What is a permissible angle for down hand gunning without special agreement?

The permissible angle for down hand gunning without special agreement is beneath 30 degrees. This specification is important in refractory practices because maintaining an appropriate angle during the gunning process ensures that the material is applied effectively and adheres properly to the substrate. When gunning at angles greater than this, there is a risk of the material not being applied uniformly, which can lead to potential failures in the refractory lining, decreased performance, and shorter service life.

The choice of 30 degrees as an upper limit is based on best practices and safety considerations within the industry. It allows for optimal material flow and application while minimizing the chances of material slumping or falling. Adhering to this guideline helps in maintaining the integrity of the installation.