Snap-Lock Branch Duct · Straight Runs & Assembly

Snap-lock pipe with adjustable elbow

Small branch turn

ConnectionAdjustable elbow slip joints
SupportBand/strap near elbow

Before you start

  • Confirm the branch size, route, fitting sequence, terminal location, and connection details against the approved drawing.
  • Inspect every snap-lock edge before assembling the pipe. A flattened, torn, or overbent lock will not stay closed just because it was hit harder.
  • Check the pipe for crushed ends, dents, out-of-round sections, and shipping damage before it is lifted.
  • Stage the correct pipe, fittings, approved fasteners, sealant, hand tools, hangers, and access equipment before starting the run.
  • Check that the adjustable elbow can make the required turn without being opened beyond its usable range.

Tools and materials

Snap-lock pipe, adjustable elbow, approved fasteners, approved sealant, marker, angle finder or level, hand seamer, screw gun, and a hanger located near the elbow.

Lay it out

  1. Measure the required turn from the actual branch centerlines.
  2. Set the elbow angle on the floor and mark its inlet, outlet, and plane.
  3. Check that every adjustable seam will remain accessible for inspection and sealing.

Set and support it

  1. Support the pipe on both sides of the turn when required.
  2. Keep a hanger close enough that the elbow cannot rotate.
  3. Do not let the elbow hang from a spin-in, boot, or single slip joint.

Make the connection

  1. 1

    Rotate the gore sections to the required angle on the floor.

  2. 2

    Seat every gore section and confirm none is partly separated.

  3. 3

    Mark the angle and plane before lifting.

  4. 4

    Connect and fasten the first pipe end.

  5. 5

    Rotate the elbow to the marked plane and connect the second end.

  6. 6

    Seal the pipe joints and required adjustable seams.

  7. 7

    Load the supports and confirm the elbow holds its angle.

Check the install

  • The elbow holds the intended angle.
  • All gore seams remain tight.
  • The inlet and outlet centerlines continue cleanly into the branch.
  • The fitting is not rolled or under spring tension.

Common mistakes

  • Trying to set the angle overhead.
  • Opening the elbow until the gore seams barely overlap.
  • Connecting one end before checking the plane of the other.
  • Leaving the elbow unsupported so it rotates.

Stop and ask

Stop if the elbow must be opened beyond its usable range, a gore seam separates, the fitting cannot hold the angle, or the turn creates an unapproved restriction.