Study on the alternatives to the secondary surface preparation in - - PowerPoint PPT Presentation

2007/9/7 JASNAOE/RINA ISST2007 1

Study on the alternatives to the secondary surface preparation in protective coatings

Naoki OSAWA, Osaka University Koichiro UMEMOTO, Kawasaki Shipbuilding, Ltd. Yukinori NAMBU, Universal Shipbuilding, Ltd. Tatsuya KURAMOTO, Mitsui Engineering & Shipbuilding, Ltd.

2007/9/7 JASNAOE/RINA ISST2007 2

Introduction (1)

Secondary surface preparation (SSP) Be effective in preventing coating defects. IMO/PSPC's requirements To apply grinding weld beads contaminant ISO8501-3 grade P2 Blowholes have to be removed or filled up. Mechanical grinding of sharp edges "2R or 3 path grinding or equivalent"

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Introduction (2)

Blowholes

• Usually dressed out by repair welding.
• Contingent works, such as surface re-preparation and removal of

dust, are associated.

Puttying blowholes

• No need for contingent works. We can save the manpower

substantially.

Protective performance of the top coat on the puttied blowholes

has not been investigated.

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Introduction (3)

Mechanical grinding of edges

It takes a great amount of labour.

Coating materials with better E.R.R.

Coating system, which makes

DFTSHARP EDGE > DFTGRINDED EDGE has not been developed yet.

Ferro-Magnetic Pigment (FMP) paint

The force that draws the pigments toward the edge is

produced when a magnetic field is applied.

E.R.R. and coating performance under the actual process

condition in shipyards have not been investigated.

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Objectives

The effectiveness of puttying as an alternative to

repair welding for blowhole dressing is discussed by comparing the protective performance for the cases with blowholes dressed out by puttying and that without blowholes.

Edge retention behaviours and anti-corrosive

performances of a FMP paint system applied to the steel plates with various edge geometries are

• investigated. The effectiveness of stripe coating

with FMP paint as an alternative to mechanical grinding of sharp edges is discussed

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Methodologies

Anti-corrosive performance measurements Spray cabinet tests JIS K5600-7-1 (ISO7235), 5% NaCl solution, 35ºC Immersion tests JIS K5600-6-2 (ISO2812-2) in 3% NaCl solution. Rating Blisters: ASTM D-714, rusts: ASTM D-610. Adhesion Measurements Knife-cut test (JIS K5400-8.5.3) Tape peeling is not applied.

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Blowhole dressing by puttying Specimens (1)

• T-weld joints specimens

(x 20 pieces)

• Blowholes
• Exist in 16 of 20 specimens,
• Max. dia.= 3mm
• Surface preparation:

Sa 2.5 (grid blast)

• 100% solid epoxy / polyamide putty
• Chugoku Marine Paints (CMP), BUNDET PUTTY
• Drying time: 3Hr. (surface dry), 8Hr. (hard dry)
• Top coat
• Tar epoxy system (CMP BISCON HB-200)
• Modified epoxy system (CMP NOVA-2000)
• DFT: 173~442µm

Plate size (mm) Main plate 50 x 100 x 8 Attached plate 50 x 50 x 8 Leg length 5~8 mm

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Blowhole dressing by puttying Specimens (2)

After blasting (Sa2.5) After puttying As weld After top coating Drying time Tp=0, 3, 8 Hrs. Reverse side burn damage

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Blowhole dressing by puttying Test conditions (1)

• Specimens with reverse side burn damage
• Heated by LP gas flame
• Top coat is re-applied after grinding
• Test conditions
• No blowhole / With blowholes (puttied)
• Putty drying time Tp=0, 3, 8 Hrs.
• Paint system: tar epoxy / modified epoxy
• No burn damage / with burn damage
• Four specimens for each condition
• Two for the immersion test (300 days)
• Two for the salt spray cabinet test (1000 Hrs.)
• Knife-cut tests are performed for puttied specimens.

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Blowhole dressing by puttying Test conditions (2)

321~370 YES modified epoxy 8 1~8 D2 295~367 YES tar epoxy 8 1~11 D1 224~330 NO modified epoxy

• NO

B4 173~317 NO modified epoxy 1~9 B3 261~333 NO modified epoxy 3 2~4 B2 214~416 NO modified epoxy 8 1~5 B1 177~274 NO tar epoxy

• NO

A4 235~370 NO tar epoxy 5~14 A3 201~315 NO tar epoxy 3 1~2 A2 347~442 NO tar epoxy 8 4~13 A1 DFT on weld bead [µm] reverse side burn damage paint system Tp [Hr]

• Num. of

blow- holes Name

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Blowhole dressing by puttying Coating performance (1)

Blistering/corrosion results (the immersion

test in 3.0% NaCl solution)

100/100 10/10 10/10 10/10 10/10 D2 100/100 10/10 10/10 10/10 10/10 D1 100/100 10/10 10/10 10/10 10/10 B4 100/100 10/10 10/10 10/10 10/10 B3 100/100 10/10 10/10 10/10 10/10 B2 100/100 10/10 10/10 10/10 10/10 B1 100/100 10/10 10/10 10/10 10/10 A4 100/100 10/10 10/10 10/10 10/10 A3 100/100 10/10 10/10 10/10 10/10 A2 100/100 10/10 10/10 10/10 10/10 A1 300 180 90 30 knife peeling test results Exposure time (days) Name

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Blowhole dressing by puttying Coating performance (2)

Blistering/corrosion results (the salt splay

cabinet 5.0% NaCl solution)

100/100 10/10 D2 100/100 10/10 D1 100/100 10/10 a B4 100/100 10/10 a B3 100/100 10/10 B2 100/100 10/10 B1 100/100 10/10 A4 100/100 10/10a A3 100/100 10/10 A2 100/100 10/10 A1 knife-peeling test results Exposure time = 1000 Hr Name

a Rust on the specimen's end faces stain the coating film of the weld bead.

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Blowhole dressing by puttying Validity of puttying (1)

The performance of the top coats applied on the

putty-upped blowholes is almost equivalent to that for the cases without blowhole.

Loss of the coating performance coming from the

shortening of the putty drying time is not recognized.

Loss of the performance of the top coat applied on

putty-upped blowholes coming from the reverse side burn damage is not recognized.

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Blowhole dressing by puttying Validity of puttying (2)

The performance for the puttying case is

better than or equivalent to that for the repair- welded case.

Dressing by 100% solid epoxy / polyamide

putty is an effective alternative to repair welding.

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Ferro-Magnetic Pigment paint Experimental (1)

KA32 steel, t=12mm Inorganic zinc rich primer (DFT=15µm) Cut by a laser cutting system Edge preparation: machining / grinder Top coat: Modified epoxy (NOVA2000) / FMP Three specimens for each test condition (edge

• geom. / top coat)

1 specimen: coating thickness measurement 1 specimen: immersion test in NaCl solution for 270 days 1 specimen: salt spray cabinet test for 1000 hours

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Ferro-Magnetic Pigment paint Experimental (2)

Edge geometries Top coat application

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Ferro-Magnetic Pigment paint Experimental (3)

FMP paint application

Magnetic flux near the free edge

> Magnetic flux on the flat surfaces.

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Ferro-Magnetic Pigment paint Experimental (4)

Test conditions

FMP paint 20G 20G-M FMP paint 45G 45G-M FMP paint 45M 45M-M FMP paint 90M 90M-M modified epoxy 20G 20G-N modified epoxy 45G 45G-N modified epoxy 45M 45M-N modified epoxy 90M 90M-N Paint system Edge geometry Name

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Ferro-Magnetic Pigment paint Cross section views

Modified epoxy FMP GEOM 90M GEOM 45G GEOM 20G

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Ferro-Magnetic Pigment paint Film thickness

111.8% 108.2% 188.9 329.2 169 304.3 20G-M 146.8% 100.7% 199.1 339 135.6 336.6 45G-M 127.1% 107.1% 278 338.4 218.7 316 45M-M 243.1% 703.5 134 444.8 90M-M 95.8% 13.5% 103.4 26.7 107.9 198.1 20G-N 75.7% 28.8% 97.3 53.6 128.5 185.9 45G-N 71.1% 27.7% 85.4 41.8 120.1 150.7 45M-N 45.2% 68.5 115.1 187.9 90M-N Lower edge Upper edge Lower edge Upper edge ERR(%) DFT at the edges DFT on the plate face DFT on the cutting surface Name

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Ferro-Magnetic Pigment paint Film thickness: summary

DFTs at the edges for FMP paint system

>> DFTs at the edges for ordinary paint system

Ordinary paint system

ERR is less than or nearly equal to 100% for all edge

geometries.

The smaller the bevel angle, the smaller ERR. The minimum ERR is less than 30%.

FMP paint system

ERR is larger than 100% for all edge geometries. The smaller the bevel angle, the larger ERR. The maximum ERR exceeds 240%.

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Ferro-Magnetic Pigment paint Coating performance (1)

Corrosion (ASTM D-610) results as a function

• f immersion time in 3.0% NaCl solution.

7 8 10 10 10 20G-M 10 10 10 10 10 45G-M 10 10 10 10 10 45M-M 8 8 8 10 10 90M-M 8 8 8 10 10 20G-N 5 5 6 7 10 45G-N 8 8 8 10 10 45M-N 6 7 7 8 10 90M-N 270 180 90 60 30 Exposure time (days) Name

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Ferro-Magnetic Pigment paint Coating performance (2)

Corrosion (ASTM D-610) results as a function

• f the exposure time in the salt spray cabinet.

10 10 20G-M 10 10 45G-M 10 10 45M-M 10 10 90M-M 10 10 20G-N 6 7 45G-N 8 10 45M-N 8 10 90M-N 1000 500 Exposure time hours) Name

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Ferro-Magnetic Pigment paint Coating performance: Summary

Most of the specimens coated with the

• rdinary paint system fail by corrosion, while

most of the specimens coated with FMP paint system show no corrosion products.

When a specimen coated with FMP paint

system displays corrosion during a test, the specimen with the same edge geometry and coated with the ordinary system also fails, and its corrosion proceeds faster.

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Ferro-Magnetic Pigment paint Validity of FMP paint system (1)

The protective performance of a specimen

with sharp edge coated by FMP paint system is higher than or equivalent to that of specimens with edge preparation coated by the ordinary paint system.

FMP paint is an attractive alternative to

mechanical grinding of edge because it can eliminate the need for a great amount of labour.

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Ferro-Magnetic Pigment paint Validity of FMP paint system (2)

Problems to be solved:

A technique, that enables us to apply magnetic

field to a member in a ship hull, has not been established.

Colour of the ferromagnetic pigment is limited to

blackish colours.

Protective performance may be deteriorated when

iron fillings are attracted and it enters the coating film.

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Conclusions

The protective performance of a top coat applied on a weld bead

with blowholes which is dressed out by 100% solid epoxy / polyamide putty is better than or equivalent to that for the case where blowholes are dressed out by repair-welding. Puttying by 100% solid epoxy / polyamide putty is an effective alternative to repair welding for blowhole dressing.

A thick area of coating along sharp edge is created when FMP

paint system is applied as a top coat. Edge retention behaviour is improved when the bevel angle decreases. The protective performance of a specimen with sharp edge coated by FMP paint system is higher than or equivalent to that of specimens with edge preparation coated by ordinary paint system. FMP paint is an attractive alternative to mechanical grinding of edge because it can eliminate the need for a great amount of labour.

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Acknowledgements

Special thanks to:

Research Committee on Revision of Steel Ship

Manufacture Method, JASNAOE

• Prof. Yasumitsu Tomita (Kinki Polytechnic College-

Kyoto)

• Mr. Kazuhiko Kumagawa (Sasebo Heavy Industries,

Ltd.)

• Mr. Fukumi Hamaya and Mr. Tomoki Sunayama

(Mitsubishi Heavy Industries, Ltd.)

Chugoku Marine Paint, Ltd. Technical Centre

• Dr. Satoru Furumoto