For diva safety use only Ctype clamps for grounding during both cutting and welding

The clamp must be firmly secured to the work piece for the arc-striker plate when cutting nonconducting materials. The diver may elect to lightly tack weld the clamp in place where there is a possibility that it may work loose.

When cutting or melting nonconductive materials, such as concrete, rock, coral, mastic, rope, or marine growth, a striker plate is necessary to strike an arc. This metal plate is connected to the ground cable and placed next to the material to be cut. If the rod ignition is lost, the rod is relit from the striker plate by repeating the ignition procedure. Each subsequent rod must be lit from the striker plate in the same manner.

The BROCO 1/4-inch ultrathermic rod may be used for steel up to 1/2 inch thick for maximum cutting economy. The 1/4-inch rod leaves a narrow kerf and is preferred for line cutting. However, in bad visibility or for heavier steels, the 3/8-inch rod will give higher production. For materials 1/2 inch thick and over, the 3/8-inch rod is preferred. For materials several inches thick, saw and wedge cutting (analogous to chopping a tree with an axe) may be necessary to make entry space for the cutting process.

wRule-of-thumb" estimates for rod diameter versus plate thickness and length of cut per rod for an experienced operator are given in Table 2-13.

_ The oxygen flow rate is determined by the regulator pressure, bottom depth, and pressure losses in the lines. While oxygen flow rate is usually not critical for successful cutting, it is more critical for thicker materials. Thus, a higher psi is required to ensure the molten slag is blown away, otherwise the rod will be snuffed out as the rod is pushed into the cut. Satisfactory cutting can be performed within a fairly wide range of oxygen flow. However, a low flow rate (low pressure) may slow down the operation and require more diver attention, tiring the diver. A high flow rate (high pressure) may needlessly tire the diver by creating excessive reaction force at the nozzle.

Recommended pressure settings for the oxygen regulator are listed in Table 2-14.

Based on a standard oxygen cylinder of 244 ft3 at a pressure of 2,200 psi, one cylinder will be consumed for each 15 to 20 3/ 8-inch-diameter (18-inch-long) rods consumed.

The ultrathermic electrode will melt cast iron, stainless steel, and nonferrous metals. For these materials the length of cut per rod is reduced from that given in Table 2-13. When cutting these materials, the tip must be firmly buried in the work.

Table 2-13

Length of Cut for BROCO Ultrathermic Electrodes

Table 2-13

Length of Cut for BROCO Ultrathermic Electrodes

Rod Diameter

Plate Thickness

Length of Cut Per Rod

(in.)

(in.)

(in.)*

1/4

1/4

20 to 25

Was this article helpful?

0 0

Post a comment