STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

Mud Pumps 631
Cleaning the Discharge Strainer
The discharge strainer often becomes clogged with pieces of piston and valve
rubber. This may increase the pump pressure that is not shown by the pressure
gauge beyond the strainer. The strainer should be inspected and cleaned
frequently to prevent a pressure buildup.
Lost Circulation Materials
Usually special solids, such as nut shells, limestone, expanded perlite, etc.,
are added to the drilling muds to fill or clog rock fractures in the open hole
of a well. Most of these lost circulation materials can shorten the life of pump
parts. They are especially hard on valves and seats when they accumulate on
the seats or between the valve body and the valve disc.
Parts Storage
Pump parts for high-pressure service are made of precisely manufactured
materials and should be treated accordingly. In storage at the rig, metal parts
should be protected from rusting and physical damage, and rubber parts should
be protected from distortion and from exposure to heat, light, and oil. In
general, parts should remain in their original packages where they are usually
protected with rust-inhibiting coatings and wrappings and are properly supported
to avoid damage. Careless stacking of pistons may distort or cut the sealing lips
and result in early failures. Hanging lip-type or O-ring packings on a hook or
throwing them carelessly into a bin may ruin them. Metal parts temporarily removed
from pumps should be thoroughly cleaned, greased, and stored like new parts.
Pump Performance Charts
The charts showing the performance of duplex pumps are shown in Table 4-38
[17]. The charts showing the performance of triplex pumps are shown in Table
4-39 [17]. A chart listing the pump output required for a given annular velocity
is shown in Table 4-40 [18]. A chart listing the power input horsepower required
for a given pump working pressure is shown in Table 441 [19].
Mud Pump Hydraulics
The required pump output can be approximated as follows [20-221:
Minimum Q (gal/min):
Qi, = (30 to 50) D,
(4-36)
or
(4-34)
where D, =
hole diameter in in.
D = pipe diameter in in.
$ = mud specific weight in lb/gal
(text continued on pagp 644)