If the ice builds up to an excessive degree, it could threaten structural stability. It may also obstruct or impair the operation of valves and gauges. The gas outlet temperature of the vaporiser could fall too, causing embrittlement of downstream equipment. Under these circumstances it is important to defrost the vaporiser.
Where processes are intermittent, there are alternate banks of vaporisers or equipment is in sunny, well-ventilated locations, defrosting can often occur naturally. However, in some circumstances you will need to manually de-ice the equipment and it is important to do it correctly. Never attempt to remove the ice mechanically.
- Use hot water or steam.
- Work from the top of the equipment downwards.
- Ensure the run-off is appropriately managed (e.g. adequately drained).
- Ensure you provide safe access arrangements when working on larger vaporisers. Specialist access equipment may be needed to reach the top of the unit, for example a Mobile Elevated Working Platform (MEWP) or scaffold tower.
- Use cold water, especially where vaporisers are in use, as it can increase the volume of ice build-up.
- Use naked flames or de-icing compounds.
- Use metal hammers, picks and other mechanical items.
- Remove ice from the bottom of the vaporiser until the ice above it is cleared. If the ice from the bottom is removed first, ice may fall from the higher parts of the equipment, risking operator injury and damage to the equipment.
The frequency of de-icing will depend upon individual site circumstances. It could be each shift, daily, weekly, monthly or throughout periods of winter weather.
If you find your system requires regular de-icing, it is better to plan for this in advance on a scheduled basis before significant ice forms. It is far easier and safer to remove light ice build-up, so a daily equipment check is recommended. Check for ice build-up, visible or audible leaks and for mechanical damage, and take the appropriate action as necessary.