triplex pump part 2

Triplex PumpTraining Module

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December 1999

Schlumberger Confidential

2.3 Fluid End

There are 5 different Dowell Fluid Ends available for the PG SeriesPower End. The most common ones are the 'G', 'L' and 'H' ends. Theother fluid ends ('R' and 'S') are for special applications requiringextremely high pressures such as stimulation work.


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They are machined from forged AISI 4340 steel or better. The fluid endswith the higher-pressure ratings are usually Autofrettaged* to lengthenthe fluid end's life. Autofretagging is similar to the process used in makingartillery gun barrels - this improves the metal's resistance to fatigue.

Fluid End SpecificationsMODEL PLUNGER

SIZE(INCHES)

MAXPRESSURE

(PSI)

MAX FLOWRATE*(BPM)

BBL/REVPINION

THO ('H') 5 5,500 10.3 0.00681TLO ('L') 4½ 7,000 8.4 0.00553TGO ('G') 3¾ 10,000 5.8 0.00384TRO ('R') 3 15,000 3.7 0.00245

Note:It is recommended that you use both discharge ports for flow rates over8.2 BPM due to the erosion of the discharge port, bushing and also thedischarge manifold. Maximum Fluid End pressure limitations are based onPower End Maximum Rod Load rather than the pressure limitations of thefluid end.

*The Maximum flow rate of a Triplex Pump is calculated on the basis of97% volumetric efficiency.

* Auto frettaging is a heat treatment process where the material is heat-treated and stress relieved simultaneously at high pressure.


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December 1999


The entire assembly of the PG05 Series (steel frame) Triplex Pump,including chaincase, power end and fluid end weighs 5,250 lbs. (2.4tones). The PG05 power end is used on offshore skid units like the CPS362 where unit weight is not a critical factor. It is also used in corrosiveenvironments such as offshore areas where the PG03 power end, whichhas a magnesium frame, would be prone to severe corrosion. The PG03power end is used on CPT 372, CPT 462 and CPS 310 Heli-Unit becauseweight is an important design factor.

CPS 362

CPT 372


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3.0 Lubrication System

It is obvious that a pump capable of outpouring 300 HHP (HydraulicHorsepower) power requires considerable moving parts which must bekept lubricated in order to function efficiently at a reasonable temperature.It must also be dependable, with an acceptable operating life. Eachcomponent - the Chain Case, Power End and the Fluid End - has its ownlubrication system to satisfy its individual requirements.

3.1 Chain CaseMethod of lubrication Splash (chains and sprockets)

Grease (bearings and seals)Lubricant (oil). SAE 40 WT(grease) moly-basedCapacity 0.5-1 galLevel Dipstick (full mark, pump stopped)

Each chain case is equipped with either a sight glass or a dipstick forindicating the oil level in the case. The oil level indicator should becenterlined with the bottom of the input shaft.

Note: When checking the oil level, always remove the dipstick and allowthe oil level to settle, then check the correct level by re-inserting andremoving the dipstick.

Too much as well as too little oil in the Chain Case can actually cause itto overheat. When a chain case is overheated, the bearing grease sealsare usually damaged first. If overheating continues, severe damage canresult to the bearings and chain as the overheated oil breaks downchemically, losing its viscosity and also its lubricating and coolingproperties. The bearing grease is also affected by the high temperature,resulting in the grease not lubricating the bearings correctly, thusproducing more heat.


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3.2 PG Series Power endMethod of lubrication Force FeedFlow rate 15- 20 gpmOil pressure 25-45 psiLubricant SAE 80w-90 WT

Gear Oil(above 32 deg F)

SAE 80 WT (below 32 deg F)

Capacity 17 gallons(This is only the sump volume and doesnot include filter and hose capacity)

Level indicator Dipstick or 1/2 " below main bearing capsMaximum Oil temperature 160 deg F

(70 deg C)

The Power End frame is actually the reservoir for the Power Endlubricant.

It should be noted that when check the oil level always remove thedipstick and allow air to escape from the tube then replace the dipstickand check for correct level.


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Oil is taken from the power end sump by a mechanically or hydraulicallydriven oil pump, and returned under pressure to the power end through afilter. After the filter, it flows to a cross fitting in the line. At the cross, thelubricating oil is directed to:

1. Both ends of the main shaft, and to each of the crossheads.

2. A pressure relief valves is used to maintain a constant flow andmaximum system pressure.

Since pressure in any hydraulic system is a result of resistance and this isa hydraulic system. Also since the flow rate will vary with engine RPM’s.The pump is sized that it will still maintain adaquate oil pressure at lowengine speeds, not idle, but as the components wear lower oil pressurewill result. This can create problems when the powerend is working atvery low rate’s and high discharge pressures, the engine is at to low ofRPM’s to create enough oil pressure to maintain a good film of oil on theeccentric bearings and the rod load is high, the two combined createcatastraphic powerend failures. This is just one reason it is alwaysimportant to watch and maintain powerend oil pressure. Proper sizing ofthe fluid end can prevent these type of failures.

There are two different styles of powerend oil filters and arrangementsused, one being internal by-pass (parker brand is the new style) the otherbeing external by-pass (old style). A by-pass around the oil filter ensurescontinued flow of oil in the event the filter becomes plugged. This iscontrolled by the by-pass relief valve. On the old style it is usuallymounted directly to the filter and has a hose, which directs any by-passflow to the downstream side of the filter. On the new style the by-pass isinternal of the filter housing and has a pre-determined differential setting.The new style filters have an indicator which clearly indicates when and ifthe filter is by-passing. Color coded- green being good and Red being By-passing. This indicator only works when the oil is flowing through it andshould be checked during the job and recorded on the STEM I report.

The oil pressure is controlled by a relief valve in the system usuallymounted directly to the bottom of the power end frame. A pressure gaugemounted on the control panel or directly on the power end lube oil circuitlets the operator monitor the system oil pressure on each pump. The oilmust be kept clean at all times. A milky appearance usually indicateswater contamination. (Refer to section on Care & Maintenance of thePower End and also the Trouble Shooting Guide in the Appendix to helpidentify possible problems and correct them.


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December 1999


It should be noted that there are oil seals inside the either main shaftbearing cap of the power end. When these seals wear the result will belower oil pressure, primarily seen on the gauge, because the gauge is tiedin directly to the cap.

Brown & Sharpe

WebsterorTyronePump


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December 1999


Below are pictures of a pressure relief valve. These valves are very easy toadjust the setting. Simple remove the large cap turning the adjustment screwclockwise will increase pressure, turning it counter clockwise will reduce thepressure setting. Always consult your maintenance department before tamperingwith any adjustments.


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December 1999


Below are pictures of a power end lube pump on a CAT 3176 Deck engine of aCPT 372. This is a vane type hydraulic pump. This pump is directly mounted tothe gear train on the engine via a splined input shaft. If the shaft seal were toleak on this type mounting, typically the result would be a noticeable increase inthe engine oil level.


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December 1999


Here are pictures of a Tyrone Brand power end lube pump. This is a gear typehydraulic pump. When these pumps are mounted on one of the rear auxiliarydrive gears of a Detroit Diesel Engine. It must be mounted using an angle driveadapter, which reduce the input Rpm’s. The auxiliary drive on these enginesrotates at twice the engine Rpm’s. The Tyrone pump uses a straight input shaft,special care must be taken when installing the tapered drive adapter on thisstyle pump. The spacing of the drive gear is critical so the gear will set correctlyin the center of the driving gear of the angle drive. Failure to do so can result inloose of oil pressure to the power end in critical situations. Special instructionsare located in the Maintenance Bulletins and in the Maintenance CD Set. Againif the seal were to leak on this style mounting it would increase the oil level in theengine, this would be noticed long before noticing a decrease in the power endoil level due to the differences in volumes between the engine and the powerend.


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December 1999


Another of the power end lube pumps is the Webster Brand pump; these geartype pumps are obsolete and must be replaced with Tyrone pump. When doingso a complete kit must be ordered for replacement, as the angle drive must bemachined to except a mounting adapter and special mounting screws.


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December 1999


Some earlier model units used “Brown and Sharpe” gear type lube pumps.These pumps were typically driven by a hydraulic pump and mounted under theframe of trucks or on some “Offshore skids”.

All of these pumps are positive displacement type pumps.


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December 1999


Fluid End Lubrication Systems

Next we will discuss the two different Fluid End lubrication systems. The first ofwhich uses an air-driven pump to transfer packing oil to the plungers. Checkvalves are installed directly to the fluid end in the event of complete packingfailure, product such as cement will not migrate into the small oil lines.

The divider block is used in these systems.

3.3 Fluid EndFor optimum packing life, it is essential that the plungers and the packingbe properly lubricated. It takes only a few seconds for improperlylubricated packing to begin leaking. This in turn will ruin the plungers bydamaging their polished surface, especially when pumping abrasive fluidssuch as cement slurry or drilling mud. Inadequate lubrication also causesheat generation, which also shortens the life of the packing. The type ofoil used plays an important roll in packing life. A good oil to use is aSteam Cylinder oil, when if you look at it a triplex pump is just that aCylinder. Steam cylinder oils have a large amount of tactafiers this allowsit to stick to the plunger much longer than conventional motor oil. SteamCylinder oils usually have a high viscosity above 400 to 1000, the bestone to use depend on your climate. The Alemite pump used for thelubrication system is actually a grease pump so the high viscosity is not aproblem for this pump. Another factor is the high viscosity decreases theoil consumption tremendously, which offsets any cost differentials.

Note: Never reuse packing oil as dirt and debre will alwayscontaminate the system and damage the pump and plug the dividerblocks.


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December 1999


3.3.1


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December 1999


The Divider blocks uses a code with either the number 12 or 24, the number 12indicates that the block will discharge out of one side. The number 24 indicatesthe block will discharge out of both sides. This cannot be changed. The blockcannot be plugged in any port, because the block must complete it’s cycleplugging any hole will stop the cycle and shut down the whole lubricationsystem. If it becomes necessary to abort lubrication to a centrifugal pump forexample. The hose can be rerouted to the reservoir to allow the block tocontinue its cycle.


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December 1999


Lubrication System No. 1- Alemite PumpMethod of lubrication Force Feed(air-driven Alemite pump)Lubricant Packing Lubrication oilCapacity 20 gals (average)

The air-operated pump (Alemite Pump) delivers lubricating oil to a dividerblock (McCord Divider Block) which in turn delivers oil equally to eachplunger. The outlet from the divider block is connected through a checkvalve to each individual fluid end-packing bore. From there, it goes intothe fluid end and enters the lantern gland for even distribution to thepacking. The Alemite pump also provides lubrication to the C-Pumps via aparallel discharge line, or on older units via the divider block.

The current Alemite pump used on the PG series (cementing) pumps isthe Model 9668 medium pressure (5:1 ratio) pump. The pump sectionworks in conjunction with the Pneumatic Logic Air Motor Model 338066-A1.


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To adjust the Alemite pump rate, first set the air pressure regulator tobetween 110-120 psi. Then control the desired amount of packing lube oilby regulating the metering valve on the discharge side of the pump.Unlike previous model Alemite pumps, adjusting the lubrication by thesound of the air motor will cause over lubrication and will not help tominimize environmental waste.

Note:On the Model 338066-A1 Pneumatic Logic Air Motors, an air lubricatorsystem must not be used as on previous Alemite pumps. These motorsare already packed with Teflon lubricant and require no additionallubricate except during service/repair. But does require clean dry air.

Note:A blockage in any of the oil delivery lines will normally mean the failure ofthe entire plunger lubricating system, since the McCord Divider Block willnot operate at all if any of its outlet ports are blocked. Accordingly, on allcurrent-generation pump units, a lube oil filter is installed downstream ofthe Alemite pump.

Refer to the section on Care & Maintenance in this manual formaintenance and trouble-shooting of the Alemite Pump, Lube Oil Filter,and the McCord Divider Block. Additional information can also be found inthe Maintenance Manual (Section 1-Lubrication, Bulletin Numbers804 and 982).

triplex pump part 2

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