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Anti-Gas Lock Plunger |
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The DHI Plunger imparts a
positive opening traveling valve to prevent gas locking
and reduce pump flumping. With most Reverse Flow Injection
(RFI) applications the gas to water ratio is high therefore,
both gas locking and pump flumping are the two largest
problems associated with DHI's RFI system.
Why
Why use a DHI Plunger versus the closest known art?
- The DHI Plunger has a more dynamic design,
is stronger and will operate in deeper wells
- The DHI Plunger is offered in a variety
of sizes, lengths, fits and materials that
the providers of the closest know art don't
provide
- Many more advantages exist
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What
What makes the DHI Plunger have a more dynamic design,
be stronger and allows it to operate in deeper wells?
- Constructed out of 28% stronger material
- Less but adequate valve travel, thus reducing
the impulsive force for each operated stroke
- A more dynamic design that minimizes stress
concentration
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Detail Description
See Figure #1 for reference
On the downstroke, the valve (D) at the bottom of
the free-traveling plunger positively opens to allow
the disposal fluid to enter the annular area around
the rod (B) outer diameter and the inner diameter
of the free-traveling plunger (C). Simultaneously,
as the plunger is moving
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down, the disposal fluid
in the pump barrel is transferred from the bottom of
the plunger to the top and gas locking can't occur.
On the upstroke, the valve (B) sealing surface mates
against the bottom plunger (C) seat, lifting the disposal
fluid plus gas into the rest of the Reverse Flow Injection
(RFI) system as has been conventionally done.
The thermal sprayed plunger is hard-surfaced with plasma-sprayed
alloy powder that is the same powder as what is utilized
in conventional spray metal plungers and is to API specifications.
The substrate material is made from steel with a tensile
yield strength of 120,000 psi or greater or for example
17-4 PH stainless steel. The metal-to-metal sealing
surface at the bottom of the plunger is hard-faced.
The unique design of hard-surfacing and hard-facing
creates outstanding wearing surfaces which are corrosion,
abrasion, erosion resistant, have low-stress, and maintain
retention of hardness at elevated temperatures.
Advantages
- Eliminates Gas Locking and "Required
Pump Pounding"
Eliminates DHI's largest
operational problem with the RFI system
- Reduces Pump Flumping
U-tubing is less likely
to occur when pump is operating
- Improves Volumetric Efficiency of the RFI
System
Less power consumption
- Reduces Problems Associated with Solids
in the Disposal Fluid
Longer and more reliable
life cycle with fewer problems
- Dynamic Design
Greater strength for deep
wells and high injection pressure
Larger flow areas and clearances
Reduced stress concentration
resulting in longer life and less corrosion
effects
Rod guides located on the
rod permits no rod wear versus when the guides
are located on the ID of
plunger
- Wide Spectrum of Sizes
Offered in the required
variety of sizes, lengths and fits
- Short Travel Length of Valve
Reducing impulsive force, extending
life and increasing total load limit
- Eliminates the Traveling Valve
Lower assembly cost, less
leak paths and less mechanical parts
Eliminates the traveling
valve ball and seat, traveling valve cage,
seat plug and plunger coupling
- Lengthens the Working Stroke
Shortens the plunger assembly
length, increasing the working stroke length
Greater pump capacities
without lengthening the pump barrel
- Interchangeability
Interchanges with both API
and DHI valve rods and interchanges with API
standard pump barrels
Designed and manufactured
to API specifications
- Low Manufacturing Cost - Low Cost/Benefit
Ratio
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Sizes, Lengths and Fits
*Specify normal length in whole feet (thousandths of
meters). Actual pitch length (PL) shall be nominal length
(NL) plus 3 in. (76.2mm).
Actual Pitch Length
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Nominal Length (NL) ft. - |
2 |
3 |
4 |
5 |
6 |
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Pitch Length (PL) in. - |
27 |
39 |
51 |
63 |
75 |
†Outside diameter shall be basic size minus the
specified clearance (fit), with a tolerance of +0.0000,
-0.0005 in. (+.000,-.013mm).
** Customized pitch lengths can be provided upon special
request.
F1 - Modified API line pipe thread. See table L for
details.
F2 - API straight thread (*Non-API).
| †OD |
1.0625" |
1.2500" |
1.5000" |
1.7500" |
2.0000" |
2.2500" |
| F2 |
0.6250-18* |
0.7500-16 |
1.0000-14 |
1.3125-16 |
1.5604-14 |
1.75-14 |
Section View
1 ¼" Finite Element Analysis
Analysis - Sensitivity Study - Design Optimization
Below are two figures representing the magnitude of
the stress and where stress is concentrated on two areas
of the 1 ¼" plunger. This finite element
analysis does not define this plunger design but assist
to progressing to a better design.
For the full FEA report over the 1 ¼" DHI
Plunger, see Appendix D in DHI's Manual of Practice.
Solid Model of Plunger
1 ¼" Plunger Rating and Specifications
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Maximum 1 ¼"
Pump Depth: 9,500 ft
Maximum Peak Pump Load: 5,300 lbs
˜ 164.2 slugs
Maximum Acceleration at Impact: 3.2
ft/s2
Maximum Operating Temperature: 600oF
Maximum Valve Travel: 0.315"
Pump flumping can only occur in a
static condition when the pump intake
pressure is 2.5 times higher then
the pump discharge pressure.
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Materials
| Item A |
17-4 PH Stainless Steel ASTM A564
Type 630, AMS 5643 |
| Item B |
Cr-Ni Precipitation Hardening |
| Item C |
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Annealed |
H900 |
H1150 |
| Item D |
Tensile Typical |
150,000psi |
190,000psi |
145,000psi |
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Yield Typical |
110,000psi |
170,000psi |
125,000psi |
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Elongation (% in 2") |
10 |
10 |
19 |
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Reduction of Area |
40% |
35% |
60% |
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Brinell Hardness |
320 |
411 |
311 |
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Average Cutting Speed 80 ft/min
(annealed) 125 ft/min (H1150) |
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Weldability (excellent for hard-facing) |
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See the Appendix for more information |
Hard Facing of Item C and D
See Figure #1 and fabrication prints
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Stellite hard facing is an alloy
with chromium, tungsten and cobalt. In addition
see the appendix for more information. |
Precision Grinding and Lapping of Item C and D
See Figure #1 and fabrication prints
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See DHI's Manual of Practice (MOP) |
Thermal Spray of Item C
See Figure #1 and fabrication prints
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See DHI's Manual of Practice (MOP) |
Fabrication and Assembly Prints
Manufacturing and Quality Control Procedures
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See DHI's Manual of Practice (MOP) |
Additional Figures of the 1 ¼" DHI Plunger
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