April 06, 2021

Pipe Bursting and Splitting

Pipe bursting and pipe splitting are trenchless methods used to replace existing pipelines with PE100 in the same alignment without physically removing the existing pipeline. Bursting and splitting, by using the existing alignment to replace a pipe, avoids the need to secure any additional right-of-way to install the PE100 replacement pipe. Bursting and splitting can be used to upsize the pipeline thereby increasing its flow capacity if this is necessary.​

Pipe bursting is used to replace brittle pipes such as clay, asbestos cement, concrete and cast iron by pulling through the host pipe a static or dynamic bursting head to fragment the existing pipe and an expander cone, sometimes incorporated in the bursting head, to push the fragments outwards into the surrounding ground. Simultaneously, a new PE100 pipe attached to the back of the bursting head is installed in the same alignment as the original pipe.

Pipe splitting is used to replace ductile pipes such as steel, ductile iron and plastics through cutting them into segments along their length using an internal head with cutter blades. As with pipe bursting a new PE100 pipe attached to the back of the cutting head is installed in the same alignment as the original pipe.

There are three methods of pipe bursting: pneumatic, hydraulic, and static pull. The difference between them is in the source of energy and the method of breaking the old pipe. Pneumatic and hydraulic methods use dynamic force to break the old pipe whereas static pull uses a constant pull force. The selection of a specific method depends on soil conditions, groundwater conditions, degree of upsizing required, type of new pipe, construction of the existing pipeline, depth of the pipeline and availability of experienced contractors with suitable equipment. Static pipe bursting has replaced pneumatic bursting as the most commonly used variant primarily because of the absence of shock waves generated by a dynamic burster, which can cause damage to adjacent buried utilities.Pipe splitting is necessarily a static pull method.​  

PIPE BURSTING / SPLITTING - PE100 APPLICATIONS for more details of pulling processes.The rod puller is then operated slowly until the burster/spitter head is safely inside the old main, after which it can be operated at its normal speed until the burster/splitter head emerges at the rod puller.The continuous display and recording of the pulling force on the  at the winch is important in order to ensure that it cannot be subjected to and damaged by excessive pulling forces. In some countries (Germany, Spain & UK) the tensile forces on the new pipe must be monitored throughout the pipe bursting/splitting process. Measurement of tensile force is not feasible with dynamic pipe bursting methods so a weak link can be incorporated at the pulling head; this is normal practice in the US gas industry, for example. The weak link will fail under high tension thus providing overload protection but precautions should be taken to arrest the winch wire which may fly at high speed into, and if not contained possibly out of, the exit excavation.

PIPE BURSTING / SPLITTING - EQUIPMENT
The main equipment used in pipe bursting and splitting is the burster/splitter head, an expander which may be incorporated into the burster/splitter head, pulling rods, a rod puller or winch and a hydraulic power pack. All dynamic and static burster heads incorporate cutting blades or cutting roller discs to concentrate the cutting forces Today's static heads have a leading end much smaller in diameter than the trailing (bursting) end, small enough to fit through the pipe that will be replaced. This guides the expander head through the existing pipe; it may also include "fins" that make first contact with the existing pipe. Using these fins as the primary breaking point is a very effective way to ensure that the pipe is broken along the entire circumference. All of the equipment used in a pipe bursting operation is powered by one or multiple hydraulic power generators.For small diameters of brittle pipe material, such as cast iron or asbestos cement, the head is usually a simple blade and cone, such as these:

PIPE BURSTING / SPLITTING - PE100 APPLICATIONS for more details of pulling processes.The rod puller is then operated slowly until the burster/spitter head is safely inside the old main, after which it can be operated at its normal speed until the burster/splitter head emerges at the rod puller.The continuous display and recording of the pulling force on the  at the winch is important in order to ensure that it cannot be subjected to and damaged by excessive pulling forces. In some countries (Germany, Spain & UK) the tensile forces on the new pipe must be monitored throughout the pipe bursting/splitting process. Measurement of tensile force is not feasible with dynamic pipe bursting methods so a weak link can be incorporated at the pulling head; this is normal practice in the US gas industry, for example. The weak link will fail under high tension thus providing overload protection but precautions should be taken to arrest the winch wire which may fly at high speed into, and if not contained possibly out of, the exit excavation.

PIPE BURSTING / SPLITTING - EQUIPMENTThe main equipment used in pipe bursting and splitting is the burster/splitter head, an expander which may be incorporated into the burster/splitter head, pulling rods, a rod puller or winch and a hydraulic power pack. All dynamic and static burster heads incorporate cutting blades or cutting roller discs to concentrate the cutting forces Today's static heads have a leading end much smaller in diameter than the trailing (bursting) end, small enough to fit through the pipe that will be replaced. This guides the expander head through the existing pipe; it may also include "fins" that make first contact with the existing pipe. Using these fins as the primary breaking point is a very effective way to ensure that the pipe is broken along the entire circumference. All of the equipment used in a pipe bursting operation is powered by one or multiple hydraulic power generators.For small diameters of brittle pipe material, such as cast iron or asbestos cement, the head is usually a simple blade and cone, such as these:      

PIPE BURSTING / SPLITTING - PE100 APPLICATIONS for more details of pulling processes.The rod puller is then operated slowly until the burster/spitter head is safely inside the old main, after which it can be operated at its normal speed until the burster/splitter head emerges at the rod puller.The continuous display and recording of the pulling force on the  at the winch is important in order to ensure that it cannot be subjected to and damaged by excessive pulling forces. In some countries (Germany, Spain & UK) the tensile forces on the new pipe must be monitored throughout the pipe bursting/splitting process. Measurement of tensile force is not feasible with dynamic pipe bursting methods so a weak link can be incorporated at the pulling head; this is normal practice in the US gas industry, for example. The weak link will fail under high tension thus providing overload protection but precautions should be taken to arrest the winch wire which may fly at high speed into, and if not contained possibly out of, the exit excavation.

PIPE BURSTING / SPLITTING - EQUIPMENTThe main equipment used in pipe bursting and splitting is the burster/splitter head, an expander which may be incorporated into the burster/splitter head, pulling rods, a rod puller or winch and a hydraulic power pack. All dynamic and static burster heads incorporate cutting blades or cutting roller discs to concentrate the cutting forces Today's static heads have a leading end much smaller in diameter than the trailing (bursting) end, small enough to fit through the pipe that will be replaced. This guides the expander head through the existing pipe; it may also include "fins" that make first contact with the existing pipe. Using these fins as the primary breaking point is a very effective way to ensure that the pipe is broken along the entire circumference. All of the equipment used in a pipe bursting operation is powered by one or multiple hydraulic power generators.For small diameters of brittle pipe material, such as cast iron or asbestos cement, the head is usually a simple blade and cone, such as these:​

PIPE BURSTING / SPLITTING - PRACTICALITIES are available to reduce this riskSoil Types and their effectsIn order to ensure successful pipe bursting/splitting works it is essential to know the ground conditions. The method displaces fragments of the existing pipe into the soil and thus is most appropriate for compressible soils. Ground conditions suitable for pipe bursting/splitting include clays, silt, generally soft cohesive material. Loose and medium sands and gravels are also feasible.Diameter, pressure and Length RangeFor pressure pipes and services pipe bursting and pipe splitting can be used in diameters from 50mm to 800mm and over lengths of up to 200 metres in a single pull. These are the limits of the system and there is a trade-off between diameter and length with upsizing also an important factor in determining the practicality and length possible.
Pressure is a function of the SDR of the installed PE100 pipe
EXCAVATIONSDESIGN, SPECIFICATION & PLANNING
Design

Fluid design for capacity of new pipeline to determine diameter needed.Select SDR based on operating pressureCheck tension load capacity during pull-in
Specification

Specify maximum allowable tensile load during pull-in
Specify end fittings and service connection details.
Specify coated PE100 pipe if necessary
Planning

The suitability of employing pipe bursting depends on numerous factors including burst length, host pipe material, upsize diameter, and geological conditions. Potable water replacement projects typically involve installing new lines of 90mm, 180mm, 200 mm, 250 mm, or 300 mm between valve locations. Gas mains also are frequently upsized using pipe bursting/splitting. Size-for-size replacement is also commonplace for both water and gas. Where upsizing is required it is most commonly by one or two pipe sizes, for example from 150 to 200 mm, 200 mm to 250 mm or 250 to 300 mm. Upsizing by more than this requires considerable planning and experience on the part of the contractor.

As the old main is to be destroyed, its internal and structural condition are of no consequence, but the pipe material, class, and diameter must be known to ensure that the correct bursting head and expansion cone are selected, and that the pulling equipment can provide sufficient force.The route of the old main should be carefully traced and examined for bends that could cause the burster to get stuck, and any bend that is located should be trial holed to determine if it needs to be cut out prior to the insertion. Pit location at such bends may be advisable. Pit locations in general should take into account maximum feasible lengths for the diameter, upsizing and soil conditions expected.

If there are connections along the route, as there would be in a local distribution main, then all such connections should be accurately located as they will need to be cut out before the bursting starts.Equipment selection is critical to the success of pipe bursting and splitting. The following Table gives an indication of winch/rod puller capacities necessary for a range of host pipe sizes. Note again that these are winch capacities and are based on tensile force required to pull the bursting/splitting head through the host pipe being burst/split. They are not representative of the tensile load on the PE100 pipe itself which is limited to much lower levels. PE100 pipe manufacturers’ literature provides the maximum allowable tensile loads on pipes.

EXCAVATIONS
See also Excavations, pit sizes, Space and Access
DESIGN, SPECIFICATION & PLANNING
Design
- Fluid design for capacity of new pipeline to determine diameter needed
- Select SDR based on operating pressure
- Check tension load capacity during pull-in

Planning
The suitability of employing pipe bursting depends on numerous factors including burst length, host pipe material, upsize diameter, and geological conditions. Potable water replacement projects typically involve installing new lines of 90mm, 180mm, 200 mm, 250 mm, or 300 mm between valve locations. Gas mains also are frequently upsized using pipe bursting/splitting. Size-for-size replacement is also commonplace for both water and gas. Where upsizing is required it is most commonly by one or two pipe sizes, for example from 150 to 200 mm, 200 mm to 250 mm or 250 to 300 mm. Upsizing by more than this requires considerable planning and experience on the part of the contractor.

As the old main is to be destroyed, its internal and structural condition are of no consequence, but the pipe material, class, and diameter must be known to ensure that the correct bursting head and expansion cone are selected, and that the pulling equipment can provide sufficient force.The route of the old main should be carefully traced and examined for bends that could cause the burster to get stuck, and any bend that is located should be trial holed to determine if it needs to be cut out prior to the insertion. Pit location at such bends may be advisable. Pit locations in general should take into account maximum feasible lengths for the diameter, upsizing and soil conditions expected.

If there are connections along the route, as there would be in a local distribution main, then all such connections should be accurately located as they will need to be cut out before the bursting starts.Equipment selection is critical to the success of pipe bursting and splitting. The following Table gives an indication of winch/rod puller capacities necessary for a range of host pipe sizes. Note again that these are winch capacities and are based on tensile force required to pull the bursting/splitting head through the host pipe being burst/split. They are not representative of the tensile load on the PE100 pipe itself which is limited to much lower levels. PE100 pipe manufacturers’ literature provides the maximum allowable tensile loads on pipes.

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