1. Surface treatment
The surface of the valve to be painted shall be treated according to the following requirements.
① The surface of the valve to be painted should be pre-treated in strict accordance with the substrate treatment requirements required by the paint manufacturer or the surface treatment requirements for paint application specified by the user.
② Apply appropriate cleaning agent to remove stains and grease before surface treatment.
③Surface treatment should be carried out above 3℃ above the dew point temperature and below 80% relative humidity.
④ If there are special requirements for sand blasting or shot blasting, the surface should be free of oxide skin, rust and other contaminants.
⑤ The surface treatment of the valve products must be sprayed within 3h, more than 3h surface treatment must be carried out again.
2. Paint coating
Paint coating should be carried out according to the following requirements.
① Painting conditions should be in accordance with the provisions of the product specification.
② Strictly according to the volume ratio or weight ratio for the group ratio.
③ The main agent and curing agent should be mixed separately with power mixer. In the main agent to join the curing agent, you need to use a power mixer to mix, this time according to the need to add diluent mixing after use, diluent must be selected to correspond to the model specifications, do not match the diluent can not be arbitrarily used.
④ According to the choice of different painting equipment (such as brush, roller, hand spraying or electrostatic spraying), the thickness of the coating is different, the choice of the number of times the paint is different, generally 3 times.
⑤ If you choose to paint the paintbrush, the direction of painting should be taken first up and down after the left and right to paint, brush dipping paint can not be too much, brush the paint distance can not be too large to avoid the paint film is too thin. If you choose to spray, the gun should be moved back and forth, each time to cover half of the last move to ensure that the paint film thickness of each part of the uniform.
(6) due to the valve's opening and closing limit device caused by the valve local cover, in the paint should always open and close the valve for painting (such as ball valves, plug valves, limit block position, etc.).
(vii) the back of the valve 3 flanges and the bottom of the valve must be painted evenly, end flange holes need to be dipped in epoxy zinc-rich anti-rust paint brush.
⑧ painted primer need to use an emery cloth or sandpaper to repair the primer smooth and flat.
The time that can be used after mixing the paint is different with the type of paint. It is a double control value of time and temperature, the higher the temperature, the shorter the time.
⑩ should be strictly in accordance with the paint can be re-coating time and drying time to perform.
3. General paint spraying thickness
For the painting thickness of the non-processing surface of the valve, it is recommended that the first layer should be coated with epoxy zinc rich antirust paint m, the second layer should be coated with epoxy ferric oxide antirust paint 20μm, and the third layer should be coated with epoxy top coat with a dry film thickness of 25μm.
4. Painting Precautions
Precautions for painting are as follows.
①After mixing the paint, it is prohibited to use the paint which exceeds the usable time.
② The compressed air used for spraying paint must be de-oiled and de-watered, and can be used for painting only when it is above 3℃ above the dew point temperature and below 80% relative humidity.
③After the use of painting tools, the thinner should be cleaned up in time to avoid not easy to clean up after curing.
④ Strictly observe the safety precautions stipulated by the relevant national regulations.
5. Inspection
The inspection items to be carried out after painting are as follows.
(1) Surface inspection
All surfaces must be free of dust and chlorides after paint application.
(2) Visual inspection
The paint coating should be continuous and flat, with uniform colour, no blisters, no small holes, no scratches or any irregularities.
(3) Paint coating thickness test
Wet film thickness test, each batch of valves need to do 3 groups of thickness measurements, each group measuring the value of 4 points, the average of the 4 point readings need to be consistent with the minimum value of the thickness of the said paint coating, and each reading shall not be less than 75% of the minimum thickness. Dry film thickness test with non-destructive testing instrument, measuring instrument needs to be calibrated every 8h.
(4) Adhesion test
First of all, use a razor blade to cut two 15mm cuts in the paint coating, the two cuts need to cross the paint to the surface of the steel, and was about 30 ° of the "X" shape, and then scrape up the paint coating at the intersection of a razor blade until the surface of the steel, if the paint peeled off at the intersection of the more than "X If the paint peeled off at the intersection exceeds the "X" threshold (the "X" threshold shall be 2mm unless otherwise specified by the Demanding Party) or if the peeled flakes are fragile, the test shall be deemed to have failed. The coating surface is honeycomb-shaped resulting in a decrease in the adhesion of the paint coating is considered unqualified.
(5) sampling test
Valve products, paint quality inspection sampling, according to GB/T 2828.1 general inspection level.
(6) test records
Paint inspectors should fill out the "paint inspection record sheet" every day.