When Hot-Gunning Refractory Is a Better Option Than a Cold Cleaning Patch

Category: Tips
5 October 2016,

As a full service refractory contractor who prides ourselves in doing the job right, we always strive to create the best cost-effective long-term solution when it comes to protecting your people, production schedule and heat processing equipment.

But sometimes, the realities of your production schedule justify short-term fixes instead of the best “long-term solution.”

On a recent job, our customer had a void in the sidewall of their furnace that went from the molten metal line to the roof. The “best” repair would have been to perform a cold cleaning patch. Production was at peak capacity so downtime would have cost them at least 5 days of production loss by bringing the furnace down, draining it, repairing the furnace and cycling the unit back up to operation temperature and charging the furnace with new metal.

hot-gunning refractory

hot gunning better than cold cleaning patch

The alternate option was hot-gunning a temporary patch – making the repairs while the furnace was still running at a hot temperature. We use special nozzles that introduce water at the end of the nozzle to perform this type of work. The hope is that this patch would last until their next scheduled downtime a few months away.

Here’s how we analyzed the situation for hot-gunning compared to the full cold cleaning patch.


  • Speed – we could make the repair the next day
  • Budget – our costs were between $5,000 to $10,000 for the hot-gunning work, instead of $20,000 for the cold cleaning patch
  • Downtime – our customer wouldn’t require 5 additional days of downtime, which would put them further behind schedule and cost them tens of thousands of dollars in lost production


  • Quality – the patch was temporary and might not last until their scheduled downtime. If it failed, we’d need to add another patch

The customer opted for hot-gunning the refractory, since it was a more cost-effective solution for the near term than the more permanent fix which required significant downtime. The repair cost was far less than the lost production cost.

cold cleaning patch

When to Consider Hot-Gunning

Hot-gunning refractory can be an effective stop-gap for numerous types of heat processing equipment. It’s typically effective with reheat furnaces, rotary kilns and melt shops. Boilers can be tricky, depending on the ability to access to surface.

If you have concerns over a possible hot spot, or a problem area in your high temperature equipment, get a second opinion from F.S. Sperry and see if there are other options.

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