rebuilding a mud pump free sample

If you run a mud rig, you have probably figured out that the mud pump is the heart of the rig. Without it, drilling stops. Keeping your pump in good shape is key to productivity. There are some tricks I have learned over the years to keeping a pump running well.

First, you need a baseline to know how well your pump is doing. When it’s freshly rebuilt, it will be at the top efficiency. An easy way to establish this efficiency is to pump through an orifice at a known rate with a known fluid. When I rig up, I hook my water truck to my pump and pump through my mixing hopper at idle. My hopper has a ½-inch nozzle in it, so at idle I see about 80 psi on the pump when it’s fresh. Since I’m pumping clear water at a known rate, I do this on every job.

As time goes on and I drill more hole, and the pump wears, I start seeing a decrease in my initial pressure — 75, then 70, then 65, etc. This tells me I better order parts. Funny thing is, I don’t usually notice it when drilling. After all, I am running it a lot faster, and it’s hard to tell the difference in a few gallons a minute until it really goes south. This method has saved me quite a bit on parts over the years. When the swabs wear they start to leak. This bypass pushes mud around the swab, against the liners, greatly accelerating wear. By changing the swab at the first sign of bypass, I am able to get at least three sets of swabs before I have to change liners. This saves money.

Before I figured this out, I would sometimes have to run swabs to complete failure. (I was just a hand then, so it wasn’t my rig.) When I tore the pump down to put in swabs, lo-and-behold, the liners were cut so badly that they had to be changed too. That is false economy. Clean mud helps too. A desander will pay for itself in pump parts quicker than you think, and make a better hole to boot. Pump rods and packing last longer if they are washed and lubricated. In the oilfield, we use a petroleum-based lube, but that it not a good idea in the water well business. I generally use water and dish soap. Sometimes it tends to foam too much, so I add a few tablets of an over the counter, anti-gas product, like Di-Gel or Gas-Ex, to cut the foaming.

Maintenance on the gear end of your pump is important, too. Maintenance is WAY cheaper than repair. The first, and most important, thing is clean oil. On a duplex pump, there is a packing gland called an oil-stop on the gear end of the rod. This is often overlooked because the pump pumps just as well with a bad oil-stop. But as soon as the fluid end packing starts leaking, it pumps mud and abrasive sand into the gear end. This is a recipe for disaster. Eventually, all gear ends start knocking. The driller should notice this, and start planning. A lot of times, a driller will change the oil and go to a higher viscosity oil, thinking this will help cushion the knock. Wrong. Most smaller duplex pumps are splash lubricated. Thicker oil does not splash as well, and actually starves the bearings of lubrication and accelerates wear. I use 85W90 in my pumps. A thicker 90W140 weight wears them out a lot quicker. You can improve the “climbing” ability of the oil with an additive, like Lucas, if you want. That seems to help.

Outside the pump, but still an important part of the system, is the pop-off, or pressure relief valve. When you plug the bit, or your brother-in-law closes the discharge valve on a running pump, something has to give. Without a good, tested pop-off, the part that fails will be hard to fix, expensive and probably hurt somebody. Pop-off valve are easily overlooked. If you pump cement through your rig pump, it should be a standard part of the cleanup procedure. Remove the shear pin and wash through the valve. In the old days, these valves were made to use a common nail as the shear pin, but now nails come in so many grades that they are no longer a reliable tool. Rated shear pins are available for this. In no case should you ever run an Allen wrench! They are hardened steel and will hurt somebody or destroy your pump.

One last thing that helps pump maintenance is a good pulsation dampener. It should be close to the pump discharge, properly sized and drained after every job. Bet you never thought of that one. If your pump discharge goes straight to the standpipe, when you finish the job your standpipe is still full of fluid. Eventually the pulsation dampener will water-log and become useless. This is hard on the gear end of the pump. Open a valve that drains it at the end of every job. It’ll make your pump run smoother and longer.

The 2,200-hp mud pump for offshore applications is a single-acting reciprocating triplex mud pump designed for high fluid flow rates, even at low operating speeds, and with a long stroke design. These features reduce the number of load reversals in critical components and increase the life of fluid end parts.

The pump’s critical components are strategically placed to make maintenance and inspection far easier and safer. The two-piece, quick-release piston rod lets you remove the piston without disturbing the liner, minimizing downtime when you’re replacing fluid parts.

Cavitation is an undesirable condition that reduces pump efficiency and leads to excessive wear and damage to pump components. Factors that can contribute to cavitation, such as fluid velocity and pressure, can sometimes be attributed to an inadequate mud system design and/or the diminishing performance of the mud pump’s feed system.

Although cavitation is avoidable, without proper inspection of the feed system, it can accelerate the wear of fluid end parts. Over time, cavitation can also lead to expensive maintenance issues and a potentially catastrophic failure.

When a mud pump has entered full cavitation, rig crews and field service technicians will see the equipment shaking and hear the pump “knocking,” which typically sounds like marbles and stones being thrown around inside the equipment. However, the process of cavitation starts long before audible signs reveal themselves – hence the name “the silent killer.”

Mild cavitation begins to occur when the mud pump is starved for fluid. While the pump itself may not be making noise, damage is still being done to the internal components of the fluid end. In the early stages, cavitation can damage a pump’s module, piston and valve assembly.

The imperceptible but intense shock waves generated by cavitation travel directly from the fluid end to the pump’s power end, causing premature vibrational damage to the crosshead slides. The vibrations are then passed onto the shaft, bull gear and into the main bearings.

If not corrected, the vibrations caused by cavitation will work their way directly to critical power end components, which will result in the premature failure of the mud pump. A busted mud pump means expensive downtime and repair costs.

As illustrated in Figures 1 and 2, cavitation causes numerous pits to form on the module’s internal surface. Typically, cavitation pits create a stress concentration, which can reduce the module’s fatigue life.

Washouts are one of the leading causes of module failure and take place when the high-pressure fluid cuts through the module’s surface and damages a sealing surface. These unexpected failures are expensive and can lead to a minimum of eight hours of rig downtime for module replacement.

To stop cavitation before it starts, install and tune high-speed pressure sensors on the mud suction line set to sound an alarm if the pressure falls below 30 psi.

Accelerometers can also be used to detect slight changes in module performance and can be an effective early warning system for cavitation prevention.

Although the pump may not be knocking loudly when cavitation first presents, regular inspections by a properly trained field technician may be able to detect moderate vibrations and slight knocking sounds.

Gardner Denver offers Pump University, a mobile classroom that travels to facilities and/or drilling rigs and trains rig crews on best practices for pumping equipment maintenance.

Program participants have found that, by improving their maintenance skills, they have extended the life of fluid end expendables on their sites. They have also reported decreases in both production and repair costs, as well as reductions in workplace hazards.

Severe cavitation will drastically decrease module life and will eventually lead to catastrophic pump failure. Along with downtime and repair costs, the failure of the drilling pump can also cause damage to the suction and discharge piping.

When a mud pump has entered full cavitation, rig crews and field service technicians will see the equipment shaking and hear the pump ‘knocking’… However, the process of cavitation starts long before audible signs reveal themselves – hence the name ‘the silent killer.’In 2017, a leading North American drilling contractor was encountering chronic mud system issues on multiple rigs. The contractor engaged in more than 25 premature module washes in one year and suffered a major power-end failure.

Gardner Denver’s engineering team spent time on the contractor’s rigs, observing the pumps during operation and surveying the mud system’s design and configuration.

The engineering team discovered that the suction systems were undersized, feed lines were too small and there was no dampening on the suction side of the pump.

There were also issues with feed line maintenance – lines weren’t cleaned out on a regular basis, resulting in solids from the fluid forming a thick cake on the bottom of the pipe, which further reduced its diameter.

Following the implementation of these recommendations, the contractor saw significant performance improvements from the drilling pumps. Consumables life was extended significantly, and module washes were reduced by nearly 85%.

Although pump age does not affect its susceptibility to cavitation, the age of the rig can. An older rig’s mud systems may not be equipped for the way pumps are run today – at maximum horsepower.

It may be impractical to flush system piping during drilling operations. However, strainer screens should be checked daily to remove any debris or other flow restrictions.

The positive displacement mud pump is a key component of the drilling process and its lifespan and reliability are critical to a successful operation.

The fluid end is the most easily damaged part of the mud pump. The pumping process occurs within the fluid end with valves, pistons, and liners. Because these components are high-wear items, many pumps are designed to allow quick replacement of these parts.

Due to the nature of its operation, pistons, liners, and valve assemblies will wear and are considered expendable components. There will be some corrosion and metallurgy imperfections, but the majority of pump failures can be traced back to poor maintenance, errors during the repair process, and pumping drilling fluid with excessive solids content.

A few signs include cut piston rubber, discoloration, pistons that are hard to remove, scored liners, valve and seat pitting or cracks, valve inserts severely worn, cracked, or completely missing, and even drilling fluids making their way to the power end of the pump.

The fluid end of a positive displacement triplex pump presents many opportunities for issues. The results of these issues in such a high-pressure system can mean expensive downtime on the pump itself and, possibly, the entire rig — not to mention the costly repair or replacement of the pump. To reduce severe vibration caused by the pumping process, many pumps incorporate both a suction and discharge pulsation dampener; these are connected to the suction and discharge manifolds of the fluid end. These dampeners reduce the cavitation effect on the entire pump which increases the life of everything within the pump.

Poor maintenance — such as improper valve and seat installation — is another factor. Improper cleaning when replacing a valve seat can leave sand or debris in the valve seat area; preventing the new seat from properly forming a seal with the fluid cylinder, causing a pathway for a washout to occur. It is important to pull up on a seat firmly by hand and make sure it doesn’t pop out and is properly seated. The seats must be seated well, before resuming repairs. You should never reuse a valve seat if at all possible.

The fluid end is the most easily damaged part of the mud pump. The pumping process occurs within the fluid end with valves, pistons, and liners. Because these components are high-wear items, many pumps are designed to allow quick replacement of these parts.

A washout occurs when fluid and solids enter the area behind or underneath a valve seat and erode the sealing surface. Washouts are usually caused by one of three issues: a worn or cracked valve seat, improper cleaning of the valve seat and deck which creates a poor seat seal, and excessive sand content in your drilling fluid. Worn or cracked valve seats can allow fluid to enter the area around the valve seat and seat deck, creating a wash point on the valve seat and causing it to cut into the fluid cylinder and seat deck.

Additionally, the throat (inside diameter) can begin to wash out from extended usage hours or rather quickly when the fluid solids content is excessive. When this happens it can cut all the way through the seat and into the fluid end module/seat deck. This causes excessive expense not only from a parts standpoint but also extended downtime for parts delivery and labor hours to remove and replace the fluid module. With that said, a properly operated and maintained mud recycling system is vital to not only the pump but everything the drilling fluid comes in contact with downstream.

If you spot a washout on any of the fluid end parts, you need to replace the part immediately. A washout can get much worse very quickly, leading to costly repairs.

A well-placed suction stabilizer can also prevent pump chatter. Pump chatter occurs when energy is exchanged between the quick opening and closing of the reciprocating pump’s valves and the hammer effect from the centrifugal pump. Pump isolation with suction stabilizers is achieved when the charge pumps are isolated from reciprocating pumps and vice versa. The results are a smooth flow of pumped media devoid of agitating energies present in the pumped fluid.

Suction stabilizer units can mitigate most of the challenges related to pulsations or pressure surges, even in the most complex piping conditions. The resulting benefits prevent expensive unplanned downtime and decrease costs and inconvenience associated with system replacements and repairs.

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Mystique Mud pump Coolant and Lubricant extends mud pump liner and piston life and provides internal lubrication and extra cooling to the coolant system of mud pumps. It extends the life of all liners, even ceramic. Mystique will not cause corrosion or rusting of iron, and is safe with all alloys. Recommened dilution rate of 12.5%. (25 gallons will treat a 200-gallon system.) For use on closed systems.

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