Note: Descriptions are shown in the official language in which they were submitted.
1
PROCESS FOR COATING A THREADED TUBULAR COMPONENT, THREADED
TUBULAR COMPONENT AND RESULTING CONNECTION
Field of the invention
The present invention relates to a tubular component used for drilling and
working
hydrocarbon wells, and more precisely to the threaded end of such a component,
said end being
male or female in type and capable of being connected to a corresponding end
of another
component to form a connection.
The invention also relates to a process for producing a galling-resistant film
on such a
tubular component.
Background of the Invention
A component which is "used for drilling and working hydrocarbon wells" means
any
element which is substantially tubular in form intended to be connected to
another element of the
same type or otherwise to finally constitute either a string for drilling a
hydrocarbon well or a
riser intended for maintenance (also known as work-over risers) or for
working, such as risers, or
for a casing string or tubing string used in working wells. The invention is
also applicable to
components used in a drill string, such as drill pipes, heavy weight drill
pipes, drill collars and
the portions of pipe connections and heavy weight pipes known as tool joints.
Each tubular component comprises one end provided with a male threaded zone
and/or
one end provided with a female threaded zone each intended to be connected by
screwing with
the corresponding end of another component, the assembly defining a
connection.
Threaded tubular components are connected under defined stresses in order to
satisfy the
requirements for tightening and sealing imposed by the service conditions,
knowing that at the
well, the threaded tubular components may be required to undergo several
makeup-breakout
cycles.
The conditions for use of such threaded tubular components give rise to
different types of
stresses which make it necessary to use coatings on the sensitive portions of
such components
such as the threaded zones, abutments or sealing surfaces.
CA 2815723 2018-01-05
2
Screwing operations are generally carried out under a high axial load, for
example the
weight of a tube several metres in length to be connected via the threaded
connection, possibly
localized by a slight misalignment of the axis of the threaded elements to be
connected, which
induces risks of galling at the threaded zones and at the metal/metal sealing
surfaces. For this
reason, it is necessary to coat the threaded zones, the abutment surfaces and
the metal/metal
sealing surfaces with lubricants.
Furthermore, the threaded tubular components are stored (sometimes for several
years),
then made up in a hostile environment. This is the case, for example, in an
offshore situation
with a salt spray and in an onshore situation when sand, dust or other
pollutants are present.
Thus, it is necessary to use coatings that counter corrosion, on the surfaces
which have to
cooperate by screwing (threaded zones) or by interfering contact (metal/metal
sealing surfaces).
It is also necessary to treat the surfaces against corrosion.
Environmentally, however, it appears that using screwing greases conforming to
API
(American Petroleum Institute) standard RP 5A3 does not constitute a long-term
solution
because such greases, which contain heavy metals, can be expelled from the
tubular components
and released into the environment or into the well, resulting in plugging
which necessitates
special cleaning operations. Furthermore, such greases do not provide
sufficient protection
against corrosion and have to be applied on site for each screwing operation.
Summary of the Invention
In order to overcome the problems of requiring a long-term corrosion
resistance and
resistance to galling and to satisfy environmental prerogatives, the principal
protagonists in the
field of threaded connections have been actively developing solid dry coatings
(i.e. not pasty and
not tacky like greases) which are both lubricants and protect against
corrosion, and which can be
applied definitively, at the factory, to the tubular components.
In particular, coatings which are inert as regards the environment and which
are resistant
to wear are being developed.
CA 2815723 2018-01-05
CA 02815723 2013-04-24
WO 2012/062426 3 PCT/EP2011/005524
The present invention is based on the discovery that using
polyaryletherketones enables
to obtain lubricating dry films which are highly resistant to wear, anti-
galling, have high
mechanical strength, with a low coefficient of friction and which are
resistant to extreme
hydrocarbon well working conditions. The solutions employed can also be
adapted to various
grades of metal for the connections for the tubular components cited above.
The use of such polyaryletherketones and their properties in the context of
threaded
tubular components as defined above have neither been described not suggested
in the prior art.
More precisely, the invention concerns a threaded tubular component for
drilling or
working hydrocarbon wells, said tubular component having at one of its ends a
threaded zone
produced on its outer or inner peripheral surface depending on whether the
threaded end is male or
female in type, in which at least a portion of the end is coated with at least
one lubricating dry film
comprising at least 65% by weight of a polyaryletherketone.
Optional characteristics, which are complementary or substitutional, are
defined below.
The polyaryletherketone is selected from a polyetheretherketone (PEEK), a
polyetherketone
(PEK) and mixtures thereof.
The lubricating dry film has a structure with a degree of crystallinity in the
range 10% to
35%.
The lubricating dry film further comprises at least one class 4 solid
lubricant in a proportion
by weight in the range 10% to 35%.
The lubricating dry film comprises a perfluoroalkoxyethylene copolymer in a
proportion by
weight in the range 10% to 30%.
The lubricating dry film comprises a mechanical reinforcing agent selected
from the list of
the following pigments: carbon black, mica, wollastonite, nanometric aluminium
oxide, nanometric
titanium oxide, glass powders, nano-diamond, nanometric WS2 or WS2-fullerenes,
in a proportion
by weight in the range 1% to 15%.
CA 02815723 2013-04-24
WO 2012/062426 4 PCT/EP2011/005524
The portion coated with lubricating dry film has previously undergone a
surface preparation
step selected from the group constituted by sanding, manganese phosphatation,
electrolytic
deposition of Cu or Cu-Sn-Zn alloys, and Fe and Zn alloys deposited by
projection.
The portion coated with lubricating dry film has previously been coated with
an undercoat
of polyetheretherketone with a semi-crystalline structure and containing mica
pigments.
The entire threaded zone is coated with lubricating dry film.
The threaded tubular component comprises a metal/metal sealing surface, said
sealing
surface being coated with lubricating dry film.
The invention also concerns a threaded tubular connection comprising a male
threaded
tubular component and a female threaded tubular component made up one into the
other, in which
at least one of said threaded tubular components is as defined above.
The invention also concerns a process for coating a threaded tubular component
for drilling
or working hydrocarbon wells, said tubular component having at one of its ends
a threaded zone
produced on its outer or inner peripheral surface depending on whether the
threaded end is male or
female in type, comprising the following steps:
= producing a mixture comprising a polyaryletherketone powder in suspension
in
water, in proportions in the range 25% to 35% by weight;
= applying said mixture to a portion of the end of said threaded tubular
component;
= drying the portion of the end thus coated at a temperature in the range
100 C to
150 C for a period in the range 5 to 10 minutes;
= heating the thus coated portion of the end to a temperature in the range
350 C to
450 C for 5 to 15 minutes at a rate of increase in temperature in the range 10
C to
20 C per minute;
= cooling the thus coated portion of the end to ambient temperature at a
cooling rate of
less than 10 C per minute, in order to obtain a principally crystalline
structure.
Optional characteristics, which are complementary or substitutional, are
defmed below.
CA 02815723 2013-04-24
WO 2012/062426 5 PCT/EP2011/005524
The mixture also comprises a coalescing agent with a rapid evaporation rate
with a
boiling point in the range 100 C to 200 C and in proportions in the range 2.5%
to 10% by
weight.
The mixture further comprises a non-ionic wetting and dispersing agent in
proportions in
the range 2.5% to 10% by weight.
The mixture also comprises at least one class 4 solid lubricant in proportions
in the range
3% to 12% by weight.
The class 4 solid lubricant is a perfluoroalkoxyethylene copolymer in a
proportion by
weight in the range 3% to 12%.
The mixture also comprises a mechanical reinforcing agent selected from the
list of the
following pigments: carbon black, mica, wollastonite, nanometric aluminium
oxide, nanometric
titanium oxide, glass powders, nano-diamond, nanometric WS2 or WS2-fullerenes,
in a proportion
by weight in the range 0.5% to 5%.
The portion of the end is coated using a pneumatic spray system, the diameter
of said
system being in the range 0.7 to 1.8 mm and the air pressure being in the
range 4 to 6 bars.
A surface preparation step selected from the group constituted by sanding,
manganese
phosphatation, electrolytic deposition of Cu or Cu-Sn-Zn alloys, and particles
of Fe and Zn alloys
deposited by projection is carried out before applying the mixture to the
portion of the end.
A surface preparation step consisting of producing an undercoat of
polyetheretherketone
with a semi-crystalline structure and containing mica pigments is carried out
before applying the
mixture to the portion of the end.
The invention also concerns a process for coating a threaded tubular component
for drilling
or working hydrocarbon wells, said tubular component having at one of its ends
a threaded zone
produced on its outer or inner peripheral surface depending on whether the
threaded end is male or
female in type, which comprises the following steps:
6
= heating a portion of the end of said threaded tubular component to a
temperature in
the range 360 C to 420 C, preferably to a temperature close to 400 C;
= projecting PEK and/or PEEK powders onto the portion of the end of said
threaded
tubular component;
= maintaining the
thus coated portion of the end at a temperature in the range 360 C to
420 C, preferably at a temperature close to 400 C, for a period in the range 1
to 4
minutes;
= cooling the thus coated portion of the end to ambient temperature at a
cooling rate of
less than 10 C per minute, in order to obtain a principally crystalline
structure.
Advantageously, a step for degreasing the portion to be coated is carried out
before heating
said portion.
According to an aspect, the invention relates to a threaded tubular component
for drilling or
working hydrocarbon wells, said tubular component comprising at one of its
ends a threaded
zone produced on its outer or inner peripheral surface depending on whether
said end is male or
female in type, wherein at least a portion of the threaded zone is coated with
at least one
lubricating dry film comprising at least 65% by weight of a
polyaryletherketone and having a
structure with a degree of crystallinity in the range of 10% to 35%.
According to another aspect, the invention relates to a process for coating a
threaded tubular
component for drilling or working hydrocarbon wells, said tubular component
comprising at
one of its ends a threaded zone produced on its outer or inner peripheral
surface depending on
whether said end is male or female in type, the process comprising the
following steps:
= producing a mixture comprising a polyaryletherketone powder in suspension
in
water, in proportions in the range 25% to 35% by weight;
= applying said mixture to a portion of the threaded zone;
CA 2815723 2018-01-05
6a
= drying the portion of the threaded zone thus coated at a temperature in
the range
100 C to 150 C for a period in the range 5 to 10 minutes;
= heating the thus coated portion of the threaded zone to a temperature in
the range
350 C to 450 C for 5 to 15 minutes, at a rate of increase in temperature in
the range
10 C to 20 C per minute; and
= cooling the thus coated portion of the threaded zone to ambient
temperature at a
cooling rate of less than 10 C per minute, in order to obtain a lubricating
dry film
comprising at least 65% by weight of a polyaryletherketone and having a
structure
with a degree of crystallinity in the range of 10% to 35%.
According to yet another aspect, the invention relates to a process for
coating a threaded
tubular component for drilling or working hydrocarbon wells, said tubular
component
comprising at one of its ends a threaded zone produced on its outer or inner
peripheral surface
depending on whether said end is male or female in type, the process
comprising the following
steps:
= heating a portion of the end of said threaded tubular component to a
temperature in
the range 360 C to 420 C;
= projecting polyetherketone (PEK) and/or polyetheretherketone (PEEK)
powders
onto the portion of the end;
= maintaining the thus coated portion of the end at a temperature in the
range 360 C
to 420 C, for a period in the range 1 to 4 minutes; and
= cooling the thus coated portion of the end to ambient temperature at a
cooling rate of
less than 10 C per minute, in order to obtain a lubricating dry film
comprising at
least 65% by weight of a polyaryletherketone and having a structure with a
degree of
crystallinity in the range of 10% to 35%.
CA 2815723 2018-01-05
6b
Brief Description of the Drawings
The features and advantages of the invention will be described in more detail
in the
description which follows, made with reference to the accompanying drawings.
Figure 1 is a diagrammatic view of a connection resulting from connecting two
tubular
components by makeup;
Figure 2 is a diagrammatic view of a screwing curve for two threaded tubular
components;
Figure 3 is a diagrammatic view of a substrate coated with a lubricating dry
film;
Figure 4 is a diagrammatic view of a test set-up;
Figure 5 is a diagrammatic view of another test set-up;
Figures 6 and 7 show test curves.
Detailed Description of the Invention
The threaded connection shown in Figure 1 comprises a first tubular component
with an
axis of revolution 10 provided with a male end 1 and a second tubular
component with an axis of
revolution 10 provided with a female end 2. The two ends 1 and 2 each finish
in a terminal
surface which is orientated radially with respect to the axis 10 of the
threaded connection and are
respectively provided with threaded zones 3 and 4 which cooperate mutually for
mutual
CA 2815723 2018-01-05
CA 02815723 2013-04-24
WO 2012/062426 7 PCT/EP2011/005524
connection of the two components by screwing. The threaded zones 3 and 4 may
be of the
trapezoidal, self-locking, etc thread type. Furthermore, metal/metal sealing
surfaces 5, 6
intended to come into sealed interfering contact against each other after
connecting the two
threaded components by screwing are provided respectively on the male and
female ends close
to the threaded zones 3, 4. Finally, the male end 1 ends in a terminal surface
7 which comes into
abutment against a corresponding surface 8 provided on the female end 2 when
the two ends are
made up one into the other.
The Applicant has also foreseen other configurations wherein the abutment
formed in the
present case by the two contact surfaces 7 and 8 is replaced by self-locking
tightening
cooperation of the threaded zones 3, 4 (see US 4 822 081, US RE 30 467 and US
RE 34467).
As can be seen in Figures 1 and 3, at least one of the threaded tubular
connections is
coated over a portion of its end 1, termed the substrate 11, with a
lubricating dry film 12
comprising at least 65% by weight of a polyaryletherketone, said dry film 12
having a structure
with a degree of crystallinity of at least 10%. It will be recalled here that
the degree of
crystallinity is measurable by the enthalpy of fusion or crystallization (AH )
of the polymer. The
theoretical enthalpy of fusion for a totally crystalline polyaryletherketone,
in particular a
polyetheretherketone (PEEK) is 122 J/g according to Hay and Coll (Polymer
Communications,
= 1984, 25, 175-178). The presence of a degree of crystallinity of at least
10% has the advantage
of offering excellent mechanical properties, in particular a good torque on
shoulder resistance.
However, it is preferable to keep the degree of crystallinity below 35% to
preserve the
characteristics of the film, in terms of adhesion and protection, of the
surface preparation against
corrosion.
The polyaryletherketones used in the invention may be obtained from aqueous
polyetheretherketone dispersions or from aqueous polyetherketone dispersions.
These aqueous
dispersions may comprise organic or inorganic mechanical reinforcing agents
such as mica
pigments of the muscovite and/or biotite type constituted by aluminium
silicate and hydrated
CA 02815723 2013-04-24
WO 2012/062426 8 PCT/EP2011/005524
potassium or magnesium, amorphous aluminium oxides with a gamma crystalline
structure and
with a particle size in the range 20 to 300 nm, titanium dioxide pigments with
a particle size in
the range 10 to 100 nm, perfluoroalkoxyethylene copolymer resins (PFA),
amorphous carbon
black pigments, synthetic graphite powders with a diameter of less than 5 rim,
nano-diamond
powders obtained by detonation and with a particle size in the range 4 to 6
run, C type glass with
a fibre thickness in the range 1 to 1.3 pm with a diameter D90 < 50 m, WS2
fullerene nano
materials with a particle size in the range 80 to 220 nm, or WS2 tungsten
bisulphide lamellar
pigments with a particle size D50 = 55 nm.
Polyetheretherketones, the abbreviation for which is PEEK, and
polyetherketones the
abbreviation for which is PEK, are obtained by a nucleophilic substitution
type synthesis
pathway. Polyetherification results in rigid semi-crystalline polymers with
high melting points.
They fall into the category of the most high performance materials in the
thermoplastic material
range. They have a glass transition temperature of 143 C and, because of their
semi-crystalline
nature, retain their excellent mechanical properties up to temperatures close
to their melting point
which is 343 C. Their quasi-linear and aromatic structure provides PEEK and
PEK with
excellent long-term thermal stability.
The molecular structure of polyetheretherketones is as follows:
11 111 0
The molecular structure of polyetherketones is as follows:
0
/ a
_n
With a glass transition temperature of 157 C and a melting point of 374 C,
polyetherketones, PEKs, offer extended performance at high temperatures
compared with
CA 02815723 2013-04-24
WO 2012/062426 9 PCT/EP2011/005524
polyetheretherketones, PEEKS, while having all the same advantages such as
rigidity, solidity and
chemical resistance.
The continuous service temperature is 240 C and the deformation under load
temperature
exceeds 300 C for reinforced grades of PEEK and PEK compared with other
polymers.
PEEK has high level mechanical properties and retains its properties up to 250
C for
tensile strength and up to 300 C for bending strength. These mechanical
characteristics are
greatly improved by incorporating 10% to 30% of solid lubricants such as
graphite, carbon
black, fluorinated PTFE type polymers or perfluoroalkoxyethylene (PFA) type
resins, or glass
fibres.
PEKs supply up to three times the wear resistance of PEEKS at high
temperatures and
retain their mechanical and physical properties at temperatures of more than
30 C above those
for PEEK while accommodating higher loads without permanent deformation.
PEEKS and PEKs have chemical resistance, in particular against saturated salt
solutions,
gaseous hydrogen sulphide at 200 C and also resistance to hydrolysis at 200 C
under 1.6 MPa
with a temperature resistance comparable to fluorinated polymers. Table 1
clearly shows the
superior mechanical properties of PEEK and PEK compared with fluorinated
polymers (PTFE
and PFA).
Properties PEEK PEK PTFE PFA
Melting point ( C) 343 372 327 310
Continuous service 260 280 260
260
temperature ( C)
Tensile strength (MPa) 100 100 14-35 28-
31
Tensile modulus (GPa) 3.5 3.5 0.55
0.78
_
Bending modulus (GPa) 4 4 0.45
0.67
Hardness (Shore D) D85 D85 D50-D55 D60-D64
Compressive strength 118 118
12
(MPa)
Density 1.3 1.3 2.1-2.2 2.1-2.2
Table 1
Various implementations are possible for PEKs and PEEKS, but involve a
transformation
by melting at a temperature in the range 370 C to 420 C. Deposition may be
carried out by
10
electrostatic powder projection, by spraying aqueous dispersions and by
thermal projection. In
the molten state, PEEKs and PEKs are not sensitive to corrosion, but they may
be polluted by the
moulds formed from alloys containing copper or chromium (as in certain grades
of martensitic
stainless steels comprising 13% of chromium, for example) which will catalyse
degradation and
produce coatings less resistant to oxidation. Overall, after transformation by
melting, PEKs and
PEEKs adhere well to metal, especially if it is not well polished. The
permitted roughness
represents between 20% and 25% of the total desired thickness of the dry film.
The adhesion
may be increased using an undercoat as an adhesion promoter or by using a
surface treatment by
mechanical abrasion (sanding or shot blasting), by mordanting in chromic acid
or by plasma
treatment with an oxidizing agent of the air, or 02 type or even a NH3 type
reducing agent. At
the same time, superficial oxidation of almost all metals tends to reduce the
adhesion of the
polymer. Heating the metal in an inert atmosphere or by induction proves to be
necessary in
order not to modify the surface energy of the support. Finally, the cooling
must be sufficiently
slow to result in good re-crystallization, and to conserve the intrinsic
properties of the polymer,
such as wear resistance and scratch resistance. Rapid cooling would produce an
amorphous
coating which could still be re-crystallized by annealing the parts at 200 C
for 30 minutes. The
mechanical properties of the polymer may be increased by increasing the
crystallinity by means
of a controlled cooling process, for example with a cooling rate of 10 C/m in
from 400 C to
250 C followed by a constant temperature stage of 30 minutes to 1 hour at 250
C.
In a first stage, the Applicant investigated obtaining a polyaryletherketone
coating from
an aqueous suspension of polyetheretherketone sold by Victrex under the
VicoteTM F800 series
name which can contain at least one solid lubricant, preferably a fluorinated
polymer of the
perfluoroalkoxyethylene copolymer resin type to strengthen the wear resistance
and/or at least
one inorganic carbon black type solid compound to strengthen the abrasion
resistance. The
physic-chemical characteristics of the various aqueous phase Vicote F800
series suspensions are
evaluated in Table 2.
CA 2815723 2018-01-05
CA 02815723 2013-04-24
WO 2012/062426 11
PCT/EP2011/005524
Physico-chemical Vicote F804 Vicote F805 Vicote F807Blk
characteristics
Appearance White liquid White liquid Black liquid
.
Solids (% by wt) 37 37 37
pH 6 5.5 5.5
ISO viscosity 6 mm 55 55 30
(second)
Particle size (D90 10 gm 10 gm 10 gm
diameter)
Melting point ( C) 343 343 343
_
Continuous service 260 260 260
temperature ( C)
Perfluoroalkoxyethylene 10% of solids 30% of solids
copolymer resin (PFA)
_
Inorganic compound - Carbon black
Table 2
The Applicant has also accurately determined the composition of aqueous
suspensions of
polyetheretherketone powder. In particular, it was established that the
aqueous suspensions may
preferably comprise in the range 25% to 35% by weight of a PEEK powder with a
particle size
D90 of 10 gm sold by Victrex under the trade name Vicote 704.
The aqueous suspensions may also comprise solid lubricant particles from at
least one of
classes 1, 2 and 4 and preferably in the range 3% to 12% by weight of a solid
lubricant from
class 4 in the form of a fluorinated powder of the perfluoroalkoxyethylene
copolymer type sold
by DYNEON under the trade name Hyflon PFA with a mean particle size in the
range 20 to 30
gm.
The term "solid lubricant" as used here means a solid and stable body which,
on being
interposed between two frictional surfaces, can reduce the coefficient of
friction and reduce wear
and damage to the surfaces. These bodies can be classified into different
categories defined by
their functional mechanism and their structure, namely:
= class 1: solid bodies owing their lubricating properties to their
crystalline structure, for
example graphite, zinc oxide (ZnO) or boron nitride (BN);
= class 2: solid bodies owing their lubricating properties to their
crystalline structure and
also to a reactive chemical element in their composition, for example
molybdenum
12
disulphide MoS2, graphite fluoride, tin sulphides, bismuth sulphides, tungsten
disulphide,
or calcium fluoride;
= class 3: solid bodies owing their lubricating properties to their
chemical reactivity, for
example certain chemical compounds of the thiosulphate type, or Desilube 88
sold by
Desilube Technologies Inc;
= class 4: solid bodies owing their lubricating properties to a plastic or
viscoplastic
behaviour under frictional stress, for example polytetrafluoroethylene (PTFE)
or
polyamides.
The aqueous suspensions may comprise mechanical reinforcing agents, preferably
in the
range 0.5% to 1 % by weight of carbon black pigments sold by Evonik under the
trade name
PrintexTM with a BET specific surface area in the range 25 to 300 m2/g and a
mean particle size
in the range 1 to 5 tin.
The aqueous suspensions may comprise a coalescing agent, preferably with a
rapid
evaporation rate and a boiling point in the range 100 C to 200 C, of the
ethylene glycol mono-
butyl ether type, in the range 2.5% to 10% by weight and more preferably in
the range 2.5% to
5% by weight of the suspension in order to facilitate coalescence or formation
of a film by
external plastification of the polymer entities and to modify the surface
tension of the suspension
in order to facilitate spreading.
The aqueous suspensions may comprise a surfactant, and preferably a non-ionic
wetting
and dispersing agent of the sodium dioctylsulphosuccinate type (a compound of
sulphuric acid
and an aliphatic ester in a mixture of water and ethanol) in the range 2.5% to
10% by weight and
preferably in the range 2.5% to 5% by weight of the suspension in order to
improve wetting of
the support and prevent the powders from settling out of the solution.
Regarding the process for depositing a dry film on the portion of the. end 1,
2 of the
threaded tubular component, the Applicant has established that the Vicote 704
CA 2815723 2018-01-05
CA 02815723 2013-04-24
WO 2012/062426 13 PCT/EP2011/005524
polyetheretherketone powder grade may be applied by projection using an
electrostatic gun using
either a dry or wet procedure.
In a first variation, the portion of the end 1,2 is pre-heated to 400 C before
applying the
PEEK powder. Next, the coated portion is maintained at a temperature in the
range 360 C to
420 C for 2 minutes and preferably at the initial temperature of 400 C to
generate a good surface
appearance. The operation may be repeated several times in order to produce
the desired
thickness. The powder must have been dehydrated for a minimum of 2 h at 180 C.
In a second variation, the portion of the end 1, 2 is coated by pneumatic
spraying of a
cold aqueous suspension of Vicote 704 powder which may or may not have been
reinforced. For
this process, it is preferable for the portion of the end 1, 2 to be perfectly
clean and degreased
using a solvent, preferably a polar aprotic solvent such as acetone.
Application may be carried out using a pneumatic gun spraying system with a
gravity
feed gun and cup, the portion of the end 1, 2 being at ambient temperature.
The temperature of
the mixture is preferably close to the ambient temperature, said ambient
temperature preferably
being in the range 20 C to 30 C.
The diameter of the gun nozzle is preferably in the range 0.7 to 1.8 mm and
the minimum
air pressure of 4 bars is preferably in the range 4 to 6 bars.
The coated part is then left at ambient temperature for a period in the range
5 to 10
minutes.
The part is placed in an oven or furnace at a temperature of 120 C for a
period in the
range 5 to 10 minutes. This drying operation may be carried out by induction,
for example.
Next, the part is placed in a furnace either at 400 C or at a lower
temperature, followed by
raising it to 400 C at a rate in the range 10 C to 20 C/min.
Once the maximum temperature of the metal has been reached, the portion of the
threaded end 1, 2 is left at this temperature for 5 to 15 minutes and
preferably for at least 10
minutes in order to allow the dry film to fuse completely and form a
homogeneous film.
CA 02315723 2013-04-24
WO 2012/062426 14 PCT/EP2011/005524
The threaded end portion 1, 2 is then taken out of the furnace and allowed to
cool to
ambient temperature. The cooling rate is preferably slow, namely in the range
1 C/min to
200 C/min in order to obtain a semi-crystalline structure.
An alternative to electrostatic projection consists of applying a Vicote
powder by dry
thermal projection onto the portion of the threaded end 1, 2 using a heat gun.
In this process, it is
preferable for the portion of the end 1, 2 to be perfectly clean and degreased
with a solvent,
preferably a polar aprotic solvent such as acetone.
The part is pre-heated in an oven or furnace at 260 C. The Vicote powder is
applied to
the part using a heat gun with a vector gas allowing the fine particles of
polyaryletherketone to
be heated to the melting point, accelerated and transported to the substrate.
The operation is
followed by rapid cooling in air to ambient temperature. The operation may be
repeated several
times in order to obtain the desired thickness.
The thickness of the dry coating is in the range 20 to 70 pm, preferably in
the range 30 to 50
The tests consist of evaluating a certain number of parameters, namely:
= the frictional torque at the surfaces in contact under high Hertz
stresses (Bridgman
test);
= the adhesive force of the film on the substrate (Scratch test, cross
hatch test);
= the wet medium exposure resistance;
= the water immersion resistance;
= the high pressure wear resistance (Falex test).
The Bridgman test enables to determine the tribological characteristics of dry
film -
pigments during a screwing operation specific for "premium" connections. More
precisely, the
torque on shoulder resistance CSB, also known as the ToSR (torque on shoulder
resistance), is
simulated and determined. This torque arises during screwing operations
specific for premium
connections used in the oil industry and represented in Figure 2.
CA 02815723 2013-04-24
WO 2012/062426 15 PCT/EP2011/005524
The curve in Figure 2 expresses the screwing (or clamping) torque as a
function of the
number of rotational turns made. As can be seen, a profile for the screwing
torque of "premium"
connections breaks down into four portions.
In a first portion P1, the external threads of the male threaded element (or
pin) of a first
component of a threaded tubular connection as yet have no radial tightening
with the internal
threads of the corresponding female threaded element (or box) of a second
component of the
same threaded tubular connection.
In a second portion P2, the geometrical interference of the threads of the
male and female
threaded elements generates a radial tightening which increases as screwing
continues
(generating a small but increasing screwing torque).
In a third portion P3, a sealing surface at the external periphery of the end
portion of the
male threaded element interferes radially with a corresponding sealing surface
of the female
threaded element to produce a metal/metal seal.
In a fourth portion P4, the front end surface of the male threaded element is
in axial
abutment with the annular surface of a makeup abutment of the female threaded
element. This
fourth portion P4 corresponds to the terminal phase of makeup.
The makeup torque CAB which corresponds to the end of the third portion P3 and
to the
start of the fourth portion P4 is termed the shouldering torque.
The makeup torque CP which corresponds to the end of the fourth portion P4 is
termed
the plastification torque. Beyond this plastification torque CP, it is assumed
that the male
makeup abutment (end portion of the male threaded element) and/or the female
makeup
abutment (zone located behind the annular abutment surface of the female
threaded element) is
(or are) subjected to plastic deformation, which may degrade performance as
regards the
tightness of the contact between the sealing surfaces by plastification of the
sealing surfaces as
well.
CA 02815723 2013-09-29
WO 2012/062426 16 PCT/EP2011/005524
The difference between the values for the plastification torque CP and the
shouldering
torque CAB is termed the torque on shoulder resistance CSB (CSB = CP ¨ CAB). A
threaded
tubular connection is subjected to an optimum tightening at the end of makeup,
which is the
guarantee for optimum mechanical strength of the threaded connection, for
example as regards
tensile forces, but also as regards accidental break-out in service, and for
optimum sealing
performances.
The designer of a threaded connection is thus obliged to define, for a given
type of
threaded connection, a value for the optimum makeup torque which, for all
connections of this
type of connection, must be lower than the plastification torque CP (in order
to avoid
plastification of the abutments and the resulting disadvantages) and be higher
than the
shouldering torque, CAB. Ending makeup with a torque which is less than CAB
cannot
guarantee correct relative positioning of the male and female elements and
thus of an efficient
interference fit between their sealing surfaces. Furthermore, there is a risk
of break-out. The
effective value of the shouldering torque CAB fluctuates greatly from one
connection to another
for the same type of connection as it depends on the diametral and axial
machining tolerances of
the male and female threads and sealing surface(s); the optimal makeup torque
should be
substantially higher than the shouldering torque CAB.
As a consequence, the higher the value of the torque on shoulder resistance
CSB, the
larger the margin for defining the optimized makeup torque, and the more the
threaded
connection will be resistant to operational stresses.
Friction tests were carried out using a Bridgman type machine. This type of
machine has
in particular been described in the article by D Kuhlmann-Wilsdorf et al,
"Plastic flow between
Bridgman anvils under high pressures", J. Mater. Res., vol 6, no 12, Dec 1991.
A diagrammatic
and functional example of a Bridgman machine is illustrated in Figure 5.
This machine comprises: a disk DO which can be driven in rotation at selected
speeds; a
first anvil EC1, preferably conical in type, permanently attached to a first
face of the disk DQ; a
CA 02815723 2013-04-24
WO 2012/062426 17 PCT/EP2011/005524
second anvil EC2, preferably conical in type, permanently attached to a second
face of the disk
DQ, opposite its first face; first EP1 and second EP2 pressure elements, such
as pistons, for
example, which can exert the selected axial pressures P; a third anvil EC3,
preferably cylindrical
in type, which is permanently attached to one face of the first pressure
element EP1; a fourth
anvil EC4, preferably cylindrical in type, which is permanently attached to
one face of the
second pressure element EP2.
To test a lubricant composition, two pieces of a material identical to that
constituting a
threaded element are covered with said composition in order to form the first
Si and second S2
specimens. Next, the first specimen Si is interposed between the free faces of
the first EC1 and
third EC3 anvils, and the second specimen S2 between the free faces of the
second EC2 and
fourth EC4 anvils. Next, the disk DO is rotated at a selected speed while
applying a selected
axial pressure P (for example of the order of 1 GPa) with each of the first
EP1 and second EP2
pressure elements, and the makeup torque to which each specimen Si, S2 is
subjected is
measured. The axial pressure, the rotation speed and the angle of rotation are
selected in the
Bridgman test in order to simulate the Hertz pressure and the relative speed
of the abutment
surfaces at the end of makeup. Using such a machine, it is possible to fix
several different
pairings of parameters (makeup torque, rotation speed) in order to impose
predetermined makeup
torques on specimens Si and S2, and thus to check whether these specimens Si
and S2 closely
follow a given makeup torque profile, and in particular whether they can reach
a number of
completed turns before galling which is at least equal to a threshold value
selected with respect
to the selected makeup torques.
In the present case, the selected contact pressure was 1 GPa and the rotation
speed was
1 rpm. The test specimens were formed from stainless steel containing 13% Cr,
machined then
coated with different dry film formulations.
The Scratch test, shown diagrammatically in Figure 4, allows the adhesive
force or
adhesion of a film on a surface or surface preparation to be determined. The
method, consisting
18
of shearing and deforming a film with a spherical bead subjected to an
increasing load, also
allows two major tribological parameters to be determined, namely the
coefficient of friction and
the critical load corresponding to the appearance of a loss of film cohesion.
The experimental conditions employ a spherical indenter formed from lnconelTM
718 with
a diameter of 5 mm and a metal specimen formed from XC48 carbon steel which
had been
treated by zinc or manganese phosphatation or an electrolytic Cu-Sn-Zn
deposit. The
parameters were: a load increasing from 10 N to 310 N at a load increase rate
of 15 N/s or a
load increasing from 250 N to 750 N at a load increase rate of 25 N/s. The
bead displacement
rate was 2 mm/s for a period of 20 s (the track length was 40 mm). The
measured coefficient of
friction is considered to be low when it is in the range = 0.05 for a load
of ION and p. = 0.09
for a load of 310 N. A [t of 0.07 was measured for a load of 310 Non a carbon
steel surface. It
should be noted that it is necessary to clearly set out the load and operating
conditions for the test
for each type of coating.
The cross hatch test consists of evaluating the resistance of a mono- or multi-
layer
coating to being separated from a substrate when the coating is cross-hatched
by making
incisions until said substrate in accordance with a classification into six
categories. Excellent
adhesion of the coating to the substrate must correspond to class 0 of ISO
standard 2409 (2007):
perfectly smooth edges to the incisions, none of the cross hatch squares
detached. In order to
take the environment into account, the cross hatch test is carried out after
being placed in a moist
medium (35 C and 90% RH). No change in appearance, no blistering no corrosion,
no cracking,
no scaling corresponding to the classifications in ISO standard 4628, and no
loss of adhesion are
characteristics of good moisture resistance.
The corrosion tests consist of a neutral salt spray test carried out in a
climatic chamber
under the following conditions: 35 C with a 50 g/L salt solution with a
density in the range 1.029
to 1.036 at 25 C, with a pH in the range 6.5 to 7.2 at 25 C and recovered at a
mean rate of 1.5
mL/h.
CA 2815723 2018-01-05
CA 02815723 2013-04-24
WO 2012/062426 19 PCT/EP2011/005524
Specimens that were intact without rusting then had to correspond to the Re0
class of
ISO standard 9227 after exposure. The method provides a means of verifying
that the
comparative quality of a metallic material with or without a corrosion
protective coating
(metallic or organic coating on metallic material) is maintained.
The water resistance tests consist of subjecting the specimens to an
accelerated corrosion
test in accordance with DIN standard 50017 carried out in a climatic chamber.
This test,
comprising one cycle per day, consists of depositing water vapour by
condensation under the
following conditions: 35 C, 90% relative humidity (RH) for 8 hours, then
allowing the specimen
to dry. After 7 cycles, a check is made to see whether the substrate protected
by the coating has
corroded.
Excellent resistance must correspond to the classifications in ISO standard
4628: no
corrosion, no blistering, no cracking, nor scaling of a chromium or carbon
steel plate treated or
not treated by phosphatation with zinc (8 to 20 g/m2 deposit of phosphate) or
manganese or
treated by an electrolytic deposit of a ternary Cu-Sn-Zn alloy with an
intermediate layer of Ni.
The water immersion test is much more severe than the water resistance test of
DIN
standard 50017. It consists of testing the water resistance of the coatings.
It is derived from
ASTM standard D870-09 relating to industrial and automobile paints.
Immersion in water may cause coatings to degrade. Knowledge regarding the
manner in
which a coating resists immersion in water is useful for predicting its
service life. Rupture or
failure in a water immersion test may be caused by a number of factors, in
particular a deficiency
in the coating itself, contamination of the substrate, or insufficient surface
preparation. Thus, the
test is useful for evaluating the coatings alone or complete coating systems.
The test consists of half immersing a specimen in demineralized water for a
period of 168
hours at 40 C in an oven. Adhesion, blistering, rust, or blowholes are
observed visually to
indicate the sensitivity of the coating to water.
CA 02815723 2013-04-24
WO 2012/062426 20 PCT/EP2011/005524
The high pressure wear resistance (also termed the Falex test) uses a rotating
indenter
compressed between two V-shaped blocks as described in Figure 6. The Falex
test is used in
particular at high speeds to evaluate anti-wear and extreme pressure
properties of lubricant fluids
in accordance with ASTM standard D 2670 and ASTM D 3233, but it is also used
at low speeds
to evaluate solid lubricants in accordance with ASTM method D 2625. The Falex
test is adapted
to accommodate threaded connections used in working hydrocarbon wells in that
it uses:
= a semi-closed contact geometry (to trap a third lubricating body);
= a pressure-speed range which matches up with that of the connections;
= the possibility of carrying out single direction or alternating tests in
order to
simulate make up and break out type operations.
The test conditions are as follows:
= load = 785 N;
= rotational speed of indenter = 60 rpm;
= mean metal/metal contact pressure = 560 MPa;
= indenter sliding speed = 20 mm/s.
The aim of this test is to simulate and evaluate endurance in terms of galling
resistance
for the various films without the need to carry out the evaluation on
connections. This test
means that the performance of the various coatings can be compared with actual
tests on the
connection. The galling criterion is defined using ASTM standard D 2625-94
relating to the
measurement of the loading capacity of the solid lubricant film and
corresponds to a sharp
increase of the torque compared with the initial state of the order of 1130
N.mm or of the
coefficient of friction of the order of 0.15 for a load of 785 N. In general,
galling is observed
when the applied load decreases irrespective of the materials and
configuration.
The Applicant has evaluated the performance, especially tribo-rheological
performance,
of various films obtained with aqueous suspensions of polyetheretherketone in
order to compare
CA 02815723 2013-04-24
WO 2012/062426 21 PCT/EP2011/005524
them, inter alia, with those observed with a thermoset film of the
fluoroethane type or a
viscoplastic film with a waxy thermoplastic matrix.
The fluoroethane film consists of an aqueous dispersion of
fluoroethylenevinylether cured
using an aliphatic polyisocyanate hardener.
The waxy thermoplastic matrix comprises at least one polyethylene wax and
mainly an
overbased calcium sulphonate in which friction modifying pigments are
dispersed, as described
in patent WO 2008/139058.
In a first stage, the Applicant evaluated the adhesion, the coefficient of
friction, the anti-
corrosion protection and the water immersion characteristics of aqueous
suspensions of
polyetheretherketone on various substrates that had received a particular
surface preparation
treatment:
= as-machined XC48 carbon steel (XC48 AsM);
= Z20C13 stainless steel (13Cr);
= XC48 carbon steel with zinc (PhZn) or manganese (PhMn) phosphatation;
= XC48 carbon steel with electrolytic Cu-Sn-Zn deposit (TA).
Tables 3, 4 and 5 summarize the adhesion results obtained respectively for
aqueous
suspensions of Vicote F804, Vicote F805 and Vicote F807B1k on specimens that
have received
different surface preparations by means of the Scratch test and by means of
the cross hatch test in
accordance with ISO standard 2409.
It will be recalled herein that the Scratch test characterizes the adhesive
force of a high
performance material, preferably thermoset or thermoplastic, as a function of
an increasing
applied load. The critical load, determining rupture at the interface and thus
the adhesive force of
the material, is higher when the material is resistant and adhesive. A minimum
critical load of
310 N corresponds to a minimum adhesion for pressures which may reach 1.1 GPa
below which
an increase in the quantity of wear product occurs in the contact and thus
galling resistance is
insufficient.
CA 02815723 2013-04-24
WO 2012/062426 22
PCT/EP2011/005524
For the cross hatch test in accordance with ISO standard 2409, which provides
a
measurement of the adhesion after damage by Scratching the material to the
interface, a mark of
0 corresponds to excellent adhesion while a mark of 5 defines very poor
adhesion.
Surface preparation XC48 AsM PhMn TA
Adhesion, Scratch test (Lc, in N) 242 750 400
Adhesion, ISO 2409 0 0 0
Table 3: adhesion performance of Vicote F804
Surface preparation XC48 AsM 13Cr PhMn
TA
Adhesion, Scratch test (Lc, in N) 253 246 750 294
Adhesion, ISO 2409 0 0 0 0
Table 4: adhesion performance of Vicote F805
Surface preparation XC48 AsM 13Cr PhZn PhMn
TA
Adhesion, Scratch test (Lc, 750 254 50 750 188
in N)
Adhesion, ISO 2409 0 0 5 0 0
Table 5: adhesion performance of Vicote F807Blk
The films tested had insufficient adhesive forces irrespective of the surface
preparation
carried out on carbon steels with zinc phosphatation, except for carbon steels
with manganese
phosphatation. In addition, the polyetheretherketone film had little
compatibility with a zinc
phosphatation type surface treatment.
In order to explain these results, the Applicant also evaluated the incidence
of roughness
obtained without phosphatation. Since the adhesion mechanism for a
polyetheretherketone film is
principally physical by mechanical keying, the roughness of the substrate is a
determining factor.
At the same time, it is recommended to sand the substrate by projection in
order to obtain a
roughness Ra (Ra being the arithmetic mean with respect to the mean line for
the amplitude of the
roughness) of 20% or 25% of the thickness of the desired fmal film in order to
ensure good
adhesion of the film i.e. a roughness Ra in the range 4 tim to 6 [tm minimum.
The roughness was
determined using a rugosimeter in accordance with ISO standard 1997.
Surface preparation XC48 AsM 13Cr PhZn PhMn TA
Ra ( m) 0.9 0.05 0.09 0.8 0.05 1.6
0.1 1 0.2
Rz (p.m) 4.8 0.2 0.9 0.1 5.1 + 0.3 11.1
1.0 8 + 1.4
Table 6: roughness of test specimens as function of surface preparation
CA 02815723 2013-04-24
WO 2012/062426 23 PCT/EP2011/005524
Table 6 illustrates that a relatively high roughness obtained by manganese
phosphatation
offers a better degree of adhesion. It also shows that very slightly polar
surface preparations,
such as the electrolytic deposition of ternary Cu-Sn-Zn, do not facilitate
adhesion.
In view of these first results, the Applicant elected, to determine the
corrosion resistance,
only substrates with naturally low resistance to corrosion, thereby excluding
martensitic stainless
steel containing 13% chromium for which the critical adhesion load for
polyetheretherketone
films was more than 180 N.
The thicknesses of films produced by cold pneumatic spraying were in the range
20 to 45
vm. The degree of rusting in the range Re0 and Re9 was determined in
accordance with ISO
standard 4528-3. The degree of blistering and detachment in the range 2S2 (low
concentration of
blistering and of small dimensions) and 5S5 (generalized blistering and of
large dimensions) was
determined in accordance with ISO standard 4628-2. The results are summarized
in Tables 7 and 8.
Exposure time
Surface 24h 48h 250h 750h
1000 h
preparation
XC48 AsM Re9
TA Re2 Re3/4+
Detachment
Table 7: corrosion resistance for different surface preparations with Vicote
F805
Exposure time
Surface 24h 48h 250h 750h
1000 h
preparation
XC48 AsM Re8 Re9
PhMn Rel Re2 Re3
TA Re0 Re0 Rel Rel
Re1/2 +
detachment
Table 8: corrosion resistance for different surface preparations with Vicote
F807Blk
The corrosion resistance of surface preparations coated with the monolayer
polyetheretherketone film was broadly insufficient except for the Cu-Sn-Zn
electrolytic deposit,
despite the low adhesion or strong loss of cohesion of the film under stress.
The results also
show that the Vicote F807Blk polyetheretherketone film comprising an inorganic
carbon black
type compound has relatively better corrosion resistance compared with Vicote
F805 irrespective
of the surface preparation. The absolute best result was obtained with the
electrolytic deposit
CA 02815723 2013-04-24
WO 2012/062426 24 PCT/EP2011/005524
with only 5 spots of corrosion after 1000 hours. It was observed that adding
an electrically
conductive carbon black reinforcing agent reinforced the mechanism for
protection against
corrosion by acting as a sacrificial anode.
Finally, the Applicant evaluated the mean coefficients of friction of a film
subjected to
abrasive wear by means of a Scratch test over a wide load range between 10 N
and 750 N. The
results are summarized in Table 9.
Film Vicote F804 Vicote F805 Vicote F807B1k
Surface XC48 TA XC48 TA XC48 13Cr PhMn TA
preparation AsM AsM AsM
Mean CoF 0.198 0.173 0.069 0.075 0.073 0.112 0.135
0.127
(10-310 N)
Table 9: mean coefficient of friction, Scratch test
The coefficients of friction of the polyetheretherketone films were less than
0.135
irrespective of the surface preparation and reached 0.075 for a mean contact
pressure of 500 MPa
for a polyetheretherketone comprising a fluorinated polymer of the
perfluoroalkoxyethylene type.
The first results show that monolayer polyetheretherketone films are
sufficiently
lubricating with an anti-corrosion performance which depends not only on the
composition of the
film but also on the adhesion of the substrate.
In a second stage, the Applicant then developed a means for improving the
adhesion and
the anti-corrosion performance. The Applicant wanted to replace sanding when
this was not
possible due to the geometry of the parts to be coated. Above all, the
Applicant investigated not
modifying the composition of the commercial films studied. In fact, adding
adhesion promoters
or corrosion inhibiting pigments in proportions of more than 10% increases the
PCV (pigment
concentration by volume) beyond the PCV for which there is just enough binder
to coat the
powdered substances (pigments and fillers) and as a result the porosity and
loss of cohesion of
the film obtained from commercially available aqueous suspensions.
Other alternatives using Vicote 704 polyetheretherketone powder may also be
foreseen.
The Applicant investigated increasing the adhesion with an undercoat of the
adhesion
promoter type. Direct adhesion between materials is rare. Since direct
adhesion is principally
CA 02815723 2013-04-24
WO 2012/062426 25 PCT/EP2011/005524
but not uniquely linked to Van der Waals interactions, it only occurs with
very smooth materials
which are extremely clean (mica or silicon, for example), which are brought
into intimate
contact, i.e. to within distances on the atomic scale (nanometric). Thus, this
is often impossible
to carry out if the surfaces are rough, but in contrast is entirely suitable
for films with low
roughness.
Thus, the Applicant principally investigated a film compatible with the
process for
obtaining a polyetheretherketone film by melting at 400 C.
The undercoat may be a projected deposit of alloys of iron and zinc, sold
under the trade
name Dacroforge Z by Dacral to replace zinc phosphatation, but the process for
obtaining it by
mechanical projection equivalent to sanding/shot blasting limits it use in
hollow bodies which
have small diameters and are short in height.
The undercoat is preferably a filled polyaryletherketone. The solution
comprising, inter
alia, mica pigments of the muscovite or biotite type in proportions of 25% to
50% by weight in
an organic polyetheretherketone binder is sold under the trade name Vicote
F817 by the supplier
Victrex.
The process for application and melting the undercoat is identical to that for
the upper
layer. In contrast, a rapid cooling rate is desired in order to obtain a less
crystalline structure that
is more insulating in order to retard the initiation of corrosion pits and to
reduce the passive
current density of the material.
The thickness of the undercoat may be in the range 30 to 40 tim.
The anti-corrosion and adhesion properties of the undercoat evaluated using
two
processes with different cooling kinetics are summarized in Tables 10 and 11
respectively.
CA 02315723 2013-04-24
WO 2012/062426 26 PCT/EP2011/005524
Exposure time
Surface Cooling kinetics 24 h 48 h 250 h 500 h
750h 1000 h 1500 h
preparation _
XC48 asM 120 C/min Re0 Re0 Re0 Re0 Re0 Re0 +
Re0/1+
2S2
2S2
blistering
blistering _
TA 120 C/min Re0 Re0 Re0 Re0 Re0 Re0 +
Re0 +
2S2
detachment
blistering
_
XC48 asM 400 C-260 C Re0 Re0 Re0 Re0 Re0 Re0/1 +
Re0/1 +
15mn at 260 C 3S2
3S3
260 C-T amb blistering
blistering
TA 400 C-260 C Re0 Re0 Re0 Re0 Re0 Re0/1 +
Re0/1 +
15mn at 260 C 3S2
3S3
260 C-T amb blistering
blistering
Table 10: corrosion resistance for different surface preparations with Vicote
F817
undercoat =
Surface preparation XC48 asM TA
Adhesion, Scratch test (Lc, N) 350 344
Adhesion, ISO 2409 0 0
Mean COF (10-310 N) 0.164 0.160
Table 11: adhesion performances and coefficient of friction for Vicote F817 .
The Vicote F817 undercoat was sufficiently protective and adhesive but not
sufficiently
lubricating. The lubricating properties were supplied by the upper
polyaryletherketone layer.
The anti-corrosion, adhesion and double layer friction performances are
summarized in
Tables 12 and 13. The total thickness of the film comprising the undercoat and
the upper layer
(topcoat) was in the range 40 to 70 rim.
Exposure time
Topcoat Undercoat Surface 24 h 48 h 250 h 500
750h 1000 h 1500 h
preparation h
Vicote Vicote XC48 asM Re0 Re0 Re0 Re0 Re0 Re0
+ Re0/1+
F807B1k F817 2S2
2S2
blistering
blistering
PhMn
Re0 Re0 Re0 Re0 Re0 Re0 Re0
TA Re0 Re0 Re0 Re0 Re0 Re0 +
Re0 +
27 detachment
blistering
Dacroforge XC48 asM Re2 Re4 - - - -
Z
CA 02815723 2013-04-24
WO 2012/062426 27 PCT/EP2011/005524
Table 12: corrosion resistance for different double layer surface preparations
Topcoat Vicote F804 Vicote Vicote F807 Blk
F805
Undercoat Vicote F817 Dacro-
forge Z
Surface XC48 TA XC48 XC48 PhMn TA XC48
preparation asM asM asM asM
Scratch 441 662 >750 675 637 >750 >750
adhesion
test (Lc,
Adhesion, 0 0 0 0 0 0 0
ISO 2409
Mean COF 0.117 0.114 0.061 0.086 0.085 0.084 0.129
(10-310 N)
Table 13: adhesion performance and double layer coefficient of friction
The coefficients of friction for a mean contact pressure of 500 MPa were
sufficiently low,
particularly for the Vicote F807 Blk film wherein t = 0.085 irrespective of
the surface
preparation, and are comparable to the coefficients of friction for a
fluoroethane or epoxide
thermoset film, and must allow a shouldering torque value of less than 70% of
the optimum
makeup torque to be obtained.
Overall, the coefficient of friction, the adhesion and the anti-corrosion
protection of the
polyetheretherketone film are considerably improved, preferably with a
polyetheretherketone
undercoat with mica pigment filler and more particularly an upper layer of
polyetheretherketone
comprising at least one fluorinated polymer that deforms plastically under
stress and/or a carbon
black type mechanical reinforcing pigment.
Finally, the Applicant evaluated the tribo-rheological behavior of the film by
means of a
Bridgman test in order to determine the value of the torque on shoulder
resistance. The torque on
shoulder resistance value obtained for Vicote F807 Blk was equal to 85% of the
reference value
for API RP 5A3 grease on XC48 carbon steel and Z20C13 stainless steel.
However, the
difficulty in preparing the specimens due to the process for producing the
film and the small
diameter of the specimens meant that this value cannot be considered to be an
absolute reference.
The crystalline structure and many potential Van der Waals type intermolecular
interactions in
CA 02815723 2013-04-24
WO 2012/062426 28 PCT/EP2011/005524
the polyetheretherketone point to the strong cohesion of the material and a
high shear strength, and
thus probably to a substantially higher torque on shoulder resistance value.
At the same time, the Applicant evaluated the galling resistance of the film
by means of a
Falex test. The configuration of a test matched to a connection may comprise a
pair of V shaped
blocks, Vee blocks, with different surface preparations coated with PEEK film
in a mono or double
layer and an as machined XC48 carbon steel indenter or Z20C13 stainless steel
indenter containing
13% chromium.
The test conditions using a load of 785 N correspond to a mean pressure in the
contact of
150 MPa which is relatively close to that recorded during screwing at the
start of shouldering at the
threads and the bearing surface (100-300 MPa) and a pressure-velocity modulus
(PV) = 11.2
MPa.m/s which is close to that establishing the wear law in the threading at
the load flanks with PV
=5 MPa.m/s.
The Applicant studied Vicote F805 and F807B1k reinforced
polyetheretherketones.
Figure 6 shows the very good endurance of the double layer Vicote F817/Vicote
F807 Blk
film compared with the waxy thermoplastic solution in current use on the
connection and despite a
ternary electrolytic deposit type surface treatment considered to be anti-
galling (see document
WO 2008/032872). Galling, defined in accordance with ASTM standard D 2625-94,
was never
obtained, while it was obtained with the HMS3 waxy thermoplastic solution
after 51 minutes. The
relatively low and constant coefficient of friction, IA = 0.08, characterized
very low abrasive wear.
In order to determine the limits to the galling resistance of the film below,
the Applicant
evaluated the endurance and the coefficient of friction of the film using the
Falex test for increasing
loads in the range 1335 N to 4200 N. The sliding speed was 10 nun/s, as
opposed to the 20 nun/s
employed before. The results are shown in Figure 7.
The results show that galling does not occur for mean contact pressures of 350
MPa and
confirm the very high wear resistance of the film for the present invention.
The coefficient of
friction also decreased as the pressure increased and was in the range 0.056
to 0.078.
CA 02815723 2013-04-24
WO 2012/062426 29 PCT/EP2011/005524
In order to confirm the galling resistance and the coefficient of friction
observed in the
laboratory using the Falex and Scratch test on specimens, in particular of
carbon steel with an
electrolytic Cu-Sn-Zn deposit, the Applicant carried out makeups on 7" 29# L80
VAM TOP HT
connections, which are highly sensitive to galling. The makeup torque was
29900 N.m.
The female end 2 of carbon steel was treated by electrolytic deposit and the
male end 1 was
treated by zinc phosphatation and coated with a UV curable acrylic resin
described in patent
publication WO 2006/104251. The double layer PEEK film was applied to the
treated coupling
with a cooling rate of less than 5 C/min. Table 14 summarizes the makeup
results.
Product name Number of makeup Ratio of
1st No of makeups with
procedures without shouldering torque shouldering torque
galling
compared with respect <70% of makeup
to makeup torque torque
Vicote F807 Blk 17 57% 10
Table 14: comparison of 7" 29# L80 VAM TOP HT-CW UD makeup results
The makeup results obtained confirm the remarkable anti-galling nature of
polyetheretherketone film and in particular reinforced polyetheretherketone
film.
Female end Male end
Number of makeups without
galling
Carbon steel + electrolytic Cu- Carbon steel 17
Sn-Zn deposit + PEEK double + zinc phosphatation
layer + UV acrylic resin
Table 15: results of 7" 29# L80 VAM TOP HT makeups
Thus, the present invention proposes a lubricant film having very interesting
galling
resistance properties when it is applied to a carbon steel surface or steel
surface comprising at
least 13% chromium. It also allows the use of electrolytic deposits of the
binary Cu-Sn or
ternary Cu-Sn-Zn type to be dispensed with.
