Manual of XZ320 Horizontal Directional Drill
41
7.1.6 Ensure that mud can be jetted from all nozzles.
7.2 Re-expanding prompt
7.2.1 Strive to straighten drilling route during plan.
Inspect bending extreme of back towing materials for gradual bending.
Mud quality is important for re-expanding so it is required to know soil
quality, underground water, additive and mixed mud. Re-expanding needs
more mud by comparing with pivot hole drilling.
7.2.2 Definition of mud requirements
Re-expanding is not successful until there is sufficient mud. Required mud
consumption depends on dimension of re-expanding hole, drawn materials
and soil conditions.
The section is to describe how to define the minimum mud consumption
under ideal conditions. Mud consumption during actual construction shall
be larger than suggested consumption or re-expanding hole may be dry
and unsuccessful.
7.2.2.1 Define dimension of re-expanding hole and outer diameter of drawn
materials shall be defined and required mud consumption can be known
according to Appendix A.
For instance, a re-expanding hole of 15.2 cm (namely, 6 inches) needs at
least 19L/m (1
．
47 gallon/foot) while a back towing material of 7.6cm needs
at least 5L/m (0.37 gallon/foot).
7.2.2.2 Mud consumption required by every foot or meter of re-expanding
can be calculated by difference of mud consumption required by
re-expanding hole and volume of back towing materials. For instance,
drilling for 1m needs at least 14L mud (and every foot needs 1.1 gallons).
7.2.2.3 Mud consumption required by the hole can be estimated by
multiplying result by re-expanding length.
7.2.2.4 Pressure estimation
Required mud flow and pressure can be defined according to nozzle
diameter shown in Appendix B.
Actual mud flow and pressure relate to nozzle quantity of re-expanding
heads.
8 Disassembly of auger stem
Warning!Do not hold the head of auger stem or it may be
damaged. Hold the auger stem and strive to close to front jaw
vice (2) when connector is between wrenches. Please refer to
top-stm.ru
Summary of Contents for XZ320
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