Ship special coating (cabin coating) experience sharing one

China Paint Network
News: has done a number of special coating projects, has previously sent some posts related to special coating, and now in accordance with the special coating operation of the inspection procedures, the construction process will be shared with you.
is called ---tank coating in English, cabin coating, so in a broad sense, liquid cargo compartment, fresh water cabin and the whole cabin ballast cabin coating, should be included in the scope of special coating. Special coating of
coatings
is generally pure epoxy (for finished oil tankers), phenolic epoxy (class II chemicals and finished oil tankers), inorganic zinc (chemical ship), crude oil tankers also belong to the cabin coating, only in the phased stage began
painting
, closed after pulling the wool welds, the use of ballast cabin paint, commonly known as "alt coating."
special coating compared with the general paint construction, the use of a variety of special equipment, can be all-weather construction, so there is a simple saying, the use of special
smearing equipment
paint construction, is special coating, very image.
General special coating before the start of work, especially before the main sanding, requires adjacent compartments or structural surfaces of the fireman and tightness must end, to ensure the integrity of the paint film, commonly known as the "heteropaedic structure", including deck surfaces, ballast cabins on both sides , under ballast, before and after the completion of the adjacent compartment, if the special coating is completed, once the structural modification or re-welding phenomenon, the paint in the cabin will be difficult to repair, especially the high burn point, so the special coating is not like Pu Tu, there is repeated burn damage and repair phenomenon.
the following construction procedures or inspection items of special coating construction:
one. Scaffolding
scaffolding is the most basic requirements are safe, easy to construct and inspect, by steel pipe and net plate composition, steel pipe bottom plus rubber base to prevent displacement and static electricity, horizontal ends with rubber pipe blocking, to prevent water and sand into, resulting in increased cabin cleaning workload. The height of the scaffolding should be controlled at 1800 to 2000mm, and the distance between the cabin walls should be maintained at 200 to 300mm, the narrowest distance should be guaranteed at more than 150mm, the mesh plate should be steel structure, width of 300mm, length generally according to the cabin requirements of 1500mm, 3000mm and Other different requirements of specifications, both ends of the mesh plate also need rubber protection, the same layer between the plate should have 20 to 30mm spacing, the width of the construction aisle should be at least 600mm, that is, two mesh plate tiled, the mesh plate and steel pipe between the rubber mat, with wire fastening, to prevent static electricity generation during construction. Permanent stainless steel pipe support should be installed at the slope, and permanent stainless steel towing seats should be installed around the wall to enhance the stability of the scaffolding and ensure that the steel pipe does not come into contact with the construction
surface; Lighting
cabins need to ensure adequate lighting, light intensity should ensure 200Lux (MarineLine company requirements 500Lux) (one Lux unit equals one meter candlelight), in order to facilitate construction and inspection, coating until the completion of qualified, cabin lighting and other electrical equipment must be explosion-proof type;
3. Pre-sanding
should be confirmed before moving the gun all stainless steelseats are protected with rubber, pre-sanding requires the floor and all manual weld areas to be sa2.5; , other large surface areas are treated at Sa2 level to the maximum possible exposure to plate and weld defects to reduce the cleaning after the main sanding. For inorgand zinc matching, the entire cabin is required in accordance with Sa2.5; Processing. It is worth noting that the construction team in the pre-sanding will only use waste sand treatment cargo tank to save costs, should remind them that if not exposed as much defects as
possible at this stage, will inevitably cause the main sand after leaving a large number of structural problems to deal with, and once the need for rewelding is bound to burn adjacent paint compartments; Structural treatment
structure treatment is also the work of re-welding and polishing, generally before pre-flushing should be close to the seam area of rough grinding, in order to expose the weld's dark pores. Pre-flushed after the structural treatment, requires all weld surface no pores, splashes, weld tumor, bite edge, 'R' hole and free edge should be angled to R2mm, plate surface no skin, scratch and corrosion pit, bite edge width and depth should not exceed 1mm, pores should be expanded after re-welding, dense pores require carbon planing to open and then weld. During grinding work, not too much lubricant should be added to the grinder to prevent contamination of the walls. Close seam area in the welding area, the opposite side will generally use semi-circular ceramics to melt seepage, ceramics are tin foil paper attached to the close seam, after welding, ceramics are removed, but will leave a large number of glue marks on both sides of the weld, these glue marks in the structure should also be removed together. Relatively speaking, do inorganic zinc matching, for the highest requirements of structural treatment, after treatment of welds and automatic welds are similar, all the pits on the plate including steel ball indentation, corrosion pits and small scratches need to be polished smoothly. When doing structural treatment, an awning should be set up at the mouth of the hole to control humidity to reduce rust return, easy to repair
inspection; In addition to oil washing inspection:
structure after the approval of the need to carry out de-oil washing work, the use of special industrial detergent de-oiling, washing should use high-pressure fresh water cleaning, pressure guaranteed at least 200 bar or more, the soluble salt content of fresh water used should be less than 350us/cm, after washing timely drying, at this time the surface of the plate should be uniform rust, such as line rust, indicating that the washing is not thorough, some places are only water. A small amount of oil found during the inspection can be removed with thinner, if there is a large amount of oil or large-scale leakage, need to be re-washed. After washing the salt test, according to the process requirements, the salt test must be after the main sanding, so the test results after washing water for reference only, can not be used as a standard requirement, after washing the salt content, according to experience, 100 mg / m2 or less can be considered
qualified; Main sanding inspection and cleaning inspection:
before the main sanding start, should first ensure that the adjacent three pairs of compartment structure and washing qualified, all holes in advance sanding and do a primer protection, hole back top position along the free edge to deal with 100mm width of the area and do a good job of one-time primer, all stainless steel pipe system in the cabin with rubber protection. It is best to determine the order of construction according to the wind direction of the season, the entrance and exit of the rain-proof pontoon at the mouth of the cave should be in the downwind place, in order to avoid dust leakage from the sand chamber pollution adjacent to the paint compartment, the top of the rain-proof pontoon must not accumulate water and should be convenient for people to enter and exit. Collect sand samples for soluble salt test and hardness test, abrasive specifications should be between 0.5 and 1.5mm, its moisture content should not exceed 0.2% of the weight ratio.
soluble salt test of abrasives: on-site collection of 100g sand samples, put in 100ml of pure water, shake for 5 minutes, sit for 1 hour, shake for another 5 minutes, remove the water samples and filter them, test the conductivity of water samples, requires less than 250us/cm;
simple way to test hardness: place the sand sample between two pieces of glass, press the glass hard, if the glass can be left with sand indentation, indicating that the hardness of the sand is up to standard.
When the main sand report inspection, should be on the deck to observe the cabin entrance and exit cleaning, the deck surface there is no sand accumulation water, dehumidifier air conditioning water directly flow on the deck of the sand punch chamber, the entrance should be placed net plate, rainy days should ensure that rainwater will not enter the cabin, the cabin entrance should have enough dry cloth to prevent artificial water into the cabin. All personnel should wear clean cloth gloves and shoe cover before entering the cabin. When entering the cabin inspection to confirm structural defects, atmospheric holes need to be welded and polished, small pores can be drilled with samples, grinding machine flat. Then do salt testing, the use of pure water testing, and now with Wahaha pure water test has become a set trend. The salt content value of the random detection site in the cabin shall be less than 50 mg/m2; (ISO8502-6 standard), each cabin test more than 6 points (guaranteed that each side of the cabin has a test point), in general, the floor, especially the sewage well area salt is the highest, at least two points to test, in addition to corrosion pits and rough areas, salt is easy to exceed the standard, if the salt exceeds the requirements, must be re-washed sand until the salt standard. Cleaning inspection requires the use of vacuum sand absorption, vacuuming, top-down inspection, steel pipe mesh plate no accumulation of sand ash, confirm that the ends of the foot steel pipe closed intact, fastener cleaning, wall surface cleanliness to reach tape test Rating1 (IS) O8502-3 standard), the relative humidity control in each area of the cabin is less than 50%, the steel plate temperature is kept between 10 degrees Celsius to 40 degrees Celsius, and above the dew point 3 degrees above, all sand surface to Sa2.5; Grade (surface should be free of visible grease, dirt, oxide skin, rust, paint coating and impurities, residue traces should be spot-like or striped slight spots), roughness between 45-85um.
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