Hypertherm XPR300, Instruction Manual

Page: 217 / 402

Operation
6
XPR300 Instruction Manual 809480 217
Processes for special applications
Underwater cutting
Underwater cutting can suppress the noise, smoke, and glare that plasma cutting produces.
Underwater cutting also decreases the heat-affected zone on the workpiece. On mild steel, it also
decreases cutting speeds and produces a rougher cut edge with increased dross.

You can expect the noise levels to average less than 70 decibels for many
processes during underwater cutting of metals that are up to 75 mm
(3 inches) below the water surface.
Make sure to satisfy the following conditions before you do underwater cutting:

Do not cut under water with fuel gases that contain hydrogen. It can cause an explosion.

Do not cut aluminum alloys under water or on a water table, unless you have installed the
correct safety equipment from your table manufacturer or cutting machine supplier.

Consult with your cutting machine supplier, the table manufacturer, and other experts prior
to cutting aluminum to implement a risk assessment and mitigation plan that eliminates the
risk of detonation by preventing hydrogen accumulation.

Do not cut a workpiece that is more than 75 mm (3 inches) below the surface of the water.
It can negatively affect cutting system performance.

Do not use True Hole ® processes underwater. True Hole processes are not compatible with
underwater cutting.

True Hole cutting on a water table is possible only if the surface of the
water is lowered to at least 25 mm (1 inch)
below the bottom surface of
the workpiece. For information about True Hole processes, contact your
cutting machine supplier or regional Hypertherm Technical Service team.

Make sure that the torch is perpendicular (at a 90° angle) to the workpiece.
WARNING
Underwater cutting with fuel gases or aluminum can create an explosion
hazard.
• Do NOT cut under water with fuel gases that contain hydrog en.
• Do NOT cut aluminum alloys under water or on a water table, unless you
can prevent the accumulation of hydrogen gas.
Doing so can result in an explosion during cutting system operation.