January 10, 2002
This article provides tips for safe oxyfuel cutting and welding. It offers specific practices for using cylinder valves, regulators, hoses, tips, and torches.
Research, development, and field experience have resulted in the evolution of reliable equipment and safe installation, operation, and servicing practices. However, accidents can occur when equipment is improperly used or maintained. Most safe practices are based on common sense, while others may require technical volumes to explain. The following tips will help you use your oxyfuel equipment properly and safely.
Gas cylinders always should be upright and fastened securely to a wall, welding cart, or similar structure to keep them from tipping over. The fasteners must be made of nonflammable material.
Before attempting to attach the regulator to the cylinder valve, turn the valve opening away from you, open it slightly, and then close it. This should remove any loose dirt from the valve opening that could damage the regulator inlet nipple.
Remember, the valve opening and the inlet nipple should be shiny and clean inside and outside. This is particularly important for the oxygen cylinder. Oil or grease in the presence of oxygen is flammable or even explosive. Never allow oxygen to contact oil, grease, or other flammable substances.
Before opening the cylinder valve, make sure the pressure regulator adjusting screw, or T handle, is turned out, or counterclockwise. Charge the regulator by cracking the cylinder valve open slowly. This will prevent damage to the regulator seats from the sudden heat of compression.
Once the inlet or high-pressure gauge reading stops rising, open the oxygen cylinder valve all the way. The most an acetylene cylinder valve should be opened is 1-1/2 turns and, preferably, no more than a three-quarter turn.
Remember that leaving the T handle turned in, thinking it will save your settings or save you time the next day, is wrong. As the contents of the cylinder decrease, the regulator outlet pressure increases, so the settings will change. Even if you are using a top-of-the-line, two-stage regulator, leaving the T handle turned in is dangerous and damaging to the regulator. Turn the valve off when the regulator isn't in use and back out the T handle.
When the regulator is not under pressure, make sure that both gauge needles are resting on the peg at zero. If they aren't, your pressure settings will be wrong and you may be sending back partially filled cylinders to your supplier. Be sure to use regulators with flashback valves.
Never alter a regulator in any way. If at all possible, do not use adapters. Also, never stand in front of or behind a regulator when opening the cylinder valve. Always stand where the cylinder is between you and the regulator.
When a regulator is new or has come back from the repair shop, it has a plastic protector cap on the inlet nipple. Save it—when the regulator is not in use (not attached to a cylinder valve), put the cap back on it. If you want a nice, clean regulator, put it in a resealable plastic bag. If you work in a dusty shop, you can put the bag over the regulator when it's on the cylinder, which keeps it looking nice and new.
The twin red-green oxyfuel gas hose is the cheapest and the most overlooked item. It also is to blame for many accidents.
If you use your cutting equipment for production work, keep a spare hose on hand. Do not repair the hose unless it's in good condition. Do not use tape to repair a hose leak. Use the shortest hose possible because the longer the hose, the more oxygen and fuel gas are wasted and the more pressure will drop at the torch. Keep excess hose off the floor if possible.
Always make sure your equipment is rated for the tip size you have selected. Wrong tip size can result in flashback. Always keep a spare tip available. Flashback arresters can provide a certain measure of protection by preventing a flashback from reaching upstream equipment.
When lighting the torch, be sure the spark lighter is away from the tip, to the side. Do not obstruct the gas flow. Don't use the torch as a hammer or a prybar.
With a little care and safe practices, your oxyfuel equipment can give you many years of service.
Photos courtesy of Smith Equipment, Watertown, S.D.
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