Spiral pipe starts bulging or unzipping at the lockseam
Bulging or unzipping spiral pipe means the pipe/joint is not handling the pressure or system condition. Stop the test/startup and verify gauge, pressure class, joint, and replacement/reinforcement options.
Do not keep pressurizing spiral duct that is unzipping or bulging at the seam.
Check
Stop or secure the system/test if the seam is actively opening.
Confirm duct diameter, pressure class, pipe type, gauge/material, and shop markings if available.
Check if pressure spiked due to closed dampers, blocked outlets, VFD ramp, or wrong test setup.
Inspect hangers and joints near the bulged section.
Ask before adding any sleeve or clamp as a permanent fix.
Steps
Stop or secure the system/test if the seam is actively opening.
Confirm duct diameter, pressure class, pipe type, gauge/material, and shop markings if available.
Check if pressure spiked due to closed dampers, blocked outlets, VFD ramp, or wrong test setup.
Inspect hangers and joints near the bulged section.
Ask before adding any sleeve or clamp as a permanent fix.
Say this to your foreman
The spiral lockseam is bulging/opening at [location] during [test/startup]. I checked pressure condition and pipe markings. Do you want this section replaced with rated pipe or held for an approved repair detail?