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18/8-321 N

Unitor 18/8-321 N is a rutile basic type electrode for welding stainless and acid resistant steel containing 16–18% chromium, 10–14% nickel and 2–3% molybdenum.

It is suitable for all welding positions. When welding tanks containing corrosive elements, it must be remembered that the final bead must be laid on the side exposed to corrosion, to prevent intercrystalline corrosion. The electrode will operate on AC or DC polarity. It is always preferable to use DC positive when welding stainless or acid-resistant steel.

Use a brush with stainless steel wire bristles when cleaning up the weld. If an ordinary wire brush is used, iron oxides will be deposited in scratches left by the brush, as this can lead to corrosion. The dark oxide deposit formed on either side of the bead should also be removed. Best result is obtained using Unitor Pickling Gel to remove discolouration and oxides after welding. For welding stainless/ acid-resitant steel to low alloy steel, use Unitor electrode 23/14-322 N.

Welding:

1. Use a short arc. A long arc will increase arc tension, resulting in lower current output and poor fusion.

2. The electrode should be held almost at right angles to the work piece.

3. When terminating the weld, the elec­ trode should be move in a circle over the molten pool and finally moved quickly backwards in the groove for a distance of approx.10 mm. The formation of a pore containing high melt point slag in the middle of the crater is thereby avoided.

2nd run

1st run

Welding piping and flanges.

3.01

4. The electrode must be protected against humidity and welding with damp electrodes should not be attempted.

A stainless steel electrode should have the same alloy composition as the base material, but there are certain exceptions. An electrode of high alloy content may be used for welding material which has a slightly lower alloy content than the electrode.

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