Field joint coating material and a process for making a field joint

Abstract

The invention relates to a field joint coating material based on a fast curable olefin liquid formulation and a process of making a field joint wherein this coating material is used.

Claims

1. A process of coating a field joint on a steel pipe having at least two pipe sections joined to each other, the process comprising the following steps: (i) abrading or sand blasting a bare metal surface of the steel pipe at a position of the field joint; (ii) applying a corrosion protective layer consisting of a fusion bonded epoxy on the bare metal surface, then applying an adhesive layer directly on the corrosion protective layer without an intervening layer of epoxy material, wherein the adhesive layer is of an olefin type adhesive is a modified linear low-density polyethylene resin or a modified polypropylene resin, having from 0.2% to 10% by mass of a maleic anhydride graft content; (iii) abrading and cleaning end cuts of factory applied parent coating resins; (iv) placing a mould around the steel pipe in an area of the field joint to define a cavity between an internal surface of the mould and the field joint; (v) injecting a field joint coating material based on a curable olefin liquid formulation in the cavity; wherein the field joint coating material comprises: (a) at least one olefin monomer or at least one oligomer able to undergo polymerization and optionally crosslinking, and (b) a catalytic system able to activate the polymerization and optionally the crosslinking of the at least one olefin monomer or the at least one oligomer.

2. The process according to claim 1, wherein the catalytic system is adapted to activate ring opening metathesis polymerization of a norbornene-type cycloolefin monomer.

3. The process according to claim 1, wherein the mould is maintained under cooling to minimize a cycle time for the process.

4. The process according to claim 1, further comprising purging the mould with nitrogen prior to the injecting of the field joint coating material.

5. The process according to claim 1, further comprising heating surfaces of the end cuts of the parent coating resins prior to the injecting of the field joint coating material.

6. The process according to claim 1, wherein the catalytic system comprises a compound represented by the following formula (1): ##STR00006## where Z indicates an oxygen atom, sulfur atom, selenium atom, NR.sup.12, PR.sup.12, or AsR.sup.12, where R.sup.12 indicates a hydrogen atom; halogen atom; or one selected from the group consisting of C.sub.1 to C.sub.20 organic groups which may contain at least one atom selected from the group consisting of halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, and silicon atom; R.sup.1 and R.sup.2 respectively independently indicate a hydrogen atom; halogen atom; or one selected from the group consisting of C.sub.1 to C.sub.20 organic groups which may contain at least one atom selected from the group consisting of halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom and silicon atom, where the groups may be substituted and, further, may bond together to form rings; X.sup.1 indicates any anionic ligand; L.sup.1 indicates a hetero atom-containing carbene compound or a neutral electron donor compound other than a hetero atom-containing carbene compound; where R.sup.1, R.sup.2, X.sup.1, and L.sup.1 may respectively independently and/or in any combination bond together to form multi-dentate chelate ligands; R.sup.7 and R.sup.8 respectively independently indicate a hydrogen atom, or one selected from the group consisting of C.sub.1 to C.sub.20 alkyl groups, C.sub.2 to C.sub.20 alkenyl groups, and C.sub.6 to C.sub.20 heteroaryl groups, where the groups may be substituted and, further, may bond together to form rings; and R.sup.9, R.sup.10, and R.sup.11 respectively independently indicate a hydrogen atom; halogen atom; or one selected from the group consisting of C.sub.1 to C.sub.20 organic groups which may contain at least one atom selected from the group consisting of halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, and silicon atom, where the groups may be substituted and may bond together to form rings.

7. The process according to claim 6, wherein the compound of formula (1) is the compound having the general formula (5): ##STR00007##

8. The process according to claim 1, wherein the catalytic system comprises a compound represented by the following formula (2): ##STR00008## where m is 0 or 1; O is an oxygen atom, nitrogen atom, sulfur atom, methylene group, ethylene group, or carbonyl group; is a single bond or double bond; R.sup.1 indicates a hydrogen atom; halogen atom; or one selected from the group consisting of C.sub.1 to C.sub.20 organic groups which may contain at least one atom selected from the group consisting of halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom and silicon atom, where these groups may be substituted and, further, may bond together to form rings; X.sup.1 and X.sup.2 respectively independently indicate an anionic ligand; L.sup.1 indicates a hetero atom-containing carbene compound or a neutral electron donor compound other than a hetero atom-containing carbene compound; where R.sup.1, X.sup.1, and L.sup.1 may respectively independently and/or in any combination bond together to form multi-dentate chelate ligands; and R.sup.13 to R.sup.21 are each a hydrogen atom; halogen atom; or one selected from the group consisting of C.sub.1 to C.sub.20 organic groups which may contain at least one atom selected from the group consisting of halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, and silicon atom, where the groups may be substituted, and further, may bond together to form rings.

9. The process according to claim 8, wherein the compound of formula (2) is the compound having the general formula (6): ##STR00009##

10. The process according to claim 1, wherein the at least one olefin monomer is a norbornene-type cycloolefin monomer.

11. The process according to claim 10, wherein the at least one olefin monomer is dicyclopentadiene.

12. The process according to claim 1, wherein an entirety of the adhesive layer is in direct contact with the corrosion protective layer.

13. The process according to claim 1, wherein an entirety of the adhesive layer overlaps with the corrosion protective layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: Schematic representation of a field joint. For the sake of clarity the second arrow of layer 3 and 3 are not represented but it should be understood that the figure is symmetrical.

(2) In FIG. 1, (1) denotes a steel pipe, (2) denotes a weld, (3) denotes a corrosion protective layer consisting of epoxy or epoxy phenol primer or fusion bonded epoxy (FBE), (3) denotes an adhesive layer, (4) a first layer of solid polyethylene or polypropylene, (5) denotes a thick insulating polypropylene foam and (6) denotes a final solid or polyethylene or polypropylene layer.

(3) FIG. 2: Schematic representation of a mould used in the method of forming a field joint. (7) denotes a flash, (8) denotes a vent, (9) denotes a water channel for water having a temperature in the range of typically 20 C. to 40 C., (10) denotes the welded location, (11) denotes a sealing gasket, (12) denotes a gate and (13) denotes a mix head location.

DETAILED DESCRIPTION OF THE INVENTION

(4) The present invention is based on the use of a fast curing liquid based olefin formulation to produce a field joint coating without the need to treat the thermoplastic or thermoset cut back of parent coating resins of the pipe either by applying a primer on the cut back surface or by increasing the surface energy by the means of a plasma or a corona treatment. The parent coating resin is factory-applied, and is a few centimeters thick and based on solid, synthetic, or foamed polymeric materials. After pipes welding and conventional preparation of the weld and the bare metal adjacent to the weld, epoxy primer or epoxy phenol primer is applied on the metal followed by the projection of the adhesive layer coat thus ensuring the continuity of the parent coating first 2 layers. After preparation of the cut back by simple cleaning and abrading a mould is put in place around the field joint area and the curable liquid formulation is injected by the means of an injection unit. Due to the liquid and non polar olefin nature of the curable formulation, perfect wetting and chemical welding is achieved after curing between the polyolefin layers of the parent coating and the cured (polymerized) olefin formulation, thus preventing water ingress and hydrolysis leading to in service field joint deterioration.

(5) Additionally the curable formulation catalytic system can be adjusted to offer curing time compatible to any size of field joint coating. Due to the very low viscosity of the curable olefin formulation simple and fast operated mould can be used for injecting the said curable olefin formulation.

(6) Additionally the high heat deflection temperature achieved by the curable formulation after curing and the possibility to use a water cooling system on the mould reduce the cycle time to minutes even when the coating is thicker than 50 mm.

(7) Referring to FIG. 1 a pipeline field joint is formed between two lengths of steel pipe (1) welded together at weld (2). Each length of pipe (1) is coated with a factory applied coating comprising a corrosion protective layer (3) consisting of epoxy or epoxy phenol primer or fusion bonded epoxy (FBE), an adhesive layer (3), a first layer of solid polyethylene or polypropylene (4), a thick insulating polypropylene foam (5) and a final solid or polyethylene or polypropylene layer (6). The factory applied coatings (3), (3), (4), (5), (6) on each length has been cut back to form a double chamfer and leave the steel pipe exposed in the region of the weld.

(8) It is to be understood that the scope of the invention is not limited to the example above and that the factory applied coating can take any suitable form and may comprise a single polypropylene layercoating (3), (3) and (4)or two polypropylene layerscoating (3), (3), (5) and (6). Also, the factory applied parent coating may be cut back in any suitable way. In accordance to well known methods after the two lengths of pipe have been welded together the exposed steel pipe and adjacent factory coating are cleaned. Several different cleaning processes may be employed to clean the joint, for example the exposed steel surface may be blast cleaned using abrasive particles and the polypropylene coated surfaces may be cleaned and abraded using a powered abrasive disc. The entire joint area may then be blown clean with compressed air in order to remove any dust particles. Typical cleaning complies with a standard of SA2 to SA3 (BS7079).

(9) An epoxy primer or epoxy phenol primer or a fusion bond epoxy is then applied on the bare metal preliminary heated by an induction heating coil to the suitable temperature. In practice the end of the polypropylene factory coatings(4), (5), (6)are protected during the corrosion protective coating (3) application that usually extends from one end of the factory applied coating (3) to the other end to form a continuous coating. Typical primer coating thickness is 250 micrometers.

(10) This operation is followed by the application of an adhesive tie layer (3) in the same conditions as for the parent coating, having a typical thickness of 500 microns. The adhesive tie layer coating could be of any of the conventionally available type for this application providing it is compatible with the chosen corrosion protective coating applied underneath.

(11) Advantageously the adhesive layer can be chosen from the family of modified linear low-density polyethylene (LLDPE) resins or modified polypropylene resins. Typical modifications include grafting the linear chain by maleic anhydride grafting, in content ranging from 0.2% by mass to 10% by mass.

(12) Advantageously the adhesive layer is a modified linear low-density polyethylene (LLDPE) resins or modified polypropylene resins having a grafting content above 4% by mass, thus avoiding the need of a corrosion protection epoxy or epoxy phenol primer.

(13) It is clear from the above description that prior to the injection of the liquid curable olefin formulation all the external surfaces are now polyolefin based polymer materials.

(14) A cylindrical mould is then located around the field joint coating and close tight around the external polypropylene surface (6) of the pipe. The mould is thermally controlled at 20 C. to provide a fast cooling.

(15) Commercially available Telene 1650 A and B formulation is then injected into the cavity defined by the inner wall of the mould and the external surface of the various layer composing the cut back of the pipe ends by the mean of an Cannon A 100 RIM injection unit equipped with an FPL 18 mixhead. The formulation is allowed to cure for 5 minutes before the mould is removed. The flashes are removed and the pipeline is move by one step to allow the next field joint to be coated.

(16) It is understood that a wide variety of fast curable formulations can be used. Such a curable olefin base formulation is typically a 2 or 3 components system but single component system can also be formulated.

(17) Because of its intrinsic nature of being based on olefin monomers, the fast curable formulation wets easily the non polar or slightly polar surface of the various olefin based material surface. The curing process can be chemically described as a combination of polymerization and optionally cross linking of the olefin monomers composing the formulation activated by the mean of a catalytically species. As the monomer unit can diffuse into the olefin based materials that compose the various layers 3, 4, 5 and 6, an interpenetrated polymer network is created in the various interface leading to a strong water tight non polar connection between the various material and the cured formulation that can be described as a chemical welding.

(18) Advantageously the surfaces of the end cuts of the parent coatings are preheated to 30 to 60 C. prior to the injection of the curable formulation in order to increase the mobility of the polymer chain therefore increasing the thickness of the chemical welding obtained after curing the formulation.

(19) The type of formulation that can be used in the invention comprises at least one cyclo-olefin monomer or oligomer, a Ring Opening Metathesis Polymerisation (ROMP) catalytic system and various additives controlling the reaction or modifying the final polymer properties. It is understood that in the case of using oligomer precursors in the curable formulation the viscosity of the formulation is still low enough to allow the use of low viscosity equipment known as RTM or RIM injection unit.

(20) Depending on the target final properties of the field joint the cyclo-olefin monomer or oligomer can have mono or multiple reactive double bonds thus polymerising into either thermoset or thermoplastic polymer.

(21) Advantageously the catalytic system used in the formulation according to the invention is a ring opening metathesis catalyst based on Molybdenum, Tungsten, Ruthenium or Osmium complexes.

(22) Catalysts based on ruthenium complexes are suitable for use as the ring opening metathesis catalyst in the formulation of this invention. As the ruthenium-based complex, compounds represented by the general formula (1) or general formula (2) shown below are suitable.

(23) ##STR00001##

(24) The general formula (1) is shown below.

(25) ##STR00002##

(26) In the general formula (1), Z indicates an oxygen atom, sulfur atom, selenium atom, NR.sup.12, PR.sup.12, or AsR.sup.12, R.sup.12 indicates a hydrogen atom;

(27) halogen atom; or C.sub.1 to C.sub.20 organic group which may contain a halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, or silicon atom, but since the effect of the present invention becomes much more remarkable, as Z, an oxygen atom is preferable.

(28) R.sup.1 and R.sup.2 respectively independently indicate a hydrogen atom; halogen atom; or C.sub.1 to C.sub.20 organic group which may contain a halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom or silicon atom, where these groups may be substituted and, further, may bond together to form rings. As examples where R.sup.1 and R.sup.2 bond together to form rings, a phenylindenylidene group or other indenylidene group which may be substituted may be mentioned.

(29) As specific examples of the C.sub.1 to C.sub.20 organic group which may contain a halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, or silicon atom, a C.sub.1 to C.sub.20 alkyl group, C.sub.2 to C.sub.20 alkenyl group, C.sub.2 to C.sub.20 alkynyl group, C.sub.6 to C.sub.20 aryl group, C.sub.1 to C.sub.20 alkoxy group, C.sub.2 to C.sub.20 alkenyloxy group, C.sub.2 to C.sub.20 alkynyloxy group, C.sub.6 to C.sub.20 aryloxy group, C.sub.1 to C.sub.8 alkylthio group, carbonyloxy group, C.sub.1 to C.sub.20 alkoxycarbonyl group, C.sub.1 to C.sub.20 alkylsulfonyl group, C.sub.1 to C.sub.20 alkylsulfinyl group, C.sub.1 to C.sub.20 alkylsulfonic acid group, C.sub.6 to C.sub.20 arylsulfonic acid group, phosphonic acid group, C.sub.6 to C.sub.20 arylphosphonic acid group, C.sub.1 to C.sub.20 alkylammonium group, C.sub.6 to C.sub.20 arylammonium group, etc. may be mentioned. These C.sub.1 to C.sub.20 organic groups which may contain a halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, or silicon atom may be substituted. As examples of the substituent, a C.sub.1 to C.sub.10 alkyl group, C.sub.1 to C.sub.10 alkoxy group, C.sub.6 to C.sub.10 aryl group, etc. may be mentioned.

(30) X.sup.1 and X.sup.2 respectively independently indicate any anionic ligand. An anionic ligand is a ligand which has a negative charge when separated from the center metal atom. For example, a halogen atom, diketonate group, substituted cyclopentadienyl group, alkoxyl group, aryloxy group, carboxyl group, etc. may be mentioned.

(31) L.sup.1 indicates a hetero atom-containing carbene compound or a neutral electron donor compound other than a hetero atom-containing carbene compound. The hetero atom-containing carbene compound and neutral electron donor compound other than a hetero atom-containing carbene compound are compounds which have neutral charges when separated from the center metal. From the viewpoint of improvement of the catalyst activity, a hetero atom-containing carbene compound is preferable. A hetero atom means an atom of Group XV and Group XVI of the Periodic Table.

(32) Specifically, a nitrogen atom, oxygen atom, phosphorus atom, sulfur atom, arsenic atom, selenium atom, etc. may be mentioned. Among these, from the viewpoint of a stable carbene compound being obtained, a nitrogen atom, oxygen atom, phosphorus atom, and sulfur atom are preferable and a nitrogen atom is particularly preferable.

(33) As the hetero atom-containing carbene compound, a compound of the following general formula (3) or (4) is preferable. From the viewpoint of improvement of the catalyst activity, a compound of the following general formula (3) is particularly preferable.

(34) ##STR00003##

(35) where in the general formulas (3) and (4), R.sup.3, R.sup.4, R.sup.5, and R.sup.6 respectively independently indicate a hydrogen atom; halogen atom; C.sub.1 to C.sub.20 organic group which may contain a halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, or silicon atom. The specific examples of the C.sub.1 to C.sub.20 organic group which may contain a halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, or silicon atom are the same as the case of the general formulas (1) and (2).

(36) Note that, R.sup.1, R.sup.2, X.sup.1, and L.sup.1 in general formulas (1) and (2) may respectively independently and/or in any combination bond together to form multi-dentate chelate ligands, but preferably X.sup.1 and L.sup.1 do not form multi-dentate chelate ligands and R.sup.1 and R.sup.2 bond together to form a ring. More preferably R.sup.1 and R.sup.2 bond together to form an indenylidene group which may be substituted, particularly preferably a phenylindenylidene group.

(37) In the general formula (1), R.sup.7 and R.sup.8 respectively independently indicate a hydrogen atom, C.sub.1 to C.sub.20 alkyl group, C.sub.2 to C.sub.20 alkenyl group, or C.sub.6 to C.sub.20 heteroaryl group. These groups may be substituted and, further, may bond together to form rings. As examples of the substituents, a C.sub.1 to C.sub.10 alkyl group, C.sub.1 to C.sub.10 alkoxy group, or C.sub.6 to C.sub.10 aryl group may be mentioned. The ring in the case of forming a ring may be any of an aromatic ring or aliphatic ring and hetero ring, but forming an aromatic ring is preferable, forming a C.sub.6 to C.sub.20 aromatic ring is more preferable, and forming a C.sub.6 to C.sub.10 aromatic ring is particularly preferable.

(38) In the general formula (1), R.sup.9, R.sup.10, and R.sup.11 respectively independently indicate a hydrogen atom; halogen atom; or C.sub.1 to C.sub.20 organic group which may contain a halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, or silicon atom. These groups may be substituted and may bond together to form rings. Further, the specific examples of the C.sub.1 to C.sub.20 organic group which may contain a halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, or silicon atom are the same as described above.

(39) R.sup.9, R.sup.10, and R.sup.11 are each preferably a hydrogen atom or C.sub.1 to C.sub.20 alkyl group, particularly preferably a hydrogen atom or C.sub.1 to C.sub.3 alkyl group.

(40) Note that, as the specific examples of the compounds of the general formula (1) and methods of production of the same, for example, the ones described in WO2003/062253 (Japanese Patent Publication No. 2005-515260A) and US2015/0240007 etc. may be mentioned.

(41) The general formula (2) is shown below.

(42) ##STR00004##

(43) In the general formula (2), m is 0 or 1 and m is preferably 1. In that case, Q is an oxygen atom, nitrogen atom, sulfur atom, methylene group, ethylene group, or carbonyl group, preferably is a methylene group.

(44) is a single bond or double bond and preferably is a single bond.

(45) R.sup.1, X.sup.1, and L.sup.1 are the same as the case of the general formula (1), and may respectively independently and/or in any combination bond together to form multi-dentate chelate ligands, but preferably X.sup.1, X.sup.2, and L.sup.1 do not form multi-dentate chelate ligands and R.sup.1 is a hydrogen atom. X.sup.2 is the same as X.sup.1 of the general formula (1).

(46) R.sup.13 to R.sup.21 are each a hydrogen atom; halogen atom; or C.sub.1 to C.sub.20 organic group which may contain a halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, or silicon atom. These groups may be substituted and may bond together to form rings. Further, the specific examples of the C.sub.1 to C.sub.20 organic group which may contain a halogen atom, oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, or silicon atom are the same as the case of the general formula (1).

(47) R.sup.13 is preferably a C.sub.1 to C.sub.20 alkyl group, more preferably a C.sub.1 to C.sub.3 alkyl group, R.sup.14 to R.sup.17 are each preferably a hydrogen atom, and R.sup.18 to R.sup.21 are each preferably a hydrogen atom or halogen atom.

(48) Note that, as the specific examples of the compounds of the general formula (2) and methods of production of the same, for example, the ones described in WO2011/079799 (Japanese Patent Publication No. 2013-516392A) and US2015/0240007 etc. may be mentioned.

(49) Among compounds having the general formula (1) or the general formula (2), compounds having the general formula (5) (VC843) or the general formula (6) (Zhan 1N) shown below are preferable:

(50) ##STR00005##

(51) The amount of use of the metathesis polymerization catalyst is usually 0.01 mmole or more with respect to 1 mole of the monomer used for the reaction, preferably 0.1 to 50 mmoles, more preferably 0.1 to 20 mmoles. By making the amount of use of the metathesis polymerization catalyst in the above range, it is possible to balance the reactivity and storage stability of the obtained polymerizable composition to a high level. A further detailed description of the type of olefin monomers, additives and catalyst that can be used in the present invention is included in the application published under EP 2 042 537 from the same applicant, which is herein incorporated by reference.

(52) Advantageously the mould is purged by nitrogen gas prior to the injection when using formulation activated by a tungsten type ROMP catalyst.

(53) Advantageously the curable formulation is selected such as to provide a thermoset polyolefin having a glass transition temperature of more than 140 C. after curing thus offering the same service temperature of the pipeline as the one offered by the parent coating.