Assembly comprising an end-fitting and an unbonded flexible pipe
The present invention relates to an assembly including an end-fitting and an unbonded flexible pipe, which end-fitting is adapted for connecting the unbonded flexible pipe to a connector. The end-fitting has a through-going opening with a centerline and a front end and a rear end, and the end-fitting further provides for establishing an electrical connection to a least one electrical heating system in the unbonded flexible pipe. Moreover, the end-fitting includes at least one first metallic part having a first surface contacting a second surface of at least one second part in the end-fitting, wherein the first surface of the first metallic part, at least in the vicinity of the through-going opening, includes a coating having a high electrically resistivity. The invention also relates to a method for providing an end-fitting having good properties in respect of reducing galvanic corrosion.
1. An assembly comprising:
an end-fitting and an unbonded flexible pipe, said end-fitting being adapted for connecting the unbonded flexible pipe to a connector, said end-fitting having a through-going opening with a centerline and a front end and a rear end, said rear end comprising a flange including a rear-most end face, and said end-fitting further comprising means for establishing an electrical connection to a least one electrical heating system in said unbonded flexible pipe,
wherein said end-fitting comprises at least one first metallic part having the rear-most end face and having a first surface contacting a second surface of at least one second part in the end-fitting,
the at least one first metallic part being electrically insulated from the at least one electrical heating system,
wherein the first surface of the first metallic part includes a portion at and defining the through-going opening having a coating having a high electrically resistivity of at least 10 7 Ω·m.
2. An assembly according to claim 1 , wherein the second part is a metallic part and said second surface comprises a coating having a high electrically resistivity, and wherein said second part is axially spaced from the rear-most end face.
3. An assembly according to claim 1 , wherein at least a part of the coating comprises a bushing.
4. An assembly according to claim 1 , wherein the second part is a non-metallic part.
5. An assembly according to claim 1 , wherein the second part is an electrical insulating part.
6. An assembly according to claim 1 , wherein the electrical heating system comprises one or more armour layers selected among carcass, tensile armour and pressure armour.
7. An assembly according to claim 6 , wherein the one or more armour layers are axially spaced from the rear-most end face.
8. An assembly according to claim 1 , wherein the electrical heating system comprises one or more wires.
9. An assembly according to claim 1 , wherein the coating is selected from an epoxy coating, a polyurethane coating, a polytetrafluoroethylene coating, a fluorinated ethylene propylene coating, a polyvinyl chloride coating, an enamel coating, a ceramic coating, a glass coating and combinations thereof.
10. An assembly according to claim 1 , wherein the coating is applied with a thickness from about 0.05 mm to about 5 mm.
11. An assembly according to claim 1 , wherein the end-fitting comprises an insulating coating on the outer surface.
12. An assembly according to claim 1 , wherein the end-fitting comprises a protective sleeve.
13. An assembly according to claim 1 , wherein the end-fitting is housed in an electrical insulating housing.
14. An assembly according to claim 1 , wherein said at least one electrical heating system is axially spaced from the rear-most end face.
15. An assembly according to claim 1 , wherein said at least one electrical heating system includes at least a pair of wires extending radially through the end-fitting to an outer surface of the end-fitting, the pair of wires being insulated from the end-fitting, and the end-fitting configured to allow connection of each wire of the pair of wires to an armour layer of the flexible pipe while insulating the end-fitting therefrom.
16. A method for reducing the risk of galvanic corrosion in an end-fitting for connecting an unbonded flexible pipe comprising electrical heating means to a connector, said method comprises:
providing an end-fitting having a flange and a through-going opening with a centerline and a front end and a rear end, said rear end including a rear-most end face, and the end-fitting comprising means for establishing an electrical connection to the heating means in said unbonded flexible pipe, said end-fitting comprises at least one first metallic part having the rear-most end face and having a first surface adapted for contacting a second surface of at least one second part in the end-fitting and having a portion of the first surface disposed at and defining the through-going opening;
subjecting the first surface and the second surface of the first metallic part for a treatment to obtain a substantially clean surface;
applying a coating having a high electrical resistance to the cleaned first surface and the cleaned second surface; and
curing the applied coating to obtain a coating being an electrically insulating coating having an electrically resistivity of at least 10 7 Ω·m,
wherein the end-fitting includes at least the first metallic part being electrically insulated from the heating means.
17. A method according to claim 16 , wherein the second surface of the second part is subjected to a treatment to obtain a substantially clean second surface and applying the clean second surface with a coating having a high electrical resistance.
18. A method according to claim 16 , wherein the coating is selected from an epoxy coating, a polyurethane coating, a polytetrafluoroethylene coating, a fluorinated ethylene propylene coating, an enamel coating and combinations thereof.
19. A method according to claim 16 , wherein treatment of the surface is a sand blasting, a mechanical cleaning, a chemical etching, an electro polishing or a combination of two or more of the mentioned treatments.
20. A method according to claim 16 , comprising the further step of applying an adhesive layer to the cleaned surface.
21. An assembly comprising:
an end-fitting and an unbonded flexible pipe, said end-fitting being adapted for connecting the unbonded flexible pipe to a connector, said end-fitting having a through-going opening with a centerline and a front end and a rear end, said rear end comprising a flange including a rear-most end face, and said end-fitting further comprising means for establishing an electrical connection to a least one electrical heating system in said unbonded flexible pipe,
wherein said end-fitting comprises at least one first metallic part having the rear-most end face and having a first surface contacting a second surface of at least one second part in the end-fitting, the at least one first metallic part being electrically insulated from the at least one electrical heating system,
wherein the first surface of the first metallic part includes a portion at and defining the through-going opening-having a coating having a high electrically resistivity of at least 10 7 am, and
wherein the unbonded flexible pipe enters the end-fitting at the front end and is terminated in the end-fitting and wherein said first surface of the first metallic part defining the through-going opening is located further away from the unbonded flexible pipe than the means for establishing an electrical connection.