Mud pump fluid ends · liner size against pressure and flow at rated power, displacement per stroke, module pressure class and hydrostatic test, forged two-piece modules, shot-peened or autofrettaged bores, valves and connections
The fluid end, or wet end, of a reciprocating mud pump is the high-pressure part where pistons running in replaceable liners draw drilling fluid in through suction valves and push it out through discharge valves; on a triplex it can be three forged modules bolted to the power end. Ask three things first: what liner sizes it takes and what pressure and flow each gives at the pump's rated power, what pressure class and test the modules carry, and how the modules are made to resist fatigue and stress-corrosion cracking.
Fluid end modules and assemblies for triplex mud pumps on drilling rigs, including liners, pistons, valves and seats, and valve covers, as complete assemblies. Frac (well-service) pump fluid ends, centrifugal mud pumps, complete mud pumps and individual expendables sold alone are outside this page except where compared.
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01
NOV's 12-P-160 triplex mud pump is rated at 1,600 input hp (1,193 kW) at 120 strokes per minute with a 12 in (304.8 mm) stroke, and its performance table shows how liner size trades pressure for flow at that power: 7 in liners give about 720 gpm at a maximum of 3,430 psi, 6 in liners 529 gpm at 4,670 psi, 5 in liners 367 gpm at 6,720 psi, and 4½ in liners 297 gpm at 7,500 psi. It notes that 5,000 psi and 7,500 psi versions are both available. [1]
NOV's FB-1600 and FC-1600 brochure gives the same kind of table for its 1,600 hp pumps, with a 7 in maximum liner on a 12 in stroke and a 5 in, 7,500 psi API discharge flange, and states that its flows assume 100% volumetric efficiency and 90% mechanical efficiency. [2]
Editorial calculation: a 6 in liner on a 12 in stroke sweeps π/4 × 6² × 12 ≈ 339 in³ ≈ 1.47 US gal per stroke; three cylinders at 120 spm give about 3 × 1.47 × 120 ≈ 529 gpm, matching NOV's table. At 4,670 psi that flow carries 4,670 × 529 / 1,714 ≈ 1,441 hydraulic hp, which at 90% mechanical efficiency needs about 1,600 input hp, the pump's rating; real volumetric efficiency below 100% gives less flow.
Give the supplier the pump make, model and stroke, rated power and speed, liner sizes to be used, required pressure and flow over the well programme, pressure class (5,000 or 7,500 psi), drilling fluid type (water- or oil-based, solids, H2S), valve pot size, suction and discharge connections, and whether standard or premium (autofrettaged) modules are wanted.
02
The 12-P-160 sheet lists a hydrostatic test pressure of 10,000 psi for the fluid cylinders, a 10 in suction connection, a 6 in discharge cross with an API 10,000 psi ring-joint flange and an API Mod. 7 valve pot. Its fluid ends use forged, two-piece interchangeable modules: standard modules have shot-peened bores and premium modules autofrettaged bores, which NOV says increase fatigue life and resistance to stress-corrosion cracking, with three- and four-year warranties against cracking respectively. Screw-type quick-change valve covers, a spray system that cools and lubricates pistons and liners, and two-piece piston rods that let pistons come out without disturbing liners are listed as features. [1]
The FB-1600 brochure lists API No. 7 valve pots, valve-over-valve arrangement and a metal-to-metal liner lock. [2]
Editorial note: ask the supplier for the module material and heat treatment, bore treatment, pressure rating and test certificate per module, valve and seat sizes, and interchangeability with your existing pumps.
Nabors' patent application US 2026/0176946 A1 describes a mud pump fluid end with a mono block body sized for a pump pressure rating of at least 8,500 psi, which it says can reach up to or above 10,000 psi so the same rig pump can later serve fracturing work. It states that the difference between a 7,500 psi design and an 8,500 psi design lies in material choice (stainless steel versus another material for lower-pressure designs) and wall thickness; its stainless example body measures 64 in long, 32 in high and 20 in wide, with internal passages from about 4 in (discharge bore) to about 8 in (valve regions) in diameter, and the same mono block layout is offered for 7,500 psi pumps to keep replacement parts interchangeable. [4] Editorial calculation: 8,500 psi is about 13% above the 7,500 psi module class in NOV's sheet, and 10,000 psi equals the hydrostatic test pressure NOV lists for its 12-P-160 cylinders. [4] [1]
03
Suppliers linked to this page list mud pump fluid end modules or assemblies; each card links to the page reviewed.
Listings include L-shaped 7,500 psi fluid end modules and fluid end upgrading, drilling mud pump fluid end modules, mud pump fluid end assemblies with wear plates, and fluid end modules with other drilling equipment. Ask each for pump compatibility, pressure class, bore treatment and test records.
04
A 2016 paper in the University POLITEHNICA of Bucharest Scientific Bulletin (Series D) on mud pump valve wear describes three valve and seat designs. Full-open seats have no support webs; it says the valve body and seat "are usually made of alloyed steel, forged, with heat treatments", with a one-piece body "in order to withstand the high drilling pressures (34.5-51.7 MPa)", while the four-web design has a two-part valve body and is described as suited to low and medium pressures. The paper states that polyurethane valve inserts withstand drilling temperatures up to 82 °C (180 °F), that inserts of special compounds reach 93 °C (200 °F), and that bonded, non-replaceable inserts are offered for high-pressure drilling. Standard valve springs are carbon steel, with stainless steel offered for longer life. [3]
The authors modelled flow through an API size 7 valve assembly by finite-element analysis, with drilling fluid of 1,200 kg/m³ density and 20⋅10⁻³ Pa⋅s viscosity at a 4 m/s inlet velocity. Velocity in the gap between valve body and seat rose from 8.2 m/s at a 22 mm valve lift to 18.7 m/s at 5 mm. At 5 mm lift, changing the 45° seat angle by ±5° gave 19.1 m/s at 40° and 19.9 m/s at 50°. The highest velocities sat at the bottom of the valve body and the top of the seat, the areas the authors correlate with wear. [3]
The paper notes that leaks from worn valve inserts are not visible and are detected only at an advanced stage, when keeping a constant discharge pressure becomes difficult; the pump must then be stopped and the damaged valves replaced. Editorial note: ask the supplier for valve API size and type, seat angle, design valve lift, insert material and its temperature rating, and spring material.
05
This is a functional reference built from the sources cited; it is not one maker's specification.
| Part | Role | Fix in the order |
|---|---|---|
| Fluid module (cylinder) | Contains pressure; forged. [1] | Pressure class, bore treatment. |
| Liner and liner lock | Piston bore; sets flow and pressure. [1] [2] | Sizes and lock type. |
| Piston and rod | Displace fluid. [1] | Piston type; two-piece rod. |
| Suction and discharge valves | Control flow; valve pot size. [1] [2] | API valve size. |
| Valve covers and retention | Access for maintenance. [1] | Cover type. |
| Manifolds and connections | Suction and discharge. [1] | Sizes and flange ratings. |
| Liner spray system | Cools and lubricates. [1] | Spray pump and fluid. |
06
A fluid end quotation needs values for your pump. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.
| Field | What it means and published values | Ask the supplier for |
|---|---|---|
| Rated Power (kW) | Example pump: 1,600 hp (1,193 kW). [1] | Pump rating. |
| Stroke Length (mm) | Example: 12 in (304.8 mm). [1] | Stroke. |
| Max Pump Speed (rpm) | Example: 120 spm rated. [1] | Rated speed. |
| Valve Seat Angle (°) | Valve design. | Seat geometry. |
| Valve Lift (mm) | Valve design. | Lift. |
| Fluid End Material | Forged modules. [1] | Steel and heat treatment. |
| Max Operating Temperature (°C) | Fluid and elastomers. | Limit. |
| Max Operating Pressure (MPa) | 5,000 or 7,500 psi (34.5 or 51.7 MPa). [1] | Class and test. |
| Suction Connection Size (in) | Example: 10 in. [1] | Size and flange. |
| Discharge Connection Size (in) | Examples: 5 or 6 in. [2] [1] | Size and rating. |
| Weight (kg) | Handling. | Module weight. |
07
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Pump: [make; model; stroke; power; spm] Liners: [sizes] Duty: [pressure; flow] Class: [5,000 or 7,500 psi] Fluid: [type; solids; H2S] Module: [standard or autofrettaged; material] Connections: [suction; discharge; valve pot]
These companies list mud pump fluid ends.
Lists fluid end modules including L-shaped 7,500 psi modules, fluid end upgrading and expendables.
Product scope checked 2026-10-11
Lists drilling mud pump fluid end modules with other oilfield equipment.
Product scope checked 2026-10-11
Lists mud pump fluid end assemblies with pistons, valves and wear plates.
Product scope checked 2026-10-11
Lists fluid end modules with drilling equipment.
Product scope checked 2026-10-11
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
At fixed pump power, NOV's table shows smaller liners giving less flow but higher maximum pressure, e.g. 7 in at 720 gpm and 3,430 psi versus 5 in at 367 gpm and 6,720 psi. [1]
NOV's premium modules have autofrettaged bores, which it says increase fatigue life and resistance to stress-corrosion cracking compared with shot-peened standard modules. [1]
NOV lists a 10,000 psi hydrostatic test for the 12-P-160 fluid cylinders. [1]
A 2016 paper in the University POLITEHNICA of Bucharest Scientific Bulletin gives up to 82 °C (180 °F) for polyurethane valve inserts and up to 93 °C (200 °F) for inserts made of special compounds. [3]
Nabors' patent application US 2026/0176946 A1 describes a stainless mono block fluid end rated for at least 8,500 psi, reaching up to or above 10,000 psi, with wall thickness and material setting the rating. [4]
Sources checked 2026-10-11. The first two sources are NOV (National Oilwell Varco) documents for its own mud pumps; their figures are examples, not limits for other makes. The Nabors patent application describes one company's high-pressure fluid end design, and the university paper covers valve wear.
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