U.S. patent application number 16/465066 was filed with the patent office on 2019-12-19 for scaling and corrosion resistant fluid conduit.
The applicant listed for this patent is Aramco Services Company, Hai CHANG, Xubin GAO, General Electric Company, Lawrence Bernard KOOL, Limin WANG, Dalong ZHONG, Hui ZHU. Invention is credited to Hai Chang, Xubin Gao, Lawrence Bernard Kool, Limin Wang, Dalong Zhong, Hui Zhu.
Application Number | 20190382898 16/465066 |
Document ID | / |
Family ID | 62241132 |
Filed Date | 2019-12-19 |
United States Patent
Application |
20190382898 |
Kind Code |
A1 |
Kool; Lawrence Bernard ; et
al. |
December 19, 2019 |
SCALING AND CORROSION RESISTANT FLUID CONDUIT
Abstract
A fluid conduit (10) is provided having (a) a fluid conduit
exterior surface (14); (b) a fluid conduit interior surface (16);
(c) an electroless nickel protective coating (18) disposed upon one
or both of the fluid conduit interior surface and the fluid conduit
exterior surface; and (d) a layer (20) of Ni.sub.3S.sub.2 disposed
upon and substantially covering the electroless nickel protective
coating. The fluid conduit can be any fluid conduit through which a
fluid may be caused to pass, such as a downhole tubular used in oil
and gas production, or a gas liquid cyclonic separator. And a
hydrocarbon production tube, a method of producing a fluid conduit
comprising a nickel sulfide protective layer, a machine component
comprising at least one surface having a protective outer layer are
provided. The combination of the electroless nickel inner
protective coating with an outer layer of Ni.sub.3S.sub.2 affords
articles such as fluid conduits and machine components with
exceptional scale and corrosion resistance.
Inventors: |
Kool; Lawrence Bernard;
(Niskayuna, NY) ; Gao; Xubin; (Shanghai, CN)
; Zhu; Hui; (Shanghai, CN) ; Wang; Limin;
(Marlborough, MA) ; Chang; Hai; (Shanghai, CN)
; Zhong; Dalong; (Shanghai, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KOOL; Lawrence Bernard
GAO; Xubin
ZHU; Hui
WANG; Limin
CHANG; Hai
ZHONG; Dalong
Aramco Services Company
General Electric Company |
Niskayuna
Shanghai
Shanghai
Niskayuna
Shanghai
Shanghai
Houston
Schenectady |
NY
NY
TX
NY |
US
CN
CN
US
CN
CN
US
US |
|
|
Family ID: |
62241132 |
Appl. No.: |
16/465066 |
Filed: |
November 30, 2016 |
PCT Filed: |
November 30, 2016 |
PCT NO: |
PCT/CN2016/107912 |
371 Date: |
May 29, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 18/1662 20130101;
C23C 18/36 20130101; C23C 28/322 20130101; C23C 18/32 20130101;
C23C 18/165 20130101; C23C 28/34 20130101 |
International
Class: |
C23C 18/36 20060101
C23C018/36; C23C 18/16 20060101 C23C018/16; C23C 28/00 20060101
C23C028/00 |
Claims
1. A fluid conduit, the fluid conduit defining an interior volume
and comprising: (a) a fluid conduit exterior surface; (b) a fluid
conduit interior surface; (c) an electroless nickel protective
coating disposed upon at least one of the fluid conduit interior
surface and the fluid conduit exterior surface; and (d) a layer of
Ni.sub.3S.sub.2 disposed upon and substantially covering the
electroless nickel protective coating.
2. The fluid conduit according to claim 1, wherein the layer of
Ni.sub.3S.sub.2 is characterized by an average thickness in a range
from about 1 to about 100 microns and hermetically isolates the
electroless nickel protective coating from the fluid conduit
interior volume.
3. The fluid conduit according to claim 1, wherein the layer of
Ni.sub.3S.sub.2 is characterized by one or more morphologies
selected from the group consisting of one or more nanosheet
morphologies, one or more nanowire morphologies, one or more
rod-like morphologies, one or more block-like morphologies, and
combinations of two or more of the foregoing morphologies.
4. The fluid conduit according to claim 1, wherein the layer of
Ni.sub.3S.sub.2 is characterized principally by one of i) one or
more nanosheet morphologies, ii) one or more nanowire morphologies,
iii) one or more rod-like morphologies, and iv) one or more
block-like morphologies.
5-7. (canceled)
8. The fluid conduit according to claim 1, wherein the electroless
nickel protective coating is configured as a bilayer coating
comprising an inner electroless nickel bond layer comprising from
about to about 20% by weight phosphorous based on a total weight of
the electroless nickel bond layer, and an electroless nickel outer
layer comprising hard particles selected from the group consisting
of diamond, silicon carbide, boron nitride, talc, and combinations
of two or more of the foregoing.
9. The fluid conduit according to claim 8, wherein the hard
particles are present in a range from about 10 to about 40 percent
by weight based on the total weight of the electroless nickel outer
layer.
10. The fluid conduit according to claim 1, wherein a metallurgical
bond is formed between the fluid conduit interior surface and the
electroless nickel protective coating.
11. The fluid conduit according to claim 1, wherein the fluid
conduit is selected from the group consisting of production tubing,
valves, storage vessels, reaction vessels, surface pipelines,
subsea pipelines, cyclonic separators, wellheads, manifolds,
blowout preventers, Christmas trees, and exhaust gas conduits.
12. The fluid conduit according to claim 1, wherein the fluid
conduit is a tube for transporting a hydrocarbon production
fluid.
13-21. (canceled)
22. A method of producing a fluid conduit comprising a nickel
sulfide protective layer, the method comprising: (a) heating a
fluid conduit comprising an electroless nickel protective coating
disposed upon a surface of the fluid conduit in contact with a
fluid comprising hydrogen sulfide; and (b) depositing a protective
layer of Ni.sub.3S.sub.2 upon and substantially covering the
electroless nickel protective coating.
23. The method of claim 22, wherein said heating is carried at one
or more temperatures in a range from about 100 to about 400 degrees
centigrade.
24. The method according to claim 22, wherein the protective layer
of Ni.sub.3S.sub.2 is characterized by an average thickness in a
range from about 1 to about 100 microns and hermetically isolates
the electroless nickel protective coating.
25. The method according to claim 22, wherein said fluid comprising
hydrogen sulfide further comprises water.
26. The method according to claim 22, further comprising a post
deposition annealing step which converts an initial Ni.sub.3S.sub.2
morphology into an alternate Ni.sub.3S.sub.2 morphology.
27. A machine component comprising at least one surface having a
protective outer layer, the protective outer layer comprising: (a)
an inner electroless nickel coating; and (b) a layer of
Ni.sub.3S.sub.2 disposed upon and substantially covering the
electroless nickel coating.
28. (canceled)
29. The machine component according to claim 27, wherein the layer
of Ni.sub.3S.sub.2 is characterized by one or more morphologies
selected from the group consisting of one or more nanosheet
morphologies, one or more nanowire morphologies, one or more
rod-like morphologies, one or more block-like morphologies, and
combinations of two or more of the foregoing morphologies.
30. The machine component according to claim 27, wherein the layer
of Ni.sub.3S.sub.2 is characterized principally by one of i) one or
more nanosheet morphologies, ii) one or more nanowire morphologies,
iii) one or more rod-like morphologies, and iv) one or more
block-like morphologies.
31-33. (canceled)
34. The machine component according to claim 27, wherein the
electroless nickel protective coating is configured as a bilayer
coating comprising an inner electroless nickel bond layer
comprising from about 10 to about 20% by weight phosphorous based
on a total weight of the electroless nickel bond layer, and an
electroless nickel outer layer comprising hard particles selected
from the group consisting of diamond, silicon carbide, boron
nitride, talc, and combinations of two or more of the
foregoing.
35. The machine component according to claim 34, wherein the hard
particles are present in a range from about 10 to about 40 percent
by weight based on the total weight of the electroless nickel outer
layer.
36. (canceled)
37. The machine component according to claim 27, which component is
a compressor blade, a turbine blade, a turboexpander blade, a
turbocharger vane, a diffuser vane, an inlet guide vane, an outlet
guide vane, a pump vane, a fane blade, a mixer blade, an impeller,
a bearing, a bushing, a motor housing, a pump housing, a compressor
housing, a shroud, a rotor, a stator, a driving rod, a strut, a
gear box, a gear wheel, a piston, a piston rod, a spring, a
cantilever arm, a seal, a rivet, a bolt, a nut, a washer, a screw,
a dowel, or a combination of two or more of the foregoing machine
components.
38. (canceled)
Description
[0001] This disclosure relates to protective coatings useful in
corrosive and scale forming environments. In particular, this
disclosure relates to equipment comprising such scale and corrosion
resistant coatings and methods of producing such equipment.
BACKGROUND
[0002] Fluid conduits and other equipment used in the oil and gas
industry are frequently subjected to harsh conditions under which
the conduits and equipment may undergo significant operational
degradation as a result of corrosion and scaling of surfaces in
contact with a production fluid. In oil and gas wells in which the
production fluid is rich in hydrogen sulfide, corrosive scaling can
be particularly severe. For example, production tubing may become
rapidly clogged with iron sulfide scale under sour gas conditions
wherein moderate to high concentrations of hydrogen sulfide and
carbon dioxide are in contact with production tubing surfaces at
temperatures and pressures prevailing in the downhole environment.
Such clogging due to scale formation limits the productivity of the
well and, in some instances, forces the well to be shut down.
Preventing the formation of scale extends the useful life and
productivity of the well.
[0003] Despite significant enhancements in the scaling and
corrosion resistance of fluid conduits and equipment used in the
oil and gas industry, further improvements are needed. This
disclosure provides details of novel and robust coating systems
having outstanding scale and corrosion resistance, and which are
suitable for use in a wide variety of applications in which
corrosion and scale formation present operational challenges.
BRIEF DESCRIPTION
[0004] In a first set of embodiments, the present invention
provides a fluid conduit, the fluid conduit defining an interior
volume and comprising (a) a fluid conduit exterior surface; (b) a
fluid conduit interior surface; (c) an electroless nickel
protective coating disposed upon at least one of the fluid conduit
interior surface and the fluid conduit exterior surface; and (d) a
layer of Ni.sub.3S.sub.2 disposed upon and substantially covering
the electroless nickel protective coating.
[0005] In a second set of embodiments the present invention
provides a hydrocarbon production tube defining a flow channel and
comprising (a) a tube exterior surface; (b) a tube interior
surface; (c) an electroless nickel protective coating disposed upon
at least one of the tube interior surface and the tube exterior
surface; and (d) a layer of Ni.sub.3S.sub.2 disposed upon and
substantially covering the electroless nickel protective
coating.
[0006] In a third set of embodiments the present invention provides
a method of producing a fluid conduit comprising a nickel sulfide
protective layer, the method comprising: (a) heating a fluid
conduit comprising an electroless nickel protective coating
disposed upon a surface of the fluid conduit in contact with a
fluid comprising hydrogen sulfide; and (b) depositing a protective
layer of Ni.sub.3S.sub.2 upon and substantially covering the
electroless nickel protective coating.
[0007] In a fourth set of embodiments, the present invention
provides a machine component comprising at least one surface having
a protective outer layer, the protective outer layer comprising:
(a) an inner electroless nickel coating; and (b) a layer of
Ni.sub.3S.sub.2 disposed upon and substantially covering the
electroless nickel coating.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0008] Various features, aspects, and advantages of the present
invention will become better understood when the following detailed
description is read with reference to the accompanying drawings in
which like characters may represent like parts throughout the
drawings. Unless otherwise indicated, the drawings provided herein
are meant to illustrate key inventive features of the invention.
These key inventive features are believed to be applicable in a
wide variety of systems which comprising one or more embodiments of
the invention. As such, the drawings are not meant to include all
conventional features known by those of ordinary skill in the art
to be required for the practice of the invention.
[0009] FIG. 1 illustrates a fluid conduit according to one or more
embodiments of the present invention.
[0010] FIG. 2 illustrates a fluid conduit according to one or more
embodiments of the present invention.
[0011] FIG. 3 illustrates a machine component according to one or
more embodiments of the present invention.
[0012] FIG. 4 is a scanning electron micrograph of a coating
prepared according to one or more embodiments of the present
invention.
[0013] FIG. 5 is a scanning electron micrograph of a coating
prepared according to one or more embodiments of the present
invention.
[0014] FIG. 6 is a scanning electron micrograph of a coating
prepared according to one or more embodiments of the present
invention.
DETAILED DESCRIPTION
[0015] In the following specification and the claims, which follow,
reference will be made to a number of terms, which shall be defined
to have the following meanings.
[0016] The singular forms "a", "an", and "the" include plural
referents unless the context clearly dictates otherwise.
[0017] Approximating language, as used herein throughout the
specification and claims, may be applied to modify any quantitative
representation that could permissibly vary without resulting in a
change in the basic function to which it is related. Accordingly, a
value modified by a term or terms, such as "about" and
"substantially", are not to be limited to the precise value
specified. In at least some instances, the approximating language
may correspond to the precision of an instrument for measuring the
value. Here and throughout the specification and claims, range
limitations may be combined and/or interchanged, such ranges are
identified and include all the sub-ranges contained therein unless
context or language indicates otherwise.
[0018] As noted, in one or more embodiments the present invention
provides a corrosion and scale resistant fluid conduit comprising
at least one surface having an electroless nickel (EN) protective
coating disposed thereon. A layer of Ni.sub.3S.sub.2, at times
herein referred to as Heazlewoodite, is disposed upon and
substantially covers the electroless nickel protective coating. The
inventors have discovered that nearly all EN protective coatings
surprisingly undergo reaction with hydrogen sulfide at moderate
temperature and high pressure to form a layer of scale resistant
Heazlewoodite on the surface of the EN protective coating initially
in contact with a fluid containing hydrogen sulfide. Upon exposure
of the EN protective coating to hydrogen sulfide at moderate
temperature and high pressure, nickel within the EN protective
coating is converted to Ni.sub.3S.sub.2 at or near the surface of
the EN coating. The EN coating is thus consumed to some degree
during the formation of the Ni.sub.3S.sub.2 layer. As more nickel
reacts with hydrogen sulfide to form Ni.sub.3S.sub.2, the EN
coating becomes substantially covered with Ni.sub.3S.sub.2 and, as
a result, encounters between hydrogen sulfide and nickel atoms
present in the EN coating are reduced over time and growth of the
Ni.sub.3S.sub.2 layer slows and eventually ceases. Provided the EN
coating is of sufficient thickness at the outset of exposure to
hydrogen sulfide, the product resulting from such exposure at
moderate temperature and pressure will be a layer of Heazlewoodite
disposed upon and substantially covering the unconsumed portion of
the underlying EN protective layer. Under such circumstances, the
unconsumed portion of the underlying EN protective layer is
hermetically isolated from contact with the environment provided
the structural integrity of the layer of Heazlewoodite is
maintained. Example 1b (coupon 1b) in the Experimental Section of
this disclosure is illustrative. Of the initial 1 mil (25.4
microns) thick high phosphorous EN protective coating, 25 microns
of the original nickel-phosphorous coating remain following
reaction with hydrogen sulfide in the presence of brine at
160.degree. C. at a pressure of 2000-3000 psi and deposition of a
10-micron thick Ni.sub.3S.sub.2 overlayer. The Ni.sub.3S.sub.2
overlayer was determined to cover 100% of the outer surface of the
unconsumed portion of the underlying EN protective coating and
hermetically isolates it from further contact with brine and
hydrogen sulfide.
[0019] The Ni.sub.3S.sub.2 overlayer so produced exhibits
outstanding scale resistance as is demonstrated experimentally
herein. For example, iron sulfide scale FeS (Mackinawite), formed
by corrosion of an iron source in the presence of hydrogen sulfide,
does not adhere to the Ni.sub.3S.sub.2 overlayer. Moreover, the
Ni.sub.3S.sub.2 overlayer is shown to be structurally robust and
survives both continuous rotation through brine solution at 300 rpm
at 160.degree. C. and high pressure, and explosive decompression
test conditions. It is believed that the Ni.sub.3S.sub.2 overlayer
will likewise be resistant to other types of scale formation, for
example for example the formation of scales comprising calcium
carbonate (calcite), barium sulfate, (barite), magnesium carbonate,
magnesium sulfate, calcium minerals, iron minerals, silica,
dolomite, calcium sulfate, iron carbonate, Fe.sub.2O.sub.3,
Fe.sub.3O.sub.4 (magnetite), FeS.sub.2 (iron pyrite),
Fe.sub.7S.sub.8 (pyrrhotite), alpha FeOOH, Fe.sub.2(OH).sub.3Cl,
beta-FeOOH, and the like.
[0020] In one or more embodiments, the Ni.sub.3S.sub.2 overlayer is
characterized by an average thickness in a range from about 0.5 to
about 100 microns. In one or more alternate embodiments, the
Ni.sub.3S.sub.2 overlayer is characterized by an average thickness
in a range from about 1 to about 20 microns. In yet another set of
embodiments, the Ni.sub.3S.sub.2 overlayer is characterized by an
average thickness in a range from about 1 to about 10 microns.
[0021] The Ni.sub.3S.sub.2 overlayer has been observed by the
inventors to form in various morphologies depending on the nature
of the initial EN protective coating and/or the conditions under
which the Ni.sub.3S.sub.2 overlayer is formed. Thus, the
Ni.sub.3S.sub.2 overlayer formed by reaction of a portion of a 1
micron thick high phosphorous electroless nickel coating exhibits a
blocky crystalline morphology after prolonged exposure to hydrogen
sulfide and brine at moderate temperature and high pressure (See
Coupons 1a and 1b, Tables 1 and 2). Contrast this with the rod
shaped crystalline morphology of the Ni.sub.3S.sub.2 overlayer
observed when an initial 2-micron thick high phosphorous
electroless nickel coating is exposed to hydrogen sulfide for a
shorter period of time (16 hours) at moderate temperature and
pressure (See Coupons 2a and 2b, Tables 1 and 2). The inventors
have observed experimentally the formation of Ni.sub.3S.sub.2
overlayers having nanowire morphologies, rod-like morphologies and
block-like morphologies; and believe that other Heazlewoodite
morphologies such as nanosheet morphologies may be formed as well.
In addition, combinations of two or more of such morphologies may
be present in a given Ni.sub.3S.sub.2 overlayer. Further, it is
believed that higher energy Ni.sub.3S.sub.2 morphologies may be
converted to more stable forms upon prolonged heating, for example.
Thus, in one or more embodiments, the overlayer of Ni.sub.3S.sub.2
is characterized by one or more morphologies selected from the
group consisting of one or more nanosheet morphologies, one or more
nanowire morphologies, one or more rod-like morphologies, one or
more block-like morphologies, and combinations of two or more of
the foregoing morphologies. Ni.sub.3S.sub.2 overlayer morphologies
were determined by x-ray diffraction (XRD) and scanning electron
microscopy. In one or more embodiments, the Ni.sub.3S.sub.2 layer
is initially formed with a nanowire morphology which is transformed
under the reaction conditions first to a rod-like morphology and
finally to a block-like morphology
[0022] The EN protective coating may contain one or more of a high
phosphorous electroless nickel coating, defined as containing from
10 to 20 percent by weight phosphorous based on the total weight of
the coating; a mid phosphorous electroless nickel coating, defined
as containing from 8 to 9 percent by weight phosphorous based on
the total weight of the coating; and a low phosphorous electroless
nickel coating, defined as containing less than 8 percent by weight
phosphorous based on the total weight of the coating. In one or
more embodiments, the EN protective coating is a multilayer coating
comprising one or more high phosphorous electroless nickel
coatings, one or more mid phosphorous electroless nickel coatings,
one or more low phosphorous electroless nickel coatings, or a
combination of two or more of the foregoing high, mid and low
phosphorous EN coatings. In one or more embodiments, the EN
protective coating comprises at least one EN coating devoid of
phosphorous (See for example, coupon 3a of Table 1 in which the EN
protective coating is a bi-layer comprising an outer electroless
nickel boron outer layer essentially free of phosphorous and a high
phosphorous electroless nickel inner layer in direct contact with
the T95 steel substrate. It should be noted that the heat treatment
referred to in Example 3 (coupon 3a), 350.degree. C. for 1 hour,
may have resulted in migration of phosphorous into the electroless
nickel boron outer layer, and conversely migration of boron into
the electroless nickel phosphorous inner layer. Such heat treatment
may also result in a metallurgical bond being formed between an EN
inner layer and the substrate. Such a metallurgically bound layer
is at times herein referred to as a bond layer. Multilayer EN
protective coatings may be prepared stepwise, for example by
coating the substrate first with a phosphorous-containing EN
coating and subsequently subjecting the EN coated substrate to a
second electroless nickel coating step. Those of ordinary skill in
the art will understand that phosphorous-containing EN protective
coatings may be prepared by reduction of dissolved nickel ions with
a phosphorous-containing reducing agent such as sodium
hypophosphite (NaPO.sub.2H.sub.2) in the presence of a substrate
immersed in a medium comprising the dissolved nickel ions and the
phosphorous-containing reducing agent. By substituting a
boron-containing reducing agent, for example diborane
(B.sub.2H.sub.6), for the phosphorous-containing reducing agent an
EN protective coating containing boron instead of phosphorous may
be obtained.
[0023] In one or more embodiments, the EN protective coating
comprises solid particles enhancing one or more performance
characteristics of such EN coating. For example, the EN protective
coating may contain hard particles (nanoparticulate and larger)
such as diamond, silicon carbide, cubic boron nitride, talc silica,
alumina, and combinations thereof which enhance abrasion
resistance. Alternatively, the EN protective coating may contain
soft particles such as polytetrafluoroethylene (PTFE) particles and
carbon black particles which enhance resistance to damage caused by
movement of a coated surface of a first machine component such as
an impeller blade in close proximity to a surface of a second
machine component such as a housing. In multi-layer EN protective
coatings the particles; hard, soft or a combination thereof, are
advantageously present in the outermost EN coating, for example as
shown in FIG. 2 of this disclosure. In one or more embodiments, the
EN protective coating comprises solid particles in a range from
about 10 to about 40 percent by weight based on the total weight of
the particular EN coating containing such particles. In an
alternate set of embodiments, the EN protective coating comprises
solid particles in a range from about 10 to about 25 percent by
weight based on the total weight of the particular EN coating
containing such particles. In yet another set of embodiments, the
EN protective layer comprises solid particles in a range from about
10 to about 15 percent by weight based on the total weight of the
particular EN coating containing such particles. It should be noted
that the presence in the EN protective coating of soft particulates
such as PTFE or hard but heat sensitive particles may limit the
maximum temperature at which a particular EN protective coating may
be subjected during heat treatment. For example, the structural
integrity and/or performance characteristics of EN protective
coatings comprising PTFE particles may be compromised if subjected
to a heat treatment protocol exceeding about 250.degree. C. owing
to decomposition of the PTFE within the EN matrix.
[0024] Fluid conduits provided by the present invention and
comprising (a) a fluid conduit exterior surface; (b) a fluid
conduit interior surface; (c) an electroless nickel protective
coating disposed upon at least one of the fluid conduit interior
surface and the fluid conduit exterior surface; and (d) a layer of
Ni.sub.3S.sub.2 disposed upon and substantially covering the
electroless nickel protective coating, include useful items such as
conduits for transporting fluids in the oil and gas industry, for
example tubing used in downhole tubular applications in hydrocarbon
production wells. In addition to downhole tubing used in
hydrocarbon production, conduits provided by the present invention
include any sort of structure though which a fluid may be caused to
pass, including without limitation, valves, manifolds, blowout
preventers, Christmas trees, wellheads, surface pipelines, subsea
pipelines, exhaust gas flow lines, cyclonic separators,
liquid-liquid separators, and the like. In some embodiments, the
fluid conduit is a storage vessel. Storage vessels qualify as fluid
conduits in the sense that fluids flow into and out of storage
vessels. In another embodiment, the fluid conduit is a continuous
reactor.
[0025] In one embodiment, the present invention provides a method
of producing a fluid conduit comprising a corrosion and scale
resistant nickel sulfide protective layer, the method comprising:
(a) heating a fluid conduit comprising an electroless nickel
protective coating disposed upon a surface of the fluid conduit in
contact with a fluid comprising hydrogen sulfide; and (b)
depositing a protective layer of Ni.sub.3S.sub.2 upon and
substantially covering the electroless nickel protective coating.
Contact between the electroless nickel protective coating and
hydrogen sulfide is carried out at moderate temperatures and
moderate to high pressures; the temperature being in one or more
embodiments, temperatures in a range from about 100.degree. C. to
about 400.degree. C., and the pressure being one or more pressures
in a range from about 500 to about 3000 psi. In one or more
embodiments, contact between the electroless nickel protective
coating and hydrogen sulfide is carried out in the presence of an
aqueous solution comprising one or more dissolved salts such as
sodium chloride, potassium bromide, lithium iodide, calcium
chloride, calcium bromide, and combinations of two or more of the
foregoing salts. In one or more embodiments, contact between the
electroless nickel protective coating and hydrogen sulfide may
advantageously be carried out in the presence of one or more protic
acids, such as hydrogen chloride, hydrogen bromide, hydrogen
iodide, formic acid, and acetic acid. In one or more embodiments,
an exogenous protic acid is employed.
[0026] Turning now to the figures, FIG. 1 illustrates a fluid
conduit 10 according to one or more embodiments of the present
invention. In one or more embodiments, the fluid conduit 10 is a
hydrocarbon production tube shown in cross section. Fluid conduit
10 defines an interior volume 12, at times herein referred to as a
fluid flow path, through which a fluid may be caused to pass, and
comprises a fluid conduit exterior surface 14 and interior surface
16 which together define the thickness the fluid conduit wall
bounded by surfaces 14 and 16. An electroless nickel protective
coating 18 is disposed on the fluid conduit interior surface 16. In
one or more embodiments, a metallurgical bond (not shown) is formed
between the electroless nickel protective coating and the fluid
conduit interior surface. A layer 20 of Ni.sub.3S.sub.2, also known
as Heazlewoodite, is disposed upon and substantially covers the
electroless nickel protective coating 18. As used herein, the terms
"substantially covers" and "substantially covering" in reference to
the Ni.sub.3S.sub.2 layer and adjacent electroless nickel
protective coating means that at least 80 percent of the surface
area of the electroless nickel protective coating is covered by
Ni.sub.3S.sub.2. In one or more embodiments, at least 95 percent of
the surface area of the electroless nickel protective coating is
covered by Ni.sub.3S.sub.2. In an alternate set of embodiments, at
least 99 percent of the surface area of the electroless nickel
protective coating is covered by Ni.sub.3S.sub.2.
[0027] Referring to FIG. 2, the figure shows a fluid conduit 10
according to one or more embodiments of the present invention. The
figure may represent, for example, a hydrocarbon production tube, a
fluid conduit defining a fluid flow path within a compressor, a
fluid conduit defining a fluid flow path within a gas-liquid
separator, a fluid conduit defining a flow path within a valve, and
like fluid conduits. In the embodiment shown, the electroless
nickel protective coating is configured as a bilayer coating
comprising an inner electroless nickel bond layer 22 comprising
from about 10 to about 20% by weight phosphorous based on a total
weight of the electroless nickel bond layer, and an electroless
nickel outer layer 24 comprising hard particles 26 selected from
the group consisting of diamond, silicon carbide, boron nitride,
talc, and combinations of two or more of the foregoing hard
particle types. A layer 20 of Ni.sub.3S.sub.2 substantially covers
and hermetically seals electroless nickel outer layer 24 from fluid
contact with the interior volume 12 defined by the fluid
conduit.
[0028] Referring to FIG. 3, the figure represents a machine
component 30 according to one or more embodiments of the present
invention. The figure may represent, for example, an impeller
blade, a compressor blade, an expander blade, a baffle, a diffuser
within a fluid pump, a valve gate, and like machine components.
During operation, machine component 30 may be disposed within a
fluid conduit provided by the present invention, for example a
fluid conduit defining a fluid flow path within a compressor, a
fluid conduit defining a fluid flow path within a gas-liquid
separator, a fluid conduit defining a flow path within a valve, and
like fluid conduits. In the embodiment shown, a protective outer
layer 32 is disposed upon the machine component surface 34. The
protective outer layer 32 comprises an inner electroless nickel
coating 18, and a layer 20 of Ni.sub.3S.sub.2 disposed upon and
substantially covering the electroless nickel coating. In one or
more embodiments, the layer of Ni.sub.3S.sub.2 hermetically seals
the electroless nickel coating 18 from fluid contact with the
environment. In one or more embodiments, the electroless nickel
coating 18 hermetically seals the machine component surface 34 from
fluid contact with the environment, as in the case wherein at least
a portion of the electroless nickel coating 18 remains in fluid
contact with the environment following deposition of the layer 20
of Ni.sub.3S.sub.2.
[0029] Referring to FIG. 4, the figure presents scanning electron
micrographs showing the typical appearance of electroless nickel
phosphorous-coated (ENP-coated) test coupon surface before and
after exposure to hydrogen sulfide (See Experimental Part, Example
1a/1b, Tables 1 and 2). In the embodiment shown, are 2000.times.
and 10000.times. magnification SEM images of ENP-coated test coupon
1a (Table 1) before exposure to hydrogen sulfide and
ENP/Ni.sub.3S.sub.2 test coupon 1b (Table 2) after exposure to
hydrogen sulfide at moderate temperature and high pressure. The SEM
images of test coupon 1a show the smooth electroless nickel coating
18 covering essentially all of the coupon surface.
ENP/Ni.sub.3S.sub.2-coated test coupon 1b shows a deposit of
Ni.sub.3S.sub.2 covering essentially all of the ENP coating. Note
that lighter colored surface deposits 40 have been identified by
XRD and EDS as Mackinawite (FeS) and are shown experimentally
herein to represent FeS formed by corrosive scaling of an uncoated
T95 steel control coupon and deposition upon the Ni.sub.3S.sub.2
surface coating of test coupon 1b. In FIG. 4 and elsewhere herein,
the Heazlewoodite (Ni.sub.3S.sub.2) layer 20 can be clearly seen to
be a conformal, micro- or nano-crystalline coating with low
affinity for FeS. The Ni.sub.3S.sub.2 layer 20 has been found to
adhere tenaciously to the underlying electroless nickel coating
18.
[0030] Referring to FIG. 5, the figure presents scanning electron
micrographs showing a second ENP-coated test coupon surface before
and after exposure to hydrogen sulfide (See Experimental Part,
Example 2a/2b, Tables 1 and 2). In the embodiment shown,
2000.times. and 10000.times. magnification SEM images of ENP-coated
test coupon 2a (Table 1) before exposure to hydrogen sulfide and
ENP/Ni.sub.3S.sub.2-coated test coupon 2b (Table 2) after exposure
to hydrogen sulfide at moderate temperature and high pressure. The
SEM images of test coupon 2a show the smooth electroless nickel
coating 18 covering essentially all of the coupon surface.
ENP/Ni.sub.3S.sub.2-coated test coupon 2b shows a deposit of
Ni.sub.3S.sub.2 covering essentially all of the ENP coating. Again,
lighter colored surface deposits 40 were identified by XRD and EDS
as Mackinawite (FeS) derived from the unprotected control coupon
present during exposure to hydrogen sulfide. Again, the
Heazlewoodite (Ni.sub.3S.sub.2) layer 20 can be clearly seen to be
conformal with the surface of the underlying electroless nickel
coating 18. Moreover, layer 20 shows low affinity for FeS. When
resubjected to the hydrogen sulfide-brine test protocol detailed in
the Experimental Part herein, the Ni.sub.3S.sub.2 grains were shown
by SEM to coarsen and grow in size while retaining low affinity for
iron sulfide scale 40. Repetition of the hydrogen sulfide-brine
test protocol a third and fourth time showed minimal further growth
of the Ni.sub.3S.sub.2 grains, while the quantity of visible FeS
surface deposits appeared to have decreased. This suggests that, as
the Ni.sub.3S.sub.2 consolidates, it becomes more anti-stick with
respect to FeS deposition.
[0031] Referring to FIG. 6, the figure presents scanning electron
micrographs showing an eletcroless nickel boron coating (ENB
coating) disposed upon a high phosphorous electroless nickel bond
layer (not visible in the micrograph) before and after exposure to
hydrogen sulfide (See Experimental Part, Example 3a/3b, Tables 1
and 2). The overlayer 20 of Ni.sub.3S.sub.2 which formed on the
surface of outer ENB coating was particularly anti-stick with
respect to FeS scale. This observation is consistent with it being
one of the more hydrophobic coatings prepared during the course of
this study, as was established by contact angle measurements. While
not wishing to be bound by theory, it is thought that the enhanced
hydrophobicity of the Ni.sub.3S.sub.2 layer results from the
nano-nodular microstructure of the surface, which makes it
difficult for FeS deposits to achieve sufficient contact with the
surface to adhere. The nano-nodular microstructure of the EN
coating 18 observed in test coupon 3a, is reproduced in test coupon
3b following exposure to the hydrogen sulfide-brine test protocol
described in the Experimental Part as a result of the fine
microstructure of the Ni.sub.3S.sub.2 overlayer 40. It is
noteworthy that, as in the case of ENP coatings, nanocrystalline
Ni.sub.3S.sub.2 grows on the ENB surface, however, it grows with a
finer microstructure than Ni.sub.3S.sub.2 grown on the ENP
coatings. The Ni.sub.3S.sub.2 layer appears to be highly conformal
to underlying nano-nodular ENB surface, indicating good adhesion
between the ENB and Ni.sub.3S.sub.2 layer.
Experimental Part
General Methods
[0032] Test coupons had dimensions of 2.87 inches by 0.87 inches by
0.125 inches and were made of T95 steel. Electroless nickel
coatings were applied by a commercial vendor, Surface Technology,
Inc. Robbinsville N.J. 08691.
[0033] Representative coated test coupons are illustrated by
entries 1a-7a, 11a-12a, 15a and 26a of Table 1. The test coupons
were characterized and shown to be uniformly coated.
TABLE-US-00001 TABLE 1 Test Coupon Electroless Nickel Coatings
Example/ Electroless Nickel Coating Underlayer Outerlayer Heat
Coupon Composition thickness thickness treatment 1a Mono-layer:
high phosphorous ENP.sup.(1) -- 1 mil -- 2a Mono-layer: high
phosphorous ENP -- 2 mil -- 3a Bi-layer: ENB.sup.(2) over high 1
mil 1 mil 350.degree. C. phosphorous ENP 4a Bi-layer: High
phosphorous.sup.(3) ENP + 1 mil 0.5 mil 250.degree. C. 20-25% PTFE
over high phosphorous ENP 5a Bi-Layer: High phosphorous ENP + 1 mil
1 mil -- 20-25% PTFE over high phosphorous ENP 6a Bi-Layer: Low
phosphorous.sup.(4) ENP + 1 mil 1 mil -- 10% cubic boron nitride
over high phosphorous ENP 7a Bi-Layer: Low phosphorous ENP + 1 mil
1 mil 350.degree. C. 10% cubic boron nitride over high phosphorous
ENP 11a Bi-Layer: Mid phosphorous.sup.(5) ENP + 1 mil 4 mil
350.degree. C. 10% Nano-Plate .TM..sup.(6) over high phosphorous
ENP 12a Bi-Layer: Low phosphorous ENP + 1 mil 1 mil 350.degree. C.
35% CDC-2-HD.sup.(7) over low phosphorous ENP.sup.5 15a Bi-Layer:
Mid phosphorous ENP + 1 mil 4 mil 350.degree. C. 20% SiC.sup.(8)
over high phosphorous ENP 26a Mono-Layer: Low phosphorous ENP + --
4 mil 350.degree. C. 35% CDC-2-HD Key: .sup.(1)Electroless nickel
phosphorous. .sup.(2)Electroless nickel boron. .sup.(3)High
phosphorous ENP contains 10 to 20% by weight P. .sup.(4)Low
phosphorous ENP contains less than 8% by weight P .sup.(5)Mid
phosphorous ENP contains 8 to 9% by weight P. .sup.(6)Sub-micron
nanoparticulate diamond available from Surface Technology, Inc.
.sup.(7)Micron scale diamond particles present in Composite Diamond
Coating .TM. available from Surface Technology, Inc.
.sup.(8)Silicon carbide.
[0034] In model scaling experiments test coupons were mounted on a
rotating cage apparatus and rotated at 300 rpm while in contact
with a brine solution within a heated autoclave pressurized with
hydrogen sulfide and nitrogen gas. An uncoated T95 steel test
coupon was placed in close proximity to the electroless
nickel-coated test coupons in order to model corrosive scale
formation conditions in which the uncoated T-95 steel test coupon
serves as the iron source for FeS scale. Test coupons were weighed
before and after being subjected to hours-long exposure to hydrogen
sulfide and brine. All electroless nickel-coated test coupons
(2a-7a, 11a, 12a and 26a) were observed to increase in weight or
remain unchanged in weight (test coupons 1a and 15a) following the
model scaling experiments, and all uncoated T95 steel control
coupons were observed to decrease in weight following the model
scaling experiments. Further, the surface appearance of the
electroless nickel-coated test coupons was transformed from a
lustrous reflective surface appearance characteristic of
electroless nickel coatings, to a dull gray-green surface
appearance. The uncoated T-95 steel test coupons turned black under
the test conditions.
Preparation of Heazlewoodite (Ni.sub.3S.sub.2) Coatings on
Electroless Nickel-Coated Substrate
[0035] Heazlewoodite (Ni.sub.3S.sub.2) coatings were unexpectedly
formed on electroless nickel coated substrates during corrosive
scaling tests. The tests were carried out in a one-liter C276 steel
autoclave equipped with a purge tube and rotating cage apparatus on
which were secured five electroless nickel-coated test coupons (See
Table 1) and an uncoated control coupon made of T95 steel. A 1
molar sodium chloride solution (500 mL), an amount sufficient to
completely submerge all six coupons, was purged continuously in a
premixing unit with oxygen free nitrogen gas (99.9999%) over
several hours at ambient temperature. The oxygen level in the brine
solution was monitored with CHEMetrics ULR CHEMets kit capable of
determining the concentration of dissolved oxygen in the brine in a
range from about 0 to about 20 parts per billion (ppb). In
representative experiments the brine was considered strictly anoxic
when the concentration of dissolved oxygen was less than 4 ppb.
Once the brine was judged to be strictly anoxic it was transferred
to the autoclave under a nitrogen atmosphere. A mixture of hydrogen
sulfide and nitrogen gas at atmospheric pressure and ambient
temperature (4% H.sub.2S in N.sub.2) (2.0 liters, approximately 100
milligrams of H.sub.2S) was introduced into the autoclave bringing
the initial pressure in the autoclave to 55 psi. The pressure
inside the autoclave was boosted to 1450-1500 psi using a high
pressure pump to introduce additional nitrogen gas. The autoclave
was then heated at 160.degree. C. at a pressure of 2250-2370 psi
for approximately 16 hours while rotating the rotating cage at 300
rpm. The autoclave was allowed to cool to ambient temperature and
was vented through a H.sub.2S scrubber and purged with nitrogen.
The test coupons were rinsed with deionized water, dried and
characterized variously by weight gain, explosive decompression
testing, X-ray powder diffraction (XRD) and electron microscopy.
Representative Ni.sub.3S.sub.2 coated test coupons are illustrated
by entries 1b-7b, 11b-12b, 15b and 26b of Table 2.
TABLE-US-00002 TABLE 2 Electroless Nickel Coatings with
Ni.sub.3S.sub.2 Outer Layer Ni.sub.3S.sub.2 Example/ layer
Ni.sub.3S.sub.2 layer Ni.sub.3S.sub.2 % Scale % Mass Coupon
thickness morphology Coverage Resistance Gain 1b 0.5-1.0 Blocky
100% good 0.0 microns crystals 2b.sup.(1) 1-2 Rod shaped 100% good
0.0147 micron.sup.(2) crystals 3b NA.sup.(3) NA.sup.(3) 100% good
0.018 4b NA.sup.(3) NA.sup.(3) NA.sup.(3) Very good 0.0927 5b
NA.sup.(3) NA.sup.(3) NA.sup.(3) Very good 0.051 6b NA.sup.(3)
NA.sup.(3) NA.sup.(3) Very good 0.0613 7b NA.sup.(3) NA.sup.(3)
NA.sup.(3) good 0.156 11b NA.sup.(3) NA.sup.(3) NA.sup.(3) Very
good 0.0601 12b.sup.(4) 10 micron Blocky, with 100% Very good
0.0563 some embedded diamond 15b.sup.(5) 10 micron Continuous, 100%
Very Good blocky, mixed with SiC crystals 26b.sup.(6) 10 micron
Continuous 50% Very good 0.0395 with exposed diamond particle
surfaces Key: .sup.(1)Single 16 hour cycle as described above but
with higher initial H.sub.2S pressure (100 psi versus 55 psi).
.sup.(2)Ni.sub.3S.sub.2 layer passed explosive decompression test.
.sup.(3)Not Ascertained .sup.(4)Two 16 hour cycles with initial
H.sub.2S pressure of 55 psi. .sup.(5)Prolonged exposure to hydrogen
sulfide-brine protocol. .sup.(6)Single 16 hour cycle as described
above but with higher initial H.sub.2S pressure (100 psi versus 55
psi), higher brine concentration (3 molar) and the addition of a
source of soluble Fe.sup.2+ ions.
[0036] The electroless nickel-Ni.sub.3S.sub.2 coated coupons were
observed to have excellent resistance to scale adhesion on the
outer Ni.sub.3S.sub.2 layer which in nearly all instances covered
essentially 100% of the outer surface test coupon. In one instance,
test coupon 26a was observed to provide a Ni.sub.3S.sub.2 coating
covering only about 50% of the surface of the test coupon. This was
thought to be due to the relatively high concentration of diamond
particles in the original electroless nickel mono-layer.
Notwithstanding the partial covering observed for test coupon 26b,
the Ni.sub.3S.sub.2 outer layer exhibited very good resistance to
scale accretion. The exposed diamond particle surfaces at the outer
surface of the Ni.sub.3S.sub.2 layer were apparently non-stick with
respect to FeS scale as well.
[0037] The experimental results indicate that the thickness of the
Heazlewoodite layer may be limited to about 10 microns. Thus,
coupon 1b having an initial layer of Ni.sub.3S.sub.2 having a
thickness between about 0.5 and 1.0 microns thick, was subjected to
extended exposure to hydrogen sulfide and brine over a twenty-one
day period during which the Ni.sub.3S.sub.2 layer grew in thickness
to about 10 microns. Of the initial 1 mil (25.4 microns) thick high
phosphorous ENP layer, 25 microns of a nickel-phosphorous layer
remained following deposition of the Ni.sub.3S.sub.2 overlayer.
Coupons 12b, 15b, and 26b comprised Ni.sub.3S.sub.2 layers about 10
microns thick. Thus it appears that longer reaction times and/or
higher concentrations of hydrogen sulfide did not result in
Ni.sub.3S.sub.2 coatings having thicknesses greater than 10
microns.
Method 1: Preparation of Heazlewoodite (Ni.sub.3S.sub.2) Coating on
an Electroless Nickel-Coated Hydrocarbon Production Tube
[0038] A hydrocarbon production tube approximately 30 feet in
length, threaded at both ends, having an outer diameter of
approximately 4.5 inches and having inner and outer surfaces is
first coated with the electroless nickel coating composition of
Example 1a of Table 1 of this disclosure on the inner surface of
the tube to a thickness of approximately 2 mil. As noted, such
electroless nickel coatings may be applied by commercial
applicators such as Surface Technology, Inc. of Robbinsville, N.J.
A first end of the tube is sealed with a first threaded steel cap
likewise coated with 2 mil of the high phosphorous ENP coating of
Example 1a. The tube is then moved into a vertical position open
end up. Sufficient 1 molar sodium chloride brine solution to fill
approximately three quarters of the length of the tube is added to
the tube through the open end. The open end of the tube is then
sealed with a second threaded steel cap, likewise coated with 2 mil
of the high phosphorous ENP coating of Example 1a. The second
threaded steel cap is equipped with gas inlet and gas outlet ports.
The headspace within the tube is purged with nitrogen at
atmospheric pressure and then pressurized with 4% hydrogen sulfide
in nitrogen gas mixture to 1400 psi. The tube is then inserted
horizontally into an oven equipped with roller bearings which allow
the tube to be rotated at approximately 60 rpm. The oven is sized
such that the entire length of the tube may be heated during a
single heating cycle without moving the tube horizontally through
the oven at any point during the heating cycle. The oven
temperature is raised to approximately 160.degree. C. and heated at
that temperature for 24 hours while rotating the tube at 60 rpm.
The tube is allowed to cool and is vented through a hydrogen
sulfide scrubber while purging with nitrogen gas. The brine
solution is recovered for reuse and the tube is rinsed inside and
out with fresh water and allowed to dry. The product hydrocarbon
production tube comprises an electroless nickel protective coating
disposed upon the interior surface of the tube and a layer of
Ni.sub.3S.sub.2 disposed upon and substantially covering the
electroless nickel protective coating.
Method 2: Preparation of Heazlewoodite (Ni.sub.3S.sub.2) Coating on
an Electroless Nickel-Coated Hydrocarbon Production Tube Under
Strictly Anoxic Conditions
[0039] The method is essentially the same as Method 1 herein with
the exception that the brine solution is thoroughly deoxygenated
prior to addition of the brine to the tube, and such addition is
carried out under a strictly anoxic atmosphere. A source of ferrous
ions (ferrous chloride) is added, again under strictly anoxic
conditions. The open end of the tube is then sealed with a second
threaded steel cap, likewise coated with 2 mil of the high
phosphorous ENP coating of Example 1a. The second threaded steel
cap is equipped with gas inlet and gas outlet ports. The headspace
within the tube is purged with nitrogen at atmospheric pressure and
then pressurized with 4% hydrogen sulfide in nitrogen gas mixture
to 1400 psi. The tube is then inserted horizontally into an oven
equipped with roller bearings which allow the tube to be rotated at
approximately 60 rpm. The oven is sized such that the entire length
of the tube may be heated during a single heating cycle without
moving the tube horizontally through the oven at any point during
the heating cycle. The oven temperature is raised to approximately
160.degree. C. and heated at that temperature for 24 hours while
rotating the tube at 60 rpm. The tube is allowed to cool and is
vented through a hydrogen sulfide scrubber while purging with
nitrogen gas. The brine solution is recovered for reuse and the
tube is rinsed inside and out with fresh water and allowed to dry.
The product hydrocarbon production tube comprises an electroless
nickel protective coating disposed upon the interior surface of the
tube and a layer of Ni.sub.3S.sub.2 disposed upon and substantially
covering the electroless nickel protective coating.
[0040] The foregoing examples are merely illustrative, serving to
illustrate only some of the features of the invention. The appended
claims are intended to claim the invention as broadly as it has
been conceived and the examples herein presented are illustrative
of selected embodiments from a manifold of all possible
embodiments. Accordingly, it is Applicants' intention that the
appended claims are not to be limited by the choice of examples
utilized to illustrate features of the present invention. As used
in the claims, the word "comprises" and its grammatical variants
logically also subtend and include phrases of varying and differing
extent such as for example, but not limited thereto, "consisting
essentially of" and "consisting of" Where necessary, ranges have
been supplied, those ranges are inclusive of all sub-ranges there
between. It is to be expected that variations in these ranges will
suggest themselves to a practitioner having ordinary skill in the
art and where not already dedicated to the public, those variations
should where possible be construed to be covered by the appended
claims. It is also anticipated that advances in science and
technology will make equivalents and substitutions possible that
are not now contemplated by reason of the imprecision of language
and these variations should also be construed where possible to be
covered by the appended claims.
* * * * *