IPC 308.6 Sway Bracing - Explained

[jar546]

Here’s an educational summary of IPC code section 308.6 on sway bracing:

• Scope of the Code: Applies to horizontal drainage or waste pipes that are 4 inches (102 mm) or larger.
• Conditions for Bracing:
  • Bracing is required where a pipe fitting changes the flow direction by more than 45 degrees.
  • This is to counteract the forces generated by the change in flow direction, which could otherwise move the pipe.
• Nature of Flow and Forces:
  • Wastewater flow in large pipes (4 inches and larger) can surge significantly, especially when multiple smaller branches discharge into them.
  • These surges create waves of high flow, impacting fittings and potentially causing movement in the direction of flow.
• Consequences of Unbraced Fittings:
  • Direction-changing fittings may move, pulling the upstream piping with them.
  • This lateral movement can lead to "swaying" of downstream piping, potentially causing failure in pipe couplings and connections.
• Rationale for Bracing:
  • Rigid bracing or similar supports are mandated to prevent the upstream pipe and its fittings from moving in the direction of flow.
  • This ensures the downstream piping remains stable and does not sway sideways.
• Exceptions to Bracing Requirements:
  • Upstream bracing is not required where the flow direction changes into a vertical pipe. Vertical pipes are supported differently and do not sway side to side.
  • The code does not apply to buried piping, as the backfill provides necessary support to prevent movement.

 

[jj1289]

We are running into this issue currently. We mentioned that they need to comply with IPC sections 308.6 and 308.7. They started installing these "brackets" on the schedule 40 PVC. We asked for the installation instructions. We finally got them and the "brackets" they are using are for hubless cast iron, not for PVC.