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6122
Welding, Cutting, Brazing, and Grinding |
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1.0
Introduction
Welding, brazing, cutting, and grinding of metal are common parts of Jefferson Lab fabrication and construction activities. Because of the high temperatures involved and the potential for fire and serious personal injury, care must be taken to ensure that work is performed safely. Care must also be taken to ensure the quality of a weld or braze as this has direct impact on the ultimate safety associated with the component being welded or brazed.
This chapter is primarily a guide for workers and supervisors who use welding, brazing, cutting, and grinding processes. It applies to all welding, non-vacuum brazing, hot cutting, and abrasive grinding on site by employees, users, temporary help, or subcontractors.
At Jefferson Lab, there are two locations in which such hot work is permitted:
·
A permanent
permissible area such as a weld shop.
Weld shops are established by a Standard Operating
Procedure (SOP). (See ES&H Manual Chapter 3310 Operational Safety Procedure Program
for more information.)
·
A temporary work
area with safeguards defined using a Fire Hazard Work Permit (FHWP) which is
valid for a specified time not exceeding five consecutive days. (See ES&H Manual Chapter
6122 Appendix T2 Fire Protection: Hot
Work Permit for more information.)
Specialty welding applications at Jefferson Lab include electron beam welding and laser beam welding. Electron beam welding is used in the Test Lab to fabricate super conducting RF cavities. Safe use of the electron beam welder is addressed in an SOP. Laser beam welding activities are addressed in a relevant Laser Safety Operating Procedure (LSOP).
2.0
Hazard Avoidance
The major hazards associated with welding and cutting are:
·
Skin damage from
UV light exposure
·
Fire and the risk
of burns from open flames
·
Electric shock
and physical hazards (eye particulate injury, burns, etc.)
·
Respiratory
health effects due to inhalation of fumes and consumable material by-products
·
Physical hazards
specific to compressed
gas in welding applications
·
Physical hazards
associated with weld or braze failure
Significant factors that influence exposure to these hazards include:
·
Variables in the welding process
o Differences in type of welding
o
Different base
metals
o
Different
consumable material
·
Work area
physical limitations
o
Outdoor vs.
indoor location
o
Accessibility and
working space
·
Ventilation
·
Personal
protective equipment (PPE)
·
Designer
experience and knowledge
·
Operator
experience and knowledge
·
Examiner/Inspector
experience and knowledge
ES&H Manual 6122 Appendix T6 Welding and Brazing Program defines the process of weld and braze design, welder/brazer performance, examination, inspection and documentation. Welds and brazes produced according to the specifications in the program will provide an adequate level of safety commensurate with Jefferson Lab policy.
Each of the hazards associated with actual welding, brazing, cutting or grinding operations is addressed in a technical appendix to this chapter. Ensuring that each appendix and the hazard information therein is understood in full, addressed in the task hazard analysis, and incorporated in the appropriate technical work document before conducting welding, brazing, cutting, or grinding work will protect the safety of Jefferson Lab employees and facilities.
Jefferson Lab follows the guidance in the American National Standards Institute (ANSI) document Z49.1, Safety in welding, Cutting, and Allied Processes for all welding and cutting processes conducted on Jefferson Lab the site. A copy of ANSI Z 49.1 is available in the Environmental, Safety, Health, and Quality (ESH&Q) Safety Lab. This standard references other ANSI standards as applicable. The basic requirements are outlined in this chapter; however, when planning new welding activities, consult with the ESH&Q Industrial Safety Representative to ensure that all requirements are met.
Workers can suffer injuries from material handling, impact type injuries, and from high noise levels produced by grinding. It is important that all these hazards be assessed and mitigated before hot work begins. In addition, many types of portable welding equipment are heavy and mounted on wheels. This equipment must be secured from accidental movement before operation.
It is not necessary to have a direct view of a welding arc to injure the eyes. Sufficient light can reflect from nearby surfaces to cause “welder’s flash” – especially with a prolonged exposure. See ES&H Manual Chapter 6122 Appendix T1 Prevention of Skin and Eye Damage from Welding Arcs for more information.
Tungsten inert gas (TIG) welding is common at Jefferson Lab. This form of electric arc welding is a fire hazard because the arc temperature can reach 20,000 °F and the weld pool 4,530 °F. Although TIG welding does not usually present an open flame or produce sparks, slag, or spatter, it can present a significant fire hazard. Additionally, phosgene gas may be created when TIG welding within 200 feet of chlorinated hydrocarbons like trichloroethylene, methylene chloride, or trichloroethane.
Some materials that are safely handled at normal temperatures can become acutely toxic and difficult to manage when heated to their vaporization point, forming fumes. Examples include lead, cadmium, beryllium, and any radioactive materials. Even sanding, grinding, or other similar actions can release dangerous particles.
Maintaining the condition of welding equipment is the key to safe welding. Jefferson Lab requires annual inspection of welding and cutting equipment by qualified Jefferson Lab staff or a subcontractor. The inspection must include a high potential check for good transformer isolation. This inspection is usually performed by a subcontractor and the check date is indicated on a sticker affixed to the machine. No welding machine shall be used if the inspection has expired. If any welding or cutting equipment is judged by the operator or by subject matter experts to be incapable of reliable and safe operation, the equipment shall be removed from service and tagged with a “Danger, Do Not Operate” tag. Qualified personnel shall repair the equipment before it is returned to service.
Only equipment designated by management for the purposes of conducting welding, cutting, or brazing shall be used.
Soldering
and the associated hazards are addressed in ES&H Manual Chapter 6680
Lead Handling and ES&H
Manual Chapter 6630 Appendix T2 Ventilation Controls for Respiratory Hazard
Mitigation.
Fire/explosion can be avoided by taking appropriate precautions:
·
Do not cut, weld,
braze, or grind in the presence of combustible
or flammable fluids or atmospheres (gases, vapors, or dusts).
·
Do not cut, weld,
braze, or grind on drums, barrels, tanks, or other used containers.
·
Inspect cracks
and holes in floors, walls, and ceilings of the work area to verify that no
person or combustible
material will be exposed to sparks should they pass through a crack, hole, or
penetration.
·
If the object to
be worked on cannot readily be moved to a routine welding area, move all combustible
material at least 35 feet (10.7 m) from where the hot work will take place.
·
If any remaining combustibles
cannot be moved, protect the combustibles
with appropriate guards and covers.
·
Do not cut, weld,
braze, or grind inside a building if you have reason to suspect the sprinkler
system (if present) is not working properly.
·
Do not mix aluminum grinding dust
and iron or steel grinding
dust. Such a mixture can explode under
special conditions. Finely divided
aluminum mixed with finely divided ferrous oxide forms thermite,
a compound that burns at greater than 3000°C.
·
Use personnel designated for “fire watch”
to prevent or extinguish accidental fires associated with cutting, welding, brazing, or grinding
operations that produce sparks.
Burns and personal injury can be minimized by:
·
Keeping objects
which have been heated by hot work away from combustibles
and people until they cool.
·
Wearing the
proper PPE
– leather gloves and aprons, eye protection (glasses/welders helmet, face
shields), and other clothing designed to protect workers from UV, IR, hot slag,
and sparks.
·
Using welding curtains and shields
·
Posting a notice
where individuals may unknowingly come in contact with hot material remaining
from welding. (Consult
Jefferson Lab ESH&Q staff for assistance with producing appropriate signs.)
Toxic fumes and smoke can be controlled by:
· Ensuring adequate ventilation during the hot work process. (Consult Jefferson Lab ESH&Q staff for assistance evaluating ventilation needs.)
·
Reviewing
ES&H Manual Chapter
6122 Appendix T4 Respiratory Health Effects Due to Inhalation of Fumes and
Welding, which contains important information on minimizing
worker exposure to fumes and gaseous welding
by-products.
Special consideration for Thoriated
Tungsten Welding Electrodes:
Sharpening or grinding welding electrodes that contain thorium, a radioactive metal, can generate dust. Like radioactive contamination, this dust can pose an ingestion or inhalation hazard. The hazard due to external radiation exposure is minimal.
Thoriated tungsten welding electrodes are used infrequently at Jefferson Lab. The Radiation Control Group has determined that the radiation exposure to thorium from routine welding activities at Jefferson Lab is minimal and below the threshold for application of radioactive material and personnel exposure controls in ES&H Manual Chapter 6310 Ionizing Radiation Protection.
If a weld calls for the use of thoriated tungsten welding electrodes, contact the Radiation Control Group to review work practices before sharpening or grinding welding electrodes that contain thorium. This will allow the Radiation Control Group to continue to track the use of thoriated tungsten welding electrodes, recommend best practice for sharpening or grinding thoriated tungsten welding electrodes, and determine if or when radiological controls should be applied.
Normal ventilation controls for welding fumes serve to mitigate the hazard associated with inhalation of thorium during welding. Current best work practices that minimize exposure to this dust include electrode sharpeners that contain the resulting dust and ESH&Q assisted disposal of grinding dust.
Other safety measures:
·
Protect worker
from electrical shock by maintaining electrical welding equipment in good
condition. Repair any damaged leads
promptly. Refer to ES&H Manual 6122 Appendix T3 Electrical
Shock and Physical Hazard Prevention.
·
If work involves
heavy objects, ensure worker has adequate foot protection, and material
handling assistance.
·
Ensure that all
compressed gases and fuels are stored and transported properly, and that any
regulators, valves, hoses, and fittings are in good repair. See ES&H Manual
Chapter 6122 Appendix T5 Control of Physical Hazards Associated with Use of
Compressed Gases in Welding for more detailed information.
·
If work involves
potentially radioactive
materials, before starting work contact the Radiation Control Group. (See ES&H Manual Chapter 6310 Ionizing Radiation Protection).
·
Be aware that hot work is especially dangerous in confined
spaces and requires a confined
space permit. See ES&H Manual Chapter 6160 Confined Space Entry for more information.
Personal protection and awareness:
·
Observe and
follow awareness signs.
·
Do not bring combustibles
or flammables into an area where welding, cutting, brazing, or grinding occurs.
·
When passing
through a fabrication work area, be aware that welding may be in progress, and stay on marked walkways.
·
When you are in
an area with arc welding in progress, do not look at the arc or its reflection
off bright or shiny surfaces.
·
If you encounter
exposure to a welding arc, correct the situation with the welder,
supervisor, and area safety
warden.
·
Thoroughly clean
a grinding machine of all aluminum dust before grinding iron or steel.
3.0
Responsibilities
In addition to the following responsibilities specified to ensure workplace safety, ES&H Manual Chapter 6122 Appendix T6 Welding and Brazing Program provides detailed responsibilities for the quality and safety of each weld and braze.
Worker:
·
Do not operate welding, cutting, or brazing equipment without specific authorization by your
supervisor.
·
Follow all
guidance in this chapter and any authorizing Fire Hazard Work Permit.
·
Take the
initiative to work safely.
·
Remain present
and undistracted during hot work operations.
·
Be alert for any
condition that could lead to a fire, including possible problems in adjacent
areas.
·
Guard passersby
from welding hazards.
·
Interrupt the
work when a hazardous condition develops and deal with the situation
appropriately.
·
Remain on the
scene for at least thirty minutes after completion of hot work in order to detect, extinguish or report a fire
resulting from stored heat.
Line manager (where FHWP activity will occur):
·
Establish
permissible areas for hot work and ensure that only approved
equipment, such as torches, manifolds, and regulators, are used during the hot work.
·
Ensure that
personnel involved are appropriately trained and aware of the hazards and
mitigations associated with hot work.
·
Ensure that the
area is appropriately configured and made fire-safe.
·
Recognize and
address potential complications such as environmental or radiological
conditions or the effect of operations on other nearby activities.
·
Coordinate hot work activities with the area Safety
Warden, work coordinator, and Building Manager (if applicable).
·
Ensure that
workers performing hot work have received the appropriate medical certification. See ES&H
Manual Chapter 6820 Medical Monitoring, or contact
Jefferson Lab Occupational Medicine (x7539).
·
Subcontracting
Officer’s Technical Representatives (SOTRs) must ensure that all
contractors are advised on the work area specific hazards regarding flammables,
combustibles,
and hazardous conditions that may be encountered during hot work.
·
Designate a
permit authorizing individual (PAI) who will be responsible for the safe
operation of hot work activities. (See
PAI responsibilities below.)
Permit Authorizing Individual (PAI):
·
Responsible for
the safe operations of hot work activities in a particular area. The PAI cannot be the person doing
the hot work. The PAI can be the supervisor.
·
Identify
site-specific flammable materials, fire hazards, or hazardous processes present
or likely to be present in a hot work area.
·
Use the Fire
Hazard Work Permit (See ES&H Manual Chapter
6122 Appendix T2 Fire Protection: Hot
Work Permit) to authorize hot work performed outside of permanent welding areas.
·
The PAI can use
the permit to:
o
Ensure the
protection of combustibles
from ignition by hot work.
o
Determine if a fire watch is required and ensure that properly trained
individuals perform this duty.
o
Ensure that fire
protection and extinguishing equipment is available to workers performing hot work.
o
Coordinate with
Facilities Management any necessary deactivation and reactivation of fire detection
systems in the work area.
o
Address all
associated hazards.
·
Inspect work area
and initial permit daily.
ESH&Q Industrial Safety Representative:
· Assists line management by managing the inspection program for welding equipment used at Jefferson Lab.
· The Industrial Safety Representative ensures that:
o Annual inspections of welding equipment must be performed by qualified maintenance personnel.
o A certification record of inspected equipment includes the date of the inspection, the inspector’s signature, and the equipment serial number or other unique identifier.
4.0
Qualifications
Additional
qualifications for personnel performing welding and brazing
operations are provided in ES&H Manual Chapter
6122 Appendix T6 Welding and Brazing Program.
Hot Work Operator:
·
A person who has
been properly instructed and qualified by their supervisor to operate welding, brazing, grinding, and/or cutting equipment at Jefferson Lab.
·
Has been
medically certified by Jefferson Lab Occupational Medicine.
·
A person trained
in the use of the available fire extinguishers (Jefferson Lab Fire Safety
Training) and familiar with:
o
Inherent hazards of the work site and of the hot work
operation.
o
The two closest exit routes from the building.
o
Use of the building fire alarm system (closest
pull station).
o
Emergency procedures in the event of fire (911
calls, for example).
Permit Authorizing Individual (PAI):
· The supervisor or designee, knowledgeable in welding, brazing, cutting, and grinding, and able to apply the guidance in ES&H Manual Chapter 6122 Appendix T2 Fire Protection: Hot Work Permit to ensure that the proposed work area is rendered safe for hot work.
· Refer to the Fire Safety Chapters in the 6900 series for additional information.
5.0
Program Summary
Welding, cutting, brazing, and grinding of metal introduces significant potential hazards into the workplace. Supervisors, subcontractors and Lab staff must ensure that these activities are carefully planned, coordinated, and the hazards controlled.
Job Hazard Analysis, work control documents, and subcontractor specifications are used to ensure that hazards are identified and mitigated before work is started.
When hot work is to be performed outside of an authorized area, a Fire Hazard Work Permit is required and must be posted in a conspicuous place near the work. Use the guidance in ES&H Manual Chapter 6122 Appendix T2 Fire Protection: Hot Work Permit to ensure that the area is made fire safe.
More detailed guidance is given on welding safety practices in ES&H Manual Chapter 6122 Appendix T1 Prevention of Skin and Eye Damage from Welding Arcs, ES&H Manual Chapter 6122 Appendix T3 Electrical Shock and Physical Hazard Prevention, ES&H Manual Chapter 6122 Appendix T4 Respiratory Health Effects Due to Inhalation of Fumes and Welding and ES&H Manual Chapter 6122 Appendix T5 Control of Physical Hazards Associated with Use of Compressed Gases in Welding.
ES&H Manual Chapter
6122 Appendix T6 Welding and Brazing Program covers all welding and brazing
operations conducted by Jefferson Lab. Welding and brazing
operations specifically covered include weld/braze design and weld/braze
classification; weld/braze procedure specification and qualification;
weld/braze performance qualification; examination and inspection; material
control and documentation. The Welding
and Brazing Program provides a single program for Jefferson Lab that meets
federal regulatory mandates and adopts sound practices derived from national
consensus standards. Each weld and braze
produced in accordance with the requirements stated in ES&H Manual Chapter
6122 Appendix T6 Welding and Brazing Program will provide an adequate level
of safety commensurate with Jefferson Lab policy.
Figure 1: Required Signage for Welding
Areas
Protect yourself and others. Read and
understand this information.
Fumes and gases can be hazardous to your health.
Arc Rays can injure eyes and burn skin
ELECTRIC SHOCK can KILL
Before use, read and
understand:
Manufacturer’s Instructions,
Material Safety Data
Sheets, and
Safety Practices in
Chapter 6122 Welding, Brazing, Cutting, and Grinding Safety.
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ISSUING
AUTHORITY |
CHAPTER
AUTHOR |
APPROVAL
DATE |
EFFECTIVE
DATE |
EXPIRATION
DATE |
REV. |
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ESH&Q Division |
10/31/07 |
10/31/07 |
10/31/10 |
0 |
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