CN112570238A

CN112570238A - Repairing method for special primer for MARK-III-fuel tank of LNG ship

Info

Publication number: CN112570238A
Application number: CN202011185676.4A
Authority: CN
Inventors: 刘涛; 叶慧; 杨小毅; 陆君杰; 赵微微; 张晓明
Original assignee: Shanghai Jiangnan Changxing Shipbuilding Co Ltd
Current assignee: Shanghai Jiangnan Changxing Shipbuilding Co Ltd
Priority date: 2020-10-30
Filing date: 2020-10-30
Publication date: 2021-03-30

Abstract

The invention relates to a method for repairing a special primer for an MARK-III-bunker of an LNG ship, which is divided into 3 different grades of a first grade, a second grade and a third grade according to the damage degree of the primer, and adopts corresponding primer repairing methods aiming at the different grades, thereby avoiding the method that the primer in the area is completely removed and recoated by the traditional method, shortening the repairing period, saving manpower and material resources and improving the ship building efficiency.

Description

Repairing method for special primer for MARK-III-fuel tank of LNG ship

Technical Field

The invention relates to the field of ship coating construction, in particular to a method for repairing a special primer for an MARK-III-fuel tank of an LNG ship.

Background

The LNG ship is a special ship for transporting liquefied gas at a low temperature of-163 ℃, is a product with high technology, high difficulty and high added value, and is a marine super-freezing vehicle. The storage tank system of the prior liquefied natural gas carrier has two types of self-supporting and film type, the film type LNG carrier is superior to the self-supporting LNG carrier in the aspect of comprehensive performance, the prior MARK-III-fuel tank film type storage system is the most advanced and environment-friendly fuel tank maintenance system, and the insulating material of the storage tank is bonded with a fuel tank by using special resin, so that the special primer for the fuel tank is used as a transition layer between the steel surface of the fuel tank and the resin to ensure that the bonding force between the resin and the steel is strong enough.

In the ship construction, after special primer spraying construction is carried out in the fuel cabin segmentation stage, the fuel cabin is formed by being folded in the whole cabin in a period of 2.5 months, so that a damaged coating needs to be polished and repaired; the repairing needs to ensure that the coating quality of the fuel tank in the repairing area reaches the standard, and also needs to ensure that the coating film thickness of the adjacent area does not exceed the standard, so that the problem that the construction period is delayed and the quality is uncontrollable due to repeated reworking is avoided.

Disclosure of Invention

Aiming at the problems, the invention provides a method for repairing a special primer for an MARK-III-fuel tank of an LNG ship, which adopts different repairing methods aiming at different degrees of damage, shortens the repairing period and ensures that the repaired primer meets the quality requirement, and the technical aim of the invention is realized by the following technical scheme:

a method for repairing a special primer for a MARK-III-fuel tank of an LNG ship is characterized in that the primer is divided into different grades according to the damage degree of the primer, and corresponding primer repairing methods are adopted according to the different grades.

Further, the primer is divided into 3 grades of first grade, second grade and third grade according to the damage degree of the primer, wherein the first grade is that only the surface of the coating has scale and floating dust; the second level is coating damage and no coating bottom surface steel is seen; and the third level is coating damage visible coating bottom surface steel.

Further, the method comprises the steps of:

s1, after the fuel compartment carrying and folding are completed, carrying out grade evaluation on the damaged area of the primer according to the damage degree, and carrying out grade marking, wherein the grade comprises a first grade, a second grade and a third grade;

s2, taking repairing measures for the first-stage area, the second-stage area and the third-stage area respectively, and wiping off the scale and the floating dust on the surface of the coating in the first-stage area; polishing the coating in the secondary area to obtain a coating groove with the roughness of 40-75 μm, and then performing paint repair on the groove; in the tertiary zone, the coating is cleaned with a tool, with a treatment grade of SA2.5 or ST3, and paint repair is performed after cleaning.

Further, the environment temperature is 5-45 ℃ and the humidity is 50-85% RH when the primer is repaired; the surface temperature of the steel is at least 2.7 ℃ higher than the dew point temperature.

Further, in the primary area, a diluent is dipped to clean the surface of the coating, and the diluent is matched with the primer.

Further, in the secondary area, manual coating is adopted for paint repair, in the tertiary area, paint spraying is adopted for paint repair, and the periphery of the area is shielded during spraying.

Further, the dry film thickness of the repaired primer is 35-90 μm.

Compared with the prior art, the method has the advantages that the priming paint is divided into different grade areas according to the damage degree of the priming paint, corresponding repairing measures are taken aiming at the different areas, the traditional one-cut repairing mode is avoided, the repairing period is shortened, manpower and material resources are solved, the quality of the repaired priming paint can be guaranteed through the nozzle, the proportion control and the spraying pressure, and the thickness range cannot be exceeded.

Detailed Description

The technical solution of the present invention is further described below with reference to specific embodiments:

a method for repairing a primer dedicated to a MARK-iii-bunker of an LNG carrier, the method comprising:

1. after the special primer construction is carried out on the MARK-III-fuel cabin of the LNG ship in the stage of segmentation, the cabin surface of the MARK-III-fuel cabin of the LNG ship is subjected to coating protection by adopting three-proofing cloth, aluminum foil glue and the like.

2. After the MARK-III-fuel tank sections of the LNG ship are welded and assembled on the platform, the assembly of the sections is completed in a dock, and finally the complete fuel tank is formed.

3. And after the scaffold is erected inside the MARK-III-fuel tank of the LNG ship, arranging the primer repairing of the whole tank of the fuel tank.

4. Removing the coating protection, evaluating the primer coating, and dividing the primer coating into a first grade, a second grade and a third grade according to the damage degree of the primer coating, wherein the surface of the area corresponding to the first grade only has scale and floating dust; the area corresponding to the second level is coating bottom surface steel without coating damage; the third level is coating damage visible coating bottom surface steel; and classifying the damaged area according to the grade, and marking the damaged area, wherein the marking comprises the grade and the repair range.

5. According to the grade division, different repairing modes are adopted for different grade areas; in the first-level area, wiping and cleaning the scale and the floating dust by using a wiping cloth dipped with a diluent matched with the primer; manually polishing the area by using abrasive paper in a secondary area to polish a groove of a primer coating, wherein the roughness of the groove is 40-75 mu m, and then performing paint repair by using a roller or a brush to ensure that the thickness of a dry film of the coating is controlled at 35-90 mu m; cleaning the three-level area by adopting a sand blasting or grinding mode, wherein the treatment grade is required to reach SA2.5 grade or ST3 grade, then spraying paint, shielding the peripheral area during spraying, and controlling the thickness of a dry film of the primer coating to be 35-90 mu m; when the primer is repaired, the environment temperature is 5-45 ℃, and the humidity is 50-85% RH; the surface temperature of the steel is at least 2.7 ℃ higher than the dew point temperature.

When paint construction is carried out by adopting a spraying mode, a spraying pump is adopted for spraying, the pressure of the spraying pump is 0.15-0.25Mpa, the output pressure of the paint is 7.6-9.7Mpa, the spraying speed is 60-80cm/s, a nozzle of a spraying gun adopts a B-type nozzle, the B-type nozzle is a Changjiang river B-type nozzle of 14B25 type, the length of a belt of the spraying pump is 25-30m, a primer is formed by mixing and stirring a main agent of PTA paint and a curing agent of PTB paint according to a volume ratio of 4:1, 30% of diluent is added at the same time, the pressure of a pneumatic stirrer is controlled between 0.3-0.5Mpa, and the stirring process is carried out for 3 minutes, so that the paint is fully cured.

The present invention is further explained and not limited by the embodiments, and those skilled in the art can make various modifications as necessary after reading the present specification, but all the embodiments are protected by the patent law within the scope of the claims.

Claims

1. The method for repairing the special primer for the MARK-III-fuel tank of the LNG ship is characterized in that the method divides the primer into different grades according to the damage degree of the primer, and adopts corresponding primer repairing methods aiming at the different grades.

2. The method of claim 1, wherein the primer is classified into three classes, i.e., first class, second class and third class according to the damage degree of the primer, wherein the first class is that the surface of the coating is only rusted and dusty; the second level is coating damage and no coating bottom surface steel is seen; and the third level is coating damage visible coating bottom surface steel.

3. The method of claim 2, comprising the steps of:

4. The method for repairing a primer dedicated for MARK-III-bunkering of an LNG ship as claimed in any one of claims 1 to 3, wherein the primer is repaired while satisfying an ambient temperature of 5 to 45 ℃ and a humidity of 50 to 85% RH; the surface temperature of the steel is at least 2.7 ℃ higher than the dew point temperature.

5. The method of claim 3, wherein the diluent is dipped in the primary zone to clean the surface of the coating.

6. The method of claim 3, wherein the paint repair is performed by hand coating in the secondary region, and paint spray coating is performed in the tertiary region, and the periphery of the region is shielded during the paint spray coating.

7. The method of claim 3, wherein the dry film thickness of the repaired primer is 35-90 μm.