When gunning stoppages exceed 30 minutes, what thickness lining should be retained?

When gunning stoppages exceed 30 minutes, it is crucial to retain the full thickness of the lining. This practice ensures that the integrity and performance of the refractory installation are maintained. Holding the full thickness is vital because any significant delay in applying the gunned refractory can lead to issues with bonding and can result in cold joints in the refractory lining. Cold joints may not adhere properly, potentially reducing the lining's overall effectiveness and lifespan.

In scenarios where stoppages occur, allowing the lining to cure, and retaining the full thickness helps prevent weaknesses that can arise from incomplete applications or inadequate curing. This ensures that the refractory maintains optimal thermal and physical properties, essential for its function in industrial applications.

Other responses suggest reducing the thickness or eliminating the lining entirely, which can compromise the structural integrity and functionality of the refractory materials in service. Hence, maintaining the full thickness after extended stoppages aligns with best practices in refractory installation and helps avoid complications down the line.