1. Corrosion prevention of seamless steel tubes
Seamless steel pipes are corroded according to the requirements of the drawings. Coal tar epoxy paint is used to coat glass fibre cloth and finish paint is used to prevent corrosion.
Exterior wall construction process: pipeline rust removal paint primer first paint second paint glass fiber cloth topcoat;
Inner wall construction process: pipeline rust removal primer first paint second paint third paint


Corrosion requirements:
1. The surface of the pipeline should be cleaned of grease, dust, rust and oxide before priming. The quality standard Sa2.5 for sand blasting and rust removal is adopted.
2. The surface of the pipe should be rusted and then primed. The time interval shall not exceed 8 hours. When using primer, the bottom should be dry. Primer brush is even and full, and should not appear condensation or foaming. No scrubbing is allowed at both ends of the tube in the range of 150-250mm.
3. After the primer is dry on the surface, brush it with a brush and cover it with a glass cloth. The time interval between the primer and the first paint shall not exceed 24 hours.
4. Epoxy coal tar asphalt coating adopts two components, room temperature curing coating; glass cloth adopts glass cloth with drying, dewaxing, no boxes, edge sealing, neutral alkali, longitude and latitude density of 10 * 12 / cm ~ 12 * 12 / cm. Immediately after painting, wrap up the glass cloth. The width of the edge of the glass cloth is 30 to 40 mm, and the overlap length of the joint is not less than 100 mm. The lap joints of these layers are staggered from each other. The permeability of fiberglass cloth is more than 95%, not more than 50 mm * 50 mm blank, leaving 150 ~ 250mm trapezoidal pipe end.
5. Pipeline joint construction should be carried out after qualified welding pressure test. The edge of new and old anticorrosive pressure should not be less than 50 mm, the lap length of joint should not be less than 100 mm, and the joint should be firmly bonded and tightened.
6. Coating mechanism for outer wall of steel pipe: two sides and one side of the bottom, the total thickness of dry film is 400 microns.
7. Coating mechanism of inner wall of steel pipe: bottom three, total thickness of dry film 300 um.


2. Anti-corrosion test of seamless steel tube
1. Coating inspection and acceptance:
One. After surface coating and construction, the coated workpiece should be protected from flying dust and other debris.
After coating, the inspection should be consistent with the coating color, bright color, no wrinkles, blistering, sagging, leakage and other defects.
C. For film thickness measurement, contact film thickness gauge is used to determine the thickness of the film. The thickness of the film thickness gauge is generally determined to be 3 points, and the average value is taken.


2. Quality Inspection
One. The quality inspection is carried out by sampling test according to the design specifications.
The Bay is inspected visually by root. The surface of the coating should be uniform, flat, free of bubbles, wrinkles, bumps and uneven defects of the concave and convex coating.
C. The thickness of paint film was measured by magnetic thickness gauge, and the distance of 1.5 meters was measured at both ends and the middle circumference of a single steel pipe. The thickness of the paint film should meet two 85%: that is, 85% of the measuring point thickness meets the design requirements. The thickness of the measuring point can not be reached, and the minimum value should not be less than 85% of the designed thickness.
D. Check the pinholes with a pinhole tester. If pinholes are found, grind them with a sandpaper grinder.
That is, the film thickness or pinhole is insufficient, after re-fixing, re-inspection and re-repair, until unqualified;
F. Adhesion inspection, in the coating with a hard knife drawing 60 degrees of cut angle for spot checking, should be coated directly on the base material, with tape sticking scratches, after tearing off the tape to observe scratches, the coating should not peel off. It can also be inspected on the sample board painted under the same conditions.