FRP anti-corrosion engineering

Construction Plan for FRP Concrete Lining

overview
This construction plan has made clear requirements for material selection, construction, and inspection of the project based on the user's technical conditions.
Material selection and description of primer resin: CP95 # vinyl resin (produced by Taiwan Shangwei Fine Chemical Co., Ltd.) is selected.

Material Description: CP95 # vinyl resin is made of concrete, lined with FRP special primer transition resin, which has strong adhesion with concrete and achieves the previous epoxy resin transition.

Anti corrosion layer: Use MFE-2 # ethylene based resin (Shanghai University of Technology) surface coating resin, and use ethylene based MFE-2 #+air hardening agent.

Material Description: MFE-2 # is a vinyl ester resin. Corrosion resistance: resistant to hydrochloric acid (31%), sodium hydroxide (30%), sodium hypochlorite (effective chlorine 17%), and temperature below 60 ℃.

Fiber selection: 450g alkali free short cut felt, 30g glass surface felt (produced by Jinniu Group Fiberglass Branch).
Construction standards

On site construction and inspection shall comply with GB50212-2002 "Code for Acceptance of Building Anti corrosion Engineering".
Construction technology
Set up scaffolding, lay out pedals and secure them.
Inspect the inner surface: Remove any concrete residue from the inner surface.
Inner wall treatment: Use electric tools to polish the smooth inner wall to remove protrusions, clean the surface floating soil, and ensure that the inner surface is clean.
Bottom coat: Apply a layer of CP95 # resin evenly on the clean concrete surface, and proceed to the next process after solidification.
Repair layer: For the pits on the inner surface, fill them with resin putty to prevent the occurrence of voids and bubbles during FRP lamination.
As an anti-corrosion layer: a layer of alkali free short cut felt and a layer of glass surface felt are used, requiring all fibers to be fully impregnated and the bubbles in the FRP to be expelled. The surface is then compacted to make it flat and smooth.
Surface coating: After the anti-corrosion layer is cured, use a polishing machine to remove burrs, evenly apply a layer of fabric resin, and add 3% air hardening agent to the resin.
Inspection standards and acceptance
Provide raw material certificates and inspection reports.
The inner wall treatment shall be inspected according to the concrete base treatment in GB50212-2002.
Internal surface inspection: The internal surface should be smooth, free of impurities, fiber exposure, visible cracks, and delamination.

Construction plan for iron can lining
Metal surface pretreatment:

(1) Use electric grinding wheels, wire brushes, sandpaper and other tools to polish and remove rust from the tank body and cone seal bottom. If there is severe rust or oil stains on the tank body, sandblasting should be used for rust removal.

(2) Acid washing or sandblasting (quartz sand)

Bottom scraping putty: Apply epoxy resin primer.

Reinforcement layer laying: After the primer is dry, the hand lay method is used to lay the layer. The glass cloth must be trimmed, soaked and compacted, and the joints should be staggered by no less than 50mm,

1 layer of epoxy resin 04 glass cloth+2 layers of structural resin short cut felt and 2 layers of structural resin 04 cloth are alternately laid.
Inner lining layer paving: 1 layer of inner lining resin 04 glass cloth+1 layer of inner lining resin short cut felt+1 layer of inner lining resin surface felt. After the adhesive material dries, apply another layer of coating (250g/m2 inner lining resin). The inner lining resin and surface coating are made of food grade resin.

The general service life of iron can lining is 3-5 years, and it must be used continuously, otherwise it is prone to bulging.

Construction process of FRP lining for carbon steel spherical tank

1. Open the upper and lower manholes of the tank, install a fan to replace the air inside the tank, and ensure that the air inside the tank is unobstructed.

2. Set up the scaffolding.

3. Check the concave and convex surfaces of the base material, and ensure that the surface welds are smooth and free of welding slag, burrs, pores, etc. The corner transition must be at least R10mm.

4. Sandblasting and polishing the inner wall of the tank to AS2.5 or higher. The surface of the steel should be free of visible attachments such as grease, dirt, oxide scale, rust, and paint coatings, and any residual traces should only be slight color spots in the form of dots or stripes.

5. Dust removal: Use compressed air, brushes, and cloth to remove sand particles and floating dust from the tank wall.

6. Bottom coat: Apply a layer of bottom coat resin evenly on the clean surface of carbon steel, with a dosage of about 200 grams per square meter. After solidification, proceed to the next step of construction.

7. Anti corrosion transition layer: Brush one layer of Japanese unsaturated resin, one layer of glass surface felt (30g/m2), one layer of glass fiber short cut felt (450g/m2), and one layer of Japanese unsaturated resin on the bottom coating, requiring all fibers to be fully soaked. Use a pressure roller to remove bubbles and compact, and after curing, polish and polish with a thickness of about 1.1mm.

8. Anti corrosion layer: Use Japanese unsaturated resin+(450g/m2) short cut felt+(30g/m2) glass surface felt as an anti-corrosion layer on the transition layer, lay the layer, with two felt and two surface, requiring all fibers to be soaked, use a pressure roller to remove bubbles, compact, cure, polish and polish, with a thickness of about 2.2mm.

9. Inner surface layer: After the anti-corrosion layer is completely cured, polish it with a polishing machine, remove burrs, and apply a layer of Japanese unsaturated fabric resin, with a dosage of about 200 grams per square meter and a thickness of 0.1mm.

10. Inner surface layer: Repeat the operation of step 9, apply a layer of Japanese unsaturated resin, add 3-5% air hardening agent to the resin, with a dosage of about 200 grams per square meter and a thickness of 0.1mm.

11. After the completion of all construction processes, the thickness shall be measured with a thickness gauge, and the thinnest thickness shall not be less than 87.5% of the design thickness (minimum not less than 3mm). Insufficient thickness needs to be repaired in that area to achieve the design thickness.

12. Electric spark discharge testing: When any pinholes, bubbles, or other defects are detected, a sufficiently large area must be polished off for re coating and application to achieve qualification.

13. The flatness error of the flange is less than 0.3mm.

Precautions during construction:

(1) Steps 4, 5, 6, and 7 must be completed within one day.

(2) The overlapping length of each layer's junction must be greater than 50mm, and the distance between the junction positions of each layer must be greater than 100mm.

(3) When the relative humidity of the air exceeds 80%, construction must be stopped.

(4) The surface of the treated steel structure must not be contaminated again, and when it is contaminated again, surface treatment should be carried out again.

(5) During construction, good lighting and ventilation should be maintained, and the number of operators should be minimal. They should be replaced frequently, every 2 hours. The resin used for construction should be used sparingly and frequently.