TinnerFlow™3rd YearRound DuctYELLOW · Check First
A light adjustable elbow may not belong on a high-velocity or pressure-critical run. Replace failed fittings with the approved round elbow type/radius/gauge for that system.
If a pleated or adjustable round elbow pops at the heel seam, the fitting is likely not strong enough for the pressure/velocity or it was used in the wrong place.
Stop treating it as a sealant-only leak. Check the drawing, pressure class, duct size, and approved fitting type. The likely recovery is replacing the failed elbow with a factory-rated smooth elbow, heavier-gauge fitting, or approved long-radius sweep per project detail.
Use this as training guidance. The foreman, approved drawings, project specs, manufacturer installation instructions, employer safety policy, and AHJ/code requirements always control the final answer.