ESAB ST-21 Manual

CAUTION
! !
These INSTRUCTIONS are for experienced operators. If you are not fully familiar with the principles
of operation and safe practices for arc welding equipment, we urge you to read our booklet, "Pre-
cautions and Safe Practices for Arc Welding, Cutting, and Gouging" Form 52-529. Do NOT permit
untrained persons to install, operate, or maintain this equipment. Do NOT attempt to install or
operate this equipment until you have read and fully understand these instructions. If you do not
fully understand these instructions, contact your supplier for further information. Be sure to read
the Safety Precautions on page 2 before installing or operating this equipment.
I. INTRODUCTION
The ST-21 (Part No. 995950EU) is a rugged all purpose,
water-cooled, manual MIG welding torch designed to
operate at welding currents up to 600 amperes contin-
uous duty using all types of shielding gases. The torch
utilizes a pistol grip design for convenient start-stop
welding control and easy handling, and its in-line type
construction allows all service lines to enter through
the torch barrel.
The ST-21 is intended for use with ESAB wire feeders
which have provision for water cooling and will han-
dle all types of welding wires from .035-in. diameter
through 3/32-in. diameter including flux cored wires.
Manual Number: 0-5629
Revision Date: 02-23-2022
Revision Number: AA
Language: ENGLISH
ST-21
MIG WELDING TORCH
II. DESCRIPTION
To provide maximum resistance to the abuses of day
to day service, the torch is of heavy duty construction
with all metal parts well insulated from current carrying
members. The in-line body and adjustable pistol grip
handle allows the ST-21 to be used in a variety of ap-
plications with easy maneuverability and comfortable
operation. The torch handle is easy to reposition along
the barrel to satisfy operator preference, and a trigger
lock incorporated in the grip enables the operator to
lock the trigger in a depressed position during long
welds.
To facilitate maneuverability, all service lines are inter-
nally connected to the torch body and exit from the
rear of the torch barrel.
The torch can use either threaded contact tips (long or
short) or slip-in contact tubes which are secured with
a collet nut supplied with the torch (see Table 2). The
contact tube can be quickly and easily replaced by un-
screwing the metal nozzle and collet nut, and removing
the tube. Five metal nozzles are available for use with
the ST-21; four for continuous fusion welding, and one
for spot welding applications. Nozzle sizes 8 and 10,
require a spatter liner. The water-cooling requirements
for the ST-21 are described in Section VI.
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