Mild Steel
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Defect and Repair
| Mild Steel | Defect | Repair |
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Fungal Growth Fungal growth, is resulted from the presence of fungal spores, moisture and nutrients from dirt of various types. [12] |
Spot test with sodium hypochlorite solution can be carried out for identifcation purposes. Chlorine concentration should preferably be above 3%.
Wash down with a 2% sodium hypochlorite solution or commercial bleach, with a small amount of detergent. Apply a solution with soft bristle brush and left for 3-5 min then rinse. [12] |
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Lichen Lichen is a growth incorporating both fungus and algae. Its appearance on roof is quite distinctive. [12] |
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Waterproofing Metal roof failed to maintain waterproofing integrity |
Repair the affected area. If the area too large then the major replacement has to be done.
Coating and insulation has to be re-installed. |
Notes: Table below shows the dilution required for different strength bleaches to give a 2% solution.
| % Sodium hypochlorite or % available chlorine in bleach (by weight) (NB: 10g/L = 1%) | Dilution to give 1L of 2% sodiumhypochlorite solution |
| 10% | 200ml bleach + 100mL water |
| 5% | 400mL bleach + 600 mL water |
| 4% | 500mL bleach + 500mL water |
| 3% | 670mL bleach + 330mL water |
| 2% | No dilution required |
Source: http://www.bhpsteel.com.my [12]
For more defects, please refer to the Defect Library.