When Is Double Wall Casing Need? 800mm Double Wall Casing
详细信息
Double-wall casing is selected when the structural integrity of the borehole or the casing itself is at risk. While single-wall casing is lighter and cheaper, it lacks the rigidity required for the most demanding geotechnical environments.You generally need double-wall casing in the following four scenarios:
1. High-Torque and High-Pressure Conditions
When drilling deep into dense soils or rock, the friction against the outside of the casing becomes immense.
Torque Resistance: Double-wall casing has a much higher section modulus. It can withstand the massive twisting force (torque) of a rotary rig or casing oscillator without "corkscrewing" or buckling.
Side Friction: In deep bores (often exceeding 20-30 meters), the "grip" of the soil on the casing is so strong that a single-wall pipe might tear or collapse during extraction.
2. Use of Casing Oscillators or Rotators
If the project requires a hydraulic casing oscillator, double-wall is almost always mandatory.
The oscillator grips the casing with massive hydraulic pressure to twist and push/pull it.
A single-wall casing would likely be crushed or severely dented by the oscillator's clamping collar, whereas the double-wall structure provides the necessary "crush resistance" to maintain its shape.
3. Unstable or Water-Bearing Soils (Hydrostatic Pressure)
In coastal areas or sites with high water tables, the external pressure from water and "soupy" soil can be significant.
Collapse Prevention: As you pump out the soil from inside the casing, the external pressure tries to collapse the tube inward. The reinforced ribs between the inner and outer shells of a double-wall pipe act as a bridge, preventing this "implosion."
Watertight Seals: Double-wall joints (like the Bauer-type screw joints) are designed to be more watertight, keeping the borehole dry for a clean concrete pour.
4. Working with Large Diameters and "Hammer Grabs"
When using a hammer grab (a heavy mechanical jaw dropped into the hole to remove soil), there is a high risk of the tool striking the inside of the casing.
Internal Impact: In a single-wall casing, a strike from a heavy grab can cause a "bulge" or dent that protrudes outward. This makes it extremely difficult to continue drilling or to extract the casing later.
The Buffer Zone: In a double-wall system, the inner wall protects the outer structural wall. Even if the inner wall takes a minor dent, the outer shell remains perfectly circular, ensuring the casing can still be pulled out of the ground successfully.
Summary Comparison
| Feature | Single-Wall | Double-Wall |
| Best For | Short piles, easy soil, low budget | Deep piles, high torque, oscillators |
| Soil Type | Stable clays, dry sand | Boulders, loose gravel, high water |
| Weight | Low (easier transport) | High (requires heavier cranes) |
| Durability | Moderate (prone to denting) | High (very rigid) |
800/720MM double wall casing with bauer-screw joint used bauer-bg28 rotary drill rig for cased bored pile foundation work
800mm double wall casing pipe with bauer-screw joint used on bauer-bg24 rotary drill rig for secant pile foundation work
800mm casing oscillator use heavy duty double wall casing used on bauer-bg26 rotary drill rig for cased bored pile foundation work
800/720mm double walled casing with bauer-screw connections used on bauer-bg33 rotary drill rig for drill shaft construction
800mm forge joint double wall casing with bauer-screw joint used on bauer-bg36 rotary drill rig for cased bored pile foundation work
800mm segmental casing pile with bauer-screw joint used on bauer-bg20 rotary drill rig for secant pile foundation work
800mm casing rotator use heavy duty double wall casing used on bauer-bg40 rotary drill rig for bored pile foundation work
The joints are made of 25CrMo forgings, which are wear-resistant and not suitable for deformation. The pipe body is Q345B, bolt 42CrMo material, high strength, high torque resistance. The joint bolts are double-row holes. Longer and thicker joints, suitable for high torque drilling
double walled Casing are used to stabilize the borehole wall and to maintain the verticality or to maintain the required angle in the case of inclined drilling, casings are double walled and are offered in various diameter and length ,when use casing oscillators or casing rotators , cased boreholes of more than 80m can be installed
Casings are available in lengths of 1m,2m, 3m, 4m,5m, 6m
Other diameters available on request
Cutting shoe with exchangeable blocks
exchangeable blocks have the advantage that they can be quickly replaced during operation without altering the cutting geometry of the cutting shoe , the overcut can be altered depending on the various types of teeth
Available in the following length 0.5m.1m.2m
Cutting shoe with weld-on blocks
Casing drivers
The casing driver is attached to the cardan joint on the rotary drive and is the connecting element to the casing , if the casing drive and the casing are bolted , the casings can be rotated or extracted
Available range of diameters 620 to 2,500 mm
Featurs
Tianjin Huachang Xingye Technology Co., Ltd. (often operating under the brand TJ Drilling) is a major Chinese manufacturer specializing in foundation drilling tools. Their double-wall segmental casing is widely used in global markets and is compatible with major rig brands such as Bauer-bg, Soilmec, Casagrande, San-y, and XC-MG.
Below are the detailed technical specifications and features for their double-wall casing systems.
1. Technical Design & Materials
TJ Drilling focuses on high-torque resistance and wear durability for deep foundation work in difficult soils.
Joint Material: Precision-forged 25CrMo or 42CrMo alloy steel. These are heat-treated to prevent deformation under the extreme clamping forces of oscillators.
Pipe Body: Constructed from high-strength structural steel, typically Q345B (equivalent to S355).
Internal Structure: The inner and outer shells are connected by high-density longitudinal ribs. For OD 620-1300mm, the inner tube thickness is typically 12mm; for OD 1500-1800mm, it increases to 16mm.
Connection: Conical screw joints with double-row bolt holes to ensure a watertight seal and maximum torque transfer.
2. Standard Specification Range
