Oxy-fuel Equipment and Procedures Flashcards
What is the appropriate level of welding lense for heating and cutting with oxy-fuel?
The most suitable lens for heating and cutting is either a number 4 or 5 in a green shade.
What are the best clothing for materials for welding and cutting?
The best clothing materials for welding and cutting, in order of preference, are leather, wool, denim and cotton because they repel sparks.
How can the protective qualities of welding and cutting clothing be enhanced?
Make a borax solution to apply to your clothing.
Mix: 5 parts borax
3 parts of boracic acid
In: 5 gals of water
What must you do if the If material being heated or cut contains zinc (galvanized material), cadmium or lead?
You must use an approved air line respirator.
What is a new cylinder of oxygen charged to?
A new cylinder is fully charged to 2200 psi at 70ºF (21ºC).
At what pressure are oxygen cylinders tested to and how often are they retested?
- Oxygen cylinders are factory tested to 1-1/2 times working pressure (3360 psi).
- Retested by the supplier after ten years and every five years after the first retest.
What type of thread do all oxygen cylinder connections have?
All oxygen connections have a right-hand thread.
Why should double-seated oxygen valves be opened all the way when in use?
Oxygen will leak by the valve stem if the the is not opened all the way and is allowed to seat properly.
On an oxygen cylinder, what is the rupture disc used for?
The rupture disc is a safety device that protects the oxygen cylinder from extreme pressure rise caused by heat or fire. The disc is mounted on the rear side of the cylinder valve. Its purpose is to burst at approximately 3200 psi and allow the slow, controlled escape of gas, rather than having the cylinder explode.
For acetylene, what temperature is the luminous cone of the flame?
6300ºF.
Why is an acetylene leak so dangerous?
Acetylene gas is highly flammable, and the explosive mixture of acetylene in air ranges from 2.5% to 80%.
What is the maximum safe working pressure for acetylene?
The maximum safe working pressure (MSWP) for acetylene is 15 psi.
The maximum safe working pressure (MSWP) for acetylene is 15 psi. Why can it be stored above 15 psi in a cylinder and what is the maximum pressure it can be stored at?
The combination of a porous filler and acetone allows acetylene to be stored safely in the cylinder at pressures of approximately 1.7 MPa (250 psi).
Why must an acetylene cylinder be stored upright?
Because the acetone is a liquid, the acetylene cylinder must always be used in an upright position. If the cylinder is used at an angle or on its side the acetone is drawn out of the cylinder with the acetylene.
The term draw limit means the maximum amount of acetylene that can be taken from the cylinder without drawing acetone along with the acetylene. What is the maximum draw rate for acetylene?
To prevent drawing off acetone with the acetylene, a cylinder must not be emptied faster than 1/7 of its capacity per hour (or in less than 7 hours).
When large volumes of acetylene gas are needed that would exceed one cylinder’s draw limit, what type of system should be used?
A manifold system.
What are the locations of the fusible plug on the cylinder?
Common locations for fusible plugs include:
* on the concave bottom of the cylinder.
* on the reinforcing collar or neck ring.
* on the shoulders of the cylinder.
What type of threads does an oxygen regulator have and what colour markings does it have?
An oxygen regulator has right-hand threads on both the inlet and outlet fittings and generally has green markings.
What type of threads does an acetylene regulator have and what colour markings does it have?
An acetylene regulator has left-hand threads, with an annular groove cut into the outside of the fittings on both the inlet and outlet, and generally has red markings.
How does a single-stage regulator work?
Single-stage regulators change line or cylinder pressure to operating pressure in one step. Clockwise rotation the hand control (adjusting screw) increases pressure, and counter-clockwise rotation reduces pressure. When the hand control is turned fully counter-clockwise until it freewheels, the outlet pressure is reduced to zero.
How does a two-stage regulator work?
A two-stage regulator shown in Figure 17 has two diaphragms, two metering needles and two seats. The first stage reduces the high gas pressure as it comes from the cylinder to some intermediate pressure. The second stage is the low-pressure stage that reduces the intermediate pressure to a constant pressure needed by the torch.
What is regulator creep?
Regulator creep occurs when the valve on the high pressure (first stage) or working side (second stage) of the regulator does not seat properly and gas is allowed to leak past, raising its pressure above normal. This can blow off the relief valve or rupture the bourdon tube in the low pressure gauge.
What are reverse-flow check valves used for and where are they installed?
Reverse-flow check valves are used to prevent flames from travelling in gases back from the torch to the regulator. They also prevent mixing of the acetylene and oxygen in the hoses or regulators by allowing a flow of gas in one direction only. They are installed immediately downstream from regulators or upstream from the torch.
How does an oxy-fuel welding torch work?
Oxygen and acetylene are passed through different tubes to a mixing chamber where they are mixed and then passed to the tip where the mixture can be ignited.
