Steel special: Six steps to prevent corrosion
Following a few simple rules throughout the specification and installation of precision carbon steel pipes can help prevent corrosion.
1. Good planning
Plan heating and cooling systems as a closed system with a closed expansion tank and appropriate ventilation to ensure proper filling. Watch out for continuous overpressure in the system.
Work with manufacturers to determine the best materials for each application. Ensure effective corrosion protection in accordance with BS 5970:2012 or worksheet AGI Q 151. Best practice is to not install precision carbon steel externally.
Store carbon steel in a dry environment and avoid storing on the floor. Do not store in contact with other materials if there is a chance of moisture.
Do not cover with plastic foil as this can increase the risk of condensation. Do not remove protective caps during storage. Store different pipe dimensions separately to avoid deformation.
Install carbon steel pipework in accordance with specifications and apply insulation and coatings as stated.
Only remove protective caps immediately before use.
During longer interruptions use downward-facing bends to protect open ends from dirt. Do not refit protective caps as this can cause condensation.
Testing of the system should ideally be completed using compressed air but if using water, the recommended water quality should be used and the system should be left filled where possible.
Protect pipes laid in screeds with a barrier against diffusion in accordance with BS 5970:2012 or worksheet AG Q 151, with closed-cell insulation material and corrosion protection as a minimum.
Do not use any parts with visible red rust. Do not use lubricant, which is unnecessary for press-fittings. Ensure adequate training for installers.
Fill the system once with the required water quality and leave it filled.
Completely ventilate the system and do not empty commissioned systems again.
If you must empty an already-running system, refill it within 24 hours at the most. Make sure the operator is aware of issues relating to corrosion such as maximum humidity and use of additives. Refer to the recommended test intervals as per BSRIA recommendations.
Follow the manufacturer’s guidelines on suitability and dosage of water additives or inhibitors. Consider use of mass loss corrosions device for peace of mind.
Use a closed or well-covered means of transportation to reduce the risk of moisture reaching the material.