Alb Mod Compression Packing Flashcards
Compression packing must ____ so it can either lubricate and/or seal rotating and reciprocating shafts
leak
Shaft/sleeve replacement, constant adjustments, downtime, housekeeping, environmental considerations and energy consumption are all ____ associated with packing
costs
Compression packing must ____ as opposed to acting as a static seal
control leakage
Motion on pumps and compressors can be: (3)
- Rotary
- Reciprocating
- Helical
As well as sealing, compression packing can act as a:
Bearing
Compression packing must be confined and squeezed. This is accomplished in the confined area of the:
Stuffing box of the pump or compressor or valve
Packing is confined in a stuffing box with the aid of a:
Gland follower
The throttling of fluid aids in: (3)
- Sealing
- Cooling
- Lubrication
Throttling of fluid reduces the chance of the packing running: (2)
- Dry
- Hot
If packing is allowed to run dry and hot, it can:
Permanently damage the shaft
In some cases, packing must prevent air from:
Entering the pump
______ are special profiled rings with interference fit on the shaft and walls of the stuffing box. In this case, the fluid aids the sealing fit.
Automatic packings
Automatic packings seal in ____ direction(s)
Only one
The key factor to jam-type packing relies on its impermeability to the fluid it is sealing. When packing is made of fibers and yarns, there are many voids in the packing. To assist in plugging these voids, a ____ is added.
saturant
Saturant may be made of: (3)
- Petroleum based
- Graphite
- PTFE (Teflon)
As the packing is compressed and the machine runs, saturant in the packing washes out and the packing _____ and needs to be _____
shrinks and needs to be adjusted
If overtightened, packing will act as a brake due to friction between moving parts. In the situation that packing is improperly adjusted, the saturant:
Acts as a lubricant
Roughly ___% of the wear on shafts is on the outermost rings of packing closes to the gland
70%
Note: This is on both centrifugal and reciprocating pumps and compressors
Automatic/moulded packing are made of various materials and are designed to seal automatically and are:
Pressure actuated
automatic packing does not require the same amount of manual gland adjustment as compression packing, but in the case of _____ packing, a gland allows you to change the pressure on the packing if the fluid cannot provide sufficient pressure
V-packing
Note: In other cases, the stuffing box is large enough to accommodate the use of spring loaded V packing
What two ways can you give packing more abrasion resistance? (2)
- Saturant
- Special yarns
This packing is very flexible and commonly used for reciprocating applications
Square braid
This packing is very dense and works well in high pressure applications
Braid over braid
This packing is strong and resists being deformed or extruded under high pressure
Interlocking braid
This packing is constructed by twisting strands together to form a rope
Twisted packing
This packing is made of metal foils and special alloys, and used for close tolerance rods and shafts
metal packing
This packing is a graphite ribbon that comes in rolls and is radially wrapped around the shaft to form rings of any thickness.
Radially wound packing
Note: the ribbons are wrapped around the shaft until they just fit into the stuffing box, and can be die formed outside of the stuffing box
Some of the metals used for metal packing are: (3)
- Babbitt
- Aluminum
- Copper
Spiral wound packing must be installed with the spiral oriented for:
Shaft rotation
Jam packing requires ____ and therefore is stacked to fill the stuffing box
more than one set of rings
If shaft speeds are high, the pumping medium is high temperature, corrosive, or abrasive, an additional component is necessary to aid lubricating, sealing, flushing, cooling
Lantern ring aka Steel cage
When you have a lantern ring, your stuffing box is fitted with a:
seal water connection
In some cases, with a lantern ring, you use an external water source for cooling. In other cases, you use:
The pumping medium
The lantern ring does not touch the shaft because its bore is larger than the shaft, and in most cases, is made of:
a softer material than the shaft
If the liquid entering the lantern ring is above that of the pump or valve, approximately __ psi to __ psi, the elevated pressure keeps the pumping medium inside the pump and away from the packing
10 to 15
The pressure inside a stuffing box is often below atmospheric, so instead of the medium leaking out, air leaks into the stuffing box from outside. This happens ______ and can affect pump performance
during startup
If the lantern ring is used for sealing and cooling, it is aligned under the seal water connection and must be considered when packing the pump. If the lantern ring is used to keep harmful abrasives and chemicals away from the packing, it is:
located at the bottom of the stuffing box
The approximate leakage rate of compression packing is:
40 to 60 drips per minute
Many times, compression packing requires lubrication while running. The lubrication can come from: (2)
- The pumping medium
- external supply
There are situations where lubrication is not necessary, like when a self lubricating packing is used, such as:
teflon (PTFE)
____ is a compression packing material. It is used on rotating and reciprocating shafts and valves where high temperature must be considered. Can be used with chemicals, but not strong oxidizers.
Limited to 315°C, 2500 feet per minute, and 500 PSI
Carbon yarn
____ is a compression packing material. Has a low coefficient of friction, excellent heat conductivity and chemical resistance. Less leakage than other packing, and can be used with strong acids, caustics, chemicals
Limited to 1925°C (non oxidizing environments) 2500PSI (valve) 500PSI (pump) 2500-4000 feet per minute
Graphite yarn
____ is a compression packing material. It is usually found in the most severe applications, highly corrosive and oxidizing environments as well as the food industry.
Limited to 250°C 1000-1800 feet per minute and 300 PSI
PTFE Fibre
___ is a compression packing material. It is normally found in reciprocating applications and is usually formed to a special profile, such as a V.
limited to oils, phosphate esters, solvents and water up to 148°C with maximum pressure dependent on the profile of the packing
Duck and rubber
Plastic is a compression packing material made of synthetic yarns and binders braided to form compression packing. What are the three most common materials? (3)
- Phenolic fibre
- Acrylic yarns
- kevlar filament
metal is a compression packing material that is in the form of foils or ribbons. These are rolled, twisted or crimped and often used in conjunction with other materials to form a square cross section. Often also lubricated with a saturant of both oil and graphite. What are the three most common materials? (3)
- Uncoated annealed soft copper
- Lead babbit
- Aluminum packing
____ is a compression packing material that has the same basic construction as other packing and is used in both rotating a reciprocating applications. Can be saturated with PTFE, oils, waxes or graphite. Generally used hydraulic or marine applications pumping cold water, brine, or cold oil.
Limited to 93°C, 300PSI, and 1500 feet per minute
Vegetable fibre
____ is a compression packing material that is usually impregnated and saturated with PTFE and has an interlock braiding construction. It is a tough, economical packing used in pumps and valves
Limited to 260°C, 500 PSI and 1500 feet per minute.
Commercial grade asbestos
Packing has to be replaced periodically due to: (2)
- Deterioration
- Loss of saturant
The frequency of repacking depends on: (3)
- Operating conditions
- Type/quality of packing
- If it has been installed/adjusted properly
You remove old packing using a:
packing hook/puller
If excessive wear is discovered on the shaft when changing packing, what can you do to repair it? (2)
replace the sleeve
refurbish the shaft
If old packing is unevenly worn, it indicates the pump shaft is gyrating, indicating the shaft is bent. Runout should not exceed ____”
0.003”
If old packing shows signs of extrusion, this indicates:
too much clearance between the shaft and the throat
What are four reasons that packing may prematurely fail? (4)
- Wrong type
- Wrong size
- Improper installation
- excessive heat
The best way to cut packing is using a:
Mandrel the same diameter as the shaft
If you encounter difficulty installing the packing due to the fullness, do not:
strike it with a hammer
Note: instead, roll it out
When packing a pump, seat the rings firmly, except PTFE filaments and graphite yarns, which should be:
tightened gently and firmly once the pump is running
Stagger joints in packing at least __° apart
90
When packing a pump, seat each individual ring using either: (2)
- tamping tool
- split bushing
Allow packing to ___ when starting a newly packed pump
leak freely
Leaking during the first hour of operation:
enhances the life of the pump
When a valve has been repacked and on-line for a day or so, retighten the follower even if there:
is no leakage
