Wet storage stain

Steel sheets are normally treated with a special chromate solution, under strictly controlled conditions (i.e. the sheet is passivated) before leaving the Mill. Although this process ensures long and satisfactory protection to sheets, wet storage stain or white rust can still occur. One of the main conditions which may give rise to this problem is sheets being exposed to water while stacked, which restricts air circulation between sheets. It is therefore important that sheets remain dry and that they do not come into contact with each other at any point if exposed to water. If sheets cannot be stored in a dry storage space, they should be stood on end and spaced out at the bottom. A drop in temperature after a warm, humid day may also lead to condensation of moisture throughout the stack. And because the temperature is usually at its lowest during the night, the risk of condensation is increased. The stain that is created does not compromise the integrity of the sheet, but does have a negative impact on the aesthetic value.

Edge wave and oil canning

The amount of edge wave or oil canning is dependant upon the varying mechanical properties of the coil used. Stiffeners ribs are incorporated into the troughs to minimise the effects of oil canning.

Surface contamination

Care should be taken to ensure that none of the debris arising from the fixing of steel roof remains on the sheets after completion of work. If nails, swarf, etc. are allowed to remain on roof sheets, unsightly spots will soon appear. Initially these rust sport will merely be stains from rapidly rusting fine particles of steel, if allowed to develop further, a loss of zinc coating in the stained areas will appear. Nails, particles of steel, etc. will also stain and ultimately reduce the life expectancy of sheets. Sheets are often subject to wet cement splashes that create an area that is subject to alkali attack. Cement splashes should therefore be cleaned off immediately.

Wind terraine categories

It is important to consultant an engineer at design stage, to ensure the correct specification of purlin spacing and roof sheet gauge.

Corrosion

The coast line of Africa is a particularly harsh enviroment which carries coastal chlorides. In urban areas, corrosion is accelrated by the presence of sulphur emissions from industry and traffic. The choice of the correct steel substrate is therefore important to avoid high replacement costs and losses in rentals, etc. Please request additional information from Nyumba Group in this regard.

Corrugated Sheets Limited is an industry player that adheres to the higest quaity standards and ensures that the products that reach our clients are of the highest quality. That being said, it is incumbent upon job site professionals, business owners, distributors and contractors to ensure proper care is taken to preserve and protect the integrity and attractive appearance of CSL‘s Nyumba Brand products against damage cnused by moisture, corrosive chemicals or improper handling and storage. For Corrugated Sheets Limited Nyumba Roofing Sheets, the following are some basic storage instructions that would ensure the products retain the highest quality while on the job site.

• Firstly, on a job site, order the roofing sheets on a schedule that ensures that they stay in storage the shortest time.
• Offload the roofing sheets directly to the job site or storage facility to reduce the risk of damage during translocation from one location to another.
• When manually off-loading, ensure the appropriate operatives are on hand, wearing adequate protective clothing as the roofing sheet edges are sharp.
• The sheets should be stored elevated on a raised base in a dried and a secured location not exposed to the elements i.e. wind, rain and covered with a waterproof cover or canvas tarpaulin. Do not use plastic as it causes sweating and condensation to occur.
• Moisture is what causes the most damage to roofing sheets hence the raised and slightly sloped base to ensure any errant moisture that gets on the sheets drains away.
• Sufficient support must be provided to the raised and angled bundles to avoid excessive bowing, which may result in low spots that could hold water.
• Do not store any heavy materials on top of the sheets while in storage.
• If the roofing sheets are of the pre-painted variety, store them with the coloured face facing downwards to ensure minimal scratches and damages while in storage.
• In order to prevent unwanted chemical reactions and corrosion, do not store the sheets with materials made of dissimilar metals (lead, copper, etc.).
• Strong acids (jet fuel exhaust, commercial cleaners/solvents, etc.) can degrade the finish.
• Inspect the storage site regularly to ensure moisture protection. If errant moisture on the sheets is noticed, separate the stacked sheets, wipe them down with a clean dry cloth and allow to completely dry before restacking.

NOTE TO CLIENT: If any moisture is noticed on the roofing sheets by the client on delivery, DO NOT accept the delivery and immediately contact your distributor.

Following these simple instructions would ensure the product retains the highest quality while on a work site or in storage.