triplex mud pump video factory

Since the modern mud (or slush) pump was built approximately 60 years ago, the industry has widely accepted the three cylinder or triplex style pump. Triplex mud pumps are manufactured worldwide, and many companies have emulated the original design and developed an improved form of the triplex pump in the past decade.

As in all single acting pumps, the piston exerts a load on the crankshaft. The load is then transmitted to the crankshaft main bearings, which are set in their retainers in the pump frame or housing (see Figure 2).

That the crankshaft is subjected to extreme bending loads and stress concentration areas is one of the drawbacks of the triplex design. Experience shows that all triplex pumps eventually exhibit crankshaft cracking if the operator is using the pump at higher loads and pressures, which is now common as drilling contractors are facing deeper, longer sections to drill. In the past, drillers rarely pushed the performance limitations of triplex pumps; 5,000 psi rated pumps were usually only operated at a maximum of 2,800 psi 90 percent of the time. Now contractors are encouraged to run pumps at the much higher pressures around 4,300 psi, only leaving a safety margin below the pressure relief valve setting. This means the crankshaft is subjected to extended maximum load, which inevitably shortens time to failure, probably exponentially.

Some may suggest that an increase in the number of pistons to improve flow rate will also reduce piston load. Although the middle piston load may be reduced for the same overall pump horsepower, the distance from the main bearings to the middle cam increases, which is not advantageous. For example, a five cylinder pump with the middle cam 50 in from the main bearing will have the same bending moment as a triplex with a 30 in middle cam to bearing distance. However, installing bearings close to the cams can reduce the cyclic failure problems on any pump.

For the drilling industry, the problem with this design is that few have managed to design a crankshaft where bearings can be installed anywhere other than at the crankshaft ends. Consequently, most pumps currently available have crankshafts unsupported close to the middle cam. With the middle area of the crankshaft unsupported, crankshaft failure is inevitable.

A triplex pump with a large load acting on the middle of the crankshaft of approximately 120,000 lbs and a typical distance of about 30 in from middle cam to either main bearing will exert a bending moment of 300,000 lb-ft on the crankshaft adjacent to the main bearing. If the bearing is not spherical, the bending moment where the shaft meets the bearing will coincide with the point on the shaft that the crank can no longer bend because it is restricted by the fixed bearing, which creates huge stress concentration. That load comes and goes cyclically every revolution of the pump. If the pump is rotating at 100 rpm or strokes, then in one week of drilling the crank will experience one million cycles of 300,000 lb-ft effectively switching on and off.

Another symptom of crankshaft deflection or bending is abnormal main gear wear patterns. The high unsupported load in the middle of the crankshaft effectively bows the shaft and consequently the bull gear is moved off alignment, and a strange wear pattern may appear on the gears. Although this is an undesirable occurrence, it is of little importance compared with crankshaft failure. It does explain abnormal wear on a pump used continuously at high pressure.

A pump that addresses these issues may be the solution. A quadraplex has minimal bending moments due to the close proximity of the main bearings to every cam (see Figure 7).

A fully assembled crankshaft is the best and only way to install multiple bearings close to the cams. Even though there is minimal flexure in this design, spherical bearings eliminate stress concentration or point loading. With cam to bearing distances no more than 10 in, the bending moment on a quadraplex crankshaft will be one quarter that of the triplex or five cylinder pump.

In an environment where few advances have been made in mud pump technology in the last 50 years, designers in the mud pump sector of the drilling industry can develop workable solutions to the problems and limitations inherent in triplex pumps.

The future of mud pump design will involve a solution to excessive crankshaft bending moments and address other needed areas of improvement, including piston speed, module replacement in the field, quality of discharge pressure and smoothness of flow-all combined with ease of transportation.

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Bruce Suggs, vice president of marketing and sales for White Star, speaks with DC editorial coordinator Katherine Scott about White Star’s quadraplex mud pump at its headquarters in Waller, Texas, on 17 February.

Drilling Contractor visited the manufacturing facility of White Star Pump Company in Waller, Texas, on 17 February to view a demonstration of the company’s quadraplex mud pump, which was designed to address the challenges of the conventional triplex pump.

“After working on all the different brands of (triplex) pumps, it became evident that they all had the same common issues,” said Bruce Suggs, vice president of marketing and sales for White Star. “(We) tried to build a triplex and ended up with the Quatro.”

Instead of taking an existing triplex pump and trying to make it better, White Star approached the project with a clean-sheet design. The Quatro pump features a width of only 82 in. and easily fits on a standard-width trailer, a potential advantage in areas with limited space, such as on offshore rigs and in shale plays like the Marcellus. With the fluid modules sitting inside the frame, change-out time can be reduced to 23 minutes versus up to 10 hours for conventional triplex pumps. The quadraplex pump also uses a fully assembled crankshaft that requires no castings or welding. Using a crankshaft that is fully assembled and supported by modern bearing placement dramatically reduces crankshaft bending and cracking.

Additionally, the Quatro is equipped with two pulsation dampeners, one for each pair of pistons, unlike the triplex, which carries only one. This allows mud to be dampened before it gets to the strain across, creating a quieter, smoother fluid flow and reducing vibrations.

Triplex plunger-type mud pumps feature a reciprocating, positive displacement pump design utilizing three plungers to safely transfer high-viscosity fluids under high pressure over an extended depth. Although they have many industrial applications, these pumps have become an essential part of oil well drilling rigs where they’re used to provide smooth discharge of mud and debris from oil wells.

In addition to their use in drilling and well service operations, mud pumps are also frequently used to handle corrosive or abrasive fluids, as well as slurries containing relatively large particulates, in applications like commercial car washes, wastewater treatment, cementing, and desalination operations.

DAC Worldwide’s Representative Triplex, Plunger Mud Pump Dissectible (295-418) is an economical, conveniently-sized triplex plunger-type mud pump assembly that teaches learners hands-on maintenance activities commonly required on larger mud pump assemblies used in upstream oilfield production operations.

For example, mud pump assembly is used on well sites maintain downhole backpressure, to lubricate the rotating drill bit, and to help recycle and remove rock debris resulting from drilling activities. These heavy-duty, high-pressure pumps require regular refurbishment, inspection, and repair in the field.

DAC Worldwide’s dissectible mud pump assembly is a realistic sample that’s similar in geometry, design, and operating characteristics to the larger varieties learners will encounter on the job. DAC Worldwide chooses popular name-brand pumps for its dissectibles to ensure industrial and oil and gas training relevancy.

Using the dissectible mud pump, learners will gain hands-on experience with the operating principles, regular maintenance activities, and nomenclature/parts identification at a more convenient scale in the classroom or lab.

Technical training is most effective when learners can gain hands-on practice with industry-standard components they’ll encounter on the job. The Representative Triplex, Plunger Mud Pump Dissectible features a wide variety of common, industrial-quality components to provide learners with a realistic training experience that will build skills that translate easily to the workplace.

The Representative Triplex, Plunger Mud Pump Dissectible is a sturdy unit with a complete triplex, reciprocating, 20+ bhp plunger pump with .75" plunger, 1.5" stroke, and 3" cylinder sleeve. The unit allows for complete disassembly, assembly, and inspection, including removal of plungers, packing, and valves.

The dissectible mud pump comes with a formed-steel, powder-coated baseplate. It can also be mounted on a compatible DAC Worldwide Extended Electromechanical Workstation (903). Each unit comes with the manufacturer’s installation and maintenance manual.

Shandong XinWEI DRILLING EQUIPMENT Co., Ltd. is one of the most well-known manufacturers of trenchless equipment and oilfield equipment in China. After years of unremitting efforts, it has grown into a small but powerful enterprise. Our products cover the entire field, trenchless, from a very small spare part to a very large complete rig system. Our MAIN PRODUCTS are: pump SPARE parts, mud pumps and complete sets of equipment, DC/AC motor, solid control equipment, power plant, vehicle drilling rig, workover rig, land drilling rig, drill pipe and drilling tools, etc. Based on the needs of customers, to provide customers with the best products and services. We focus on providing the best solutions for the maintenance and supply of equipment and spare parts to our overseas oilfield customers.