Presented By: Dipak SarmahRajkamal AryaDeerandra Singh YadavRaghunandan ChakkaSunil KakranDeepak Kumar

CONTENTSIntroductionTriplex & Duplex Pump CharacteristicsSuction System Design & PerformanceSuction Charge PumpAir Intrusion PreventionValve BehaviorPulsation DampenerPiston Motion Effects

INTRODUCTIONWORKING PRINCIPLEThe chain driven sprocket from the power source

is attached to the pinion shaft and causes it to turn a smaller gear. The pinion drives a larger gear i.e. bull gear. The bull gear is attached to the crankshaft; the crankshaft turns to give a back-and-forth motion to the connecting rods. The connecting rods are linked to the crossheads. The crossheads are connected to the piston rods and impart back-and-forth, or reciprocating, motion to the rods.

Fluid End Power End

Rotation of Crankshaft: Clockwise viewed from Right.View from Power end towards Fluid End.

Specifications of PT Series PumpsSr. No.

Description

A600PT A850PT A-1100

PT

A-1400PT A-1700 PT

Relevant Rigs

IR 750 E-760

IR900

E1400 E-2000 E-3000

01 Rated in HP

600HP 850HP at

175RPM

1100HP at 160RPM

1400HP at

150RPM

1700HP at

150RPM

02 Pump size(piston dia x stroke)

7″ x 8″ 71/2″ x 9″ 71/2″ x 10″ 71/2″ x 10″ 71/2″ x 12″

03 piston

size

4″, - 7″ 5″, - 71/2″ 5″, - 71/2″ 5″, - 71/2″ 5″, - 71/2″

04 Gear Ratio 4.48:1 4.48:1

05 Max Pressure (delivery)

6000 5000 psi 5000 psi 5000 5000

06 Rated Max

Pressure (Suction)

275 250 psi 250 psi 250 250

COMPONENTSPOWER FRAME: Power is made up of fabricated

steel, reinforced to assure maximum strength and rigidity. It housessupport for main bearings.

PINION SHAFT: It is integral with pinion , is heat treated and ground. It extends on both sides of pump. It rotates on double row taper roller bearing.

CRANK SHAFT: It is high quality rib reinforced casting with integral flange for mounting on gears.

BEARINGS: Main bearings – double row tapered roller. Eccentric – straight roller.

Pinion shaft – double row tapered roller/spherical bearing.

cross head pins – double row needle roller bearings.CONNECTING RODS: These are “T” sections with

solid ends made of ductile iron castings.CROSS HEADS: Nodular cross heads has bronze

shoes.FLUID CHAMBER: It is made of forged steel, fully

and individually interchangable. Solid type cylinder heads used, and also threaded valve covers.

Fluid liners have uniform lining of corrosion and abrasion resisting metal which increases liner and piston life.

METAL TO METAL LINER RETENTION: This method holds liner in place when operating in high pressures.

FLUID PISTON RODS: Rods are induction hardened high strength alloy steel. Pistons are heavy duty slurry type.

VALVES: Valves and seats are made up of heat treated forged alloy steel. Valves have replaceable polyurethane valve inserts.

LUBRICATION: The oil pump which is externally mounted supplies oil through filter to all bearings and cross head guides. Other oil pump for piston rod flushing system.

Pump base is made up of heavy structural steel, supports all elements.

DUPLEX

VS

TRIPLEX PUMP

Duplex & Triplex Pump

Double ActingDuplex Pump

Single ActingTriplex Pump

Rate of FlowRate of Flow = (Total volume per Stroke ) X

RPM

Total volume per stroke for

DADP = [4(Piston Area) – 2(Rod area)] X Stroke length

TRI = 3(Piston Area) X Stroke length

Stroke LengthUsually triplex pump stroke length is shorter ascompared to the duplex pump.

Speed Comparison for same flow rate

Duplex Triplex

Stroke length 16 12

Piston Diameter 6 6.5

Speed (for Same flow)

60 81.5

Discharge Comparison

Duplex Pump Discharge Triplex Pump Discharge

SUCTION SYSTEM

DESIGN

&

PERFORMANCE

Suction Pressure Losses

Velocity Pressure Loss (V2/2g)Frictional pressure Loss (fLV2/2gD)Vapor Pressure LossInertia Loss

Inertia Loss

Depends upon System Acceleration

Piston AccelerationAp = 0.000457 SN2 ft/sec2

Required head at inlet of the pumpH = L Ap/ g

Piston Acceleration

Problems Arising from Insufficient Suction PressureKnocking

Collision of mud against the piston because of difference of acceleration due to inertia.

SettlingSettling of solid particle during operation and shut down

Ways to Increase Suction PresureRaise level of mud in the tankCool the pumpReduce the pump speedReduce suction pipe lengthIncrease suction pipe diameterAdd a suction dampenerAdd a charging pump

SUCTION CHARGE PUMP

SUCTION CHARGE PUMPTriplex piston pump performance is optimized by

adding centrifugal auxillary charge pump to the suction system of mud pump.

The advantages with this suction charge pump are

1.Inherent flexibility 2.Easy operation and installation 3.Low cost

Charger size depends upon DiameterFriction Inertia and Acceleration.

Required Pressure

Total required pressure for triplex suction system with charger pump consists of the following

Inertia headFrictionVapour pressureVelocity head

Charger Pump CapacityThe flow rate of the charger must be equal to the maximum instantaneous flow of the piston pump as follows

Q = V*0.01068*S*N*D^2 Q = capacity in gpm V= velocity correction factor S = stroke in inches N = pump speed in RPM D = piston diameter in inches

Charger LocationInertia calculations determine if charger

pump should be located close to the mud tank or at triplex pump.

If inertia requirements are larger than atmosphere pressure, it would be necessary to push on the mud with the charger.

Charger PipingAs charger pump is centrifugal it is

required that entrance to pump must be straight for a distance of about eight suction pipe diameters.

The use of very long suction pipes from triplex pump to mud tank is undesirable as it causes friction and inertia heads requiring greater charger pump pressure.

AIR INTRUSION PREVENTION

Air Intrusion

When piston seals are worn and cylinder pressure falls to insufficient levels, air can enter triplex cylinders and lead to partial filling . This in turn results in poor pump performance and increased wear .

Improper filling of cylinder Low discharge pressureFluid slippage takes placeErroneous guage readingKnock and vibration takes place in the

discharge line

Effect Of Air Intrusion On PumpPerformance

Use supercharger to prevent air intrusionSupercharger increase pressure of fluid

and overcome inertia so that complete filling of cylinder takes place and thus stops hydaulic knock and separation

Back flash on: it prevents heating of liner.

Remedies For Air Intrusion

VALVES

Optimum pump performance largely depends upon proper selection, installation and operation of suction and discharge valves

The effects of excessive lag, sticking, hammer are studied in this chapter.

A pump valve operates like flowmeter, a device which is used to measure the flow of fluid.

The valve of pump has usually a tapered seat so seat is short than that of taper of flowmeter and valve rise is not linearly proportional to flow.

The actual behaviour of the valve depends on the four operating regimes occur during valve operation. They are

1. Initial opening 2.Medium flow 3.Maximum flow 4.closing response or lag

INITIAL OPENING

The valve operates like low pressure relief valve, where weight and spring force resist pressure in cylinder for discharge valve and pressure in suction for suction valve.

Top area of valve is large than bottom seat area, so some over pressure is needed to lift valve. The initial pop takes some time and causes piston over travel.

This initial pop does not cause and problem when pump runs at low speed, but if pump speed increases such that stoke time equals initial opening then valve lag & wear occurs.

MEDIUM FLOW

During this peroid valve position depends upon flow rate of piston.

Initial piston acceleration ceases and flow becomes steadier.

The lift of valve is directly proportional to instantaneous flow.

Vale completely surrounded by pressurzied fluid, fluid pressure does not affect the lift of valve.

The lift of suction or discharge valve depends upon the flow rate of fluid .

MAXIMUM FLOW

During this flow period valve lift is maximum, this occurs at mid stroke of piston.

At mid stroke the piston acceleration is zero.The valve lift can be made limited by means

of valve stop.Here the valve stop should be far enough

above the valve seat for sufficient lift. So that maximum flow through valve occurs.

If the lift of valve is too limited - less opening for the fluid to flow through the valve and it results in abrasive wear and pressure loss.

CLOSURE

As piston slows down at the end of stroke flow valve drops as flow decreases.

Valve responsive – valve close in proportion to decline flow

However some lag normally occurs.Closure force is the difference between valve weight + spring weight to

hydraulic force from flow.

VALVE LAGValve lag means inability of valve to close in

time.Valve lag is due to valve without spring.the

valve must close due to its own weight so lag can be high in this case.

Valve lag causes reverse flow.Reverse flow causes a decrease in pumped

fluid and it increases the valve speed towards the seat.

Valve hits harder resulting in damage to valve seat and to valve.

Valve lag may in inches.

Adequate Spring used with valve will nearly eliminate the lag.

Lag can be few thousandths of an inch.Spring should have correct ratio of spring

force to valve weight.Spring make the reduction in valve speed

so that it may hit valve seat gently.

VOLUMETRIC EFFICIENCY

Due to valve lag valve being open when piston reaches 180deg.

Late closure of suction valve - piston starting discharge stroke and pumping fluid back to suction pipe.

Late closure of discharge valve - piston starting the suction stroke even the discharge valve not closed withdrawing fluid from discharge.

Due to these effects volumetric efficiency gets reduced.

Adequate spring used can reduce spring lag causing no loss in volumetric efficiency

Valve spring requirements

Spring used in valve is very important because problems concerning the valve are reduced.

Heavy valve – avoid structural bending under pressure. Stronger valve spring is used.

Spring breaks or is left out results in valve lag or late closure of valve.

springs must be installed carefully. If springs reused it must be checked for strength, resilence,fatigue or corrosion.

PRESSURE DROPPressure drops occurs between the faces of

the valve but recovers after valve.Pressure drop across valve chamber is more

useful. pressure drop estimates the pressure

remaining in the fluid to prevent flashing or air intrusion.

STICKING VALVES

Valve may be stick. Valve sticking resists forces of weight and spring force for valve closing.

Sticking occurs mainly due to friction.All pistons in pump mounted vertically to

reduce friction.

HUNG VALVES

Valves hung due to progressive bad sticking, jamming by foreign material.

The weight of valve and spring force not sufficient for valve to come back to seat.

Spring is vital for smooth and long operation of the valve

VALVE HAMMERIt is impact of the valve on the seat with

much higher velocity.Due to lag, sticking or freeing of hung valve.Due to above reasons response time

increases causing long delay so that valve hammer occurs.

If valve hammer occurs it results in valve peening or wear to valve seat.

PULSATION DAMPENER

Pulsation DampenerTriplex pump flow naturally fluctuates due to the cyclic nature of the pump and other factors inherent in the system. Flow deficiency at the suction can lead to fluid separation and knock, and at both the suction and discharge , un steady flow ca lead to vibration and increased wear. Dampeners can steady these input and output fluctuation in flow and pressure to acceptable limit.

Contd…

Sized , operated and maintained correctly, a dampener can improve pump performance and increased part life by reducing pulsations and vibration in the system.

Dampener A dampener is a pressure vessel in communication with the mud line. These devices store excess fluid when too much is pumped and supply needed fluid to the line when too little is available. They accomplish this service with a flexible bladder separating two chambers inside the vessel. One of the chambers is charged with gas and sealed off from the other chamber, which is in direct communication with the mud line when the dampener is in operation.

Contd… As the mud line enters the dampener, the bladder retreats, expanding the fluid chamber and compressing the gas to reduce the volume of the gas chamber. When this fluid is needed back in the mud line, the compressed gas exerts pressure on the bladder and pushes fluid from the chamber.

Position of Dampener Discharge DampenerSuction DampenerDischarge dampener is usually larger of the

two because it must cope with higher operating pressure, while pressure in the suction line is normally relatively low. Suction perform other function like, they provide added fluid pressure to keep the cylinder full and prevent fluid separation and knock. This in turn allows the pump to run faster . They also steady the flow highly charged suction system to increase the performance.

Four major sources of variation in flow and pressure areVariations in pumped quantity due to the

operating characteristics of the pump.Delays due to compressibility of the pumped

fluid.Flow fluctuation caused by faulty or failing

parts in the pump.Reduced fluid delivery caused by air or gas in

the cylinder.

Various FluctuationsVelocity Fluctuation Pressure FluctuationVelocity Fluctuation : The combined flow from the

three cylinders of a triplex combine to make six velocity fluctuations per crank revolution, which produces six pressure fluctuations if dampener is not being used. Piston velocities determine flow velocity and thus the amount of pressure surge in the pump. The amount of velocity fluctuation also depends on the connnecting rod/ crank radius ratio. A lower Con rod to crank radius ratio causes greater fluctuations in piston velocity .

Pressure FluctuationsThe actual pressure rise and fall in a triplex

system is dampened so that actual pressures are lower than in a theoretical system. One reason for this that the pump and piping expand under pressure. The piping sees a pressure wave and swells over the distance the wave travels at the speed of sound in the fluid during the time of disturbance.

Induced pressure fluctuations: high resistance to flow into the dampener causes additional line pressure fluctuations.

Contd.Induced pressure fluctuations: high

resistance to flow into the dampener causes additional line pressure fluctuations. The resistance flow into the dampener must be kept to a minimum so the pressure rise is largely due to compression of the gas. There will be inertia head loss much larger than the frictional loss. These induced losses can negate dampener effectiveness if levels are too high.

Selection of DampenerCare in the selection of of he dampener and

in its installation alongwith attention to its operation will greatly reduces pulses and vibration. This should help us get longer life from the rig compenents.

PISTON MOTION EFFECTS

Piston velocity Piston movement with respect to crank-

1. At start of the stroke - 10 degree motion causes the piston movement .86% of the stroke

2. At mid of the stroke – 10 degree motion causes the piston movement 8.5% of the stroke

Piston Motion

If connecting rod is very long same piston movement .

Average piston velocity (fpm)=2.spm.stroke length(ft)

In real pumps the connecting rod ratio is much less

Contd…

Peak velocity

When throw is perpendicular to the crank, piston is at maximum velocity

Friction decreases with velocity

Least friction occurs at the peak point

Valve effectsValves are flowmeters

Velocity of the pistons develops the flow which operates the valves

Lifts is obtained by placing a valve in a flow chamber

Lifts can be altered by using different shapes, weights and springs

Piston frictionStatic friction is greater than dynamic

friction

At the start and at the end of the stroke friction is maximum

At the middle of the stroke friction is minimum.

Also varies with pressure.

Piston acceleration

Acceleration is the slope of velocity curve

At the start and end of the stroke acceleration is maximum.

At the middle of the stroke acceleration is minimum.

Alternatives

Scotch yoke –

1.Straight sliding bar is used

2.It produces the same piston motion that an infinitely long connecting rod

Offset crank-

1.The offset crank uses a connecting rod where centre of rotation of the crank is offset from centre line of the cylinder

2.One stroke longer and one stroke shorter

FITS AND CLEARENCESConnecting rod small end inner diameter and

bearing outer race O.D = 0.03 mm to 0.08mm.Cross head pin O.D. and bearing inner race I.D is

0.055 to 0.075 mm.Connecting rod big end bore and bearing outer race

O.D. is -0.094 to -0.15mm.Crank shaft and bearing inner race I.D. is -0.3048 to

-0.203mm.Pinion shaft and bearing inner race I.D. is -0.05044

to -0.0804mm.

Pinion shaft housing and bearing outer race O.D. is 0.0008 to 0.0058mm.

Crank shaft and bearing inner race I.D. is -0.0885 to -0.1105mm.

THANK YOU