UG Underground UG-07 Step 7 of 13

Reaming and Pullback

Enlarge the pilot hole and pull the conduit or conduit bundle in through a swivel and breakaway link, without damaging or overstressing it.

Watch Checklist On the Map

Crew

Drill Operator
Exit Pit Crew
Reel Crew
Foreman

Hazards

Rotating Drill String
Conduit or Reel under Tension
Inadvertent Fluid Returns (Frac-Outs)
Pinch Points at the Reel

UG-07 · OSP Hub Shorts

Watch the Video

Reaming and Pullback
Duration 1:13
Watch on YouTube: Reaming and Pullback (external site)

Crew: Drill Operator · Exit Pit Crew · Reel Crew · Foreman
Hazards: Rotating Drill String · Conduit or Reel under Tension · Inadvertent Fluid Returns (Frac-Outs) · Pinch Points at the Reel
Governing Rules: Rig manufacturer instructions · Tooling and conduit manufacturer instructions · 49 CFR 196.109 · company emergency plan · CGA Best Practices · State one-call law · 49 CFR 196.107 (pipelines)

Job / route		Date
Location / station		Locate ticket

Purpose

Enlarge the pilot hole and pull back the product without damaging it. The product is one conduit, or a conduit bundle: several conduits pulled together on one pulling head. OSP crews often pull several conduits at once. The pullback string protects the product: the swivel keeps rod rotation from twisting the conduit, and the breakaway link is there to break before any conduit is pulled past its safe pull strength. A conduit that is stretched, kinked or full of mud is a failed bore, even if it came through.

When to Do It

Trigger: the pilot bore has exited at the planned point and the exit location and depth are confirmed (UG-06).
Prerequisites: conduit and tooling on site, every reel staged, radios working between both pits.
Previous step: UG-06 Pilot Bore and Tracking.
Next step: UG-08 Other Placement Methods, or straight to UG-09 Handholes, Vaults and Pedestals when every segment is bored.

Roles

Drill operator: controls pullback speed and watches pullback force and fluid returns.
Exit pit crew: assembles and checks the pullback string.
Reel crew: keeps every conduit paying out freely and calls any problem by radio.
Foreman: checks the string and the breakaway link rating before pullback, and decides on pre-ream passes with the engineer.

Equipment and Materials

Backreamer sized for the product (one conduit or the bundle).
Swivel rated for the pull, per the tooling manufacturer.
Breakaway link rated for the product: below the conduit’s safe pull strength, or for a bundle on a written basis from the conduit and pulling-head manufacturers or the engineer (step 4).
Pulling head or pulling grip sized for the conduit or bundle, with the harness the manufacturers specify.
Conduit reel trailers: one reel per conduit, staged together, or one common reel where the conduits come packaged together.
End caps or plugs for every duct.
Tracer wire, if the design specifies it.
Radios for the drill operator and reel crew.

Safety

The strike procedures from the pilot bore (UG-06) still apply. A reamer can hit what the pilot bit missed.

Procedure

At the exit pit, remove the drill head. Assemble the pullback string per the tooling manufacturer, typically in this order: drill rod → backreamer → swivel → breakaway link → pulling head on the conduit or bundle.
Size the backreamer for the product per the engineer or the manufacturer. A common rule of thumb is about 1.5 times the product’s outside diameter.
- For a bundle, the product’s outside diameter (OD) is the bundle’s OD, not one conduit’s. PPI’s conduit note asks for a hole of at least 1.5 times the OD of the conduit or conduit bundle (PPI TN-63).
- The Bore Planning Helper estimates the bundle OD from the conduit count as the tightest packing. That is the smallest the bundle can be, so a reamer sized from it is the smallest you should use. Use a measured bundle OD or the manufacturer’s figure when you have one.
- Some permits cap the hole size: per permit. Ask the permit owner how the cap applies to a bundle before you choose the reamer.
Stage the conduit reel trailer in line with the bore, so the conduit pays out freely without sharp bends (PPI TN-63; conduit manufacturer instructions).
- For a bundle, stage every reel in line with the bore, so each conduit pays out evenly and none drags or kinks at the pit edge.
- Cap or plug every duct end, so drilling fluid and soil stay out.
- Pull tracer wire with the conduit if the design specifies it.
Choose the breakaway link rating before you pull.
- One conduit: rate the link below the conduit’s safe pull strength: per conduit manufacturer data.
- Bundle: the link carries the whole bundle’s pull, but the pull may not split evenly. A conduit whose reel drags, whose harness leg is shorter, or that rubs harder in the hole carries more than its share. PPI ties the link rating to the conduit (PPI TN-63; Handbook of PE Pipe, Ch. 14).
- Bundle: get the rating basis in writing from the conduit and pulling-head manufacturers or the engineer: per the conduit and pulling-head manufacturers. Do not add the conduits’ safe pull strengths together unless that written basis says you can.
- Bundle with no written basis: rate the link below the lowest safe pull strength of any one conduit in the bundle. That protects every conduit however the pull splits. If the link breaks on a normal pull, stop and get a written basis; do not fit a stronger link.
- One conduit maker applies the same idea to a different job: when several ducts of different sizes are pulled into an existing conduit, it limits the pull to the lowest published pull rating among the ducts. This is not an HDD rule.
- Bundle: connect the conduits with the pulling head or harness the manufacturers specify. PPI recommends a staggered pulling harness with a breakaway swivel when you pull several conduits (Handbook of PE Pipe, Ch. 14). In a staggered harness the conduit ends are offset in length, so the grips do not bunch up in one spot.
Pull back at a steady rate.
- Monitor pullback force, fluid returns and every reel.
- The rig gauge shows the rig’s pullback pressure, which includes the drag of the drill rods and reamer. It does not show the tension in the conduit, and it cannot show one conduit in a bundle taking more than its share (PPI Handbook of PE Pipe, Ch. 12 and 14). For small conduit, PPI’s conduit note recommends a device that monitors pulling tension, such as an in-line tensiometer (PPI TN-63). Ahead of a bundle it reads the bundle’s total, not each conduit’s share.
- Watch that each conduit feeds at the same rate as the pull (PPI TN-63). If a reel binds or a conduit slows or lags, radio the drill operator to stop the pull (typical practice; follow owner spec and the drill operator’s procedure). PPI TN-63 notes that a slowing feed can mean rising tension in that conduit, so it may be taking extra load and could be stretched past its safe pull strength. Free the reel only with the pull stopped, then restart smoothly.
- Keep radio contact between the drill operator and the reel crew.
- Avoid unplanned stops once the pull is moving: the hole can close in and grip the conduit, and restarting takes more pull than keeping it moving (PPI Handbook of PE Pipe, Ch. 12). Fix the cause of a stop before you restart.
For large products or difficult soil, pre-ream in passes as the engineer directs.
At the entry pit, inspect each conduit end for damage. Leave tails per owner spec, and re-seal the ducts.
Let the conduit relax before you cut it to final length where the conduit manufacturer or owner requires it, so the stretch from pullback does not pull the tails back into the hole.

Hold Points

Records to Keep

Pullback force readings, if logged.
Conduit footage marks at each end, for each conduit.
Conduit count, size and color in the bore.
Breakaway link rating used, and its basis: the written basis, or the lowest single-conduit safe pull strength.
Reel IDs for each conduit placed.
Photos of the pullback string and the conduit ends.
Damage reports and owner notifications for any facility damaged, however minor.

Common Mistakes

No swivel. Rod rotation twists and damages the conduit.
Undersized reamer. The conduit drags and can exceed its safe pull strength.
Sizing the reamer from one conduit’s OD when pulling a bundle. The hole is too small for the bundle, and pull force climbs.
Rating a bundle’s breakaway link from the sum of the conduits’ strengths. The load may not split evenly, so one conduit can be overstressed before the link breaks. Get a written basis, or rate the link below the lowest safe pull strength of any one conduit (step 4; a conservative fallback pending SME review).
Reel binding. A stuck reel spikes tension in an instant; keep a crew member watching every reel (typical practice; follow owner spec).
Uncapped conduit. Fluid and soil fill the duct, and proving (UG-10) fails.
Exceeding safe pull strength. A stretched duct may look fine and fail later.

Standards and References

Conduit and tooling manufacturer instructions.
Plastics Pipe Institute (PPI): Handbook of PE Pipe, Ch. 12 (Horizontal Directional Drilling) and Ch. 14 (Duct and Conduit), and TN-63 (safe pull strength of conduit).
Owner construction standards.
CGA Best Practices: directional drilling practices.
49 CFR Part 196: excavation near gas and hazardous liquid pipelines, including reporting any pipeline damage to the operator and calling 911 on a release.

On the Map

Backreamer: enlarges the pilot hole for the product during pullback.
Swivel: keeps rod rotation from twisting the conduit.
Breakaway Link: the sacrificial link that breaks before any conduit is pulled past its safe pull strength; for a bundle, rated on a written basis or below the lowest single-conduit strength (step 4; a conservative fallback pending SME review).
Pulling Head or Grip: connects the pullback string to the conduit or bundle.
Conduit Reel and Trailer: pays out conduit in line with the bore; one reel per conduit for a bundle.
Exit Pit: where the pullback string is assembled.
HDPE Conduit: the product being pulled in, one conduit or several.
Tracer Wire and Test Point: the locatable wire pulled in with non-metallic conduit where the design specifies it.

Bore Planning Helper: suggest a backreamer size and estimate hole volume and drilling fluid for each pass. Set the number of conduits to estimate a bundle’s OD by tightest packing, or enter a measured bundle OD.

Safe pull strength comes from the conduit manufacturer. For a bundle, the breakaway link’s rating comes from a written basis from the conduit and pulling-head manufacturers or the engineer; without one, use the step 4 fallback: rate it below the lowest safe pull strength of any one conduit in the bundle.

UG-07 · Field Checklist

Checklist

0/9items ticked

Tick each procedure step and hold point as the crew completes it. Ticks stay on this device only. They are a personal aid, not a hold-point release or a project record; follow the owner’s sign-off process.

Procedure

Step 1: At the exit pit, remove the drill head. Assemble the pullback string per the tooling manufacturer, typically in this order: drill rod → backreamer → swivel → breakaway link → pulling head on the conduit or bundle.
Step 2: Size the backreamer for the product per the engineer or the manufacturer. A common rule of thumb is about 1.5 times the product's outside diameter.For a bundle, the product's outside diameter (OD) is the bundle's OD, not one conduit's. PPI's conduit note asks for a hole of at least 1.5 times the OD of the conduit or conduit bundle (PPI TN-63).The Bore Planning Helper estimates the bundle OD from the conduit count as the tightest packing. That is the smallest the bundle can be, so a reamer sized from it is the smallest you should use. Use a measured bundle OD or the manufacturer's figure when you have one.Some permits cap the hole size: per permit. Ask the permit owner how the cap applies to a bundle before you choose the reamer.
Step 3: Stage the conduit reel trailer in line with the bore, so the conduit pays out freely without sharp bends (PPI TN-63; conduit manufacturer instructions).For a bundle, stage every reel in line with the bore, so each conduit pays out evenly and none drags or kinks at the pit edge.Cap or plug every duct end, so drilling fluid and soil stay out.Pull tracer wire with the conduit if the design specifies it.
Step 4: Choose the breakaway link rating before you pull.One conduit: rate the link below the conduit's safe pull strength: per conduit manufacturer data.Bundle: the link carries the whole bundle's pull, but the pull may not split evenly. A conduit whose reel drags, whose harness leg is shorter, or that rubs harder in the hole carries more than its share. PPI ties the link rating to the conduit (PPI TN-63; Handbook of PE Pipe, Ch. 14).Bundle: get the rating basis in writing from the conduit and pulling-head manufacturers or the engineer: per the conduit and pulling-head manufacturers. Do not add the conduits' safe pull strengths together unless that written basis says you can.Bundle with no written basis: rate the link below the lowest safe pull strength of any one conduit in the bundle. That protects every conduit however the pull splits. If the link breaks on a normal pull, stop and get a written basis; do not fit a stronger link.One conduit maker applies the same idea to a different job: when several ducts of different sizes are pulled into an existing conduit, it limits the pull to the lowest published pull rating among the ducts. This is not an HDD rule.Bundle: connect the conduits with the pulling head or harness the manufacturers specify. PPI recommends a staggered pulling harness with a breakaway swivel when you pull several conduits (Handbook of PE Pipe, Ch. 14). In a staggered harness the conduit ends are offset in length, so the grips do not bunch up in one spot.
Step 5: Pull back at a steady rate.Monitor pullback force, fluid returns and every reel.The rig gauge shows the rig's pullback pressure, which includes the drag of the drill rods and reamer. It does not show the tension in the conduit, and it cannot show one conduit in a bundle taking more than its share (PPI Handbook of PE Pipe, Ch. 12 and 14). For small conduit, PPI's conduit note recommends a device that monitors pulling tension, such as an in-line tensiometer (PPI TN-63). Ahead of a bundle it reads the bundle's total, not each conduit's share.Watch that each conduit feeds at the same rate as the pull (PPI TN-63). If a reel binds or a conduit slows or lags, radio the drill operator to stop the pull (typical practice; follow owner spec and the drill operator's procedure). PPI TN-63 notes that a slowing feed can mean rising tension in that conduit, so it may be taking extra load and could be stretched past its safe pull strength. Free the reel only with the pull stopped, then restart smoothly.Keep radio contact between the drill operator and the reel crew.Avoid unplanned stops once the pull is moving: the hole can close in and grip the conduit, and restarting takes more pull than keeping it moving (PPI Handbook of PE Pipe, Ch. 12). Fix the cause of a stop before you restart.
Step 6: For large products or difficult soil, pre-ream in passes as the engineer directs.
Step 7: At the entry pit, inspect each conduit end for damage. Leave tails per owner spec, and re-seal the ducts.
Step 8: Let the conduit relax before you cut it to final length where the conduit manufacturer or owner requires it, so the stretch from pullback does not pull the tails back into the hole.

Hold Points

Hold PointStop and Verify the Pullback StringBefore pulling, check that the swivel turns freely, the breakaway link rating and its basis (the written basis, or the step 4 fallback for a bundle) are recorded for this conduit or bundle, the pulling head or harness matches the conduit size and count, and every duct end is sealed.

Records to Keep

Pullback force readings, if logged.
Conduit footage marks at each end, for each conduit.
Conduit count, size and color in the bore.
Breakaway link rating used, and its basis: the written basis, or the lowest single-conduit safe pull strength.
Reel IDs for each conduit placed.
Photos of the pullback string and the conduit ends.
Damage reports and owner notifications for any facility damaged, however minor.

Completed by		Signature
Checked by		Notes

UG-07 v1.0.0 · https://fahmy.io/underground/ug-07/ · Printed from FAHMY. Check the page for the current version before use. FAHMY is a reference, not a substitute for owner specifications, the authority having jurisdiction, manufacturer instructions, training or qualified supervision. Follow your employer's safety program and all applicable laws.

OSP Map · HDD Bore

On the Map

BackreamerTool pulled back through the pilot hole to enlarge it for the product.
SwivelRotating link that keeps the drill string’s rotation from twisting the conduit.
Breakaway LinkSacrificial link that breaks before the pull stretches any conduit past its safe pull strength.
Pulling Head or GripFitting that connects the pullback string to the conduit or conduit bundle.
Conduit Reel and TrailerReel on a trailer that pays out conduit in line with the bore during pullback.
Exit PitExcavation where the drill head surfaces and the pullback string is assembled.
HDPE ConduitContinuous plastic duct placed by boring, plowing or trenching to carry fiber underground.Drawn in the route profile
Tracer Wire and Test PointLocatable wire placed with non-metallic duct where specified (owner spec) and tested for continuity at each enclosure.Drawn in the route profile