# What a Point-Repair Jack Does Before the Final Repair

Canonical: https://reliancetrenchless.com/en-AU/blog/point-repair-jack-role

Published: 2026-10-21 · Updated: 2026-10-21 · By Reliance Trenchless

How a trenchless point-repair jack re-rounds deformed pipes, resets displaced joints, and prepares sewer bores before lining or sleeve installation.

When a CCTV inspection crawler encounters a deformed pipe crown, an offset joint, or an inward crushing failure, contractors often assume the only choices are costly open-cut replacement or forcing an inflatable packer through the obstruction. Attempting to force a standard repair packer or mechanical sleeve into a severely restricted bore frequently leads to jammed equipment, torn bladders, or uneven resin distribution.

The [Reliance Point-Repair Jack](https://reliancetrenchless.com/en-AU/products/point-repair-jack) serves a precise, dedicated function: it is a robotic pre-treatment tool that enters the damaged pipe, exerts controlled vertical or angular hydraulic thrust, and re-rounds the deformed cross-section before any permanent lining or sleeve installation begins. As shown in our demonstration on the [Reliance Point-Repair Jack YouTube Feature](https://www.youtube.com/watch?v=V6BhM6X3oZg), this hydraulic device lifts sagging pipe crowns from DN150 up to DN600, clearing the internal bore so downstream trenchless rehabilitation can proceed without obstruction.

## The mechanical task: Re-rounding and alignment vs permanent structural repair

A critical technical distinction in pipeline asset management is separating preparatory mechanical reshaping from permanent structural rehabilitation. According to defect classification criteria in [NASSCO PACP Guidelines](https://www.nassco.org/trenchless-technology/assessment), structural cross-sectional reduction exceeding 10% prevents reliable passage of cleaning nozzles, cutters, and standard CIPP inversion plugs.

![Three-stage workflow comparing pipe defect deformation, hydraulic jack pre-treatment, and permanent trenchless repair lining.](https://reliancetrenchless.com/assets/img/Blog/point-repair-jack-role/jack-pretreatment-vs-final-repair.svg)

**Pre-treatment vs permanent lining stages:** The hydraulic jack restores roundness and clears the bore, but does not provide permanent structural sealing. Final stiffness is delivered by an Instant-Lock sleeve or cured-in-place patch.

A hydraulic point-repair jack acts strictly during the pre-treatment phase:

1. **Restoring Internal Clearance:** By applying concentrated vertical force between 50 kN and 150 kN against the crown and invert, the jack pushes pushed-in fragments or sagging thermoplastic pipe walls back into nominal circular alignment.
2. **Realigning Displaced Joint Steps:** At faulty bell-and-spigot joints where soil settlement has caused a vertical offset step, the jack's curved contact shoes straddle the invert to bring adjacent pipe barrels back into concentricity.
3. **Crucial Operational Rule:** The hydraulic jack does not provide permanent structural sealing. Once hydraulic pressure is relieved and the jack is withdrawn, unreinforced fractures will eventually settle again under soil overburden. Permanent ring stiffness must be delivered immediately following jacking by installing an [Instant-Lock Internal Repair Sleeve](https://reliancetrenchless.com/en-AU/products/instant-lock-sleeves-small) or an ambient-cured fiberglass resin patch installed on a [Sectional Repair Packer](https://reliancetrenchless.com/en-AU/products/repair-packers).

## Kinematic mechanisms: Up-down direct lift vs duck-billed scissor spreader

Depending on the defect geometry and entry access, point-repair jacks operate through two distinct mechanical configurations:

![Kinematic comparison between up-down linear hydraulic rams and duck-billed scissor spreading mechanisms.](https://reliancetrenchless.com/assets/img/Blog/point-repair-jack-role/up-down-vs-duck-billed-mechanisms.svg)

**Jack kinematics and geometry:** Direct up-down cylinders concentrate maximum vertical force (up to 150 kN) for crown sag, while duck-billed scissor jaws enter ultra-tight restrictions to pry open collapsed pipe fissures.

### 1. Up-down linear hydraulic ram

The up-down configuration utilizes a heavy-duty vertical hydraulic cylinder mounted on an axial wheeled chassis. Curved steel contact saddles are machined to match the inner radius of the target pipe diameter (e.g., DN200, DN300, DN400, or DN600).

- **Thrust Profile:** Delivers direct, pure linear thrust up to 150 kN perpendicular to the pipe axis.
- **Primary Application:** Flattened pipe crowns, localized vertical ovality in flexible pipes (HDPE, PVC, ductile iron), and high-load joint step realignment where maximum concentrated vertical force is required.

### 2. Duck-billed scissor spreader

The duck-billed configuration features tapered, low-profile jaw shoes actuated by an internal toggle or scissor linkage.

- **Thrust Profile:** Converts axial piston stroke into outward angular expansion.
- **Primary Application:** Severe bottleneck restrictions where cross-sectional loss exceeds 30% and an up-down cylinder cannot enter. The tapered wedge-shaped nose wedges into tight cracks or joint gaps, prying them open incrementally to restore sufficient bore for subsequent passes.

## Pipe material boundaries and engineering limits

Before deploying a hydraulic point-repair jack into an underground pipeline, engineering teams must review pipe material ductility and surrounding soil support:

- **Ductile Iron, Steel, and Thermoplastics (HDPE / PVC):** Excellent candidates for hydraulic re-rounding. These materials can absorb plastic deformation without catastrophic shattering, allowing the jack to push out dents and hold the restored diameter while an internal stainless steel sleeve is locked into place.
- **Vitrified Clay (VCP) and Asbestos Cement:** Brittle materials cannot undergo plastic re-rounding. Applying high hydraulic point loads directly to a cracked clay pipe will cause longitudinal fracturing. On brittle host pipes, the jack must only be used with oversized cushioned contact shoes to nudge displaced fragments back into alignment, never to force an undersized bore wider.
- **Reinforced Concrete Pipe (RCP):** High structural strength requires verifying that reinforcement cage corrosion has not compromised structural integrity. If circumferential steel rebar is snapped, jacking must be performed in small pressure increments to prevent wall collapse.

Quality rehabilitation designs referenced in [ASTM F1216](https://doi.org/10.1520/F1216-22) and [BS EN 13566-4](https://standards.iteh.ai/catalog/standards/cen/b9d4df99-b13c-41ce-bb41-2a628aeb1d1e/en-13566-4-2002) emphasize that host pipe geometry directly influences the long-term buckling resistance of internal structural liners. Pre-treating severe ovality with a point-repair jack prevents catastrophic liner wrinkling and guarantees uniform annular contact.

## Project documentation to submit before jacking

To configure the correct jack tonnage, wheel carriage, and contact saddle radius for your project, prepare the following pipeline parameters:

- **CCTV Survey Footage:** High-resolution video or continuous pan-and-tilt logs detailing the exact meterage, ovality percentage, and crack orientation.
- **Host Pipe Specifications:** Exact internal diameter, nominal wall thickness, and host pipe material.
- **Access Shaft Dimensions:** Smallest manhole opening diameter, depth to invert, and benching angle to verify insertion clearance.
- **Selected Downstream Repair System:** Whether the final structural rehabilitation will utilize sectional fiberglass-resin patches or mechanical stainless steel sleeves.

Consult the technical specifications in the [Reliance Point-Repair Jack Brochure](https://reliancetrenchless.com/assets/doc/brochures/Reliance%20Point-Repair%20Jack%20Brochure.pdf), review our [Sewer Point Repair Equipment Checklist](https://reliancetrenchless.com/en-AU/resources/sewer-point-repair-equipment-checklist), or submit your pipe inspection data through the [Point-Repair Project Enquiry Form](https://reliancetrenchless.com/en-AU/contact#product=ReliancePointRepairJack) for specialized technical support.

## References and source documents

- [Reliance YouTube — Point-Repair Jack for Deformed Sewer Pipe, DN150–600 Hydraulic Lift](https://www.youtube.com/watch?v=V6BhM6X3oZg)
- [NASSCO — Pipeline Assessment Certification Program (PACP) Defect Identification](https://www.nassco.org/trenchless-technology/assessment)
- [ASTM F1216: Standard Practice for Rehabilitation of Existing Pipelines by Inverted Cured-in-Place Resin Tube, DOI: 10.1520/F1216-22](https://doi.org/10.1520/F1216-22)
- [BS EN 13566-4: Plastics piping systems for renovation of underground non-pressure drainage and sewerage networks](https://standards.iteh.ai/catalog/standards/cen/b9d4df99-b13c-41ce-bb41-2a628aeb1d1e/en-13566-4-2002)
- [Reliance Point-Repair Jack Brochure — Hydraulic lift ratings and dimensional tables](https://reliancetrenchless.com/assets/doc/brochures/Reliance%20Point-Repair%20Jack%20Brochure.pdf)