. But such on the contrary, larger diameters are provided in more powerful equipment and required for depths such as torque and down-the-hole.
The number of segments, on the other hand, reveals the reasons behind the collapsed state of the drill string and offers an additional dimension of the extended state. A four-segment Kelly bar will be able to penetrate more meters than a three segment kelly bars of the same size, but it is bulkier and has slightly less rigidity. Five or six segment kelly bars are used for deep piles and other very deep applications.
Torque Capacity and Depth Range
The operating capacity of the torque must be either equivalent to that of the rig or in excess of it. A mistake that is commonly made is the selection of a bar with the torque rating matching the torque generated by the rig. Because of the safety factor, the bar should be capable of producing a minimum of 1.2 to 1.5 times the load torque of the rig. It is a fact that the usable torque is less than the rated torque because the soil, the bar itself, and the transmission of the dynamometer efficiency all reduce the transferred value of the force.
It was when Maria, an engineer from project department in São Paulo, had to work on design of a high-rise foundation that she was reminded of this lesson. And so the design includes a bar of 470 mm and 280 kN/m which Maria suggested for a 260 rig. Practically, it sounded like a good pairing.
However, the very same bar had considerably stiffer load than it had registered. As a result, there was excessive wear on the bar, causing the keys to the driving mechanism (tranny) to break. In less than four months, some observable cracks started appearing at section joints.
Don’t know what Kelly Bar Torque Ratings are? Please check our guide to learn about Kelly Bar Torque Ratings.
The situation was resolved with a 508 mm bar of 360 kNm, the new revised drilled column. The increase in the period of use is approximately forty percent.
| Outer Diameter (mm) | Nominal Torque (kN·m) | Sections | Max Drilling Depth (m) | Kelly Box (mm × mm) |
|---|---|---|---|---|
| 299 | 140 | 3 | 15–43 | 200 × 200 |
| 355 | 150 | 3–4 | 12–48 | 200 × 200 |
| 394 | 260 | 3–4 | 21–64 | 200 × 200 |
| 419 | 280 | 3–4 | 24–68 | 200 × 200 |
| 470 | 280–360 | 3–4 | 24–64 | 200 × 200 |
| 508 | 360 | 3–5 | 25–53 | 250 × 250 |
| 558 | 480 | 4 | 30–72 | 250 × 250 |
| 580 | 400 | 4–5 | 30–78 | 250 × 250 |
| 630 | 500 | 4 | 30–82 | 250 × 250 |
Data sourced from manufacturer specification tables. Always verify against your rig manufacturer’s requirements.
Material Standards
Kelly bars are manufactured from high-strength alloy steels. The most common grades include:
- 35CrMo: A chromium-molybdenum alloy with good strength and toughness. Common for standard-duty bars.
- Q460D: A high-strength low-alloy structural steel with yield strength of 460 megapascals. Used for interlocking bars requiring higher load capacity.
- Q550: An even higher-grade structural steel with yield strength of 550 megapascals. Used for heavy-duty and full-lock bars in rock applications.
- 27SiMn: A silicon-manganese alloy steel with excellent wear resistance. Often used for drive keys and wear-prone components.
The thickness of walls is not same for all. Regular bars are usually 18-22 millimeters in width. Bars dependent on the rock soil and the ones which are utilized with heavy loads might have 25-40 millimeters of thickness to improve resistance to folding and cte.
Different materials have different characteristics, and if you want to choose the right material for the Kelly bar, you can check out our article about Kelly Bar Materials.
Kelly Box and Drive Stub Dimensions
The Kelley socket is a unit’s square or rectangular hole mounted on a unit’s end used to impart rotary motion while drilling. Sizes usually 130 × 130 millimeters, 150 × 150 millimeters, 200 × 200 millimeters, and 250 × 250 millimeters are also common. Matching the Kelly socket to the drive stub in the unit is accountable. The combination is not suitable for certain machines, always have some incisions and vibrations and is trapped in the Wardshole, which is a pole or force tube, inside the unit, but such a situation is always accidental.
Compatibility is very important for the Kelly bar, and if you‘re not familiar with this, you can check out our article about Kelly Bar Compatibility.
Kelly Bar Selection for Your Drill Rig: 5-Step Framework
Often, it is the case that choosing a Kelly bar trench top bar to fit one’s drilling machine may be a little challenge. It requires a proper methodology to get the right answer. It usually involves the following stages.
If you want to extend the lifespan of the Kelly bar, please refer to our article on Kelly Bar Lifespan.
Step 1: Assess Soil and Rock Conditions
Proceed to the specialist’s report. Find out the major rock types you expect to drill in soft strata and then find the corresponding kelly bars. Torque friction Kelly bars are effective in friction soils like soft clay and silt. Once we have dense sand, gravel, or weathered rock we need to use lapel kelly bars. In particular, for bedrock and boulders, the bars should be interlocked on both doors. In fact, one has to apply full lock or even heavy-duty bars for those particular strata.
If the sediment is muddled with various or alternating levels, the user should consider hybrid bars or predict the timing for changes in tools between the sections.
Step 2: Determine Required Drilling Depth
It’s necessary to determine the depth of each borehole in a section, including any excessive leveling or allowing for the difference that might occur because of the additional length of a tool. A ten to fifteen percent margin should be added to that figure. Then compare this value with the permitted drilling depth in your design at the same number of sections. Note that friction bars may drill deeper than similar diameter interlocking bars because they are less in weight and less restrained.
Step 3: Match Torque to Rig Output
Make sure you refer to the manual that your company offers for the rotary drive unit and establish the limits of the torque which is there. Choose the bar in such a manner that they have the deflection of its torque which factor extends by at least 20% of the aforesaid limit. Finally, don’t forget about the effective part of torque. In hard formations, only 70-80% rated torque can be used because there is Earth resistance as well as mechanical losses. Therefore, the equipment should be selected accordingly.
One example of this is that 300 kilonewton meters of rotation needs a bar with 360 kilonewton meters. In the case of rock, it is even more necessary to have 400 or even larger scores as the safe boundaries need not be crossed.
To choose the right size for the Kelly box, please refer to our article on Kelly Box Sizes.
Step 4: Verify Rig Compatibility
Measure the Kelly box and ascertain that it fits the drive stub of the rig. Similarly, make sure that the extended length can go up to the mast top without causing problems with the winch travel. See also whether the outside diameter of the bar bounds the inside diameter of the rotating element and the possibility of using any well casings planned.
If you are managing several types of rigs then compatibility becomes much important. Bauer, Soilmec, Liebherr, Sany, XCMG, IMT, and MAIT provide different graft systems with specific engineering data. In instances where one bar can be used with all machines while another is suitable for specific operating conditions, the broad application product may be modified for use.
Step 5: Evaluate Total Cost of Ownership
It is not enough to know how much will the interlocking hop-up interlock safety pad cost maker without considering the expected time that it will serve, the frequency of maintenance checks and its maintenance, replacement and repair costs, and downtime. Sometimes the more expensive piece such as an interlocking hop-up interlock safety pad, lasts three years on such strong rock and is more business efficient than a cheaper one, which fails in eight months, costing less.
This basis was taken by maintenance workers in Jakarta near Chen and on twelve rigs. The bars stopped being chosen chaotically and the procedure for choosing them was subjected to soil reports and calculated torque. From sixteen months onwards, the bars caused 65 % less downtime in Kelly. During this period, the increased replacement rate was also reduced by 40%. The new bars needed were also paid for, even with the extra fittings, because downtimes are saved and both the period of use is extended.
Looking for custom Kelly bars built to your exact rig and soil specifications? Changsha Mingyi Machinery Equipment Co., Ltd. has been manufacturing interlocking, friction and full lock Kelly bars for all major drilling rig manufacturers. Request a custom specification quote.
Kelly Bar Integration with Rotary Drilling Rigs
In fact, the drill rig Kelly bar is not a stand-alone system but is an element of a system. Assessing how it connects to the rotary drilling rig and the tooling will help in better understanding Kelly bar selection and thereby its performance.
Rotary Drive Connection
The rotary drive is situated at the top of the rig mast. The output spindle is responsible for engaging the kelly box. In this case, the drive should secure the box well enough for transmitting the torque through the bar without any play, however, it should still allow the bar for such movements as telescopic extension and retraction. Their hammering experience is due to overshooting. They wear the bar by overloading.
Drill String Assembly
Through the adapters underneath the drilling rig kelly bar, the drill stem leads to the drilling tool. The tool that can be used for constructing bored piles is usually either a drilling bucket, an auger or a drilling barrel. It should be noted that the Kelly bar has to carry the particular tool to be used, the excavated soil, and its own parts when it is being extracted.
Tool Compatibility
The design of two elements creates different tasks. Thus, when a bucket with reservoir clay is used, there is a large pulling power. Carbide teeth are lined in the inner surface of a barrel used for rock rocks excavation which exerts large amount of pull. An earth auger in sand of low compaction brings wear during movement of the part, but compression is moderate. The Kelly bar must have a designated rating taking into account the least expected value within all possible combinations of torque, crowd force and extraction load forces.
As a result, a row of several bars is often set up by many builders. A soft adhesion bar works well in uppermost sections of soils with inferior physical properties. Once the construction reaches hard formations an interface bar replaces it. Employing a correct tool and bar combination and changing the setups at the appropriate level of penetration helps in preserving equipment and speeds up the project.
Failure in the process of using the Kelly bar? Please check out our article on Common Kelly Bar Failures.
Kelly Bar Maintenance for Longevity
A rotary drill rig kelly bar will not last long even though it is the top in the market if routine maintenance is not observed. Appreciating that rotary drilling involves the use of abrasive soils, high torque cycling, as well as the wearing of the telescopic members, it is necessary to look after it like that.
Daily Inspection Checklist
Make sure to examine the drive keys or rails for cracks, distortion, and unusual wear before you start every operation shift. Make a thorough inspection of the coupling segments for play or slackness. Look for any signs of Kelly box elongation or wall thinning. Also, scout for any distorted or cracked sections.
Every time you finish with a drilling activity, remember to brush off all the dirt and loose debris from the external parts of the drill. In particular, focus on the areas where telescopic sections touch each other and on areas where bars push into one another.
Cleaning Procedures by Soil Type
When clay or silt remains wet, they absorb moisture and keep the metal wet as well. Use water and a scrub in these areas excessively after every work shift. One of the most harmful things as far as these structures are concerned, is the drying inside the telescopic sections of the bentonite and the drilling slurry.
In the ground that contains some specified chemical solution such as acidic, alkaline or salty, be aware of the risk of the rack being buried in the ground, for approaching with least maintenance can lead to pitting, wearing out failure of the drive keys within one or two months.
Lubrication Best Practices
There is no single method of choosing the lubricator. In some interlocking methods, high-temperature grease is applied into holes of pressure keys to prevent by wear; in others, a dry mode has been recommended to reduce dust penetration into grooves. Make sure you observe the safety recommendations exactly as you received the instructions from your manufacturer. Choosing the wrong oil or putting it in the wrong place will do more damage than not using it at all.
For sliding bars, smooth lubrication of wear surfaces has the effect of reducing surface damage or chafing. Excessive lubrication should be avoided since it will attract abrasive soil particles.
Storage and Protection
Common Kelly Bar Problems and Solutions
The value of being aware of what to examine in your Kelly bar drill rig when problems emerge cannot be overstated because it is helpful regarding time and prevention. It ensures that minor damages do not culminate into a whole breakdown.
Jamming and Binding
A bar that fails to extend or retract without any hitches usually has any one of the two possible reasons. Debris present within the telescopic portion, Bent pieces of a section. Or, wear a guide strip.
Dealing with stuck dirt is usually the most approachable way of handling materials. Straightening the bent bars or sections is the easiest solution to such a problem. Deal with the issue of binding immediately as it occurs. Forcing a jammed bar with the crowd of the rig furthers the bending of the sections. A crack can develop in the joints.
Spline Wear and Drive Key Damage
Bars with interlocking mechanisms require the precise engagement of the drive keys and the locking pockets. Wear in this system can cause backlash which results in single or shock loads and increases wear out on components with time. Inspect the lock edges correctly once in every one hundred hours of operation, specifically in hard rock conditions. Eliminate burrs and flashing two millimeters or greater at once. Drive keys must be replaced as soon as they exceed the manufacturer’s wear limits.
Cracking and Fatigue Failure
Cracking typically initiates at certain geometric points of a structure, such as stress raisers, Cryogradi/s, changes in section, drive key fillets, or stress concentrations. A small crack, usually detected by dye penetrant or magnetic particle inspection, may either be cut out or repaired. On the contrary, detection in an existing crack normally would necessitate a replacement. Within hard rock formations, shorten inspection intervals by half. Under cyclical loading, the rate of fatigue is accelerated.
Over-Torque Damage
Failure to remain within a vessel’s technical limits causes damage. A threaded vessel may operate in operational mode, with severe damage observed within, which will only be revealed after the vessel has failed externally. If you suspect that a part has been overstressed, make sure to immediately inspect it. Do not depend on external signs of damage.
When to Repair vs Replace
Localized deformation should be attended by repair while indicators of minor creep and very small cracks are tolerable as well as drive keys and wear sleeves. As for the main tubes, crack inclusions, ten percent or greater thinness due to loss of uniformity, and repair cost which exceeds approximately one-half the replacement cost require that replacement be done. After the bar has been repaired, it will need testing and certification before it is put back into operation.
Kelly Bar Materials and Manufacturing Standards
One of the most important aspects affecting the performance of the rig as a whole, in the case of its specific component in the rig, is the quality of the steel used and its manufacturing tolerances.
Steel Grade Comparison
Hollow cylindrical steel tubes made of seamless steel tubing are used to construct standard Kelly bars. The choice of grade factors in the strength required, resistance hardenability, and the cost dimension. 35CrMo material is best suited for normal to moderate loads, but is that how it plays out? First, one must consider the design strength and load guarantee in the design. For certain high-strength bars such as Q460D and Q550, the splicing is controlled with temperature control. However, for high torques and low-yield materials, the splicing or joining issues are not critical.
Heat Treatment Processes
The bars are subjected to heat treatment to improve their mechanical properties after the welding and machining processes. Stress relieving via normalizing is employed after the welding. Quenching and tempering are performed to harden and strengthen the regions of concern based on the wear or contact mechanics approach such as drive keys. Excessive heat treating of steel results in carburized zones which fail under cyclic loads.
Welding and Quality Control
Because of the automated welding process and the usage of pulse spraying welding and protective gases while welding, the quality of welds in continuous bar production is on a high level. And domestic welding is preferably for repair of the defects and personal solutions. The integrated inspection package involves whether or not the material has the necessary quality certification, dimensional controls, weld integrity tests, and quality inspection of tightened sections. It is pertinent that the bars are issued with clearances of the quality aspects used in their production.
Frequently Asked Questions
How deep can a Kelly bar drill?
Though normal Kelly bars can operate up to 60 meters, there are specially designed interlocking bars which work up to 90 meters and you can customize them further to work up to 130 meters and beyond. The length of the reinforced part of the interlocking bar depends on the number of sections, the diameter of the bar and the height of the mast.
How long does a Kelly bar last?
The lifespan of the service can be different depending on the quality of land, the quality of maintenance, and the management practices. Bars can often last from one year to more if not much, provided that it is not destroyed and/or eroded, upon continuous use as in soft soils. However, because of poor maintenance, a bar that thrives in Hard Rock may require substantial repair services within a six month period. Cleaning and inspection at regular intervals are the most crucial aspects in this regard.
Can any Kelly bar fit any drill rig?
No. The extent of each rifle bar, applicable load rating, torque, and the rig’s mast structure are critical in the choice of kelly bars for the drill. The renowned manufacturers in the market such as Bauer, Soilmec, Liebherr, Sany, XCMG, IMT and MAIT, supply machines with certain construction features, ensuring that they are only fixed on certain heads. Always confirm perfect compatibility before purchasing a good.
How much does a Kelly bar cost?
Costs are dependent on the diameter, length, design, and steel grade of casing. Even the lowest-friction bars made to support smaller rigs may still be priced at a figure of a few thousand dollars. However, for large rigs, the high-strength interlocking bars will likely be more expensive. What is important is not only the price of purchase, but also the total cost of ownership, meaning costs connected with lifespan and repair and maintenance.
What causes a Kelly bar to jam?
Usually, jamming is more likely due to rubbish coming from both ends of the telescopic sections. This can be as a result of two oblique tubes purported to make a straight bar, insufficient lubrication that is not enough, corrosion, among other things. In interlocking bars, if the drive keys or the locking pockets are damaged, they can also hinder the smooth extension and contraction.
Conclusion
Kelly bar is more than just a pipeline between the derrick and the tool. It is a manufactured component that dictates torque transmission downstream into the formation, directional deflection of the hole, or the distance drilled before taking the rig for service maintenance.
The five key takeaways for your Kelly bar drill rig selection are:
- Match the bar type to your soil conditions. Friction for soft ground. Interlocking for hard rock.
- Size torque capacity with safety margins, not just to the rig’s rated output.
- Verify Kelly box compatibility, diameter clearance, and mast height before buying.
- Maintain daily inspection and cleaning routines. Prevention is cheaper than extraction.
- Evaluate total cost of ownership, not just the purchase price.
Accurate Kelly bar drill rig setup selection is not a bed of roses and requires quite a bit of time to think. This additional time will save you much more time when it matters the most, also elongates the service life of hardware hence avoiding additional replacements and above all will guarantee that the project proceeds as it was supposed to. Every aspect of the right bar corresponds to your rig, including the ground conditions, permitting depth, the nature of instruction, etc.
Ready to upgrade your Kelly bar setup? Our firm, Changsha Mingyi Machinery Equipment Co. Ltd, produces and offers wear bars of all kinds: interlocking, friction, full-lock or any other rigid line that you will require. We are more than glad to offer you the services of technical and commercial advice and prepare the quotation of traditional wears especially for the purpose of your upcoming activities. Contact us for our service.
