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 1
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" 2007/9/7 JASNAOE/RINA ISST2007 2
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. 2007/9/7 JASNAOE/RINA ISST2007 3
Introduction (3) � Mechanical grinding of edges � It takes a great amount of labour. � Coating materials with better E.R.R. � Coating system, which makes DFT SHARP EDGE > DFT GRINDED 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. 2007/9/7 JASNAOE/RINA ISST2007 4
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 2007/9/7 JASNAOE/RINA ISST2007 5
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. 2007/9/7 JASNAOE/RINA ISST2007 6
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 � Plate size (mm) Chugoku Marine Paints (CMP), BUNDET PUTTY � Main plate Drying time: 3Hr. (surface dry), 8Hr. (hard dry) � 50 x 100 x 8 Top coat � Attached plate Tar epoxy system (CMP BISCON HB-200) 50 x 50 x 8 � Modified epoxy system (CMP NOVA-2000) Leg length � 5~8 mm DFT: 173~442 µ m � 2007/9/7 JASNAOE/RINA ISST2007 7
Blowhole dressing by puttying Specimens (2) As weld After blasting (Sa2.5) Drying time Tp=0, 3, 8 Hrs. After top coating After puttying Reverse side burn damage 2007/9/7 JASNAOE/RINA ISST2007 8
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. � 2007/9/7 JASNAOE/RINA ISST2007 9
Blowhole dressing by puttying Test conditions (2) Name Num. of Tp paint system reverse side DFT on blow- [Hr] burn damage weld bead holes [ µ m] A1 4~13 8 tar epoxy NO 347~442 A2 1~2 3 tar epoxy NO 201~315 A3 5~14 0 tar epoxy NO 235~370 A4 NO - tar epoxy NO 177~274 B1 1~5 8 modified epoxy NO 214~416 B2 2~4 3 modified epoxy NO 261~333 B3 1~9 0 modified epoxy NO 173~317 B4 NO - modified epoxy NO 224~330 D1 1~11 8 tar epoxy YES 295~367 D2 1~8 8 modified epoxy YES 321~370 2007/9/7 JASNAOE/RINA ISST2007 10
Blowhole dressing by puttying Coating performance (1) � Blistering/corrosion results (the immersion test in 3.0% NaCl solution) Name Exposure time (days) knife peeling test results 30 90 180 300 A1 10/10 10/10 10/10 10/10 100/100 A2 10/10 10/10 10/10 10/10 100/100 A3 10/10 10/10 10/10 10/10 100/100 A4 10/10 10/10 10/10 10/10 100/100 B1 10/10 10/10 10/10 10/10 100/100 10/10 10/10 10/10 10/10 100/100 B2 B3 10/10 10/10 10/10 10/10 100/100 B4 10/10 10/10 10/10 10/10 100/100 D1 10/10 10/10 10/10 10/10 100/100 2007/9/7 JASNAOE/RINA ISST2007 11 D2 10/10 10/10 10/10 10/10 100/100
Blowhole dressing by puttying Coating performance (2) � Blistering/corrosion results (the salt splay cabinet 5.0% NaCl solution) Name Exposure time = 1000 Hr knife-peeling test results A1 10/10 100/100 A2 10/10 100/100 10/10 a A3 100/100 A4 10/10 100/100 B1 10/10 100/100 B2 10/10 100/100 B3 10/10 a 100/100 10/10 a 100/100 B4 D1 10/10 100/100 D2 10/10 100/100 a Rust on the specimen's end faces stain the coating film of the weld bead. 2007/9/7 JASNAOE/RINA ISST2007 12
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. 2007/9/7 JASNAOE/RINA ISST2007 13
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. 2007/9/7 JASNAOE/RINA ISST2007 14
Ferro-Magnetic Pigment paint Experimental (1) � KA32 steel, t=12mm � Inorganic zinc rich primer (DFT=15 µ m) � 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 2007/9/7 JASNAOE/RINA ISST2007 15
Ferro-Magnetic Pigment paint Experimental (2) � Edge geometries � Top coat application 2007/9/7 JASNAOE/RINA ISST2007 16
Ferro-Magnetic Pigment paint Experimental (3) � FMP paint application � Magnetic flux near the free edge > Magnetic flux on the flat surfaces. 2007/9/7 JASNAOE/RINA ISST2007 17
Ferro-Magnetic Pigment paint Experimental (4) � Test conditions Name Edge geometry Paint system 90M-N 90M modified epoxy 45M-N 45M modified epoxy 45G-N 45G modified epoxy 20G-N 20G modified epoxy 90M-M 90M FMP paint 45M-M 45M FMP paint 45G-M 45G FMP paint 20G-M 20G FMP paint 2007/9/7 JASNAOE/RINA ISST2007 18
Ferro-Magnetic Pigment paint Cross section views GEOM 90M GEOM 45G GEOM 20G Modified epoxy FMP 2007/9/7 JASNAOE/RINA ISST2007 19
Ferro-Magnetic Pigment paint Film thickness Name DFT on the DFT on DFT at the edges ERR(%) cutting the plate Upper Lower Upper Lower surface face edge edge edge edge 90M-N 187.9 115.1 68.5 45.2% 45M-N 150.7 120.1 41.8 85.4 27.7% 71.1% 45G-N 185.9 128.5 53.6 97.3 28.8% 75.7% 20G-N 198.1 107.9 26.7 103.4 13.5% 95.8% 90M-M 444.8 134 703.5 243.1% 45M-M 316 218.7 338.4 278 107.1% 127.1% 45G-M 336.6 135.6 339 199.1 100.7% 146.8% 20G-M 304.3 169 329.2 188.9 108.2% 111.8% 2007/9/7 JASNAOE/RINA ISST2007 20
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%. 2007/9/7 JASNAOE/RINA ISST2007 21
Ferro-Magnetic Pigment paint Coating performance (1) � Corrosion (ASTM D-610) results as a function of immersion time in 3.0% NaCl solution. Name Exposure time (days) 30 60 90 180 270 90M-N 10 8 7 7 6 45M-N 10 10 8 8 8 45G-N 10 7 6 5 5 20G-N 10 10 8 8 8 90M-M 10 10 8 8 8 45M-M 10 10 10 10 10 45G-M 10 10 10 10 10 20G-M 10 10 10 8 7 2007/9/7 JASNAOE/RINA ISST2007 22
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