U.S. patent application number 11/158035 was filed with the patent office on 2005-12-29 for cast flapper with hot isostatic pressing treatment.
Invention is credited to Adams, Jeffrey K., Bailey, William M., Myerly, Thomas S., Strattan, Scott C., Wilfahrt, Brian D..
Application Number | 20050284547 11/158035 |
Document ID | / |
Family ID | 35504312 |
Filed Date | 2005-12-29 |
United States Patent
Application |
20050284547 |
Kind Code |
A1 |
Strattan, Scott C. ; et
al. |
December 29, 2005 |
Cast flapper with hot isostatic pressing treatment
Abstract
Components of a subsurface safety valve are cast instead of
machined for dramatic cost savings. In particular, the flapper is
cast from a 718 nickel alloy and treated with the HIP process to
increase strength and corrosion resistance while reducing porosity.
Other downhole valve components are contemplated to be produced by
the same technique and the materials can also be varied. Depending
on the specific alloys, the resulting HIP components are either
superior in performance (e.g. strength, corrosion resistance) or
considerably cheaper to manufacture than their wrought
counterparts.
Inventors: |
Strattan, Scott C.; (Tulsa,
OK) ; Myerly, Thomas S.; (Broken Arrow, OK) ;
Adams, Jeffrey K.; (Broken Arrow, OK) ; Bailey,
William M.; (Humble, TX) ; Wilfahrt, Brian D.;
(Houston, TX) |
Correspondence
Address: |
DUANE, MORRIS, LLP
3200 SOUTHWEST FREEWAY
SUITE 3150
HOUSTON
TX
77027
US
|
Family ID: |
35504312 |
Appl. No.: |
11/158035 |
Filed: |
June 21, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60582614 |
Jun 24, 2004 |
|
|
|
Current U.S.
Class: |
148/556 |
Current CPC
Class: |
B22D 31/002
20130101 |
Class at
Publication: |
148/556 |
International
Class: |
C22F 001/10 |
Claims
We claim:
1. A method of manufacturing components for a downhole tool,
comprising: casting the component; subjecting the component to a
HIP process; finish machining said component to a desired
dimension.
2. The method of claim 1, comprising: producing engaging components
of the downhole tool.
3. The method of claim 1, comprising: producing a flapper for a
safety valve.
4. The method of claim 1, comprising: producing a seat for a
flapper in a safety valve.
5. The method of claim 1, comprising: producing a flow tube for a
safety valve.
6. The method of claim 1, comprising: using a nickel alloy for the
material for said casting.
7. The method of claim 1, comprising: using 718 nickel alloy for
the material for said casting.
8. The method of claim 1, comprising: reducing porosity of said
casting with said HIP process.
9. The method of claim 1, comprising: improving corrosion
resistance of said casting by said HIP process.
10. The method of claim 1, comprising: increasing strength of said
casting by said HIP process.
11. The method of claim 3, comprising: using a nickel alloy for the
material for said casting.
12. The method of claim 10, comprising: using 718 nickel alloy for
the material for said casting.
13. The method of claim 11, comprising: reducing porosity of said
casting with said HIP process.
14. The method of claim 12, comprising: improving corrosion
resistance of said casting by said HIP process.
15. The method of claim 13, comprising: increasing strength of said
casting by said HIP process.
16. The method of claim 14, comprising: producing engaging
components of the downhole tool.
17. The method of claim 15, comprising: producing a seat for a
flapper in a safety valve.
18. The method of claim 16, comprising: producing a flow tube for a
safety valve.
Description
PRIORITY INFORMATION
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 60/582,614, filed on Jun. 24, 2004.
FIELD OF THE INVENTION
[0002] The field of the invention is components for downhole tools
that can be cast instead of machined from bar and more particularly
subsurface safety valve components that are cast and treated by hot
isostatic pressing (HIP).
[0003] The HIP process is well known. Hot Isostatic Pressing (HIP),
the simultaneous application of heat and high pressure, has become
a standard production process in many industries. In the HIP unit a
high temperature furnace is enclosed in a pressure vessel. Work
pieces are heated and an inert gas, generally argon, applies
uniform pressure. The temperature, pressure and process time are
all controlled to achieve the optimum material properties.
[0004] The Economics of HIPping
[0005] HIP processing incorporated as an integral part of the
manufacturing process reduces scrap.
[0006] HIP frequently allows replacement of wrought components by
castings. This reduces the amount of expensive nickel alloy used
per part since the casting is near net shape.
[0007] HIP castings reduce the machining time compared to starting
with bar stock.
[0008] HIP can reduce quality assurance requirements by improving
material properties and reducing property scatter. In some cases,
the savings on radiographic costs will cover the costs of HIP.
[0009] Castings
[0010] HIP is widely used in the casting industry to remove the
internal porosity generated during the casting process. This
results in improved strength, ductility and fatigue life of the
casting. The rejection rate is reduced and the mechanical
properties of the parts are more consistent. Casting alloys that
are routinely HIPped include nickel, cobalt, aluminum and
titanium.
[0011] Powder Metallurgy
[0012] HIP consolidates fine powders into components approaching
100% theoretical density. Pre-sintered components are fully
densified or powders are encapsulated in a sealed container, then
HIPped directly into a near-net shape. The process lends itself to
the processing of tool steels, cemented tungsten carbide, copper,
nickel and cobalt alloys. Ceramics and composite materials can also
be formed in this manner.
[0013] Other Applications
[0014] HIP is used for the bonding of dissimilar material,
consolidation of plasma coatings, improvement of welds, processing
soft and hard magnetic material and a variety of ceramic
applications. In applications such as turbine engine rebuilding,
HIP removes the effects of fatigue in components, which are near
the end of their service life. The components can be rejuvenated
for further service.
[0015] In the oil and gas industry, drill bit components have been
HIPped to create hardfacing as illustrated in U.S. Pat. Nos.
6,138,779; 5,758,733 and 5,560,440. The HIP process has been
applied to cast nickel alloys requiring high strength and high
temperature resistance such as in the aircraft gas turbine industry
as illustrated in U.S. Pat. No. 6,632,299. The HIP process has been
shown to reduce porosity in titanium castings, as indicated in U.S.
Pat. No. 6,705,385. HIPping has been shown to raise the corrosion
resistance of aluminum alloys as indicated in U.S. Pat. No.
6,733,726. In the oil and gas industry Camco now a part of
Schlumberger made castings of a nickel alloy S-monel for a few
downhole tool components but discontinued the practice because the
resulting components were not acceptable to meet an industry
standard for hydrogen sulfide service. That standard MR0175 was put
out by the National Association of Corrosion Engineers (NACE) and
has been adopted by many state and national regulatory agencies and
many well operators.
[0016] Cast parts often can result in substantial cost savings over
wrought parts despite the need for some finish machining on the
cast parts. Savings of approximately 70% of the cost of a
fabricated part are possible. In the area of subsurface safety
valves, flappers and their mating seats involve intricate machining
and present an opportunity for cost savings using HIPping. Despite
the existence of the HIP process for over 30 years and the use of
subsurface safety valves throughout that period, no manufacturer
has combined the HIP technology to treat parts for downhole safety
valves as is contemplated by the present invention. In fact, those
skilled in the art have tried casting parts that used to be
fabricated, to save production cost, but have given up in the face
of the compromises required when casting the parts particularly in
the areas of strength, porosity, fracture toughness and diminished
corrosion resistance. The present invention recognizes that the
savings from casting components for downhole tools can be captured
by using HIPping. More particularly, the savings can be achieved
for cast nickel alloys and more particularly when the components
are a flapper and associated parts of a subsurface safety valve.
These and other aspects of the present invention will be more
apparent to those skilled in the art from a review of the
description of the preferred embodiment and the claims, which
appear below.
SUMMARY OF THE INVENTION
[0017] Components of a subsurface safety valve are cast instead of
machined for dramatic cost-savings. In particular, the flapper is
cast from a 718 nickel alloy and treated with the HIP process to
increase strength and corrosion resistance while reducing porosity.
Other downhole valve components are contemplated to be produced by
the same technique and the materials can also be varied. Depending
on the specific alloys, the resulting HIP components are either
superior in performance (e.g. strength, corrosion resistance) or
considerably cheaper to manufacture than their wrought
counterparts.
BRIEF DESCRIPTION OF THE DRAWING
[0018] FIG. 1 is a section view of a subsurface safety valve, shown
in the closed position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0019] FIG. 1 shows a subsurface safety valve, SSV, in the closed
position. A flapper 10 is pivoted closed by a coiled spring 12
against a seat 14 when the flow tube 16 is raised by closure spring
18 upon failure of pressure at control line connection 20. FIG. 1
illustrates a known SSV. The invention lies in the manner of
producing the components, particularly the flapper 10 and its
associated seat 22. The preferred material is a nickel 718 alloy
and it is preferably cast and HIPped and then subjected to finish
machining to get the component to its dimensional tolerances. The
HIPping reduces porosity and increases strength and improves
corrosion resistance. While the flapper can be produced by this
technique with a resultant cost savings of nearly 70% over
machining the part from bar stock, it will be understood that other
components of the SSV such as the seat 22 or the flow tube 16 or
other parts can be made from the same casting and HIPping
technique. While the preferred material for the flapper 10 is a
nickel 718 alloy, other materials can be cast and Hipped for
downhole tool components to achieve the cost savings and
performance improvements reported above.
[0020] Those skilled in the art know that although SSVs have been
available for many years, their components have been machined from
bar stock at much higher cost than casting and finish machining. On
one known occasion where casting parts for downhole tools was used
in an SSV, the parts were not HIPped and their suitability
particularly in hydrogen sulfide service was limited. Those skilled
in the art tried and failed before to produce components for SSVs
that had the necessary strength, corrosion resistance and porosity
levels to meet a variety of operating conditions downhole. This is
the case despite the availability of the HIP process for over 30
years.
[0021] While the invention focuses on casting a nickel 718 allow
for flappers in SSVs, those skilled in the art will appreciate that
other materials may be cast and HIPped for use in downhole tools as
a component. The range of components is not limited to SSVs in the
area of downhole tools. Different materials can be used for
discrete components in a given tool and be cast and HIPped to
achieve the aforesaid advantages.
[0022] While the preferred embodiment has been set forth above,
those skilled in art will appreciate that the scope of the
invention is significantly broader and as outlined in the claims
which appear below.
* * * * *