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Home > Pipeline Test Equipment > 938-96 Series Deflection Gauges

938-96 Series Deflection Gauges Sizes: 4" to 27"

Deflection Gauges (mandrels) are used to test flexible sewer pipe for out-of-roundness or deflection per ASTM specifications D3034 and F679. This testing ensures that flexible pipe has been properly bedded and backfilled (ASTM D2321) to give optimal performance.

Both steel and aluminum gauges utilize a nine arm design to ensure the pipe is tested accurately. This design also allows gravel and debris to easily pass through. Other gauges can get hung up - causing a deflection test to fail, even though the pipe is within tolerance. Sized to .01" , both deflection gauge styles meet ASTM requirements.

Deflection Requirements: ASTM Specification D3034 (4" - 15")

Nominal Size Pipe Average
Pipe ID
Base
Pipe ID*
5% Deflection
Gauge OD
7.5% Deflection
Gauge OD
4" SDR 35 3.965 3.895 3.70 3.60
6" SDR 26 5.764 5.612 5.33 5.19
6" SDR 35 5.893 5.742 5.46 5.31
8" SDR 26 7.715 7.488 7.11 6.93
8" SDR 35 7.891 7.665 7.28 7.09
10" SDR 26 9.644 9.342 8.87 8.64
10" SDR 35 9.864 9.563 9.08 8.84
12" SDR 26 11.480 11.102 10.55 10.27
12" SDR 35 11.737 11.361 10.79 10.51
15" SDR 26 14.053 13.575 12.90 12.56
15" SDR 35 14.374 13.898 13.20 12.86

Deflection Requirements: ASTM Specification F679 (18" - 27")

Nominal Size Pipe Average
Pipe ID
Base
Pipe ID*
5% Deflection
Gauge OD
7.5% Deflection
Gauge OD
18" SDR 26 17.177 16.586 15.76 15.34
18" SDR 35 17.564 16.976 16.13 15.70
21" SDR 26 20.249 19.545 18.57 18.08
21" SDR 35 20.707 20.004 19.00 18.50
24" SDR 26 22.781 21.964 20.87 20.32
24" SDR 35 23.296 22.480 21.36 20.80
27" SDR 26 25.674 24.744 23.51 22.89
27" SDR 35 26.258 25.327 24.06 23.43
30" SDR 26 29.306 28.763 27.32 26.61
*Base Inside Diameter (Base ID) - Allows for out of roundness and wall thickness tolerances as defined by ASTM standards.

Aluminum Deflection Gauges

Aluminum Fin Style Deflection Gauge:
  • Lightweight, corrosion-resistant
  • Field-verifiable without a proving ring
  • Assembles without tools
  • All sizes fit through standard 24" manhole
  • Fins for 4"-15" gauges have skid size equal to the nominal pipe size-gauge will meet regional codes and will not tip in the line
  • Nine-fin design ensures testing accuracy
  • Open design allows gravel and debris pass-through
Aluminum Fin Style Deflection Gauge

Field Verification:
Field Verification:

Fin Style Deflection Gauges are designed to be field verified by inspectors without the use of a proving ring. Simply place two fins end to end as pictured to the right and measure the width.

Add one inch to the mandrel and you have the outside dimension of the gauge. Using this method simplifies the inspector's job of verifying sizes on deflection gauges.

Aluminum Deflection Gauge Kit - includes Fins, Mandrel and Case
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Deflection Gauges Aluminum Fins Sets Only
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Mandrels for Above Aluminum Fin Sets
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Larger and custom sizes are available

Fixed Steel Style Deflection Gauges

  • Durable, zinc-plated construction resists corrosion
  • Conforms to mandrel sizing specifications-blade length is equal to or greater than the nominal pipe size
  • Nine-arm design ensures testing accuracy
  • Open design allows gravel and debris pass-through
Fixed Steel Style Deflection Gauge:

Fixed Size Steel Deflection Gauges (Larger and custom sizes are available)
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Larger and custom sizes are available - Click to download Order Form

Proving Rings

  • Used to verify deflection gauge sizes
  • Standard sizes: 6"-15" SDR 35 5% deflection and 8"-12" SDR 35 7.5% deflection
  • Custom sizes for 5"-18" also available
Proving Ring
Proving Ring

Proving Rings (Larger and custom sizes are available)
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