section 01

June 1997 HT-400 Description 1-1

HT-400 Pump Description

1Section

Assembled PumpThe HT-400 pump has three main assembliesthe power end, a spacer, and thefluid end (Figure 1.1). All HT-400 pumps have a power end and a fluid end.Spacers first became available as an option in the early 1970s. Since the early1970s, almost all HT-400 pumps have been assembled with spacers between thetwo ends, but some older models are still in use without a spacer.

Figure 1.2 (Pages 1-4 and 1-5) is a schematic of an HT-400 pump with a right-hand power end, an L-4 Cone drive spacer, and a 6-in. (15.240-cm) fluid end.

Power End Spacer Fluid End

Figure 1.1 The HT-400 pump is usedin all phases of oilfield operation topump water, cement, fracturing fluids,and other stimulation fluids. The threemain parts of the pump are (1) thepower end, (2) a spacer, and (3) thefluid end.

fi

1-2 HT-400 Pump Maintenance and Repair Manual June 1997

Figure 1.2 is referred to throughout this manual with Loc.-x identifying thelocation of parts.

Power EndThe power-end assembly reduces speed, multiplies torque, and changes rotaryaction into reciprocating action. It takes energy delivered by the engine andtransmission and changes it into energy that can be used by the fluid end.

Power ends are customized to meet job requirements and conserve space on thetrailer or truck unit. Cases are available in right- and left-hand versions. Sincethe early 1970s, fracturing pumps have been equipped with Cone drive (8.4:1)gears, while cementing pumps have Holroyd or Delroyd gear sets (8.6:1).

Other customizing features include the following:

lube systems

companion flanges

worm- and ring-gear ratios

heat exchanger design

SpacerOn most pump configurations, a steel spacer assembly is used between the fluidend and the power end. The spacer helps prevent fluids from escaping from thefluid end into the power-end cavity (sump).

All new pumps require spacers. Fracturing pumps require L-2 spacers andcement pumps require L-4 spacers.

Some spacers require push-rod noses uniquely designed to match the fluid-endsize used, while other spacers may use more than one type of wiper gland.

Fluid EndThe fluid end uses energy that has been modified by the power end to movecement, fracturing mediums, and other liquids and materials.

The HT-400 pump fluid end, which is available in five sizes, can be customizedfor many applications. The fluid end accepts a variety of discharge flanges and


plunger lubricators. Different lengths of plungers and tie bolts are used. Avariety of valve and seat combinations are available, and different springs andinserts can be installed on these valves.

Design FeaturesThe following features are unique to the HT-400 pump:

It can pump at pressures as high as 20,000 psi (137.895 MPa).

It is lightweight and compact, and can be airlifted into remote areas.

It provides high performance and long life.

It has three separate fluid-end sections that can be replaced individually.

HT-400 Power End

CaseThe case is a weldment made of high-strength steel. It has bores for the wormgear, crankshaft, and crossheads. It has lifting eyes on the top and four legs onthe bottom that are used for machining and mounting. Eight access coversfacilitate maintenance and repairs to specific parts. Twelve studs secure the fluidend to the power end.

Worm-Gear/Input-Shaft Drive FlangeThe engine and transmission deliver energy to the pump through the worm-gearinput shaft. This shaft can be equipped with sheaved or unsheaved companionflanges (Figure 1.2, Loc. 1). Unsheaved flanges are more commonly used;sheaved flanges are used for driving pumps that lubricate the fluid-end packing.


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Figure 1.2BSection view of an HT-400 pump power-end section through the crankshaft.

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Table 1.1List of Locations on Cross-Sectioned Pump (Figures 1.2A and 1.2B)Loc Description Loc Description Loc Description

1 Companion Flange 16 Thrust Ring 31 Valve Seat2 Worm Gear 17 Gear-Support Bearing 32 Valve-Seat O-ring3 Ring Gear 18 Flanged Stud 33 Guide-Bushing Retainers4 Flange-Gear/Spline-Drive Coupling 19 Crosshead 34 Suction-Valve Stop5 Connecting Rod and Bearings 20 Injector 35 Discharge-Valve Cover6 Connecting-Rod Pins 21 Bypass Valve 36 Cover Retainer7 Crosshead Shoes 22 Gauges 37 Cylinder-Head Cover8 Crosshead Slides 23 Gear Lugs 38 Packing9 Worm-Thrust Bearing 24 Gear Washers 39 Wiper Seal10 Worm Radial BearingThrust End 25 Fluid-End Section 40 Top Tie-Bolt11 Worm Radial BearingDrive End 26 Plunger 41 Bottom Tie-Bolt12 Crankshaft Main BearingNarrow 27 Plunger Tie-Bolt 42 Wiper Gland13 Crankshaft Main BearingWide 28 Plunger Nose 43 Packing Nut14 Gear-Support Bearing 29 Frac Valve 44 Crankshaft/Spline-Drive Coupling15 Oil Pump 30 Valve Insert

Note: Location numbers correspond to numbers in Figures 1.2A and 1.2B.


Worm and Ring GearsEnergy is transferred through splines of the companion flange to the steel wormgear (Figure 1.2, Loc. 2). From there, the energy passes through the teeth to thebronze ring gear (Figure 1.2, Loc. 3). At that time, speed reduction and torquemultiplication occur in the gear set.

Four gear sets have been used in the power ends. The predominant worm-gear toring-gear operating ratios are 8.4:1 and 8.6:1; therefore, the worm gear revolves 8.4times or 8.6 times to every revolution of the ring gear.

CrankshaftEnergy moves from the ring gear to the crankshaft through a splined drivecoupling (Figure 1.2, Loc. 4). The crankshaft is rough-machined from a forgedbillet. It is heat-treated and then machine-finished, drilled, and ground.

The three crankshaft journals are spaced 120 apart. Journal positioning from thecenter of the crankshaft out limits the stroke to 8 in.

Connecting Rods, Crossheads, and SlidesThe connecting rods (Figure 1.2, Loc. 5) are made of forged aluminum. The rodshave split caps and insert bearings. Crosshead ends of the rods are press-fittedwith bronze bushings. The connecting rods convert the rotary motion of thecrankshaft to a reciprocating action at the crosshead.

The cast-steel crossheads are connected to the rods by steel pins (Figure 1.2,Loc. 6). Crosshead upper and lower faces are covered by bronze shoes (Figure1.2, Loc. 7). Steel slides, secured in the case by expanding clamps, contain andguide the crossheads in their movement (Figure 1.2, Loc. 8).

BearingsRoller bearings support the rotating parts and keep them in position. The threesmaller bearings are located on the worm gear: the thrust bearing for positioningand the two support bearings (Figure 1.2, Loc. 9 through 11). Four larger mainbearings support the crankshaft (Figure 1.2, Loc. 12 and 13). The gear supportbearing supports and positions the ring gear and limits the ring gears lateralmovement (Figure 1.2, Loc. 14).


ShimsSeven groups of shims are used in the power end to adjust clearance and alignparts. Shims are used in the following locations:

behind the worm thrust-bearing retainer on the Cone drive gears to adjustthe relationship of the worm-to-ring gear

behind the oil pump to adjust clearance in the thrust bearing

under the thrust ring to adjust clearance in the gear-support bearing

under the bearing support to align the ring gear on the worm gear

on the end of the flanged stud to position the connecting rods in the cross-heads

under the shoes of the crossheads to adjust clearance between the cross-heads and the slides

on the ends of the slides to make them stick out from the case

When the shims are on the ends of the slides, the fluid end (or spacer) pressesagainst the protruding slides to hold them securely in place.

Lube SystemThe oil-filter system on the current HT-400 pump power end is a SchroederBrothers filter and strainer (Figure 1.3, Page 1-8).

The worm gear, support, and thrust bearings are submerged in sump oil. Thering gear, the crankshaft, and bearings are awash with sump oil from the oilpump. Forced lubrication is also provided.

Drilled passages in the crankshaft convey pressurized oil to the main bearingsand to the connecting-rod bearings. Oil travels through the connecting rods tothe bushings and crosshead pins.

Crosshead shoes and slides are oiled by nozzles that project through the topslides. At the highest point of travel, the rollers of the gear-support bearing arelubricated by another nozzle.


Injector and Magnetic SealOil moves to the revolving crankshaft through the injector (Figure 1.2, Loc. 20).The injector is a mandrel that has been drilled for oil passage. The injector fitsinto the end of the crankshaft. A magnetic seal restrains the oil between theinjector and crank.

One part of the seal is an O-ring in the ID that contacts the injector. The otherpart is an O-ring around the OD that contacts the crankshaft. Oil pressure andmagnets in the seal keep the parts together while the crankshaft moves.

The crankshaft drives a small shaft in the injector. The shaft can be used to drivea counter that registers approximate total volume discharged by the fluid end.Counters can be calibrated in barrels, gallons, cubic feet, cubic meters, or cubicliters. A rate meter can be operated off the injector.

Oil Pump

Pressure for all forced lubrication comes from the oil pump (Figure 1.2, Loc. 15).This pump, driven either off the end of the worm gear or driven remotely,retrieves lubricant from the power-end cavity (sump). The lubricant is thendischarged through external lines into the bypass valve on pre-1974 pumpmodels or through the strainer and into the bypass on most later models.

Figure 1.3The Schroeder strainer and filter are used on HT-400 pumps built afterApril 1974.

Strainer Filter


Bypass Valve

The bypass valve (Figure 1.2, Loc. 21) maintains lubricant pressure at 80 to 100psi (0.552 to 0.689 MPa). Pumps built before April 1974 maintain lubricantpressure at 35 to 45 psi (0.241 to 0.310 MPa). The pressure depends upon thespring used in some bypass valves or on shims behind the spring in others.

When the HT-400 pump is running slowly, the worm gear also turns slowly. Ifthe oil pump is driven by the worm gear, the output volume is relatively low. Atsuch times, the bypass remains closed and all lubricant passes on to the injectorand nozzles.

When the pump is running fast, the worm gear runs fast, and the oil pumpproduces excessive pressure. Excessive oil pressure is also produced whentemperatures are low and lubricant is thick. At such times, the bypass opens tobleed off some of the volume and relieves to the set pressure. Oil dumped by thebypass helps cool and lubricate the ring gear.

Oil Filter/Strainer System

Lubricant is discharged from the oil pump into the strainer. It then goes to thebypass through a 25-micron filter and on to the delivery points.

The strainer is a coarse mesh screen element with magnetic inserts. All of the oildelivered from the oil pump circulates through the strainer.

The filter cleans the oil that goes into the crankshaft, bearings, and crossheads.The filter uses three 25-micron disposable elements. Each disposable element isexpected to have a life of approximately 6 months between element changes.New elements should be purchased from stock.

Important Similar elements purchased from automotive suppliers are not equivalent.

Heat ExchangerDuring startup on cold days, the lubricant in the power end is cold, thick, andunable to coat moving parts. It may be so thick that it cannot be poured orpumped.

The heat exchanger heats the lubricant to a minimum operating temperature ofno less than 40F (4.44C). Coolant warmed in the engines cooling systemcirculates through the heat exchanger core, causing oil around the core to warmand become more liquid.

When the pump is in operation, the heat exchanger removes heat from the oil.This heat is dissipated by the engine radiator or by other means.


The standard heat exchanger is an external tube-and-shell unit. On some olderinstallations, the heat exchanger is attached to the bottom of the case. Sometimes,pump coolant does not come from the engine. Seawater is often used to coolpumps on offshore rigs. Many fracturing units use an air-to-oil cooling system.

GaugesTwo gauges monitor the lube system (Figure 1.2, Loc. 22). The mechanicaltemperature gauge has a sensing bulb located in the worm-gear housing. Themechanical pressure gauge is connected to the lube line leading to the nozzle ofthe gear-support bearing. The gauge needles sweep across areas of the gaugefaces that are color-coded to show operating ranges and danger zones.

Right- and Left-Hand PumpsPower ends are built in right- and left-hand units so that they can be located tomaximize available space. The main difference between the two is the location ofthe gears and the gear housing (enlarged, round part of the case).

A right-hand power end viewed from the fluid-end end has the housing on theright (Figure 1.4, Page 1-11). Housing of the left-hand power end is on the left.

Units are often mistakenly identified as right or left because of the position theyoccupy on the truck, skid, or trailer.

The ring gear is assembled differently for right- and left-hand power ends. Theright-hand ring gear assembly is secured with lugs, washers, and the clamp ringadapter. Only washers are used on left-hand units.

Another difference between right- and left-hand pumps is that more shims areused under the support for right-hand power ends. These shims offset the ring-gear outward to center it on the worm gear when the worm gear is acting uponit. Fewer shims are used under supports for left-hand power ends since the ringgear needs to be offset to the inside.

A ring of welding rod is used to fill the gap between the gear support and therace of the first main bearing on right-hand power ends. Left-hand power endsrarely require enough shims to warrant the use of this ring.


Figure 1.4To maximize available space, operators can choose a right- or left-handpower end. The difference between the units is the position of the housing from the fluid-end view.

Fluid End

Fluid-End SectionsThe fluid-end section (Figure 1.2, Loc. 25) is the chamber that the pumped liquidmoves through. The section is a steel forging that is heat-treated, machined, andprestressed.

Sections are manufactured in five sizes. Size does not indicate the measurementof the outside of the section, since all sizes are machined from identical forgings.Size refers to the horizontal bore cut for the plunger. The numbering systemdesignating size reflects this measurement.

Right Left


A 3 3/8-in. (8.573-cm) section is bored for a 3 3/8-in. (8.573-cm) diameterplunger.

A 4-in. (10.160-cm) section is bored for a 4-in. (10.160-cm) diameter plunger.



The 4/4 1/2-in. (10.160/11.430-cm) section can accommodate both 4-in.(10.160 cm) and 4 1/2-in. (11.430-cm) plungers. This situation can lead to someconfusion, since assemblies with 4-in. plungers are usually called 4-in. fluidends and those with 4 1/2-in. plungers are called 4 1/2-in. fluid ends.

Caution Do not use a 4-in. (10.160-cm) plunger in a 4 1/2-in. (11.430-cm) section for high-pressure/long-duration pumping. The fatigue life of the fluid end is shortenedif the HT-400 pump is operated above 11,200 psi (77.221 MPa). This style isobsolete.

In addition to a horizontal bore, a fluid-end section has a vertical bore on whichthe valves are located. At the top of the vertical bore is the discharge passage.

PlungersThe plunger (Figure 1.2, Loc. 26) causes fluids and materials to move through thefluid-end section. The plunger is attached to the crosshead by an arrangementconsisting of a plunger tie-bolt (Figure 1.2, Loc. 27) and a nutlike device called aplunger nose (Figure 1.2, Loc. 28). The plunger is pushed by the crosshead andpulled by the tie bolt and nose.

Several diameters of plungers are available to accommodate a wide range ofpressure/volume outputs. In general, high-pressure/low-volume operations areperformed with smaller plungers and low-pressure/high-volume operations areperformed with the larger plungers.

Two plunger lengths are in production. Tie-bolt lengths vary according to theplunger length. Short plungers are used with the L family of spacers (Section 8,Page 8-2). Most of the 5-in. (12.700-cm) and 6-in. (15.240-cm) plungers are madeso that the noses are flush. On the other plunger sizes, the noses protrude be-yond the ends.

Plungers have a hard surface that is flame-sprayed and fused with a hard,metallic powder onto the plungers and then ground for smoothness. Hard-surfaced plungers can be used for all kinds of pumping.


A B

Figure 1.5Valves direct the fluid that is moved by the plunger.(A.) As the plunger is withdrawn from a fluid-end section, a partial vacuum is created.(B.) As the plunger re-enters the fluid-end section, the fluid is pressurized.

Valves

Plungers move the fluid, and valves direct the fluid. As a plunger is withdrawnfrom a fluid-end section, a partial vacuum is created (Figure 1.5a). The suctionvalve at the bottom of the vertical bore is drawn up and away from its seat,which allows fluid to enter the chamber. At the same time, fluid already in thechamber moves in to fill the space where the plunger was.

As the plunger re-enters the fluid-end section, the fluid is pressurized (Figure1.5b). Fluid would go out the way it entered the chamber, but the suction valvemoves into contact with the seat. As pressure increases, the fluid pressure forcesthe discharge valve to move.

The discharge valve moves off its seat, and the fluid is expelled from the cham-ber. Loss of pressure inside the chamber and the force of the spring moves thevalve down to form a seal with the seat as the cycle starts again.

Valves are machined from forgings and are carburized, which means that theyare treated with a hot chemical that builds up the carbon content of the metal toa shallow depth. The surface is hard and long-wearing, but the core remains softand ductile.

Valves are available in three diameters. The smallest (#3) is used with 3 3/8-in.(8.573-cm) and 4-in. (10.160-cm) fluid ends. The intermediate valve (#4) is usedwith 4 1/2-in. (11.430-cm) fluid ends. The largest (#5) is used with 5-in.(12.700-cm) and 6-in. (15.240-cm) fluid ends.


The frac valve (Figure 1.2, Loc. 29) has become standard for all pumps, replacingthe single- and double-guided valves. The frac valve has two stems, as does thedouble-guided valve. Unlike the double-guided valve, however, it has no retain-ing clip or ring. Instead, the oversized insert is held in place by its own elasticity.A flange, built into the valve, backs the insert. Frac valves last longer than othervalves, especially when they are used in oilfield formation fracturing services.

Ball Valves

Ball valves (Figure 1.6) are used in low-rate/high-sand concentration service.Low rates are considered 2 to 5 bbl/min (0.318 to 0.795 m3/min) per pump. Ballvalves are designed for temporary installation. A pump may be outfitted for aspecial high sand-concentration job and then returned to normal after the job iscompleted.

Figure 1.6Typical 2-in. ball valve.

Special Discharge CoverSpecial Suction Stop

Wave Spring

Short Cage

2-in. Ball

Ball Valve Insert

Drop-In Seat

Frac Valve Insert

Discharge

Suction


While ball valves are expedient for low-rate/high sand-concentration service,the use of ball valves restricts all sizes of pumps to a maximum recommendedpumping rate of 5 bbl/min (0.795 m3/min). Higher rates, even during prime-upor wash-up, can cause insert malfunction. Even a 5-bbl/min rate causes someparts to erode, especially in the discharge area.

Ball-valve/frac-valve configurations and installation in relationship to sandconcentration is explained in Section 5.

Valve Springs

Valve springs, in conjunction with the fluid in motion, cause the valves to con-tact the seats. Most cylinder-shaped springs can go into the chamber with eitherside up, but the cone-shaped springs must be installed with the small end to-ward the plunger. Improper or opposite installation prevents the valves fromfully opening because the coils of conical springs become stacked before thevalves reach the end of travel.

A stiff stainless-steel spring is used on most valves. A limber stainless-steelspring can be used on the suction valve when no centrifugal pump is used tocharge (boost) the HT-400 pump, which makes priming somewhat easier.

Valve Seats

The valve seat (Figure 1.2, Loc. 31) used with frac valves is not the same as theseat used with single- and double-guided valves described in earlier manuals.Because the ID is smaller, the seating area is greater. The frac valve seat is com-pletely hardened (carburized), but only the surfaces subjected to wear are car-burized on the seat for single- and double-guided valves.

The frac-valve seat OD is tapered. It wedges into the adapter that expandsagainst the bore. O-rings on the OD of the seat and adapter seal the seat andadapter and reduce erosion caused by the fluids being pumped. New fluid endsare tapered, and the adapter is eliminated. In contrast, the OD of the seat forsingle- and double-guided valves is cylindrical. A seal is made with the bore byan O-ring and a copper seal ring on older pumps. Tapered valve seats were firstused in early 1977. Single- and double-guided valves can be used with frac-valveseats, but frac valves deteriorate rapidly when used with the seat for single- anddouble-guided valves.


Guide-Bushing Retainers

Guide-bushing retainers are installed in the bores beneath the valve seats (Figure1.2, Loc. 33). They look like wagon wheels with all but two spokes missing.Rubber guide bushings in the hubs guide the lower stems of the valves.

Retainers are available in two styles, but both have the same part number. Thenewer style has identical top and bottom sides that can be installed with eitherside facing upward. The older style must be installed with the notched side of thespokes up and the larger chamfer of the rim down. The older style is stampedTHIS SIDE UP.

Suction-Valve Stops

The upper stem of the valve used in the suction end of the chamber is guided bya rubber guide bushing in the suction-valve stop (Figure 1.2, Loc. 34). The stop iswhat the valve spring pushes against.

The stop has protrusions, or ears, that are covered by rubber boots and fit into agroove cut in the ID of the chamber. A lock spring extending beyond one of theears snaps into a vertical groove to lock the stop in position.

Valve Covers

The upper stem of the valve used in the discharge end of the chamber is guidedby a rubber guide bushing in the discharge-valve cover (Figure 1.2, Loc. 35). Thecover backs up the valve spring and plugs the top of the chamber. The covers,like the chambers, vary in diameter.

Threads in the top of the chamber secure the discharge-valve cover. A gasketand spacer ring seal it. To minimize damage to the gasket, the cover has twopieces; the cover assembly remains stationary while the cover retainer is screwedin (Figure 1.2, Loc. 36).

Cylinder-Head CoversA cylinder-head cover (Figure 1.2, Loc. 37), which looks like a valve cover with-out a guide bushing, seals the end of the horizontal bore for the plunger. It usesthe same gasket and spacer ring as the valve covers. Cylinder-head covers varyin diameter, as do the bores.

A pump can be damaged during a high-sand concentration job when sandbuilds up in front of the plunger. The plunger bottoms out against the sand and


either stretches the fluid-end attachment studs or pushes the fluid end off theunit. In addition, the plunger can be severely damaged.

A special protective cylinder-head cover is available for high sand-concentrationpumping. The cover ruptures before the plunger or fluid-end attaching studs aredamaged. A special cylinder-head cover retainer is required for the protectivecovers. This retainer catches the center portion of the cover when a sandout occurs.

Pressure PackingPressure packing prevents fluid from getting out around the moving plunger.Packing is shaped like a ring and has a V cross section (Figure 1.2, Loc. 38).

Single-stack height packing is about 1/4 in. (0.635 cm) thick. Double-stack heightpacking, as the name implies, is twice as thick. Sometimes the thicker packing isespecially useful in older, worn fluid ends.

Short Packing

Later model pumps are being equipped with a short-stack packing arrangementthat uses fewer packing rings than conventional arrangements. The short stackoffers improved packing life, especially at pressures greater than 6,000 psi(41.369 MPa). This arrangement can be used in all pump services. The short-stack arrangement (Figure 1.7, Page 1-18) uses a homogeneous rubber ring(header ring), a single ring of double-stack (or double-thick) V-type packing, athin brass backup ring, and a steel carrier. The backup ring and steel carriersecure the plunger-lube seal.

Important Do not overtighten the short-stack packing arrangement. Overtightening theshort packing arrangement will overheat the header ring and will cause theheader ring to fail prematurely.

Conventional V Packing

Squeezing the packing rings, which are nested, decreases height and increasesthe width of the V. The packing presses harder against the bore and againstthe plunger. In this way, the packing is adjustable.

Three types of packing rings are most popular:

Rings made of hard rubber and reinforced with cotton duck are best as longas no acid is being pumped. Acid attacks the cotton duck.


Rings made of soft rubber and reinforced with cotton duck are better forlow-pressure pumping. They are never used alone but are mixed with thehard rubber rings.

Rings made of Garlock 8140 are superior to the previously used Teflon-asbestos and other competitive acid-resistant packing, especially in high-pressure pumping.

Five or six packing rings, combined with packing adapters (brass) are used oneach plunger. Brass consists of a male adapter that fits into the first packingring, the lantern ring that goes between the fourth and fifth rings, and the femaleadapter that fits over the sixth ring. Section 2 of this manual details particularsizes of packing sets.

The male adapter adapts the packing set to the square end of the backing bore.The lantern ring is the point of entrance for lubricant. The female adapter mateswith the wiper-gland nut (Figure 1.2, Loc. 43) to adjust the packing set.

Figure 1.7The short-stack arrangement uses a homogeneous rubber ring, a single ringof double-stack V-type packing, a thin brass backup ring, and a steel carrier.


Wiper Glands

Wiper glands have two purposes (Figure 1.2, Loc. 42):

adjusting the pressure packing

protecting the plunger from excess fluid or oil

The latter purpose is achieved by a seal or packing.

When the plunger is withdrawn, leaked fluid is removed before it can enter thepower end. When the plunger re-enters, oil is removed before it can exit thepower end.

An evolutionary process has replaced the packing with a seal. The originalsleeve required two plastic spacer rings to make the seal fit properly into thesleeve, which was designed for packing. Sleeves built since the early 1970s aredesigned to secure the seal without spacer rings. On pumps with spacers, thewiper packing is replaced by a wiper seal (Figure 1.2, Loc. 39) attached to thepower end.

FlangesFor simplicity, the fluid-end information is presented in terms of one fluid-endsection and its contents, but actually, the pump is a triplex. Every fluid-endassembly has three sections. Pressure strokes of the single-acting plungers in thesections are staggered to make the fluid-end discharge and the power-end loadmore constant.

Discharge passages of the sections are united by seals and spacers. Flanges boltto the two outside sections and are sealed into the passage with more seals.

Blank flanges seal off the end of the passage. The blank is used when clearance isextremely limited.

The discharge manifolding is connected by straight flanges (single outlets) andell flanges (two outlets).

Fluid-End AssemblySuction manifolding is connected to the lower ends by means of a suctionheader, and is considered part of the unit that the pump is installed on ratherthan part of the pump. Most suction headers are pipes with flanges along oneside for attachment to open ends of the fluid-end vertical bores. Ends of theheaders have connections for manifolding or blanking plugs.


Fluid-end assemblies have two possible tie-bolt configurations. The first configu-ration has a top and bottom tie-bolt (Figure 1.2, Loc. 40 and 41). The secondconfiguration has three top tie-bolts. Both configurations secure the flanges andtie the upper ends of the fluid-end sections together. The single top tie-boltconfiguration requires a smaller bottom tie-bolt running through holes in thebottom of the sections to tie the lower ends together.

The three fluid-end sections used in a fluid-end assembly are the same size. Theyare identical and interchangeable. Fluid-end assemblies take their size designa-tion from the plungers that have been installed in them.

Maximum working pressures have been assigned to each of the five availablesizes of fluid-end assemblies. The amount of load the power end can withstanddetermines the maximum working pressure.

Fluid-end assemblies are secured with internal wrenching nuts that fasten to thestuds of the power ends. Shock mounts for supporting the pump assemblysometimes fasten to studs in the bottom of the two outside fluid-end sections.

Seal PlatesWhen the fluid-end assembly is bolted to the power end, one or two aluminumseal plates are installed between. A single 1/2-in. (1.270-cm) thick plate is nowbeing used. Previously, two 1/4-in. (0.635-cm) thick plates were used. The diam-eter of holes bored for the plungers varies with the fluid-end size.

Seal plates help secure the power-end slides. They produce the necessary clear-ance between the plungers and the cylinder-head covers. They seal off the powerend by forming a gasket between the fluid end and power end. These plates alsoprovide a contact point for the seals behind the wiper glands.

Plunger LubricationMost pumps have a pneumatic lube system that provides oil to the three plung-ers. The reservoir, which is remotely located, is kept partially filled with oil andis energized by compressed air. The air, which remains on top, forces the oildown and out the bottom of the reservoir. The rate of oil injection is controlledby an air regulator, which is set by a built-in pressure gauge.

Oil leaving the reservoir is delivered to the three fluid-end sections. Drilled pas-sages in the sections carry oil into the lantern rings in the middle of the packingsets. A check valve on each section prevents the pressure developed during thepower stroke from driving fluid into the lube lines.


A shutoff valve is installed in the reservoir discharge line, especially when thepumps are mounted lower than the reservoir. The valve can be closed at shut-down to prevent lubricant loss resulting from gravity flow. It also keeps the oilfrom running out when the fluid end is being repaired.

The air valve on the reservoir has a safety feature. It has a long handle thatextends above the oil filler cap when the valve is open and the reservoir ispressurized. Adding oil is possible only if the valve is turned off to exhaust thepressure.

On some pumps, a mechanically driven lube system provides oil to the packingand plungers. The oil pump used in this system is driven either off the end of theworn shaft or by a sheave on the power-end companion flange. All fluid endsproduced since the early 1970s are being made so that they can be easily con-verted to this recirculating lube system.

Spacer AssembliesMost HT-400 pumps have a spacer assembly to keep fluid from the fluid endfrom getting into the power-end sump. As with other components of the HT-400pump, the spacer assemblies can be customized. While all L Series spacers aresimilar, some are only appropriate for specialized work while others may appro-priate for several different tasks.

Similarities

Spacer assemblies have a common function and construction. All contain thefollowing components:

wiper glands

seal plates

mounting pads

Function

All spacer assemblies have the same functionto keep fluid from the fluid endfrom getting into the power end where it can contaminate the oil. When the oilbecomes contaminated (especially by acid, cement, or sand), damage to thepower end can occur rapidly.

If fluid enters the power end, it is usually through the plunger. The movingplunger carries the fluid past the pressure packing and the wiper seal (or pack-ing). Fluid can go through the center of the plunger if a nose seal starts leaking.


Spacers eliminate the problem of contamination through the plungers by

separating the power end and fluid end

keeping the plungers out of the power end

Construction

All spacer assemblies have steel frames. Some frames are welded, and some arenot. Some frames are constructed of heavy rods separating two thick plates. Theplates are cut out for three push rods that, together with the tie bolts and noses,connect the plungers of the fluid end to the power-end crossheads.

Wiper Glands

All spacers have wiper glands for each of the push rods. The wiper glandworkload is light because most of the potential contaminants drain harmlesslyoff the plunger end without contacting the push rods.

Wiper glands have either packing rings or seals. The seal requires a sleeve with alock ring. The packing requires a sleeve with an adjusting nut.

Since the seals (or packing) of wiper glands in the spacers keep oil in and dirt outof the power end, there is no need to put a seal in the wiper gland of the fluidend. The gland, however, is mounted so that the nut can be used to adjust thepressure packing.

Important Fluid ends with 6-in. (15.240-cm) diameter plungers use a modified sleeve in thegland because of an alignment problem when spacer assemblies are used. Thefluid end, and consequently the plungers and push rods, can get off-center. Themodified sleeve has been reamed so the possibility of the plunger dragging onthe gland ID is minimized.

Seal Plates

Spacer assemblies generally take the place of seal plates. Adequate clearancebetween plungers and cylinder-head covers is built into most spacer frames orinto their push rods.

When seal plates are used, they are installed between the spacer and the fluidend. Installing them between the spacer and power end would make changingsizes of fluid ends harder, since changing or removing seal plates often has to bedone at the same time.


When seal plates are used with spacers, reinforcing ribs are not used on them.The spacer frame takes over the function of keeping the plates from bowing.

Mounting Pads

Mounting pads are located on the bottom of every spacer frame but pads are notalways used. Sometimes they are used to help support the pump assembly;occasionally, they are used to attach pedestals to airlift skids. The pedestals helpsupport the spacer and fluid end when the skid is dismantled for transport.

Differences

L Spacers

L spacers were designed for minimal weight. Before they were introduced,spacers were used only on skid units and some trailers. They could not be usedon trucks because their extra weight put gross vehicle weights (GVWs) over themaximum allowed in most states.

With a length of 6 3/4 in. (17.145 cm), the L spacer became the lightest of the earlyspacers, weighing 254 lb (115.212 kg). Although this spacer did not alleviate theweight problem on trucks, it could be mounted on more units, especially onacidizing and fracturing trailers.

Since the L frame is so short, the push rods pass into the wiper glands of thefluid end. To get adequate push-rod nose-to-gland clearance, the noses musthave the same OD as the fluid-end plungers.

L-2 Spacer

The L-2 spacer was the first improvement on the earlier L-1 design. The two-piece nose of the L-2 spacer makes it possible to replace a fluid end with plung-ers of one diameter to a second fluid end with plungers of a different diameter.

The piece of the nose that contacts the plungers (the adapters) can be changedwithout disturbing plunger alignment. The piece of the nose that secures thepush rods does not have to be loosened.

Short plungers are used with L spacers. A welded steel frame is used with L-2spacers. The L-1 is no longer stocked.


L-3 Spacer

The lightest spacer is the L-3, weighing only 88 lb (39.916 kg). It has an alumi-num frame and is used in cementing applications where lower horsepower issufficient. The L-3 spacer is no longer available.

L-4 Spacer

The L-4 spacer combines some features of all of the earlier L spacers.

The L-4 has a steel-plate/steel-tube frame. It weighs 142 lb (64.410 kg) andreplaces the L-3. It can be used in all pump applications.

Components, other than the frame, are the same as the ones used in the L-3spacers.


Table 1.2Power EndCompanion Flange 1800 Series Spicer

Input Spline 3-in.10 (7.62 cm)Input Rotation Clockwise

Maximum Input Torque 7,215 lbf (9,782.227 Nm)Maximum Input Horsepower

(8.4 Gear) 800 hp (596.560 kW)(8.6 Gear) 600 hp (447.420 kW)

Input Speed w/8.4:1 or 8.6:1 Gears

2,400 (Maximum rev/min)

Gear Train Steel worm and bronze ring w/8.4:1 or 8.6:1 ratio (standard)Crankshaft Forged steel, four main bearings

Connecting Rods Three, forged aluminum, split caps, and insert bearings

Crossheads Three, cast steel

Case High-strength steel weldment

Bearing Type Roller and race

Oil System Gear pump driven off worm (std) or remoteOil Filter Replaceable elements and magnetic strainer (Schroeder)Oil Capacity 22 U.S. gal (0.083 m3)Oil Type Power-End Lubricants, Section 2, Page 2-3 to 2-5

Oil Pressure 80 to 100 psi (0.552 to 0.689 MPa)Schroeder 35 to 40 psi (0.241 to 0.276 MPa) at 190 worm-gear rev/min

Minimum Oil Flow 36 gal/min (136.275 m3/min)Weight (wet) 3,864 lb (1,752.681 kg)

HT-400 Specifications and DataThe following pages contain lists and schematics of the HT-400. Tables 1.2through 1.7 provide information regarding power-end and fluid-end compo-nents, pump assembly weights, and discharge pressures. Table 1.7 (Page 1-26)provides pump dimensions.

Figures 1.8 and 1.9 (Page 1-26) provide schematics of fluid-end flanges. Figure1.10 provides general dimension data for the HT-400 pump.


Table 1.3Pump Assembly Weight

Spacer lb (kg)Size

in. (cm) No Spacer L-4 Spacer L-2 Spacer

3 3/8 (8.573) 5,589 (2535.128) 5,731 (2599.538) 5,843 (2650.340)4 (10.160) 5,414 (2455.749) 5,556 (2520.159) 5,668 (2570.962)

4 1/2 (11.430) 5,455 (2474.346) 5,597 (2538.757) 5,709 (2589.559)5 (12.700) 5,392 (2445.770) 5,534 (2510.180) 5,646 (2560.983)6 (15.240) 5,331 (2418.101) 5,473 (2482.511) 5,585 (2533.313)

Table 1.4Fluid EndFluid-End Type Horizontal, triplex, three-piece forged steel

Plunger Type Single-acting, hard-surfaced

Valve Type Double-guided, carburized, high-contact

Valve Seats Carburized and replaceable

Pressure Packing (1) Hard and soft rubber with cotton ducking reinforcement for nonacid pumping and (2) hard rubber with cotton-polyester duck for acid pumping. Have V-shaped cross section and installed in the Fluid-End bore.

Discharge Flange (1) Blank, straight with one outlet or (2) ell with two outletsOil System External; uses pneumatic reservoir

Table 1.5Fluid-End Weight Size

in. (cm)Weightlb (kg)

3 3/8 (8.573) 1,725 (782.447)4 (10.160) 1,550 (703.068)

4 1/2 (11.430) 1,591 (721.666)5 (12.700) 1,528 (693.089)6 (15.240) 1,467 (665.420)

Table 1.6Discharge Pressure

Sizein. (cm)

Maximum Working Pressurepsi (MPa)

3 3/8 (8.573) 20,000 (137.895)4 (10.160) 14,000 (96.527)*

4 1/2 (11.430) 11,200 (77.221)5 (12.700) 9,000 (62.053)6 (15.240) 6,250 (43.092)

*For static pressure testing, such as testing lines, BOP stacks, etc., the 4-in. (10.160-cm) fluid end is rated to 15,000 psi (103.421 MPa) maximum pressure.

Table 1.7Spacer Weight lb (kg)L-4 L-2

142 (64.410) 254 (115.213)


Right-Hand EllPart No. 316.23019Connections

1 @ 3-in.-15,000 psi1 @ 2-in.-15,000 psi

StraightPart No. 316.27482Connections

1 @ 3-in.-15,000 psi

BlankPart No. 316.22980Connections

None

Left-Hand EllPart No. 316.23017Connections

1 @ 3-in.-15,000 psi1 @ 2-in.-15,000 psi

Left-Hand EllPart No. 316.21677Connections

2 @ 2-in.-20,000 psi

Right-Hand EllPart No. 316.21676Connections

2 @ 2-in.-20,000 psi

StraightPart No. 316.21013Connections

1 @ 2-in.-20,000 psi

BlankPart No. 316.21673Connections

None

Figure 1.8Flanges for 4 to 6-in. fluid ends Figure 1.9Flanges for 3 3/8-in. fluid ends

Table 1.8Pump Dimensions in. (cm)Fluid-End Size

3 3/8 (8.573) 4 (10.160) 4 1/2 (11.430) 5 (12.700) 6 (15.240)A 4.62 (11.735) 4.62 (11.735) 4.75 (12.065) 4.62 (11.735) 4.62 (11.735)B 6.75 (17.145) 6.75 (17.145) 6.62 (16.815) 6.75 (17.145) 6.75 (17.145)C 8.17 (20.752) 8.17 (20.752) 8.67 (22.022) 8.17 (20.752) 8.17 (20.752)D 52.57 (133.528) 52.57 (133.528) 52.57 (133.528) 52.57 (133.528) 52.82 (134.163)

D @ L-4 59.08 (150.063) 59.08 (150.063) 58.83 (149.428) 59.08 (150.063) 59.08 (150.063)D @ L-2 59.08 (150.063) 59.08 (150.063) 58.83 (149.428) 59.08 (150.063) 59.08 (150.063)

E 37.02 (94.031) 36.47 (92.634) 36.62 (93.015) 36.28 (92.151) 36.13 (91.770)E @ L-4 39.39 (100.051) 38.71 (98.323) 38.88 (98.755) 38.58 (97.993) 38.32 (97.333)E @ L-2 39.50 (100.330) 38.40 (100.330) 39.02 (99.111) 38.65 (98.171) 38.45 (97.663)

F 17.05 (43.307) 17.37 (44.120) 17.28 (43.891) 17.05 (43.307) 17.05 (43.307)

Dimensionsa

aDimension letters correspond to letters in Figure 1.10


Top View

23.12(58.7 cm)

16.25(41.3 cm)

2X 7/8-9 NC

CG

Crankshaft

Worm

CL

CL

4.50(11.4 cm)

7.50(19.0 cm)

24.37(61.9 cm)

2X 1.03(2X 2.6 cm)2X .56

(2X 1.4 cm)

Front View

5.12(13.0 cm)

23.12(58.7 cm)

41.60(105.7 cm)

CG10.25

(26.0 cm)

Figure 1.10HT-400 general dimensions


HT-400 Duty RatingsThe following operation limits are based on experience working with the HT-400pump in Halliburton pumping operations.

Warning Do not exceed the operation limits listed for each gear.Exceeding the operation limits can result in severe or fatalinjury as well as equipment damage.

Operation Limits (8.6:1 gear)Intermittent: Fewer than 4 hours

600 bhp (577 hhp), 100% maximum pressure, 275 crank rev/min

Intermediate: Between 4 and 8 hours


Continuous: More than 8 hours

275 bhp (264 hhp), 50% maximum pressure (Optimum pumplife is attained at 25% maximum pressure), 75 crank rev/min

Operation Limits (8.4:1)Intermittent: Fewer than 4 hours


Intermediate: Between 4 and 8 hours


Continuous: More than 8 hours

367 bhp (352 hhp), 50% maximum pressure (Optimum pumplife is attained at 25% maximum pressure), 75 crank rev/min

section 01

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