Knowledge May 17, 2017

The challenges of cold weather projects

Winter temperatures in northern Canada can easily drop to -50°C. At such extreme temperatures, steel becomes very brittle and susceptible to damage from impacts. In addition, snow load, blowing snow and ice build-up can create big problems. The product being handled can have ice particles frozen to it and can also contain loose snow.
In such extreme cold climates it’s best to be conservative in your design. Following are a few tips we have learned over the years.

  • Conveyors should be sized for handling the additional ice and snow being reclaimed with the product. Also, expect frozen lumps to come off the pile. Chutes and skirt boards should be designed to handle the largest frozen lump.
  • Snow and dust will stick to almost any surface; therefore, use steep chute angles and large radius corners between chute plates.
  • A wider than normal belt if often needed to reduce the belt load and increase the belt to product contact. The speed should also be kept fairly slow.
  • A belt designed for extreme low temperatures should be used. Those which retain their flexibility and won’t crack.
  • Avoid conveyor slopes above 12°. Generous vertical concave curve radiuses are recommended.
  • In the transition sections, special care is required to give the slippery frozen product enough time to reaccelerate.
  • Use drive pulleys with large diameters and vulcanized diamond-shaped lagging.
  • Use large diameter, low carbon shafts. Avoid high alloy steel shafts.
  • Use electrical soft-starts. They are not affected by temperature as opposed to fluid couplings. In addition, maintenance can be done in warm electrical rooms.
  • Use lubricants designed for the extreme temperature variation.
  • With extreme temperature ranges, extraordinary expansion must be accommodated in the design of conveyors and structures.
  • Use proper grade of steel for high Charpy V-notch resistance at the proper temperature range.
  • Avoid having a long outdoor conveyor from entering a warm building. Moisture condensation and freezing will tend to form on cold conveyors. It is better to have a transfer point outside the heated building onto the tail-end of a conveyor that is running warm inside of the heated building.
  • Enclosed galleries are highly recommended. At extreme cold temperatures, working conditions can become very poor; and as a result, equipment will not be maintained.
  • Use stairs and avoid ladders wherever possible. Use safety-grip grating on walkways and platforms. Northern areas have very short days, so provide good lighting along conveyors.

The above rough guidelines should help you avoid undue conveying problems during our famously harsh winters.