Oxyfuel cutting NCCER Welding Unit 2

intro ___________________is a process that uses the flame and oxygen from a cutting torch to cut ferrous metals. ______________ is produced by mixing a fuel gas with pure oxygen. The flame heats the metal and then a flow of ___________ is used to cut the metal which produces _________. (The cut metal fragments) Fast and easy way to cut metal…Not the most __________.

Protective equipment Always use safety cutting glasses with the proper shade. (shade filter of at least ____________) Wear protective clothing…sleeves, leathers, and gloves Always wear ______ or taller high top safety boots.

Fire/explosion prevention Make sure any flammable material in the work area is moved or shielded from the source of an open flame. ‘ Make sure fire extinguishers are in ____________________ and located in an well seen area. Before cutting tanks or barrels, check to see if they have contained any flammable material. Always clean and fill with water, or ______ them with a flow of _____________ to displace any oxygen.

Ventilation Always perform cutting operations in a well ____________ area. If the material contains any kind of ________________________________ coating always wear an approved full face, supplied air respirator. This will prevent you from breathing toxic fumes.

Oxygen cylinders ______________ is a colorless, odorless, tasteless gas that supports combustion. Combined with burning material, pure oxygen causes a fire to flare and burn out of control. Oxygen is stored at more than ________ psi in hollow steel cylinders. These cylinders must be tested every ____years.

Acetylene cylinders _________________ gas is a compound of carbon and hydrogen and is __________ than air. It is formed by dissolving calcium carbide in water. It has a strong, __________ like odor which is added so the gas can be detected. It is very unstable and will ___________ easily under pressure, this is why it must never exceed ______ psi when in a gaseous form. When combined with oxygen, acetylene creates a flame that burns hotter than ____________ degrees.

Acetylene cylinders Because of its explosive nature, acetylene cannot be stored above ___ psi in a hollow cylinder. To solve this problem, acetylene cylinders are filled with a porous material that creates a _____________, instead of a hollow cylinder. Acetylene cylinders must always be stored in the ____________ position and if one is ever tipped over, stand the cylinder upright and wait at least _____ hour before using. Acetylene cylinders have safety fuse plugs in the top and bottom of the cylinder that melt at_______ degrees. These prevent the tank from exploding.

Other gasses used Many fuel gasses other than acetylene can be used in oxyfuel cutting. They include natural gas, methylacetylene propadiene(MAP gas), propylene, and ___________. Flames are not as hot, but may be cheaper or safer to use. ___________ gas is mixture of acetylene and propane. __________ mixtures are stable and shock resistant and burn at around 5,193 degrees.

Liquid fuel gas cylinders Liquified fuel gases are shipped in ____________ steel cylinders. Can hold up to _______pounds of liquid fuel gas. If high volumes of gas are removed from a liquid fuel gas cylinder, the pressure will drop, and the temperature of the cylinder will also _________. A ring of ________ can sometimes form around the base of the cylinder.

Regulators ___________ are attached to the cylinder and reduce the pressure from the tank before it gets to the torch handle. Also helps maintain a steady flow of gas from the ____________. Oxygen regulators have _________ markings and always have __________ handed threads. Will read up to 3000 psi on its high pressure gauge. Acetylene regulators are _________ and have __________ hand threads. A v-notch is cut on the nut for a reminder. The high pressure gauge will read up to 400 psi.

Cutting torches 2 types… One piece cutting torch and a __________________ torch Combination torch is what we use. Consists of a cutting torch attachment that connects to a welding torch handle. The fuel gas and oxygen valves are on the torch handle. These are used in light to medium duty jobs.

Cutting tips The _______________ to be used depends on the base metal _____________ and fuel gas being used. Special tips are also made for ______________ or grooving. _____________ cutting heads are used to cut of rivets, bolts, and nuts.

Motor driven equipment A variety of ______________ and portable motorized cutting equipment is available for straight and curved cuts. CNC machines like the ____________ are used to cut metal using a computer driven system. Portable track cutting machines (_________________) can be used in the field for straight or curved cuts and beveling.

Testing for leaks As a safety precaution, always check equipment periodically for _____________ before using. The torch should be checked before __________ use. We can use _________ water to check for leaks, if ____________ form… then a leak is present.

Oxidizing flames There are 3 types of oxyfuel flames: __________ flame- burns equal amount of oxygen and acetylene. Used for all cutting operations _______________ flame- has a white feather caused by excess fuel. Length of feather depends on amount of excess gas. ______________ flame- has an excess of oxygen, inner cone is shorter and much bluer in color, more pointed than a neutral flame

Shutting down the torch Once finished cutting, always remember to shut down the torch for __________reasons. First step in shutting down is to always _________ the fuel gas and oxygen valves. Once everything is shut down, always wrap up the hose to eliminate any _____________ hazards.

Changing cylinders Once cylinders become to _______ to use, we should prepare them to be changed out. Remove the regulator and replace the cylinder cap on top of the cylinder. Mark MT(______________) and the ___________ near the top of the cylinder using soapstone.

Cutting thin steel Thin steel is __________ thick or less. ____________ can be caused when cutting due to the heat and thinness of the steel. To minimize distortion, move as _____________ as you can without loosing the cut. Hold the torch tip so that it is traveling in a 15 to _____degree angle.

Washing ____________ is a term used to describe the process of cutting out bolts or rivets. Washing tips can also be used to remove items such as blocks, angles, or channels that are _____________ onto a surface.

Gouging _______________ is the process of cutting a groove into a surface. Uses a special kind of ____________ tip. Not as effective as washing tips