OA16448A - Process for coating a threaded tubular component, threaded tubular component and resulting connection. - Google Patents

Abstract

The invention concerns a threaded tubular component for drilling or working hydrocarbon wells, said tubular component having at one of its ends (1; 2) a threaded zone (3; 4) 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 (1; 2) is coated with at least one film of polyurethane (12), 100% solid state, with an essentially rigid structure, based on a matrix of polyurethane and polyurea, in which the urethane functionality is predominant with respect to the urea functionality in a proportion of at least 55% by weight.

Description

The présent 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 and corrosionrésistant film on such a tubular component.

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 a string for drilling a hydrocarbon well, a riser or a work-over riser, 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 makeup with the corresponding end of another component, the assembly defining a connection.

Threaded tubular components are connected under defined loads in order to satisfy the requirements for an interférence fit and seal 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 loads which make it necessary to use coatings on the sensitive portions of such components such 25 as the threaded zones, abutments or sealing surface

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Makeup operations are generally carried out under a high axial load, for example the weight of a tube several métrés in length to be connected via the threaded connection, possibly localized by a slight misalignment of the axis of the threaded éléments 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 sea spray and in an onshore situation when sand, dusl or other pollutants are présent. Thus, it is necessary to use coatings that counter corrosion, on the surfaces which hâve to cooperate by makeup (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 makeup greases conforming to API (American Petroleum Institute) standard RP 5A3 does not constitute a long-terrn 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 nécessitâtes spécial cleanîng operations. Furthermore, such greases hâve to be applied on site for each makeup operation.

In order to overcome the problems of requiring a long-tenu corrosion résistance and résistance to galling and to satisfy environmental prérogatives, the principal protagonists in the field of threaded connections hâve 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 defînitively, at the factory, to the tubular components at the end of their manufacturing process and which are then ready for makeup.

In particular, coatings which are inert as regards the environment and which are résistant to wear and to atmospheric and climatic conditions are being devetoped

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Furthermore, the publication WO 2001/070918 discloses a method for depositing an antigalling coating on a threaded connection having polyuréthane resins as possible alternative binders. The anti-gailing function is provided by means of organic or inorganic compounds which are capable of releasing gas at high températures such as those encountered in a well, thereby generating an increase in the compressible free volume in the contact in order to facilitate makeup/breakout without galling. The binder is princîpally a thermoplastic polyuréthane, either mono- or bi-component, depending on the reactivity, or in aqueous dispersion.

Final! y, publication WO 2005/045188 proposes, for a tubular threaded connection of the “expandable” type, a method for depositing a coating with a liquid or pasty matrix of the polysulphide type, but also of the elastomeric polyuréthane, bi-component type, which can be cured in the combined absence of oxygen and moisture. The élongation performance is preferred over the mcchanical performance (résistance to breaking under tension, hardness, abrasion résistance, adhesive force), in contrast to that sought by the invention.

The présent invention is based on the discovery that using particular polyuréthane and polyurea matrixes means that lubricating dry films can be obtained which are highly résistant to wear, are antî-galling, hâve high mechanical strength, with a low coefficient of friction and which are résistant to extreme hydrocarbon well working conditions. The solutions employed can also be adapted to various grades of métal for the connections for the tubular components cited above.

More precisely, the invention concerne 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 dry film with a

Shore D hardness of more than 50 and comprising a matrix of polyuréthane and polyurea, in^ which the urethane functionality is prédominant with respect to the urea functionality in a proportion of at least 55% by weight.

Optional characteristics, which are complcmentary or substitutional, are defined below.

The polyuréthane and polyurea matrix is of the mono-component type.

The polyuréthane and polyurea matrix is obtained from a polyol type monomer with a high molecular weight, a chain extension agent and free aromatic isocyanates which can be cured by polyaddition using moislure.

The polyuréthane and polyurea matrix comprises;

• a multifunctional isocyanate pre-polymer with a functionality of at least 2, prepared from a mixture of polyether, polybutadiene or hydroxylated polyester polyols with a molecular mass in the range 300 to 6000 g/mol and aromatic isocyanates of the diphenylmethane diisocyanate type, in excess;

• a co-reagent of the mono- or bis-oxazolidone type in order to initiale the reaction and dilute the pre-polymer;

• an aliphatic polyisocyanate curing agent of the hexamethylene diisocyanate type in order to maintain curing;

• a catalyst for the pre-polymer of the dimorpholinodicthyl ether or dibutyl tin laurate type;

• a plasticizer to control foaming during formation of the film, in particular of the triethylene phosphate type.

The polyuréthane and polyurea matrix further comprises a moisture scavenger in order to stabilize the pre-polymer during storage by capturing residual water, said moisture scavenger being of the p-toluene sulphonyl isocyanate, trimethyl orthoformate or trimethyl orthoacetate type.

The polyuréthane and polyurea matrix further comprises a CO2 scavenger of the calcium oxide or magnésium oxide type in order to control foaming and the formation of bubbles during the reaction

The polyuréthane and polyurea matrix is of the bi-component type.

The polyuréthane and polyurea matrix is obtained from a mixture of heat-fusible polyols and polyamines with a low molecular weight which can be cured by polycondensation using an aliphatic polyisocyanate.

The polyuréthane and polyurea matrix comprises:

• a polyol pre-polymer selected from polyester, polyether and polybutadiene polyols with a molecular mass in the range 300 to 6000 g/mol cured using an aliphatic polyisocyanate;

• a heat-fusible polyamine with a functionality of 2 or more and with a molecular mass in the range 168 to 600 g/mol, in particular 4,4*-methylene-bis(2chloroaniline); and • an aliphatic polyisocyanate curing agent of the hexamethylene diisocyanate type, in excess.

The polyuréthane and polyurea matrix further comprises at least one solid lubricant as a friction reducîng agent, selected from the category of solid lubricants from class 1, 2, 3 or 4 in a proportion by weight in the range 5% to 30%.

The solid lubricant is selected from:

• a solid lubricant from class 2 of the B12S3 type;

• a solid lubricant from class 4 of the PTFE type; and a combination thereof.

The polyuréthane and polyurea matrix further comprises a corrosion inhibitor.

The entire threaded zone is coated with polyuréthane film.

The threaded tubular component comprises a metal/metal sealing surface, said sealing surface being coated with polyuréthane film.

The invention also concems 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.zjt

The invention also concems a method 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 polyuréthane and polyurea matrix as defined above, in the liquid state;

• applying the polyuréthane and polyurea matrix in the liquid state by spraying over a portion of the end of said threaded tubular component; and • curing the matrix to form a polyuréthane film with an essentîally rigid structure.

Optional characteristics of the coating method, which are complementary or substitutional, are defined below.

The polyuréthane and polyurea matrix is a mono-component matrix as defined above.

Curing of the polyuréthane film is initiated by application of a relative humidity of at least 60% RH at a température of at least 20°C optionally followed by drying.

Drying is carried out in an infrared or convection drying oven supplied with water vapour.

The polyuréthane and polyurea matrix is a bi-component matrix as defined above.

The polyuréthane film is cured by means of a bî-component spraying device with extemal mixing of hardener.

Curing of the polyuréthane film is followed by a stoving or post-curing operation at a température of 90°C.

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 in which:

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 makeup 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; Figure 6 is a diagrammatic view of another test set-up; Figures 7 and 8 show test curves.

The threaded connection shown in Figure 1 comprises a first tubular component with an axis of révolution 10 provided with a male end 1 and a second tubular component with an axis of révolution 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 mulual connection of the two components by makeup. The threaded zones 3 and 4 may be of the trapézoïdal, self-locking, etc thread type. Furthermore, mctal/metal sealîng surfaces 5, 6 intended to corne into sealed interférence contact against each other after connecting the two threaded components by makeup 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 cornes 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 présent case by the two contact surfaces 7 and 8 is replaced by self-locking interfering coopération 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 film 12 of polyuréthane with a Shore hardness of 50 or more, comprising a matrix of polyuréthane and polyurea, in which the urethane functionality prédominâtes over the urea functionality in a proportion of more than 55% by weight.

Since the urethane functionality prédominâtes over the urea functionality, a certain rigidity and a certain hardness of the film is obtained, which guarantees good abrasion résistance.

This prédominance of the urethane functionality over the urea functionality is obtained by a judicious choice of certain parameters of the method, such as the choice of components and the molecular weights,

These rigid polyuréthane coatings are distinguished by the nature of the oligomer and the eu ring agent used, but also in the nature of the reaction which occurs, the degree of curing and the method which is 100% solid state (no dissolving, nor dispersion of the polyuréthane).

According to D K Chattopadhyay (Prog. Polym. Sci. 32 ¢2007), 352-418), two reactions are at the origin of obtaining rigid polyuréthane coatings:

• an exothermic reaction between a diisocyanate and a hydroxyl-functionalized monomer (polyether, polyester polyol, scheme 1) or amine-functionalized monomer (polyamine, scheme 2) for a bi-component:

n OCN-R-NCO

Oiitocyenate nOCN-R-NCO

Diiiacyanete

O O

Il II

4-0-R'-O-C-N-R-N-C+♦ n HO-R*-OH —*

Polyol

H H

Potyu^r*8wne

Scheme 1

O O

Il II ♦ n H N-R'-NH -» + N - R'- N - C - N - R - N ·Ο ^a ’ I I I I n

	H	H H	H
Amine		Polyurea

Scheme 2 • an exothermic reaction in two steps starting from an isocyanate-functionalized polyester pre-polymer initiated by hydration (scheme 3) for a mono-component:

OCN—t--NCO OCN~p—NCO

NCO NCO c

H-^H

NCO NCO

OCN*—L-NCO OCN'*—1-NOO

NCO

Cwbfl motion

NH

T ΊΓr

Scheme 3 * »¹ ·

A first step consiste of reacting the isocyanate fonctions with water under conditions of température and relative humidity (scheme 4)

H H

Cubamc acid

Cvbon doadd·

Dllwcywt· WAar

Scheme 4

In a second step, the polyamines may react with the free poiyisocyanates (scheme 2).

Thus, the Applicant preferentiel I y dealt with rigid polyuréthanes for their mechanical properties of hardness, flexibility, rigidity under load, but above ail in order to overcome cnvironmental constraints related to émissions of volatile organic compounds (VOC).

Further, polyol polymers of low molecular mass were used to obtain low viscosity binders in order to reduce the use of organic VOC-releasing solvents, but this contributed to an increase in reactivity and made manipulation of the products restrictive. An alternative corresponded to the use of a co-reagent based on oxazolidine in particular in mono-component polymers where curing is initiated by moisture. Oxazolidines facilitate both the réduction in viscosity of the high molecular mass polyol or polyamine polymers, but their blocked aminated alcohol chemical nature means that they can initiate and accelerate curing by hydrolysis of the hydroxyl and amine reactive fonctions exposed to favourable moisture conditions.

Thus, from existing rigid polyuréthane coatings, the Applicant paid particular attention to rigid polyuréthane and polyurea coatings because of their high degree of curing which induces a dense intermolecular network producing properties of hardness, corrosion résistance and chemical résistance which are superior to other grades.

One of the major différences between a rigid and a soft (or elastomeric) polyuréthane is given by the ratio between the isocyanate-fonctionalized pre-polymer and the polyol and/or polyamine polymer. The doser the ratio is to 1, the more rigid is the polyurethane/polyurea coating obtained. One of the means for measuring rigidity and thus the degree of curing is the hardness of *

ίο the film on different scales (Shore D and Shore A or pencil hardness) using a durometer. The highest Shore hardness (> 50 Shore D) is measured for a ratio of 1, while a low Shore hardness (30 Shore A), corresponding to a soft or elastomeric coating, is measured for ratios of less than 0.4.

The Applicant was particularly interested in hybrid polyurethane/polyurea coatings which hâve other advantages linked to the combination of urethane and urea fonctions in the same coating. In contrast to the polyuréthane fraction in the cured film, the polyurea fraction provides superior cohesive energy, thermal stability and adhesion because of greater polarity. The polarity is accentuated by increasing the hydrophilic portion bonded to the urea function.

The polyurea fraction provides the coating with flexibiiity and relative insensitivity to moîsture during the method, in contrast to the polyuréthane System alone.

Since the reaction kinetics between the amine function and an isocyanate are preferential compared with those between the hydroxyl function and an isocyanate, foaming of the polyurea Systems or of Systems incorporating the polyureas is almost impossible. In ail other cases, in particular if a catalyst for the reaction is présent, foaming may resuit in a réduction in the density of the network, porosity and inferior performance.

The matrix cited above may be either mono-component in type or bi-component in type.

The mono-component polyuréthane matrix is obtained from a high molecular weight polyol type monomer, a chain extension agent and free aromatic isocyanates which can be cured by polyaddition by means of moisture.

As an example, the mono-component matrix may comprise:

• a multifunctional isocyanate pre-polymer with a functionality of at least 2, prepared from a mixture of polyether, polybutadiene or hydroxylated polyester polyols with a molecular mass in the range 300 to 6000 g/mol and aromatic isocyanates of lhe diphenyimethane diisocyanate type, in exccss;

• a co-reagent of the mono- or bis-oxazolidone type in order to initiate the reaction and dilute the pre-polymer; rfC • an aliphatic polyisocyanate curing agent of the hexamethylene diisocyanate type in order to maintain curing;

• a catalyst for the pre-polymer of the dimorpholinodiethyl ether or dibutyl tin laurate type; and • a plasticizer to control foaming during formation of the film, in particular of the triethylene phosphate type.

This mono-component malrix may further comprise a moîsture scavenger in order to stabilize the pre-polymer during storage by capturing residual water, in particular of the p-toluene sulphonyl isocyanate, trimethyl orthoformate or trimethyl orthoacetate type.

If necessary, it may also comprise a CO2 scavenger of the calcium oxide or magnésium oxide type in order to control foaming and the formation of bubbles during the reaction.

The bi-component polyuréthane matrix is obtained from a mixture of heat-fusible polyols and polyamines with low molecular weights which can be cured by polycondensation using an aliphatic polyisocyanate.

As an example, the bi-component matrix may comprise:

• a polyol pre-polymer selected from polyether, polybutadiene and hydroxylated polyester polyols with a molecular mass in the range 300 to 6000 g/mol;

• a heat-fusible polyamine with a functionality of 2 or more and with a molecular mass in the range 168 to 600 g/mol, in particular 4,4’-methylene-bis(2chloro aniline); and • an aliphatic polyisocyanate curing agent of the hexamethylene diisocyanate type, in excess.

The matrix of the invention may also comprise particles of solid lubricant from at least one of classes 1, 2, 3 and 4 in a proportion by weight in the range 5% to 30%. Preferably, said solid lubricant is selected from a solid lubricant from class 2 of the B12S3 type, a solid lubricant from class 4 of the PTFE type, and a combination thereof. /vT

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 classifîed 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 exemple molybdenum disulphide M0S2, 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 Desitube 88® sold by Desitube 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 matrix may also incorporate other additives such as a corrosion inhibitor, for example.

The coating method of the invention essentially consists of spraying the polyuréthane film in the liquid state onto the threaded tubular component then polymerizing it, which means that a coating can be obtained with superior frictional, abrasion résistance and adhesion properties.

It is a rigid polyuréthane film with a Shore D hardness of more than 50 obtained by means of a matrix of polyuréthane and polyurea not including and not requiring any addition of a solvent or diluent.

The coating method may be carried out rapidly on either the male or female portion of a tubular component.

The invention can advantageously be used to replace an acrylic-epoxy coating cured by ultraviolet light on the male portion of the connection, thereby providing superior or équivalent glide performance and anti-corrosion protection with a rigid mono-component polyuréthane.

Further, the invention means that coefficients of friction of less than 0.06 can be obtained irrespective of the pressure and the zone of the threading with a rigid bi-component polyuréthane and thus relatively low shouldering torque values can be obtained.

The superior hardness of the rigid polyuréthane coatings points to a model of friction by sliding in the contact to increase the longevity of the coating, in contrast to other coatings which are friable even under low loads.

The Applicant has preferentially selected to carry out déposition by spraying, i.e. a 100% solid state method, of a matrix of polyuréthane and polyurea with a rigid structure associated with a high hardness:

• a mono-component polyuréthane matrix obtained by polyaddition by means of initiation by moisture;

• a bi-component polyuréthane matrix obtained by polycondensation.

The mono-component film curing re action is initiatcd above a relative humidity of 60% RH at 20°C. It may be followed by drying. The curing rate is increased with an increase in the moisture level and the température.

In the case of a mono-component film, the initial curing to obtain a dry vamish can be carried out in two steps:

The first comprises the following operations:

• applying a minimum relative humidity of 70% RH for 10 minutes at 30°C; or • applying a relative humidity of 70% RH for 10 minutes at 90°C.

The second comprises the following operations:

• drying in an oven at 80°C for 2 hours; or • drying in an oven at 130”C for 15 minutes, rit

It is dry to the touch 25 minutes after curing. In ail cases after cooling, curing is carried out under relative humidity and at ambient température in air so that it is complété after a minimum of 24 hours.

Further, there are few or no risks of instantaneous corrosion or flash rusting during the drying step as the hydrophilic nature of the isocyanate portion which is slightly in excess is sufficient to prevent water from being trapped in the form of vapour or condensed as an interphase between the coating formed and the substrate. Ail of the residual water reacts with the isocyanate functions by hydrolysis to favour polymerization until the end of curing.

Drying can be carried out in an infrared or convection drying oven. The oven may be supplied with water vapour by means of a controlled humidity gencrator, if necessary.

Curing of bi-component films is much more rapid. Since the setting time may be less than 2 minutes at ambient température, curing is carried out using a bi-component spraying system, for example such as that proposed by Walther or Devilbiss with a gun with extemal hardener mixing. It is used by reacting the polyol and/or polyamine compound A and the compound or hardener B in the liquid state in a ratio in the range 1.07 to 1.12.

Stoving or post-curing at a température of 90°C directly after application can increase the curing rate and avoid reactivity with the moisture in the ambient air.

The Applicant carried out a certain number of évaluation tests.

The water résistance properties were evaluated by means of accelerated tests for exposure to moist conditions and the tribo-rheological properties of the formulated material or lubricating coating were determined by means of a Scratch test for the frictional value and the adhesion.

The galling résistance was evaluated by means of a Falex tribological test in a configuration conforming to that of the connection.

The corrosion tests consist of a sait spray lest carried out in a climatic chamber under the following conditions: 35*C with a 50 g/L saline 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.

Specimens that were intact without rusting correspond to lhe ReO class of ISO standard 9227 after exposure. The inethod provides a means of verifying that the comparative quality of a 5 metallic material with or without a corrosion protective coating (metallic or organic coating on metallic material) is maintained.

The water résistance 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 10 following conditions: 35°C, 90% relative humidity for 8 hours, then allowing the specimen to dry. After 7 cycles, a check is made to see whether the substrate protected by the dry coating has corroded.

Excellent résistance must correspond to the classifications in ISO standard 4628: no corrosion, no blistering, no cracking, nor flaking of a chromium or carbon steel plate either as15 machined or treated by phosphatation with zinc (8 to 20 g/m² deposit of phosphate) or manganèse (4 to 16 g/m² of phosphate). The reference substrate may also be treated with an electrolytic deposit of a temary Cu-Sn-Zn alloy with an intermediate layer of Ni.

The water immersion test is much more severe than the water résistance test of DIN standard 50017. It consists of testing the water résistance of the coatings. It is derived from 20 ASTM standard D870-09 relating to industrial and automobile paints.

Immersion in water may cause coatings to dégradé. 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 insuffîcient surface préparation. Thus, the 25 test is useful for evaluating the coatings alone or complété coating Systems. rjT

The test consists of half-immersing a spccimen 20 în demineralized water 21 for a period of 168 hours at 40°C in an oven 22, as shown in Figure 5. Adhesion, blistering, rust, or blowholes are observed visually to indicate the sensitivity of the coating to water. The test may be followed by determining the moist adhesion using a Scratch test.

The test known as the “Scratch test”, shown diagrammatically in Figure 4, allows the adhesive force or adhesion of a film on a surface or surface préparation to be determined. The method, consisting of shearing and deforming a film with a spherical bead subjected to an increasing load, also allows two major tribological parametcrs to be determined, namely the coefficient of friction and the critîcal load corresponding to the appearance of a loss of film cohésion. The test is particularly suitable for coatings with a sliding friction model, such as polyuréthanes.

The specimens are coated by pneu mat ic spray ing. The eu ring conditions for the film are spécifie and principally dépend on the physico-chemical characteristics of the binder.

The experimental conditions employ a spherical indenter formed from Inconel 718 with a diameter of 5 mm and a métal specimen formed from XC48 carbon steel or Z20C13 chrome steel, as-machined or with a zinc phosphatation or electrolytic Cu-Sn-Zn deposit type surface préparation.

The parameters are: a load increasing from 10 N to 310 N at a load incrcase rate of 15 N/s or a load increasing from 250 N to 750 N at a load increase rate of 25 N/s for the more abrasion-résistant coatings. The bead displacement rate is 2 mm/s for a period of 20 s (the track length is 40 mm).

The measured coefficient of friction is considered to be low when it is in the range μ = 0.05 for a load of 10 N and μ s 0.09 for a load of 310 N. A μ of 0.07 was measured for a load of 310 N on 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. ΛΓ

The cross hatch test consista of determining the résistance of a mono- or multi-layer coating to being separated from a substrate when the coating is cross-hatched by making incisions up to said substratc 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 flaking corresponding to the classifications in ISO standard 4628, and no loss of adhesion are characteristics of good moisture résistance.

The high pressure wear résistance (also termed the Falex test) uses a rotating pin 23 compressed between two V-shaped blocks 24 and 25 as described in Figure 6. The Falex test is used in particular at high speeds to evaluate anti-wear and extreme pressure properties of fabricant fluids in accordance with ASTM standard D 2670 and ASTM D 3233, but it is also used at low speeds to evaluate solid fabricants 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 ensure that a third lubricating body is trapped);

• a cylindrical geometry for the pins adapted to application of a polyuréthane type coating;

• a pressure-velocity range (PV diagram) which matches up with that of the connection;

• the possibility of carrying out single direction or alternating tests in order to simulate make and break type operations, rd

The test conditions are as follows:

• load = 785 N;

• rotational speed of pin = 60 rpm;

• mean metal/metal contact pressure = 560 MPa;

• pin sliding speed = 20 mm/s.

The aim of this test is to simulate, détermine and compare the endurance (galling résistance) of the various coatings without the need to carry out the détermination on connections.

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.

The rigid mono or bi-component polyuréthane film of the invention offers the following principal advantages:

• coating hardness greater than or equal to epoxy resins, which provides a reinforced model of friction by sliding over surfaces with no stick-slip phenomenon, which means that an anti-galling surface treatment such as electrolytic Cu-Sn-Zn deposits can be dispensed with. The properties of the coating are thus maintained over time, ensuring that M&B (make and breaks) are reproducibie;

• superior impact résistance, particularly over acrylic-epoxy resins, reinforcing the mechanical performance under shear/compressive loads;

• superior adhesion and flexîbility of the film on the substrate compared with epoxy resins, reinforcing the applicability to complex geometries such as a threading;

• reinforced electrolyte barrier effect (in particular no residual water on drying), ensuring better anti-corrosion protection, even with no corrosion inhibitors;^ • low ecological impact and great safety for the user because of the absence of volatile organic compounds (VOC);

• conservation of mechanical properties in the range -40°C to +125^qC as the glass transition températures are excluded from this range.

Current thinking in this regard faits into a number of technological camps, each with gaps:

Acrylic-epoxy resins cured using UV, particularly used as a protective coating and described in publications WO 2006/104251 and WO 2009/072486, hâve the disadvantage of not being able to be applied to a female connection or box because of the geometry of the threading.

Polyuréthane resins currently applied in the art to threaded connections are reactive elastomeric thermoplastic grades, which can advantageously provide the connection with a seal but wherein the mechanical properties are inferior to rigid polyuréthanes.

Techniques based on thermoset epoxy resins nccessitate the application of a protective lower layer protecting against corrosion, possibly a keying primer and an upper lubricating layer, necessarily increasing the manufacturing time.

In response to this technology, obtaining an ultra-résistant heat cured coating of the rigid polyuréthane type means that the frictional properties and keying properties on various surfaces or surface préparations and the protection necessary for a suitable response to the problems of a connection can be combined into a single layer irrespective of the zone of the threading which is loaded.

The Applicant focused on obtaining rigid polyuréthane coatings as follows:

• a polyuréthane mono-component marketed by the supplier HK Wentworth under the trade name Electrolube NVOC, for its 7H pencil hardness which is greater than fluorourethane, for its flexibility and for excellent adhesion to metallic substrates;

• a bi-component polyurethane/polyurea marketed by the supplier Merylithe under the trade name Isolythe 115, for its rapid method of production, for its high hardness of » »· * t

750 Hv compared with carbon steels, for its flexibility and for its high mechanical strength,

Firstly, the Applicant determined the experimental conditions for preparing a monocomponent polyuréthane coating.

The NVOC mono-component polyuréthane can be diluted in a non-hydroxylated organic solvent with no VOCs (volatile organic compounds) of the propylene carbonate type in order to adjust its viscosity. The viscosity must be in the range 70 to 200 cPs at 20°C to ensure good coverage by pneumatic spray ing.

Adding a polydimethylsiloxane silicone surfactant may be foreseen in order to improve wetting of the support.

The reaction of the polyols on the isocyanate fonctions libérâtes a large quantity of COj which may be included in bubbles or blisters. An alkaline magnésium or calcium oxide type compound may be added as a CO2 scavenger.

Application onto the substrate at ambient température in the range 10°C to 30°C was carried out by spraying using a pneumatic gun with a 1.7 mm nozzle and a pressure of 4 to 6 bars.

The coated substrate was then introduced into an oven at 90°C and cured for 10 minutes with a relative humidity of at least 80% obtained by means of water vapour generated using an Erlenmeyer flask containing water heated to boiling point disposed outside the oven and connected into the oven to a chamber device accommodating the size of the specimen via a flexible tube with heat insulation. Curing initiation was followed by a step for drying at ambient température for 72 hours.

An alternative consists of placing a container of hot water with a volume of more than 1 L inside the oven.

Other methods may be foreseen and consist of heating the substrate by induction. The water vapour is generated using an Erlenmeyer flask containing water heated to boiling point and diffased r ·* .⁴ into the vicinity of the specimen. The relative humidity is more difficult to control but remains at a level measured at between 65% and 90%.

The thickness of the moist film must be approximately 20% greater than that desired for the dry film because of the loss of CO2 during the reaction by évaporation. The thickness of the dry film is in the range 30 to 50 pm.

Secondly, the Applicant determined the experimental conditions for preparing a bicomponent polyuréthane coating.

The polyurethane/polyurea bi-components studied comprised a component A prepared from a mixture of polyester polyol and 4,4’-methylene-bis(2-chloroaniline). The component A had the feature of being liquid from 70°C because of the presence of the polyamine with a meitïng point in the range 85°C to 90°C.

In order to be able to apply it in the laboratory, the Applicant heated and homogenized component A at 90°C. In order to avoid prématuré re-crystallization, component A was diluted to 30% by weight with a compatible organic VOC-free solvent of the dibasic ester type such as a methyl ester, preferably an isobutyl ester.

Under these conditions, the diluted component A had a viscosity of less than 200 MPa.s at 20°C and less than 100 MPa.s at 90°C, and may be stored for at least two months at ambient température without risk of crystallization.

The liquid component B with a viscosity in the range 1 to 2 Pa.s was mixed into the component A at ambient température and preferably into the component A at 90°C in order to facilitate the homogeneity.

The quantities by weight employed for the mixture were 52% of diluted component A and 48% of component B.

After homogenizing for 30 to 40 seconds with slow mechanical stirring in order to avoid incorporating air bubbles, the mixture was applied to the support at ambient température using a film applicator.

The support was then introduced into a post-curing oven for 15 minutes at 90°C. The thickness of the dry film obtained was in the range 20 to 40 pm.

The results obtained will now be described.

Firstly, the Applicant evaluated the adhesion performances of the non-loaded mono and bicomponent polyuréthane coatings in order to compare them, inter alia, with those obtained for coatings of the epoxy, acrylic-epoxy and fluorourethane type.

The epoxy coating consisted of an aqueous dispersion of oligomer of the bisphenol A resin type hardened using a diamine-functionalized type hardener. This type of epoxy coating is mentioned in particular in the publication WO 2008/090411.

The acrylic-epoxy coating consisted of a resin mixture of (l-methyl-l,2-ethanediyl) bis[oxy(methyl-2,l-ethanediyl)] diacrylate and trimethylolpropane triacrylate cured using ultraviolet radiation. This type of coating, with a 3H pencil hardness, is mentioned in particular in publications WO 2006/104251 and WO 2009/072486.

The fluorourethane coating consisted of an aqueous dispersion of fluoroethylenevinylether polymer hardened using an aliphatic poiyisocyanate hardener.

The adhesion to various metallic substrates was determined using the Scratch test for ioads increasing from 10 N to 750 N corresponding to stcel/steel contact pressures in the range 1.0 to 4.5 GPa. The values for the Young’s modulus taken from the literature for rigid polyuréthane type thermoset polymcrs were in the range 4 to 5 GPa. Using these values, it was possible to estimate that the mean pressure was in the range 150 to 450 MPa for Ioads in the range 10 to 310 N. These pressures correspond to the theoretical pressures determined for the threadings during shouidering.

Table 1 summarizes the roughnesses determined using a rugosimeter in accordance with

ISO standard 1997 for the specimens used.

Surface préparation	XC48 AsM	13Cr	PhZn	PhMn	TA
Ra (pm)	0.9 ±0.05	0.09	0.8 ±0.05	1.6 ±0.1	l±0.2
Rz (pm)	4.8 ±0.2	0.9 ± 0.1	5.1 ±0.3	11.1 ±1.0	8 ±1.4
Table 1: roughness of test specimens as a funct	ion of surface préparation

«. ,·

The critical loads for the Scratch test as well as the adhesions using the cross hatch test in accordance with ISO standard 2409 (class 0 for excellent adhesion, class 5 for médiocre adhesion) are reported in Tables 2, 3, 4 and 5 respectively for an as-machined carbon steel substrate (XC48 AsM), carbon steel with zinc or manganèse phosphatation (PhZn), rolled 5 stainless steel containing 13% chromium (13Cr) and carbon steel coated with an electrolytic CuSn-Zn deposit (TA).

Tcst/chemical nature	Ref A	Ref B	RefC	RefD	RefE
FEVE resin	X	-	-	-	-
Epoxy resin	-	X	-	-	-
Acrylic-epoxy resin	-	-	X	-	-
PU 1K resin, 100% solid state	-	-	•	X	-
PU 2 K resin, 100% solid state	-	-	-	-	X
Scratch test - critical load or Le (N):	288	>310	<10	606	600
Cross hatch test (ISO 2409)adhesion class:	0/5	0/5	0/5	0/5	0/5

Table 2: comparison of adhesiveness on XC48 AsM

Test/chemical nature	Ref A	Ref B	RefC	RefD
FEVE resin	X	-	-	-
Epoxy resin	-	X	-	-
Acrylic-epoxy resin	-	-	X	-
PU 1K resin, 100% solid state	-	-	-	X
PU 2 K resin, 100% solid state	-	-	-	-
Scratch test - critical load or Le (N):	375	>310	<10	644
Cross hatch test (ISO 2409)adhesion class:	0/5	0/5	0/5	0/5 ’

Table 3: comparison of adhesiveness on PhZn

Test/chemical nature	Ref A	Ref B	RefC	RefD
FEVE resin	X	-	-	-
Epoxy resin	•	X	-	-
Acrylic-epoxy resin	-	-	X	-
PU 1K resin, 100% solid state	-	-	-	X
Scratch test - critical load or Le (N):	415	>310	<10	638
Cross hatch test (ISO 2409)adhesion class:	0/5	0/5	0/5	0/5

Table 4: comparison of adhesiveness on 13Cr

Test/chcmical nature	Rcf A	RefB	RefC
FEVE resin	X	-	-
Epoxy resin	-	X	-
PU 1K resin, 100% solid state	-	-	X
Scratch test - critical load or Le (N):	415	>310	475
Cross hatch test (ISO 2409)adhesion class:	0/5	0/5	0/5

Table 5: comparison of adhesiveness on TA

The rigid mono and bi-component polyuréthane coatings had reiatively high adhesions irrespective of the chemical nature of the surface préparation. The test allowed the capacity of the coating to remain in place in the contact under shear/compressive stress to be expressed. A high 5 adhesive force and cohésion allows sufficient séparation of the surfaces to increase the longevity and résistance to galling. The résistance of the polyuréthane coating is comparable to that of an epoxy resin and substantially higher than that of a UV curable acrylic-epoxy resin.

The rigid polyuréthane resins, and in particular the mono-component resin with curing initiated by moisture, were selected for their flexibility and impermeability over other chemical 10 natures. Table 6 shows the results of adhesion after 168 hours of immersion in demineralized water at40°C.

Test/cbemical nature	Rcf A	RefB	RefC
FEVE resin	X	-	-
Acrylic-epoxy resin	-	X	-
PU 1K resin, 100% solid state	-	-	X
Scratch test - critical load or Le β^	124	122	469

Table 6a: comparison of adhesion after immersion in demineralized water of a rigid monocomponent polyuréthane coating on XC48 AsM

Test/chemical nature	PhZn	13Cr	TA
FEVE resin	X	-	-	X	-	-	-
Acrylic-epoxy resin	-	X	-	*	X	-	•
PU 1K resin, 100% solid state	-	*	X	•	-	X	X
Scratch test - critical load or Le (N):	444	127	537	513	30	568	606
Table 6b: comparison of adhesion a	ter immersion in demineralized water of a 10(	% solid

state rigid mono-component polyuréthane coating on different substrates

The rigid mono-component polyuréthane had remarkable impcrmcability, and excellent moist adhesion. Regarding critical loads, it is important to note that adhesion was not influenced by the immersion test and could be reinforced under the test conditions, thereby confirming the importance of this technology since curing could be continued over time if the relative humidity 5 is above the reaction activation threshold. The moisture is consumed up to saturation, thereby limiting problème with blistering or poor binding of the interfacial layer.

In order to illustrate the impcrmeability of the coating, the Applicant carried out contact angle measurements on a 3 pL droplet of distilled water placed on the surface of the dry coating, using a Kruss DSA 100 goniometer (needle diameter = 0.52 mm) as shown in Table 7.

Test/chemical nature	RefA	RefB
FEVE resin	X	-
PU 1K resin, 100% solid state	-	X
Kruss DSA 100 goniometer - contact angle Θ:	84.9 ± 10.9	117.4 ±9.3

Table 7

Secondly, the Applicant evaluated the tribological performances of non-loaded rigid mono and bi-component polyuréthane coatings in order to compare them, inter alia, with those obtained for the epoxy type, acrylic-epoxy and fluorourethane type coatings.

Test/chemical nature	XC48 AsM	PhZn	TA
FEVE resin	-	-	-	-	-	-	-	X	-
Acrylic-epoxy resin	-	X (13Cr)				X	-	-	-	•
PU 1K resin, 100% solid state	-	-	X			-	X	-	X	-
PU 2 K resin, 100% solid state	-	*	-	X	-	-	-	-	-	X
Scratch test, average COF (10310N):		0.242	0.079	0.061		0.324	0.080	0.090	0.078	0.053
Scratch test, average COF (250-750N):		0.298	0.083	0.128		0.236	0.084	0.210	0.109	0.111

Table 8

Irrespective of the déposition method, the coefficient of friction for a rigid polyuréthane coating was less than μ = 0.080 for loads of 310 N or less, corresponding to metal/metal contact pressures reaching 3.5 GPa irrespective of the substrate, which ensured good lubrication even^rT^ .· » without a friction reducing additive. The coefficient of friction was in the range μ = 0.080 to μ = 0.13 for loads in the range 250 to 750 N, corresponding to metal/metal contact pressures reaching 4.5 GPa. The frictional curves on coated carbon steel illustrating these results in Figures 7 and 8 show a low, stable coefficient of friction for the 100% solid state PU 2K resin (2 components) compared with the UV curable acrylic-epoxy resin which, from a load of 200 N, cxhibited severe délamination marked by erratic, high friction. The friction in Figure 8 was increasing as a fonction of the load applied but remained less than μ => 0.12.

The low frictional value was induced by the high hardness and the relatively high adhesive force of the selected rigid polyuréthanes, thereby demonstrating a superior sliding friction model.

Stable coefficients of friction of less than μ = 0.06 for pressures in the range 150 to 400 MPa corresponding to mean pressures in the threadings during shouldering during conventional makeup mean that when making up T' 29# L80 VAM TOP HT connections, which are highly sensitive to galling (the makeup torque is 29900 N.m), relatively low values for the shouldering torque can be foreseen, as opposed to shouldering torques of between 68% and 74% for a fluorourethane resin with high frictional values especially on a carbon steel specimen with a CuSn-Zn electrolytic deposit (FR 906320).

Thirdly, the Applicant determined the intrinsic anti-corrosion properties of the coatings of the invention.

The results obtained on different surface préparations with respectively a rigid monocomponent polyuréthane and a rigid bi-component polyuréthane coating are shown in Tables 9 and 10.

	Exposure time
Surface préparation	24 h	48 h	250 h	500 h	750h	1000 h	1500 h
XC48A&M	ReO	ReO	Rel	Rel	Rel	Re2	Re3
13Cr	ReO	ReO	ReO/1	ReO/1	ReO/1	ReO/1	ReO/1
PhZn	ReO	Re0/l	Rel	Rel/2	Rel/2	Re2	Re2
TA	ReO	ReO	ReO	ReO/1	Rel	Rel/2	Re2

Table 9: corrosion résistance for rigid mono-component polyuréthane, NVOCj^

	Exposure time
Surface préparation	24 h	48 h	250 h	500 h	750h	1000 h	1500 h
XC48A1M	RcO	RoO/1	Rel	Rel/2 + 3S3 blistering	Re2 + 4S3 blistering	•	•
TA	ReO	Rc2	Re4	-	-	-	-

Table 10: corrosion résistance for rigid bi-component polyuréthane; Isolythe 115

By way of comparison, Table 11 compares the anti-corrosion performances of rigid polyuréthane coatings with other resins containing no corrosion inhibitor on the same surface préparation.

	Exposure time
Chemical nature	Surface préparation	24 h	48 h	250 h	500 h	750h	1000 h	1500 h
Resin, 100« solid state, 1K	PhZn	ReO	Re0/l	Rel	Rel/2	Rel/2	Rc2	Re2
FEVE resin	ReO	ReO	ReO	ReO	ReO/1	Rel	Re2
Acrylicepoxy resin	ReO	ReO	ReO	Rel	Rel	Rel/2	Re2
Resin, 100« solid state, 1K	XC48 AsM	ReO	ReO	Rel	Rel	Rel	Re2	Re3
FEVE resin	ReO	ReO	Rel	Re2
Acrylicepoxy resin	RcO	RcO	ReO	Rel	Re2
Epoxy resin	ReO	Re0/l	Rel	Re3	-		-

Table 11: comparison of corrosion résistance on carbon steel and zinc phosphatation

The method for depositing a 100% solid state rigid mono-component polyuréthane coating with initiation of curing by moisture is more protective than the rigid bi-component polyuréthane and may reach 750 hours exposure with a low degree of rusting on as-machined carbon steel.

Compared with other coatings, rigid polyuréthane coatings, and in particular those for which curing is initiated by moisture, exhibit superior protection against corrosion and superior passivation of the surface préparation, even without a corrosion inhibitor.

However, it should be noted that the method must be completel y controlled in order to avoid the formation of bubbles during homogenization and application. Bubbles could facilitate the diffusion of electrolytes towards the interface and initiate the corrosion mechanism.

^Oi JUIN 20β

INET CAZENAVE sari

Propriété Industrielle

500 YAOUNDE Cameroun él 22 21 32 89 - Fax: 22 20 64 14

E-mail: cabinelca«nave@iccnet.cm

Claims (22)

1, A threaded tubular component for drilling or working hydrocarbon wells, said tubular comportent having at one of its ends (1; 2) a threaded zone (3; 4) arrangée! on its outer or inner peripheral surface depending on whether the threaded end is male or female in type, characterized in that at least a portion of the end (1; 2) is coated with at least one dry film (12) with a Shore D hardness of more than 50 and comprising a matrix of polyuréthane and polyurea, in which the urethane functionality is prédominant with respect to the urea functionality in a proportion of at least 55% by weight.

2. A threaded tubular component according to claim 1, characterized in that the polyuréthane and polyurea matrix is of the mono-component type.

3. A threaded tubular component according to claim 2, characterized in that the polyuréthane and polyurea matrix is obtained from a polyol type monomer with a high molecular weight, a chain extension agent and free aromatic isocyanates which can be cured by polyaddition using moisture.

4, A threaded tubular component according to claim 3, characterized in that the polyuréthane and polyurea matrix comprises:

• a multifunctional isocyanate pre-polymer with a functionality of at least 2, prepared from a mixture of polyether, polybutadiene or hydroxylated polyester pôlyols with a molecular mass in the range 300 to 6000 g/mol and aromatic isocyanates of the diphenylmethane diisocyanate type, in excess;

• a co-reagent of the mono- or bis-oxazolidone type in order to initiate the reaction and dilute the pre-polymer;

• an aliphatic polyisocyanate curing agent of the hexamethylene diisocyanate type in order to maintain curing;

• a catalyst for the pre-polymer of the dimorpholinodiethyl ether or dibutyl tin laurate type;

‘ Λ *

• a plasticizer to control foaming during formation of the film, in particular of the triethylene phosphate type.

5. A threaded tubular component according to claim 4, characterized. in that the polyuréthane and polyurea matrix further comprises a moisture scavenger in order to stabilize the pre-polymer during storage by capturing résiduel water, said moisture scavenger being of the p-toluene sulphonyl isocyanate, trimethyl orthoformate or trimethyl orthoacetate type.

6. A threaded tubular component according to claim 4 or claim 5, characterized in that the polyuréthane and polyurea matrix further comprises a CO2 scavenger of the calcium oxide or magnésium oxide type in order to control foaming and the formation of bubbles during the reaction.

7. A threaded tubular component according to claim 1, characterized in that the polyuréthane and polyurea matrix is ofthe bi-component type.

8. A threaded tubular component according to claim 7, characterized in that the polyuréthane and polyurea matrix is obtaîned from a mixture of heat-fusible polyols and polyamines with a low molecular weight which can be cured by polycondensation using an aliphatic polyisocyanate.

9. A threaded tubular component according to claim 8, characterized in that the polyuréthane and polyurea matrix comprises:

• a polyol pre-polymer selected from polyester, polyether and polybutadiene polyols with a molecular mass in the range 300 to 6000 g/mol cured using an aliphatic polyisocyanate (component A);

• a heat-fusible polyamine with a functionality of 2 or more and with a molecular mass in the range 168 to 600 g/mol, in particular 4,4’-methylene-bis(2chloroaniline); and pff' * ,r> Ί <

I • an aliphatic polyisocyanate curing agent of the hexamethylene diisocyanate type, in excess.

10. A threaded tubular component according to one of claims 1 to 9, characterized ïn that the polyuréthane and polyurea matrix further comprises at least one solid lubricant as a friction reducing agent, selected from the category of solid lubricants from class 1, 2, 3 or 4 in a proportion by weight in the range 5% to 30%.

11. A threaded tubular component according to daim 10, characterized in that the solid lubricant is selected from:

• a solid lubricant from class 2 of the B12S3 type;

• a solid lubricant from class 4 of the PTFE type; and a combination thereof.

12. A threaded tubular component according to one of daims 1 to 11, characterized in that the polyuréthane and polyurea matrix further comprises a corrosion inhibitor.

13. A threaded tubular component according to one of daims 1 to 12, charaderized in that the entire threaded zone (3; 4) is coated with polyuréthane film (12).

14. A threaded tubular component according to one of daims 1 to 13, characterized in that it comprises a metal/metal sealing surface, said sealing surface being coated with polyuréthane film (12).

15. A threaded tubular connection comprising a male threaded tubular component and a female threaded tubular component made up one into the other, characterized in that at least one of said threaded tubular components is in accordance with one of daims 1 to 14.

16. A method for coating a threaded tubular component for drilling or working hydrocarbon wells, said tubular component having at one of its ends (1; 2) a threaded zone (3; 4) produced on its outer or inner peripheral surface depending on whether the threaded end is male or female in type, characterized in that the method comprises the following steps:

• producing a polyuréthane and polyurea matrix of the dry film as defined in one of daims 1 to 12, in the liquid state * F’ *·\ d t

• applying the polyuréthane and polyurea matrix in the liquid state by spraying over a portion of the end (l ; 2) of said threaded tubular component; and • curing the matrix to form a polyuréthane film (12) with an essentially rigid structure.

17. A method for coating a threaded tubular component according to claim 16, characterized in that the polyuréthane and polyurea matrix is a mono-component matrix of the dry film as defined in one of daims 2 to 6.

18. A method for coating a threaded tubular component according to daims 16 and 17, taken in combination, characterized in that curing of the polyuréthane film is initiated by application of a relative humidity of at least 60% RH at a température of at least 20°C, optionally followed by drying.

19. A method for coating a threaded tubular component according to claim 18, characterized in that drying is carried out in an infrared or convection drying oven supplied with water vapour.

20. A method for coating a threaded tubular component according to claim 16, characterized in that the polyuréthane and polyurea matrix is a bi-component matrix of the dry film as defined in one of daims 7 to 9.

21. A method for coating a threaded tubular component according to daims 16 and 20, taken in combination, characterized in that the polyuréthane film is cured by means of a bicomponent spraying device with extemal mixing of hardener.

22. A method for coating a threaded tubular component according to daim 21, characterized in that curing of the polyuréthane film is followed by a stoving or post-curing operation at a température of 90°C