Only cable free from repair or splices for a minimum distance
of 10 feet
from the cable end to which the electrode holder is connected shall be used, except that cables with standard insulated connectors or with splices whose insulating quality is equal to that of the cable are permitted.
What is the correct motion for cutting?
The knife should perform
a rocking motion
during cutting: the front top portion of the blade should stay on the cutting board during all times when cutting (or at least the majority of the cutting time), and the rest of the blade should go up and down.
What is the distance that floors should be free of combustible materials when welding or cutting?
Where combustible materials such as paper clippings, wood shavings, or textile fibers are on the floor, the floor shall be swept clean for a radius of
35 feet (10.7 m)
. Combustible floors shall be kept wet, covered with damp sand, or protected by fire-resistant shields.
What is placed in the electrode holder?
3 Electrode Holder – The electrode holder
connects to the welding cable and con- ducts the welding current to the electrode
. The insulated handle is used to guide the electrode over the weld joint and feed the electrode over the weld joint and feed the electrode into the weld puddle as it is consumed.
When welding or cutting in a confined space?
In confined spaces or indoors, welding or cutting operations involving metals coated with mercury-bearing materials, including paint, must be done using local exhaust ventilation or
airline respirators unless atmospheric tests under the most adverse conditions show that employee exposure is within the acceptable
…
What is the maximum allowable LEL for hot work to take place?
Lower Explosive Limit (LEL) – The lower limit of flammability of a gas or vapor at ordinary ambient temperatures expressed in a percent of the gas or vapor in air by volume. For the purposes of this procedure, the %LEL limit for hot work permit authorization is
0.0% LEL
.
Does welding melt metal?
As opposed to brazing and soldering, which do not melt the base metal, welding is
a high heat process which melts the base material
. Typically with the addition of a filler material. … Pressure can also be used to produce a weld, either alongside the heat or by itself.
What is the purpose of electrode holder?
The primary function of the electrode holder clamp is
to support the electrode, guaranteeing a good electrical contact for current passage
; it should also guarantee sufficient electrical insulation for the welding operator.
Is electrode positive or negative?
Direct current straight polarity happens when the plates are positive and the
electrode is negative
.
What can cause an electrode holder to overheat?
What can cause a properly sized electrode holder to overheat?
It can overheat if the jaws are dirty or too loose
, or if the cable is loose. What problem can occur if welding machines are stacked or placed too closely together? There may not be enough room for air to circulate to keep the machines from overheating.
What is the minimum oxygen level in a confined space?
19.5 %
Minimum acceptable oxygen level. 15 – 19% Decreased ability to work strenuously. Impair coordination. Early symptoms.
What are the characteristics that require a permit in a confined space entry?
OSHA uses the term “permit-required confined space” (permit space) to describe a confined space that has one or more of the following characteristics:
contains or has the potential to contain a hazardous atmosphere; contains material that has the potential to engulf an entrant; has walls that converge inward or floors
…
What is the single best thing you can do to protect yourself from welding fumes?
Fumes produced by basic welding of iron or steel can often be blocked by wearing a
simple N95 mask such as the 3M 8212 N95 Welding Particulate Respirator
or as a step up, an N99 mask such as the Moldex Premium Disposable Welding Respirator. Both of these have exhalation valves to keep the mask cool.
What is an acceptable LEL?
Atmospheres with a concentration of flammable vapors at or
above 10 percent of
the lower explosive limit (LEL) are considered hazardous when located in confined spaces. However, atmospheres with flammable vapors below 10 percent of the LEL are not necessarily safe. Such atmospheres are too lean to burn.
How do you calculate LEL?
To compute the LEL of any gas in air,
divide the unknown concentration by the LEL listed in the NFPA Handbook
. 100% LEL’s for 9 of Gasco’s more common gasses are shown in the table to the left. For example, if you take 2.5% Methane in air and divide it by 100% LEL of methane (5%), the result is 50% LEL.
What is LEL and UEL?
There are two types of explosive limits as far as combustion of gases is concerned: the
Lower Explosive Limit (LEL)
and the Upper Explosive Limit (UEL). The lower Explosive limit can be explained in simple words as the lowest percentage of gas that can support to light a flame when exposed to a source of ignition.
