DEPARTMENT OF LICENSING AND REGULATORY AFFAIRS  
DIRECTOR’S OFFICE  
GENERAL INDUSTRY SAFETY STANDARDS  
(By authority conferred on the director of the department of licensing and regulatory affairs  
by sections 16 and 21 of 1974 PA 154 and Executive Reorganization Order Nos. 1996-2,  
2003-1, 2008-4, and 2011-4, MCL 445.2001, 445.2011, 445.2025, and 445.2030)  
PART 12. WELDING AND CUTTING  
GENERAL PROVISIONS  
R 408.11201 Scope.  
Rule 1201. This part is intended to provide, in, about, or around places of employment,  
reasonable safety to persons involved in welding, cutting, brazing, soldering, and acetylene  
generating and to those exposed to these processes and the equipment and compressed  
gases used.  
History: 1979 AC.  
R 408.11202 Adoption and referenced standards.  
Rule 1202. (1) The following standards are adopted by reference in these rules and are  
available from Global Engineering Documents, 15 Inverness Way East, Englewood,  
Colorado, 80112, USA; telephone number: 1-800-854-7179; or at web-site:  
www.global.ihs.com, at a cost as of the time of adoption of these rules as stated in this rule.  
(a) American National Standards Institute ANSI B31.1 “Industrial Gas and Air Piping  
Systems,” 1967 edition. Cost: $96.00.  
(b) ANSI B57.1 “Compressed Gas Cylinder Valve Outlet and Inlet Connections,” 1965  
edition. Cost: $29.00.  
(c) American Petroleum Institute API 1104 “Standard for Welding Pipe Lines and Related  
Facilities,” 1973 edition. Cost: $125.00.  
(d) API PSD 2201 “Welding or Hot Tapping on Equipment Containing Flammables,”  
1963 edition. Cost: $125.00.  
(e) American Society of Mechanical Engineers ASME A13.1 “Identification of Piping  
Systems,” 1956 edition. Cost: $60.00.  
(2) The following standards are adopted by reference in these rules and are available from  
NFPA, 1 Batterymarch Park, Quincy, Massachusetts, USA, 02169-7471; telephone  
number: 1-617-770-3000; or at website: www.nfpa.org; at a cost as of the time of adoption  
of these rules as stated in this rule.  
(a) National Fire Protection Association (NFPA) Standard 50 “Bulk Oxygen Systems,”  
1971 edition. Cost: $27.00.  
Page 1  
(b) NFPA 80 “Standard for the Installation of Fire Doors and Windows,” 1974 edition.  
Cost: $27.00.  
(3) The following standard is adopted by reference in these rules, “The Fire Resistance  
Directory.” This directory is available from Underwriters' Laboratory, 2600 NW Lake  
Road, Camas, Washington, 98607-8542, USA; telephone number: 1-877-854-3577; or at  
website: www.ul.com/directories; at a cost as of the time of adoption of these rules of  
$150.00.  
(4) The standards adopted in these rules are available for inspection at the Department of  
Licensing and Regulatory Affairs, MIOSHA Regulatory Services Section, 530 West  
Allegan Street, P.O. Box 30643, Lansing, Michigan, 48909-8143.  
(5) Copies of the standards adopted in these rules may be obtained from the publisher or  
may be obtained from the Department of Licensing and Regulatory Affairs, MIOSHA  
Regulatory Services Section, 530 West Allegan Street, P.O. Box 30643, Lansing,  
Michigan, 48909-8143, at the cost charged in this rule, plus $20.00 for shipping and  
handling.  
(6) The following standard is referenced in these rules, General Industry Safety Standard  
Part 33 ‘Personal Protective Equipment,’ R 408.13301 to R 408.13398. Up to 5 copies of  
this standard may be obtained at no charge from the Michigan Department of licensing and  
regulatory affairs, MIOSHA Regulatory Services Section, 530 West Allegan Street, P.O.  
Box 30643, Lansing, MI, 48909-8143 or at website: www.michigan.gov/mioshastandards.  
For quantities greater than 5, the cost, at the time of adoption of these rules, is 4 cents per  
page.  
History: 2013 AACS.  
Editor's Note: An obvious error in R 408.11202 was corrected at the request of the promulgating agency,  
pursuant to Section 56 of 1969 PA 306, as amended by 2000 PA 262, MCL 24.256. The rule containing the  
error was published in Annual Administrative Code Supplement, 2013. The memorandum requesting the  
correction was published in Michigan Register, 2016 MR 1.  
R 408.11203 Definitions; A to C.  
Rule 1203. (1) "AC" means alternating current.  
(2) "Arc welding" means a process for joining metals by heating with an electric arc with  
or without the use of pressure with or without a filler material.  
(3) "Brazing" means a process of joining metals without melting them with a filler metal  
melting above 800 degrees F.  
(4) "Confined space" means a small or restricted space without proper life supporting  
atmosphere or in which mobility is restricted.  
(5) "Cutting" means a process in which the severing or removing of metal is effected by  
the use of an arc or flame.  
(6) "Cylinders" means containers for storing compressed gases manufactured, labeled,  
and periodically tested in accordance with specifications of the department of  
transportation regulations.  
History: 1979 AC; 2013 AACS.  
Page 2  
R 408.11204 Definitions; D to N.  
Rule 1204. (1) "DC" means direct current.  
(2) "Fire resistance" means the property of a material or assembly to withstand fire or give  
protection from it.  
(3) "Gas welding" means a process for joining metals by heating with a gas flame with or  
without the use of pressure and with or without the use of a filler material.  
(4) "Inert gas" means argon, carbon dioxide, helium, or nitrogen gas.  
(5) "Manifold" means an assembly of pipe and fittings to interconnect either single or  
multiple sources to single or multiple outlets.  
(6) "Noncombustible" means having properties which do not support combustion.  
History: 1979 AC.  
R 408.11205 Definitions; P to W.  
Rule 1205. (1) "Press welding machine" means a machine that utilizes 2 platens, 1 of  
which moves toward the other during the initial part of the machine cycle. It does not  
provide welding pressure. After 1 of the platens has moved to a stop position, the welding  
pressure required for the welding operation is applied by 1 or more air or hydraulic  
cylinders.  
(2) "Psig" means pounds per square inch as measured by a gauge.  
(3) "Resistance welding" means the joining of metals by the use of heat generated at the  
joint by the resistance to the flow of electric current and by the application of pressure.  
(4) "Soldering" means a process of joining metals without melting them using a filler  
metal melting at 800 degrees Fahrenheit, 427 degrees centigrade, or below.  
(5) "Spot welding" means a form of resistance welding in which the current and pressure  
are restricted to the spot of metal surfaces directly in contact between the electrodes.  
(6) "Storage" means the storage of filled or empty cylinders not in use.An oxidizing and  
fuel gas cylinder or cylinders used as a unit shall not be considered to be in storage.  
(7) "Water capacity" means the weight of water, as related to liquefied gas, of a volume  
equivalent to that of the cylinder.  
(8) "Welder" means a person capable of performing a manual or semiautomatic welding  
operation.  
(9) "Welding operator" means a person who operates a machine or automatic welding  
equipment.  
History: 1979 AC; 1988 AACS.  
R 408.11211 Employer and employee responsibilities.  
Rule 1211. (1) An employer shall do all of the following:  
(a) Give each employee training or a test before allowing him or her to use equipment for  
arc and gas welding and cutting.  
(b) Provide face and eye protection and foot protection as prescribed in general industry  
safety standard Part 33 “Personal Protective Equipment,” as referenced in R 408.11202.  
Page 3  
(c) Provide other personal protective clothing or equipment, such as gloves, aprons,  
hearing protection devices, respirators, lifelines, safety belts, and lanyards required to  
protect the employee from injury likely to be caused by the assigned task of welding and  
cutting. Except for long sleeve shirts required to protect the employee from ultraviolet rays  
to the arms and ankle length trousers, the personal protective clothing and equipment shall  
be provided without expense to the employee.  
(d) Provide to an employee, at no expense to the employee, protective devices such as,  
but not limited to, curtains, safety glasses, or face shields to reduce the risk of flash burn,  
sparks, and foreign bodies to all employees in the area.  
(e) Provide ventilation where necessary to protect an employee against toxic materials as  
prescribed by the Michigan Occupational Safety and Health Administration (MIOSHA)  
standards.  
(2) An employee shall comply with all of the following:  
(a) Use welding and cutting equipment as trained and authorized.  
(b) Use the protective equipment required by the employer or the hazard.  
(c) Not tamper with safety devices.  
(3) An employee in charge of the operation of oxygen or fuel-gas supply equipment, of  
oxygen or fuel-gas systems, including generators, shall be instructed and judged competent  
by the employer for this work before being left in charge. Rules and instructions covering  
the operation and maintenance of oxygen or fuel-gas supply equipment, including  
generators, and oxygen or fuel-gas distribution piping systems shall be readily available.  
History: 1979 AC; 1983 AACS; 2013 AACS.  
Editor's Note: An obvious error in R 408.11211 was corrected at the request of the promulgating agency,  
pursuant to Section 56 of 1969 PA 306, as amended by 2000 PA 262, MCL 24.256. The rule containing the  
error was published in Michigan Register, 2013 MR 11. The memorandum requesting the correction was  
published in Michigan Register, 2013 MR 21.  
R 408.11212 General requirements.  
Rule 1212. (1) A mixture of fuel gas with air or oxygen shall not be permitted except  
when consumed at a burner or torch.  
(2) Only apparatus designed for use with fuel gas or oxygen shall be used for welding or  
cutting.  
(3) The total volume of acetylene used per hour shall not exceed 1/7 of the total volume  
of the acetylene supply in the system.  
(4) Liquid acetylene shall not be used.  
(5) A cylinder to which a regulator is attached shall not be moved unless secured to a hand  
truck or powered truck designed or equipped for this purpose.  
(6) A cylinder valve shall be closed in all of the following situations:  
(a) When the cylinder is moved.  
(b) When the work is finished or is left unattended during lunch, overnight, or for any  
other prolonged period.  
(c) When the cylinder is empty.  
(d) When the regulator is removed.  
Page 4  
(7) Fuel gas shall not flow from a cylinder or manifold through a torch or other device  
equipped with a shutoff valve unless the pressure is reduced by a regulator attached to the  
cylinder or manifold.  
(8) An oxygen cylinder, cylinder valve, coupling regulator, hose, and apparatus shall be  
kept free from oily or greasy substances and shall not be handled with oily hands or gloves.  
Precautions shall be taken to prevent a jet of oxygen from striking an oily surface or greasy  
clothes or from entering a fuel, oil, or other storage tank.  
(9) Oxygen shall not be used as a substitute for compressed air or for any other use, except  
for welding or cutting or life support procedures.  
(10) Welders shall place welding cable and other equipment so that it is clear of  
passageways, ladders, and stairways or it shall be protected against damage or hazards to  
an employee.  
History: 1979 AC; 1988 AACS.  
CONFINED SPACES  
R 408.11213 Working in confined spaces.  
Rule 1213. (1) When working in a confined space, the torch valves and the gas supply  
valve and oxygen valve outside the confined space shall be shut off during lunch,  
overnight, or for any other prolonged period. Where practicable, the torch and hose shall  
be removed from the confined space.  
(2) When stick electrodes are used in a confined space, and welding is suspended during  
lunch, overnight, or for any other prolonged period, the electrode shall be removed from  
the holder and the machine shut off.  
(3) The air in a confined space shall be tested with an approved device and purged, if  
necessary, before any entry. Ventilation shall be provided in the confined spaced when an  
employee is present.  
(4) A cylinder or welding power source used in a confined space shall be placed and  
secured on the outside of the space where work is being performed.  
(5) An employee who is trained in rescue procedures, and with such equipment as is  
necessary to effect a rescue, if needed, shall be stationed outside the confined space during  
welding or cutting operations. An employer shall ensure that an effective means of  
communication is established between employees in the confined space and the attendant.  
When safety belts and lifelines are used, they shall be provided and used as prescribed in  
general industry safety standard Part 33 “Personal Protective Equipment,” as referenced in  
R 408.11202, and attached to the welder's body so that his or her body cannot be jammed  
in a small exit opening.  
(6) After welding operations are completed in a confined space, a sign or other warning  
shall be used to mark the hot metal.  
History: 1979 AC; 1983 AACS; 1988 AACS; 2013 AACS.  
Editor's Note: An obvious error in R 408.11213 was corrected at the request of the promulgating agency,  
pursuant to Section 56 of 1969 PA 306, as amended by 2000 PA 262, MCL 24.256. The rule containing the  
Page 5  
error was published in Annual Administrative Code Supplement, 2013. The memorandum requesting the  
correction was published in Michigan Register, 2014 MR 13.  
R 408.11214 Rescinded.  
History: 1979 AC; 1997 AACS.  
CYLINDERS  
R 408.11221 Cylinder marking.  
Rule 1221. (1) Compressed gas cylinders shall be legibly marked, for the purpose of  
identifying the gas content, with either the chemical or trade name of the gas. Such marking  
shall be by means of stenciling, stamping, or labeling, and shall not be readily removable.  
Whenever practical, the marking shall be located on the shoulder of the cylinder.  
(2) Unlabeled cylinders shall not be used.  
(3) Empty cylinders shall be so marked at time of depletion.  
History: 1979 AC; 2013 AACS.  
R 408.11222 Storage.  
Rule 1222. (1) An oxygen cylinder shall be stored not less than 20 feet from fuel gas  
cylinders or a highly combustible material, such as, but not limited to, oil, grease, excelsior,  
flammable gas, or a source of ignition, or shall be separated from the material by a  
noncombustible wall, not less than 5 feet (1.6 meters) high, having a fire-resistance rating  
of 1/2 hour. An oxygen cylinder shall not be stored in an acetylene generator compartment.  
The underwriters' laboratory fire resistance directory may be used as a guide to determine  
fire resistance, as adopted in R 408.11202.  
(2) A cylinder shall be stored away from heat in excess of 125 degrees Fahrenheit.  
(3) A cylinder, including an empty cylinder, which is in storage, being shipped, or has the  
regulator removed shall have the cap secured in place, if a cap is provided in the design, or  
shall be otherwise protected.  
(4) Storage shall be set up to ensure first-in, first-out usage.  
(5) A cylinder storage area shall be posted with the names of the individual gases stocked,  
and a warning shall be posted against tampering by an unauthorized employee. An assigned  
storage area shall be located where a cylinder will not be knocked over or struck by a  
passing or falling object.  
(6) Where different gases are stored, they shall be grouped by types. Groupings shall  
separate the flammable gases from the oxidizing gases as in subrule (1) of this rule.  
(7) A storage area for cylinders shall be well ventilated. A cylinder shall not be stored in  
basements or pits, except where ventilation as specified by the Michigan Occupational  
Safety and Health Administration (MIOSHA) standards is furnished to keep the area  
purged of any accumulation of gases.  
Page 6  
(8) Storage of fuel gas in a building in 1 area within 100 feet (30 meters) of another fuel  
gas storage area and not protected by an automatic sprinkler system shall be limited to a  
total gas capacity of 2,000 cubic feet (56 cubic meters approximately) or 11.8 cubic feet  
(.33 cubic meters) of liquefied gas, which is 735 pounds (333 kilograms) water capacity.  
Storage in excess of this amount shall be in a separate room or compartment with an  
exterior wall and on the top floor of the building, outside, or in a special building. All walls,  
floors, and ceilings shall be constructed of noncombustible material having a fire-resistance  
rating of 1 hour. The walls shall be continuous from the floor to the ceiling and shall be  
securely anchored. The separate room, compartment, or special building shall have no open  
flame for heat or light and shall be well ventilated. Openings from the separate storage  
room to other parts of the building shall be protected by a self-closing fire door for a class  
B opening and shall have a fire-resistance rating of not less than 1 hour. Windows in  
partitions shall be wired glass and approved metal frames with a fixed sash. Installation  
shall be in accordance with NFPA 80 “Standard for the Installation of Fire Doors and  
Windows,” 1974 edition, as adopted in R 408.11202.  
(9) Where a liquid or gaseous oxygen system is used to supply gaseous oxygen for  
welding and cutting and the system has a storage capacity of more than 20,000 cubic feet  
(560 cubic meters), measured at 14.7 psia (101.34 kPa) and 70 degrees Fahrenheit (21.1  
degrees Celsius), including unconnected reserves at the site, the system shall be as  
prescribed in NFPA 50 “Bulk Oxygen Systems,” 1971 edition, as adopted in R 408.11202.  
(10) A cylinder used for methylacetylene-propadiene, stabilized, shall be constructed of  
materials suitable for this fuel gas in the gaseous or liquid phases.  
History: 1979 AC; 1981 AACS; 1988 AACS; 2013 AACS.  
R 408.11223 General rules for cylinders--I.  
Rule 1223. (1) A chain, bracket, or other restraining device shall be used at all times to  
prevent cylinders from falling.  
(2) Acetylene or liquefied gas cylinders shall not be placed on their sides, but shall be  
stood valve end up.  
(3) A cylinder shall not be dropped, dragged, rolled on its side, or struck violently.  
(4) A cylinder shall be lifted only by cradles or enclosed platforms when using a crane or  
hoisting device. Electromagnets, hooks, ropes, or slings shall not be used.  
(5) A frozen or ice clogged valve shall be thawed either by warm air or use of warm water  
and dried before using. Boiling water or a flame shall not be used. Force shall not be  
applied to a valve or cap to loosen a cylinder frozen in place.  
History: 1979 AC.  
R 408.11224 General rules for cylinders--II.  
Rule 1224. (1) Gases shall not be mixed within a cylinder except by the supplier.  
(2) A cylinder shall not be placed where it will become a part of the electrical circuit by  
accidental grounding or where it may be burned by electric welding arc. A cylinder shall  
not be placed so that hot slag or flame will reach it or it shall be protected by a fire resistant  
shield. An electrode shall not be tapped against a cylinder to strike an arc.  
Page 7  
(3) A regulator, gauge, or hose shall not be interchangeable between fuel gas, oxidizing  
gas or inert gas. Connections for compressed gas cylinders shall be as prescribed in ANSI  
B57.1- “Compressed Gas Cylinder Valve Outlet and Inlet Connections,” 1965 edition, as  
adopted in R 408.11202.  
(4) A cylinder valve shall be opened slightly for an instant and then closed before  
connecting to a regulator or manifold to clear the valve of dust and dirt. This shall not be  
done near a source of ignition. Pressure to a regulator shall be introduced by slowly opening  
the cylinder valve. An acetylene cylinder valve shall not be opened more than 1 1/2 turns  
of the spindle.  
(5) Acetylene shall not be utilized or piped, except in cylinder manifolds, at a pressure in  
excess of 15 psig.  
(6) Only the owner of the cylinder, if the owner is qualified, or a person trained, qualified,  
and authorized by the owner, shall refill a cylinder.  
History: 1979 AC; 2013 AACS.  
R 408.11225 Cylinders; keys, handles, or wrenches; use as roller or support  
prohibited; repair; placing items on top prohibited.  
Rule 1225. (1) A cylinder without fixed hand wheels shall have keys, handles, or  
nonadjustable wrenches on valve stems while in service. A multiple cylinder installation  
shall require only 1 key or handle for each manifold. A hammer shall not be used to open  
a cylinder valve or loosen a cap.  
(2) A cylinder, whether full or empty, shall not be used as a roller or support.  
(3) A leaking cylinder or a cylinder with a valve stuck open or a valve in need of repair  
shall be taken outdoors away from sources of ignition, slowly emptied, and tagged with a  
warning sign and the manufacturer or distributor shall be notified. Complete removal of  
the stem from the cylinder valve shall be avoided.  
(4) Nothing shall be placed on top of a cylinder which would damage a safety device or  
interfere with the quick closing of the valve.  
History: 1979 AC; 1988 AACS.  
MANIFOLDING  
R 408.11231 Oxygen manifolding.  
Rule 1231. (1) An oxygen manifolding unit shall be located not less than 20 feet from  
combustible materials or separated by a noncombustible barrier, not less than 5 feet high,  
having a fire-resistance rating of at least 1/2 hour.  
(2) An oxygen manifold shall not be located in acetylene generating rooms.  
(3) Each container and manifold unit shall be labeled to show the name of the gas  
contained.  
(4) Each manifold shall be provided with approved pressure regulation devices.  
History: 1979 AC.  
Page 8  
R 408.11232 High-pressure oxygen manifolds.  
Rule 1232. (1) An oxygen high-pressure manifold shall be not more than 6,000 cubic feet,  
except as permitted in subrule (3) of this rule.  
(2) More than 1 unit may be located in a room, but they shall be not less than 50 feet (16  
meters) apart or separated by a noncombustible barrier not less than 5 feet (1.6 meters)  
high having a fire resistance of 1/2 hour.  
(3) An oxygen high-pressure manifold with an aggregate of more than 6,000 cubic feet  
(170 cubic meters approximately) shall be located outdoors in a separate noncombustible  
building or, if located in a building that is otherwise occupied, the manifold shall be located  
in a separate room of noncombustible construction having a fire-resistance rating of 1/2  
hour or in an area with no combustible material within 20 feet (6.1 meters) of the manifold.  
(4) An oxygen manifold or oxygen bulk supply system with a storage capacity of more  
than 20,000 cubic feet (560 cubic meters), including unconnected reserves, shall be as  
prescribed in R 408.11222(9).  
History: 1979 AC; 1981 AACS.  
R 408.11233 Low pressure oxygen manifolds.  
Rule 1233. (1) The operating pressure of a low pressure oxygen manifold shall be not  
more than 250 psig. The following sign shall be posted at each low pressure oxygen  
manifold:  
Low pressure manifold:  
Do not connect high pressure cylinders  
Maximum pressure--250 psig  
(2) A low pressure oxygen manifold shall have a minimum bursting pressure of 1,000  
psig and shall be protected by a safety relief valve which will relieve at a maximum  
pressure of 500 psig. The safety relief vent shall discharge outside of the plant at a point  
away from a source of ignition and where reentry could not occur.  
(3) A hose or hose connection subject to manifold pressure shall have a minimum bursting  
pressure of 1,000 psig.  
(4) An assembled manifold including leads shall be tested and proved gas tight at a  
pressure of 300 psig (2070 kPa gage). The material used for testing oxygen manifolds shall  
be oil-free and not combustible.  
History: 1979 AC.  
R 408.11234 Fuel gas manifolding.  
Rule 1234. (1) Fuel gas connected to 1 manifold inside a building shall have a total gas  
capacity of not more than 3,000 cubic feet (85 cubic meters approximately) or 11.8 cubic  
feet (.33 cubic meters) of liquefied gas, which is 735 pounds (333 kilograms) water  
capacity. More than 1 manifold unit may be located in a room, but the manifolds shall be  
Page 9  
not less than 50 feet (16 meters) apart or be separated by a noncombustible barrier not  
less than 5 feet (1.6 meters) high having a fire-resistance rating of 1/2 hour.  
(2) Fuel gas capacity on 1 manifold of more than 3,000 cubic feet (85 cubic meters  
approximately) or 11.8 cubic feet (.33 cubic meters) of liquefied gas, which is 735 pounds  
(333 kilograms) water capacity, is permissible in a separate room or compartment, as  
specified in R 408.11222(8), or located outside the building.  
(3) The pressure in the gas cylinders connected to, and discharged simultaneously  
through, a common manifold shall be approximately equal.  
(4) Manifolds shall be approved either separately for each component part or as an  
assembled unit.  
History: 1979 AC; 1981 AACS.  
Editor's Note: An obvious error in R 408.11234 was corrected at the request of the promulgating agency,  
pursuant to Section 56 of 1969 PA 306, as amended by 2000 PA 262, MCL 24.256. The rule containing the  
error was published in Annual Administrative Code Supplement, 2013. The memorandum requesting the  
correction was published in Michigan Register, 2014 MR 13.  
MANIFOLDING--SERVICE PIPING  
R 408.11241 Piping material.  
Rule 1241. (1) Piping for acetylene shall be limited to steel and ductile iron.  
(2) Piping for other gases shall be compatible with the gas.  
(3) Oxygen at pressures of more than 700 psig shall be run in stainless steel or copper  
alloy piping.  
(4) Gray or white cast iron fittings shall not be used.  
(5) Pipe and fittings shall be as prescribed in section 2 of the ANSI B31.1 “Industrial Gas  
and Air Piping Systems,” 1967 edition, as adopted in R 408.11202, except for the  
following:  
(a) Pipe shall be not less than schedule 40 and fittings not less than standard weight in  
sizes up to and including 6-inch nominal.  
(b) Copper tubing shall be type K or L.  
(6) A hose connection and hose complying with R 408.11233 may be used to connect the  
outlet of a manifold pressure regulator to piping if the working pressure of the piping is  
250 p.s.i.g. or less, and the length of the hose does not exceed 5 feet.  
History: 1979 AC; 2013 AACS.  
R 408.11242 Piping assembly.  
Rule 1242. (1) All piping shall be run as directly as practicable, shall be protected against  
physical damage, and proper allowance shall be made for expansion and contraction,  
jarring, and vibration. Piping in a tunnel, trench, or duct shall be welded or brazed. Pipe  
laid underground in earth shall be located below the frost line and shall be protected from  
corrosion. Shutoff valves shall be located outside the conduits. Oxygen piping may be  
Page 10  
placed in the same tunnel, trench, or duct with fuel gas pipe lines if natural or forced  
ventilation is provided.  
(2) Low points in piping carrying moist gas shall be drained into drip pots constructed so  
as to permit pumping or draining out the condensate at necessary intervals. A drain valve  
shall be installed for this purpose, having an outlet normally closed with screw caps or  
plugs. Open end valves or petcocks shall not be used, except that, in drips located out of  
doors, underground, and not readily accessible, a valve may be used at such points if it is  
equipped with means to secure it in the closed position. A pipe leading to the surface of the  
ground shall be cased or jacketed where necessary to prevent loosening or breaking.  
(3) A gas shutoff valve shall be provided at the pipe entrance to a building. There shall  
also be provided a shutoff valve in the discharge line from the generator, gas holder,  
manifold, or other source of supply.A shutoff valve shall not be installed in a manner that  
renders a safety relief device ineffective.  
(4) Before assembly, piping and fittings shall be freed of scale and dirt. An oxygen line  
shall be washed out with a solution such as caustic soda or trisodium phosphate. After  
assembly, piping shall be blown out with oil-free air or oil-free inert gas.  
(5) Loose dirt that may have been trapped in the pipe shall be blown out with oil-free air  
or oil-free inert gas.  
(6) Pressure testing of a pipeline shall be done in a manner to protect an employee from  
injury due to blowing out of closures and other pressure restraining devices.  
(7) A piping system shall be tested and proved gastight at 1 1/2 times the maximum  
operating pressure and shall be purged of air before being placed in service. The material  
used for testing oxygen lines shall be oil-free and noncombustible. A flame shall not be  
used to detect leaks.  
(8) Repairs on ferrous piping for other than inert gas lines shall be preceded by purging  
the lines, unless only nonsparking tools are used.When gas lines and other parts of a  
manifold system are being purged, a source of ignition shall not be permitted near the  
uncapped opening.  
(9) Outdoor ferrous and all underground piping and fittings shall be covered or painted to  
protect against corrosion.  
(10) A steel or wrought iron pipe joint shall be welded, threaded, or flanged.  
(11) A brass or copper pipe joint shall be welded, brazed, threaded, or flanged. A seamless  
copper, brass, or stainless steel tubing joint shall be brazed or gas tubing fittings used.  
Where a socket-type joint is used, it shall be brazed with silver brazing alloy or similar  
filler metal having a melting point not less than 800 degrees Fahrenheit.  
History: 1979 AC; 1981 AACS.  
R 408.11243 Installation and identification of piping.  
Rule 1243. (1) Above ground piping, station outlet, and section valves shall be identified  
as to contents by color or name, or both, as prescribed in ASME A13.1 “Identification of  
Piping Systems,” 1956 edition, as adopted in R 408.11202.  
(2) A cylinder manifold shall be installed under the supervision of an individual  
experienced in the proper practices with reference to its installation and use.  
History: 1979 AC; 2013 AACS.  
Page 11  
R 408.11244 Station outlets.  
Rule 1244. (1) A station outlet shall be equipped with a shutoff valve for each torch  
supplied from it, designated VF and VO in FIGURE 1, located upstream of other station  
outlet equipment.  
(2) A station outlet shall be provided backflow prevention devices, designated as SF and  
SO in FIGURE 1, at each station outlet, including those on a portable header, to prevent  
backflow, except where pipeline protection equipment, designated as PF in FIGURE 1, C  
is located at the station outlet.  
(3) A station outlet shall terminate with an approved union connection for a regulator or  
a hose, except that the outlet may terminate with pipe threads where a permanent  
connection is made, such as to a machine.  
(4) Each station outlet shall be equipped with a detachable seal outlet cap, secured in  
place, which shall seal the outlet except when a hose, regulator, or piping is attached.  
(5) The total volume of acetylene used per hour shall not exceed 1/7 of the total volume  
of the acetylene supply in the system.  
Page 12  
FIGURE 1  
LEGEND:  
PF  
VF  
VO  
SF  
Protective equipment in fuel gas piping  
Fuel gas station outlet valve  
Oxygen station outlet valve  
Backflow prevention devices(s) at fuel gas station outlet  
Backflow prevention device(s) at oxygen station outlet  
SO  
History: 1979 AC.  
R 408.11245 Portable outlet headers.  
Rule 1245. (1) A portable outlet header shall not be used indoors, except where conditions  
preclude a direct supply from an outlet located on the service piping system.  
(2) A master shutoff valve shall be provided for oxygen and fuel gas at the entrance of  
the portable outlet header.  
(3) A portable outlet header shall be provided the protective devices prescribed in R  
408.11252.  
Page 13  
(4) Each service outlet of a portable outlet header shall be provided with a valve assembly  
which includes a detachable outlet seal cap, chained or otherwise secured to the valve body.  
(5) A portable outlet header shall be provided a frame which will support the equipment  
in position and protect it from damage during handling and operation.  
(6) Each outlet on the service piping from which oxygen or fuel gas is withdrawn to supply  
a portable outlet header shall be equipped with a readily accessible shutoff valve.  
History: 1979 AC.  
PRESSURE DEVICES  
R 408.11251 Pressure devices.  
Rule 1251. Pressure regulating and relief devices shall be provided and set to function at  
not more than the designed pressure and to discharge away from a source of ignition.  
History: 1979 AC.  
PROTECTIVE DEVICES  
R 408.11252 Protective devices.  
Rule 1252. (1) Protective equipment shall be installed in fuel gas piping to prevent  
backflow of oxygen into the fuel gas supply system, passage of a flashback into the fuel  
gas supply system and excessive back pressure of oxygen in the fuel gas supply system.  
See PF in FIGURE 1.  
(2) The 3 functions may be combined in 1 device or provided by separate devices.  
(3) The protective equipment shall be located in the main supply line as shown in FIGURE  
1, A. In addition, an employer may use protective equipment shown in FIGURE 1, B and  
C. Where a branch is sized 2 inches or more, the protective equipment PF shall be provided  
as prescribed in FIGURE 1, B or C.  
(4) Backflow protection shall be provided by a device that will prevent fuel gas from  
flowing into the oxygen system or oxygen from flowing into the fuel-gas system. See  
FIGURE 1, A and B and PF in FIGURE 1, A, B, and C.  
(5) A pressure relief device shall be set at a pressure not more than the pressure rating of  
the backflow or flash-back protection devices, whichever is lower, and shall be located on  
the downstream side of both of these devices. Its vent shall be as large as the inlet and  
terminate in a hood or bend away from a source of ignition. The vent shall be installed  
without low points that may collect moisture. If low points are unavoidable, drip pots with  
drains closed with screw plugs or caps shall be installed at the low points. A shutoff valve  
shall not be installed in the vent line.  
(6) Fuel gas for use with equipment not requiring oxygen shall be withdrawn upstream of  
the piping protective devices.  
(7) Piping protective equipment incorporating a liquid shall have the level maintained.  
Antifreeze may be used to prevent freezing.  
Page 14  
History: 1979 AC.  
HOSES AND REGULATORS  
R 408.11253 Hoses and connections.  
Rule 1253. (1) Only approved hose and connections shall be used. A hose connection  
shall be fastened to withstand twice the working pressure without leaking, but not less than  
300 psig (2070 kPa). Oil-free air or an oil-free inert gas shall be used for the test.  
(2) Parallel lengths of hose taped together shall have not more than 4 inches out of each  
12 covered by tape.  
(3) Parallel hoses shall be color coded as follows:  
(a) Red--fuel gases.  
(b) Green--oxygen.  
(c) Black--inert gas or air.  
(4) A hose shall be repaired or replaced when it shows burns, leaks, worn places or other  
defects which could affect the safety of employees.  
History: 1979 AC.  
R 408.11254 Regulators.  
Rule 1254. Regulators shall:  
(a) Be used as specified in R 408.11224(3).  
(b) Be inspected for faulty seats and repaired when found defective.  
(c) Be repaired by authorized and trained personnel, or be returned to the supplier for  
calibration or repairs.  
(d) Not be removed until the cylinder valve is closed and the regulator drained.  
(e) Have gauges marked "Use No Oil" when used for oxygen.  
History: 1979 AC.  
GENERAL FIRE RULES  
R 408.11261 Fire precautions.  
Rule 1261. (1) Cutting and welding shall be done in designated areas free of flammables  
or conditions favorable to fire or explosion. If it is not practical to perform the work in a  
designated area, a person shall be assigned responsibility for fire safety of the job and shall  
take the following action after inspecting the job site and designating precautions to be  
taken:  
(a) Move flammables a minimum of 35 feet (10.7 m) from the area, cover the flammables  
with a fire resistant covering, or schedule the work for a time when the flammables have  
been removed.  
Page 15  
(b) Cover cracks in the floor or walls that are within 35 feet (10.7 m) of the welding or  
cutting process if they could pass sparks to other areas.  
(c) Wet down wooden floors, except when laid over concrete, and provide a bucket or pan  
containing water or sand or cover with a fire resistant shield. Where the floor has been wet  
down, arc welding operators shall be protected from shock.  
(d) Have appropriate portable fire extinguishers on hand for use by trained employees.  
(e) If there is a possibility that a smoldering fire may have started, keep an observer at the  
scene of the work for at least 30 minutes after the welding or cutting has stopped.  
(2) An observer shall be assigned whenever welding or cutting is done in an area where a  
fire could start or 1 of the following conditions exists:  
(a) Appreciable combustible materials in the building construction or contents less than  
35 feet (10.7 m) from the point of operation.  
(b) Appreciable combustible material more than 35 feet (10.7 m) away but easily ignited  
by a spark.  
(c) Wall or floor opening less than a 35 feet (10.7 m) radius from exposed combustible  
materials in adjacent areas including concealed spaces in walls and floors.  
(d) Combustible material adjacent to the opposite side of a metal partition, wall, ceiling,  
or roof which is likely to ignite by conduction or radiation.  
(3) Welding and cutting by gas utility firms on live mains is exempt from this rule when  
the main is filled under positive pressure with natural or manufactured gas and air movers  
are used to ventilate areas where fumes might accumulate.  
(4) Welding or cutting shall not be permitted in the following situations:  
(a) In an area not authorized by management.  
(b) In a sprinklered building while such protection is impaired unless a fire watch is  
provided.  
(c) In the presence of an explosive atmosphere such as mixtures of flammable gases,  
vapors, liquids, or dusts with air.  
(d) In an area nearer than 35 feet of storage of large quantities of exposed, readily ignitable  
materials such as bulk sulfur, baled paper, or cotton.  
(5) Conveyor and exhaust systems that might carry sparks to a distant combustible shall  
be protected or shut down.  
History: 1979 AC.  
R 408.11262 Welding drums, barrels, tanks, or other containers.  
Rule 1262. (1) Welding or cutting shall not be performed on drums, barrels, tanks, or  
other containers until they have been cleaned of all flammable combustible or toxic  
materials or fumes.  
(2) All pipe lines or other connections to drums, barrels, or tanks shall be disconnected or  
blanked.  
(3) Hollow spaces or cavities shall be vented and either filled with water or purged with  
an inert gas before preheating, cutting, or welding.  
(4) An opening shall be maintained during welding and cutting to vent gases or vapors.  
(5) The welded construction of a transmission pipeline shall be conducted in accordance  
with API 1104 “Standard for Welding Pipe Lines and Related Facilities,” 1973 edition, as  
adopted in R 408.11202.  
Page 16  
(6) The connection, by welding, of branches to a pipeline carrying a flammable substance  
shall be performed in accordance with API PSD 2201 “Welding or Hot Tapping on  
Equipment Containing Flammables,” 1963 edition, as adopted in R 408.11202.  
History: 1979 AC; 2013 AACS.  
Editor's Note: An obvious error in R 408.11262 was corrected at the request of the promulgating agency,  
pursuant to Section 56 of 1969 PA 306, as amended by 2000 PA 262, MCL 24.256. The rule containing the  
error was published in Michigan Register, 2013 MR 11. The memorandum requesting the correction was  
published in Michigan Register, 2013 MR 21.  
ARC WELDING AND CUTTING  
R 408.11271 Arc welding machines.  
Rule 1271. (1) An arc welding machine shall be capable of operating safely in the  
environment in which it is located. The design and construction shall enable the machine  
to carry its rated load with rated temperature rise where the temperature of the cooling air  
is not more than 104 degrees Fahrenheit and where the altitude is not more than 3,300 feet  
(1,000 m approx.).  
(2) Where unusual service conditions, such as corrosive fumes, steam, oil vapor,  
flammable gases, vibration, shock, dust, or weather exist, a specially designed machine  
shall be used.  
History: 1979 AC.  
R 408.11272 Open circuit and no-load voltages of arc welding machines.  
Rule 1272. (1) When an arc welding machine is operated without being connected to a  
load, the open circuit voltage shall not exceed the values shown in table 1 when rated  
voltage is applied to the primary winding or when a generator type arc welding machine is  
operating a maximum rated no-load speed.  
Page 17  
TABLE 1  
MAXIMUM OPEN CIRCUIT VOLTAGES OF WELDING MACHINES  
Max. Open Circuit (no-load) Voltage  
Manual and  
Welding Current  
ac  
Automatic Machines  
Semiautomatic Machines  
80 rms  
100 rms  
dc > 10% Ripple Voltage  
dc < 10% Ripple Voltage  
80 rms  
100 average  
100 average  
100 average  
(2) When welding and cutting processes require values of open circuit voltages higher  
than 100, insulation or other means shall be provided to prevent the operator from making  
accidental contact with the high voltage.  
(3) Equipment working through resistors from DC trolley voltages of 250 to 600 volts  
shall have a protective device for automatically disconnecting the power during arc off  
periods.  
(4) Automatic control devices for reducing no-load voltage below 50 volts shall be  
provided where AC welding is to be done under wet conditions that could provide a shock  
hazard.  
History: 1979 AC.  
R 408.11273 Design of arc welding machines.  
Rule 1273. (1) A controller integrally mounted in an electric motor driven welder shall  
have the capacity for carrying rated motor current and shall be capable of making and  
interrupting stalled rotor current of the motor.  
(2) Control apparatus shall be enclosed except for the operating wheels, levers, or handles.  
The handles and wheels shall be large enough to be grasped by a gloved hand.  
(3) Input power terminals, tap change devices, and live metal parts connected to input  
circuits shall be completely enclosed and accessible only by use of tools.  
(4) Welding lead terminals shall be protected from accidental electrical contact by  
personnel or metal objects. If a welding lead terminal normally used for connection to the  
work is connected to a grounded enclosure, it shall be done by a conductor at least 2 sizes  
smaller than the grounding conductor and it shall be so marked.  
(5) Portable control devices, such as push buttons, shall not be connected to an AC circuit  
of more than 120 volts. Exposed metal parts of a portable control device operating above  
50 volts shall be grounded.  
(6) Auto transformers or AC reactors shall not be used to draw welding current directly  
from any AC power source having a voltage of more than 80 volts.  
History: 1979 AC.  
Page 18  
R 408.11274 Installation.  
Rule 1274. (1) The frame or case of a welding machine shall be grounded unless the  
manufacturer does not recommend it.  
(2) The work on which the operator welds shall be grounded by a grounded metal floor,  
platen, connection to a grounded building frame, or by a direct ground to the machine. A  
wire used for grounding a work piece shall be capable of carrying the full welding current.  
(3) A conduit containing an electrical conductor shall not be used for completing a work-  
lead circuit.  
(4) A pipeline in service shall not be used as a permanent part of a work-lead circuit, but  
may be used during construction, extension, or repair if current is not carried through  
threaded joints, flanged bolted joints, or caulked joints and if special precautions are used  
to avoid sparking at connection of the work-lead cable.  
(5) Chains, wire ropes, cranes, hoists, and elevators used for carrying loads shall not be  
used to carry a welding current.  
(6) A welding cable shall be protected against damage, entanglement, or contact with  
power supply or high tension wires.  
(7) A welding machine not provided with a controller or disconnect switch as an integral  
part shall have a controller or disconnect switch with overload protection provided. A  
disconnect switch with overload protection or overload disconnect protection or equivalent  
shall be provided for each outlet used by a portable welding machine.  
(8) The rated current carrying capacity of the supply conductors for individual machines  
shall be not less than the rated primary current for the welding machine. The rated current  
carrying capacity of conductors for a group of welding machines may be less than the sum  
of the rated primary currents of the welding machines supplied. The conductor rating shall  
be determined in each case according to the machine loading based on the use to be made  
of each welding machine and the allowance permissible if all the machines supplied by the  
conductor will not be in use at the same time.  
(9) Where a welding machine is working sufficiently close to another machine so that a  
welding operator is likely to touch the exposed parts of more than 1 electrode holder  
simultaneously, the machine shall be connected so as to minimize shock hazard as follows:  
(a) DC machines shall be connected with the same polarity.  
(b) AC machines shall be connected to the same phase of the supply circuit and with the  
same instantaneous polarity.  
History: 1979 AC.  
R 408.11275 Operation.  
Rule 1275. (1) Engine fuel, cooling water, or shielding gas shall not be allowed to leak.  
(2) A welding machine shall be disconnected when being moved and turned off when not  
in use.  
(3) Electrodes shall be retracted or removed when not in use. Electrode holders not in use  
shall be placed so that they cannot make electrical contact with an employee, fuel or gas  
tanks, or conducting objects.  
Page 19  
(4) A welder shall not let live electrodes or holders touch his or her bare skin or damp  
clothing. When arc welding is performed in wet conditions or under a condition of high  
humidity, the welder shall be protected against electric shock.  
(5) Electrode holders shall not be cooled by immersion in water.  
(6) Welding shall not be permitted where fumes of chlorinated hydrocarbons are present  
unless specific ventilation and personal protective equipment is provided as specified by  
the Michigan Occupational Safety and Health Administration (MIOSHA) standards.  
(7) Before starting an arc welding operation, the welder shall do all of the following:  
(a) Make sure the work lead is secured to the work.  
(b) Make sure the magnetic work clamps are free of spatter on the contact surfaces.  
(c) Spread out the welding cable, if necessary, to prevent overheating and damage.  
(d) Make sure grounding connections are secured to a good ground.  
(e) Make sure the required switching equipment for shutting down the machine has been  
provided.  
(8) A welder shall not curl or loop welding cable around his or her body.  
History: 1979 AC; 2013 AACS.  
R 408.11276 Maintenance of arc welding machines.  
Rule 1276. (1) Spliced welding cable shall not be used within 10 feet (3.05 m) of an arc  
welding machine.  
(2) Equipment in need of repair that constitutes a safety hazard shall not be used or put in  
use until repairs are made by a knowledgeable employee or outside service.  
(3) Cut insulation on work and lead cable or exposed bare conductors of an arc welding  
machine shall be protected by electrical tape and made watertight or the conductor shall be  
replaced. Splices shall be made by insulated welded joints or pressure connectors.  
(4) An arc welding machine which has become wet shall be thoroughly dried and tested  
before use.  
History: 1979 AC.  
RESISTANCE WELDING  
R 408.11281 Resistance welding generally.  
Rule 1281. (1) An inspection shall be made of a resistance welding machine not less  
than yearly and records maintained of the findings and action taken. In addition, the  
operator shall report any defects to his or her supervisor. A defect which could cause injury  
shall be repaired before the machine is placed in operation.  
(2) Each resistance welding operation shall be analyzed and safeguards and personal  
protective equipment shall be used where a hazard is found.  
(3) The operator of a resistance welding machine and nearby employees shall be protected  
from flying sparks by shields, curtains, goggles, or a combination of a face shield and safety  
glasses as prescribed in R 408.11211.  
Page 20  
(4) A resistance welding machine shall be installed by a qualified employee under the  
direction of a licensed electrician or supervised by a welding engineer.  
(5) A disconnect switch, circuit breaker, or circuit interrupter shall be installed on or near  
the machine so that power can be shut off and locked out when the machine needs  
servicing.  
(6) A pair of ignitron tubes used in resistance welding equipment shall be equipped with  
a thermal protection switch. When used in a series connected water line, a single switch  
shall be sufficient if related to the downstream tube.  
(7) Controls for automatic, air, or hydraulic clamps and resistance machines shall be  
located or guarded to prevent accidental activation.  
(8) A foot control for a resistance welder, other than that used to apply weld pressure,  
shall be guarded to prevent accidental activation.  
History: 1979 AC; 1983 AACS; 1988 AACS.  
R 408.11282 Nonportable spot and seam welding machines.  
Rule 1282. (1) An external weld initiating control circuit for a nonportable spot or seam  
welding machine shall operate at not more than 120 volts for stationary equipment and not  
more than 36 volts for portable equipment.  
(2) Stored energy or capacitor discharge type of resistance welding equipment and control  
panels involving more than 500 volts (550 rms volts) shall be insulated and completely  
enclosed. Doors of this equipment and control panels shall be interlocked in a manner to  
interrupt the power and short circuit all capacitors when the door is opened. In addition to  
the mechanical interlock, a manually operated switch or equivalent device shall be installed  
to insure absolute discharge of the capacitors.  
(3) The door and access panel of the resistance welding machine and its control panel  
accessible at production floor levels shall be kept locked or interlocked to prevent entry by  
unauthorized employees to energized portions of the equipment. A door or access panel  
shall be considered locked if a key or wrench is required to open it.  
(4) Where an operator's fingers are inserted between the electrodes during operation of a  
press welding machine, a device or guard, such as but not limited to an electric eye, 2-hand  
control, barriers or pull backs shall be provided and used.  
(5) One or more safety emergency stop devices shall be provided on all multispot welding  
machines with a minimum of 1 stop device at each operator position.  
(6) A large welding press shall be equipped with one or more safety pins, latches, or  
blocks capable of sustaining the full static load. The blocks, pins, and latches shall be  
electrically interlocked with the power source so that when the blocks are removed from  
their storage area on the machine and inserted under the ram or platen, the machine  
becomes inoperative.  
(7) The welding transformer secondary shall be grounded by one of the following:  
(a) Permanently grounding 1 side of the welding secondary circuit.  
(b) Connecting a grounding reactor across the secondary winding with a reactor tap to  
ground.  
(c) As an alternate, on nonportable machines, arranging for an isolation contactor to open  
1 side of the line, while the welding or electronic contactor shall open the other side.  
Page 21  
History: 1979 AC.  
R 408.11283 Portable welding guns.  
Rule 1283. (1) Unless the design makes it unnecessary, a portable welding gun shall be  
counterbalanced including the cables.  
(2) All suspended portable welding gun equipment, except the gun assembly, shall be  
equipped with a safety chain or cable capable of supporting the total shock load in event of  
failure of any component of the supporting system.  
(3) When a trolley is used to support a portable welding machine with a clevis for  
attachment to a safety chain, the clevis shall be wrought or forged steel and capable of  
supporting the shock load in event of failure of the trolley.  
(4) The movable holder shall have such clearance where it enters the welding gun frame  
that a shear action cannot take place if the operator's fingers are placed on the operating  
movable holder or guarding shall be provided.  
(5) The secondary and case of a portable welding transformer shall be grounded by a  
center tapped secondary or by a center tapped grounding reactor connected across the  
secondary.  
History: 1979 AC.  
R 408.11284 Flash welding.  
Rule 1284. (1) A flash welding machine shall be equipped with a hood to control flying  
flash.  
(2) For the protection of an operator of nearby equipment, fire-resistant curtains or  
suitable shields shall be set up around the machine and in such a manner that the operator's  
movements are not hampered.  
History: 1979 AC.  
ACETYLENE GENERATORS  
R 408.11291 Acetylene generators; marking; pressure limits.  
Rule 1291. (1) An acetylene generator shall be of approved construction and permanently  
marked with the following information:  
(a) Manufacturer's name and address.  
(b) Name or model number of the generator.  
(c) Capacity in cubic feet per hour.  
(d) Weight and size of carbide of a single charge.  
(2) The carbide used shall be not more than that marked on the acetylene generator and  
the rated capacity shall not be exceeded. Unless the generator is especially rated higher, a  
carbide feed generator shall not be rated at more than 1 cubic foot per hour per single  
charge.  
Page 22  
(3) A relief valve for a generating chamber shall be set to open at a pressure of not more  
than 15 psig (103 kPa gage). A relief valve for a hydraulic back pressure valve shall be set  
to open at a pressure of not more than 20 psig (137.4 kPa gage).  
(4) A nonautomatic generator used for generating acetylene shall be set to operate at a  
pressure of not more than 1 psig (.687 kPa gage) and all water overflows shall be visible.  
(5) An acetylene generator shall be so located that there will be unobstructed space around  
it to operate the machine without interference to or from other machines or employees and  
to permit adjustment and charging.  
History: 1979 AC.  
R 408.11292 Stationary acetylene generators.  
Rule 1292. (1) An acetylene generator shall be installed level and in a manner not to place  
a strain on the generator or its connections. A generator shall be electrically grounded.  
(2) A generator shall be located where water will not freeze. Heating shall be by steam,  
hot water, or other indirect means. Open flames, fire, or other sources of ignition shall not  
be permitted inside a generator house, room, or in any enclosure communicating with them.  
Sodium chloride or other corrosive chemicals shall not be used for protection against  
freezing.  
(3) A water supply line to an acetylene generator with a noncontinuous connection shall  
terminate not less than 2 inches (5.08 centimeters) above the fill opening so that the water  
can be observed as it enters the generator. A supply line with a continuous connection shall  
be used only when the generator is provided an open overflow or an automatic water  
shutoff which will prevent overfilling the generator.  
(4) An acetylene generator shall discharge only through an open connection into a vented  
outdoor receptacle or residue pit.  
(5) Each generator shall be provided with a vent pipe of galvanized iron or steel. The pipe  
shall be secured to the building without a trap and shall be installed so that condensation  
will drain back to the generator. The pipe shall carry to outside the building and shall  
terminate in a hood or bend not less than 12 feet from the ground and 3 feet (.91 meters)  
from combustible construction, away from a window or other opening in a building and  
any source of ignition, and shall be constructed so that rain, snow, insects, or birds cannot  
obstruct the opening. The vent pipes from several generators shall not be interconnected,  
but shall lead outside separately.  
History: 1979 AC; 1981 AACS.  
R 408.11293 Gas holders.  
Rule 1293. (1) A gas holder shall be constructed on the gasometer principle, the bell being  
suitably guided. The gas bell shall move without a tendency to bind and shall have a  
clearance of not less than 2 inches (5.08 cm) from the shell.  
(2) The compressor or booster cutoff of a gas holder shall be located 12 inches above the  
landing point of the gas bell to prevent collapse of the bell.  
(3) A gas holder shall be located in a heated and ventilated room as prescribed in  
R 408.11292(2) and the Michigan Occupational Safety and Health Administration  
Page 23  
(MIOSHA) standards. When heat is not supplied, the gas holder seals shall be protected  
from freezing.  
(4) A means shall be provided to stop the generator feeding mechanism before the gas  
holder reaches the upper limit of its travel. A gas holder connected to only 1 generator shall  
have a capacity of not less than 1/3 of the hourly rating of the generator.  
(5) Protective devices shall be installed in each supply line when acetylene is used from  
a gas holder without an increase in pressure at some points but with increased pressure by  
a compressor or booster pump at other points. A low pressure protective device shall be  
installed between the gas holder and the shop piping, and a medium pressure protective  
device shall be installed between the compressor or booster pump and the shop piping (see  
FIGURE 2). Approved protective equipment is used to prevent all of the following:  
(a) Backflow of oxygen into a fuel gas supply system.  
(b) Passage of a flashback into a fuel gas supply system.  
(c) Excessive back pressure of oxygen in the fuel gas supply system. The 3 functions may  
be combined in 1 device or may be provided by separate devices.  
(6) A compressor or booster pump shall be located in a ventilated area away from sources  
of ignition.  
(7) A compressor or booster pump shall be provided with a pressure relief valve which  
will relieve at not more than 15 psig (103.5 kPa gage) as prescribed in R 408.11292(5).  
The discharge outlets of a compressor or booster pump shall be provided protective  
equipment as prescribed in R 408.11252.  
FIGURE 2  
History: 1979 AC; 2013 AACS.  
R 408.11294 Stationary acetylene generators; outside houses and inside rooms.  
Page 24  
Rule 1294. (1) An opening in an outside acetylene generator house shall not be located  
within 5 feet (1.6 meters) of an opening in another building. The walls, floor, and roof shall  
be of noncombustible construction with a 1-hour, fire-resistance rating.  
(2) Where part of a generator house is used for storage or manifolding of oxygen  
cylinders, the space to be occupied shall be separated from the generator or carbide storage  
section by construction partition walls continuous from floor to ceiling, gastight,  
constructed as prescribed in subrule (1) of this rule, securely anchored and with not less  
than 1 exterior wall. Separation walls shall be without openings. Exit doors shall be located  
so as to be accessible in an emergency.  
(3) Explosion venting for generator houses and rooms shall be provided in the exterior  
wall or roof. The venting area shall be equal to not less than 1 square foot (.092 square  
meters) per 50 cubic feet (1.42 cubic meters) of room volume and may consist of 1 or any  
combination of the following:  
(a) Walls of light, noncombustible material, preferably single-thickness, single-strength  
glass.  
(b) Lightly fastened hatch covers.  
(c) Lightly fastened swinging doors on exterior walls which swing outward.  
(d) Lightly fastened walls or roof designed to relieve at a pressure of not more than 25  
pounds (11.35 kilograms) per square foot.  
(4) The installation of an acetylene generator within a building shall be restricted to a 1-  
story building or roof or top floor of a multistory building. A generator installed inside a  
building shall be enclosed in a separate room and constructed as prescribed in subrule (2)  
of this rule.  
(5) A generator room or house shall be equipped with vents located at ceiling and floor  
levels.  
(6) Illumination during daylight hours shall be by natural light. Where artificial lighting  
is necessary, it shall be from explosion-proof fixtures and controls. Wiring shall run  
through rigid conduit with threaded connectors. Telephone and other electrically powered  
apparatus either shall be designed for an explosive atmosphere or located outside the  
generator room or house.  
History: 1979 AC; 1981 AACS; 2013 AACS.  
R 408.11295 Portable acetylene generators.  
Rule 1295. (1) A portable acetylene generator shall not be used within less than 10 feet  
(3.2 m) of combustible material other than the floor. Ceiling height shall be not less than  
10 feet (3.2 m).  
(2) A portable generator shall be located in a room with a total volume of not less than 35  
times the total gas generating capacity per charge of all generators in the room. The gas  
generating capacity in cubic feet per charge is figured by multiplying the pounds of carbide  
per charge by 4 1/2.  
(3) A portable acetylene generator shall:  
(a) Be protected from freezing. Salt or other corrosive chemicals shall not be used.  
(b) Be cleaned, recharged and the air mixture blown off outside the building.  
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(c) Not be moved by a crane or derrick when charged. When transported and operated on  
a vehicle, it shall be secured to the vehicle. The generator shall not be operated, charged or  
cleaned while vehicle motor is running.  
(d) Not be stored in a room in which an open flame is used unless the generator contains  
no carbide and has been purged of acetylene. The storage room shall be ventilated.  
(e) Be protected from any source of spark or flame.  
(4) A portable generator shall be of a type approved for portable use.  
History: 1979 AC.  
R 408.11296 Maintenance and operation.  
Rule 1296. (1) An unauthorized employee shall not enter an acetylene generator room or  
house.  
(2) Operating instructions shall be posted near the acetylene generator for ready reference.  
(3) A batch type acetylene generator shall be flushed with water and the water supply  
replenished after a charge of carbide is exhausted, before additional carbide is added.  
(4) The water carbide residue mixture shall be piped into a settling pit not a sewer pipe.  
Only the clear water from the settling pit may be discharged into a sewer pipe.  
(5) Carbide added to an acetylene generator shall refill the space provided without  
ramming the charge. Steel or other ferrous tools shall not be used.  
(6) The water chamber of an acetylene generator shall be maintained at the indicated level  
except when draining during a recharging operation.  
(7) Prior to making a repair involving a source of ignition, such as welding, soldering, or  
other hot work, the carbide charge and feed mechanism shall be removed. All acetylene  
shall be expelled by completely flooding the generator with water and disconnecting the  
generator from the piping system. Water shall be maintained in the generator until repairs  
are completed. Hot repairs shall not be made in a room or house with other acetylene  
generators unless all generators and piping have been purged.  
(8) Whenever repairs are to be made, or the generator is to be charged, or the carbide is  
to be removed, the water chamber shall be filled to the proper level.  
History: 1979 AC.  
CARBIDE STORAGE  
R 408.11297 Carbide storage; general.  
Rule 1297. (1) Carbide shall be contained in metal packages capable of containing the  
material without rupture. The package shall be made watertight and airtight without using  
a solder that would melt during a fire. The package shall have a screw top or equivalent.  
History: 1979 AC; 1997 AACS.  
R 408.11298 Carbide storage indoors.  
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Rule 1298. (1) Inside storage areas for carbide shall not be protected by a sprinkler system.  
(2) Carbide stored indoors shall not exceed 600 pounds (272.2 kilograms). The area shall  
be dry, waterproof, and ventilated. Carbide storage with cylinders of fuel gas shall not  
exceed 600 pounds (272.2 kilograms).  
(3) Packages of carbide, except for 1 of each size, shall be kept sealed. A seal shall not be  
broken when there is more than 1 pound (.454 kilograms) of any other unsealed package  
of the same size of carbide in the room.  
(4) Carbide in excess of 600 pounds (272.2 kilograms), but not more than 5,000 pounds  
(2267.96 kilograms), shall be stored as follows:  
(a) In an inside acetylene generator room or outside generator house.  
(b) In a separate room of a 1-story building, which may contain other occupancies, that is  
without a cellar or basement beneath the carbide storage area. This room shall be  
constructed as prescribed in R 408.11294 and shall not be used for any other purpose.  
(c) In a 1-story building which is without a cellar or basement and which is used for no  
other purpose. If the building is of noncombustible construction, it may adjoin another 1-  
story building, but the buildings shall be separated by an unpierced firewall. If the building  
is separated by less than 10 feet (3.2 meters) from another building, there shall be no  
openings in the mutually exposed sides within 10 feet (3.2 meters). If the carbide storage  
building is of combustible construction, it shall be not less than 20 feet (6.4 meters) from  
any other 1- or 2-story building and not less than 30 feet (9.6 meters) from any other  
building more than 2 stories.  
History: 1979 AC; 1981 AACS.  
R 408.11299 Carbide storage outside.  
Rule 1299. (1) Only unopened metal containers of carbide shall be stored outside.  
(2) The container of carbide stored outside shall be inspected monthly for water and air  
tightness and rusting.  
(3) The bottom tier of each row of carbide containers shall be placed on wooden planking  
or equivalent so that the container will not make contact with the ground or ground water.  
(4) Containers of carbide shall be used on a first in, first out basis.  
History: 1979 AC; 1981 AACS.  
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