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The rupture strength of HDPE pipes is 2.5 times the allowable tensile strength [DVGWGW323].

The cross sectional area of a pipe section used as overload protection may only amount to 40 % of the cross sectional area of the new pipe being pulled in.

(Image: Overload protection in form of a predetermined breaking point by reduction of the wall thickness)

(Table: Example calculation of an overload protection for HDPE 100 used in pipe bursting)

Illustrated example of the steps involved in the manufacturing of the overload protection in the form of a predetermined breaking point.

(Image: Step 1: New pipeline)
(Image: Step 2: Wall thickness reduction)
(Image: Step 3: Welding on of the overload protection)
(Image: Step 4: Removing the weld seam)

A cross section reduction is obtained by reducing the effective circumference of the pipe or the effective cross-sectional area.

(Image: Overload protection in form of a predetermined breaking point by reduction of the effective pipe circumference)

(Table: Overload protection)

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May 13, 2020

Modules

This module focuses on the pipe bursting method as a special method of replacing gas, water, and wastewater pipelines in the same alignment. In addition to the functional principle, the requirements on materials and equipment are presented in detail.

After completing this module, you will have a sound knowledge of:

  • variants of pipe bursting methods;
  • effects of the bursting method on the surrounding area;
  • methods of tensile force monitoring or limitation.

This lecture deals with the fundamentals of trenchless replacement of supply and disposal lines by means of gallery techniques (heading).

Definition according to DIN EN 752

Replacement:
Construction of a new drain or sewer, on or off the line of an existing drain or sewer, the function of the new drain or sewer incorporating that of the old [EN752:2008].

The replacement is always carried out at least in section lengths of the sewer using:

  • The open cut method ;
  • The semi open cut method ;
  • The trenchless method.
(Image: Replacement of sewers using the open cut method)
(Image: …

(Image: Overview of replacement methods in trenchless construction)

During gallery techniques or heading, the sewer or pipeline to be replaced is exposed, with the provision of a temporary protection, dismantled and replaced by a new one. The removal of the soil and the sewer or pipeline to be replaced is carried out manually with the aid of appropriate tools or machines e.g. excavators. Support arches of steel rods or special steel profiles that are placed into the gallery cross-section provide temporary support. …

Shuttering
The term shuttering is taken from the mining area and describes the lining of the space between the individual lining elements (support arches). Steel (steel shuttering) as well as wood (wood shuttering) can be used for the shuttering process.

Support arch
The support arches serve to reinforce the gallery. Above the support arches, at the working face, the wood or steel shuttering is pushed into the soil starting from the crown.

European standards:

DIN EN 752: Drain and sewer systems outside buildings (04/2008)

DIN EN 1610: Construction and testing of drains and sewers (10/1997)

The gallery techniques or heading requires the application of the following material, equipment and plants:

  • support arches
  • shuttering
    • wood shuttering
    • steel shuttering
  • machines for hammering in shutterings
  • machines for the removal and transport of soil
  • ventilation devices

(Image: Support arches (special steel profile) to protect the gallery) (Image: Steel shuttering) (Image: Converted mini-excavator with conveyor belt) (Image: Diffuser fan …

May 27, 2019

Modules

This module focuses on the fundamentals of the trenchless replacement of gas, water, wastewater pipelines using the gallery techniques known from the mining industry. In addition, the individual steps of the gallery heading process with steel and timber support are described - from the preparatory measures to the final work. In addition, the areas of application and limitations of gallery heading, the measures for quality assurance as well as the advantages and disadvantages of this method are presented.

After completing this module, you will have a sound knowledge of:

  • characteristics of gallery heading;
  • working steps of this form of heading;
  • relevant aspects for quality assurance.

This lecture deals with the different procedure steps of gallery techniques (heading) with steel and wood shuttering, from preparation to finished work.

The procedure is subdivided into the following working steps:

(Image: Question) (Image: Question) (Image: Question)

The procedure is subdivided into the following working steps:

Preparatory work

(Image: Construction site)

Construction

(Image: Gallery technique (heading))

Finishing work

(Image: Leaktightness)
(Image: Construction site)

The preparatory work comprises the following steps:

  • Construction site arrangement (including traffic control / traffic direction)

  • Excavation of the starting pit. A target pit is not necessary in gallery heading

  • Setting of measuring points for the geotechnical measurements before and during the jacking process (quality assurance)

  • Groundwater lowering (if groundwater is existent)

In gallery techniques or heading, the starting pit can be placed outside the run of the sewer, which prevents traffic disruptions. An example of this is shown in the illustration. In this case, the actual working galleries are reached by means of lateral galleries. Target pits are not necessary.

(Image: Arrangement of a starting pit on a green traffic island using gallery techniques (heading) with reference to [Scher77b] [Image: S&P GmbH])