Chapter III. Preventive Measures for Special Types of Work
Article 18. When the employer has workers engage in work to excavate tunnels or other pits under circumstances where the said workers may suffer from anoxia resultant from the gushing out of methane or carbon dioxide, he shall investigate into the presence and conditions of methane and carbon dioxide in the places at which the said work is carried out or in their vicinity by means of boring and other proper methods, in advance, and shall establish the methods thereby to deal with methane or carbon dioxide, at the time of the said excavation, and the steps by which the excavation is to be made, and shall make the said workers engage in the said work as mentioned above.
(Measures concerning Fire-Extinguishing Equipment, etc.)
Article 19. In terms of the use of fire-extinguishing devices or equipment, which employ carbon dioxide, as installed in underground rooms, engine rooms, holds and other places to which sufficient ventilation is not available, the employer shall assume the measures as given below:
(1) Make the said fire-extinguishing devices or equipment such
that they cannot easily fall down by being bumped by workers, or such that
their handles cannot be operated easily through accidental contact.
(2) Prohibit the workers from recklessly operating the said
devices or equipment, and also put up notices to that effect in a conspicuous
(Measures Concerning Refrigerators, etc.)
Article 20. When the employer has workers engage in work carried out in freezing rooms, refrigerators, closed cellar and other facilities or equipment tightly closed when in use, he shall assume measures thereby to keep doors or covers, which are installed at entrances or exits of the said facilities, or equipment, unclosed during the time the workers are engaged in the said work, provided that this does not apply in respect to a case in which the said facilities and equipment are in a structure that enables the doors or covers to be easily opened from the inside, or to a case in which informing or warning devices are installed inside the said facilities or equipment.
(Measures concerning Welding)
Article 21. When the employer has workers engage in welding with argon, carbon dioxide, or helium inside of tanks, boilers or reaction towers or in places where sufficient ventilation is not available, he shall assume either of the measures given below:
(1) Make ventilation thereby to maintain oxygen concentration
in the air at not less than 18% in the places in which the said work is
to be carried out.
(2) Have the workers use air respirators, etc.
2. The provisions of Article 7 shall apply in respect to air respirators, etc., in item 2 of the preceding paragraph.
3. In a case as provided for by item 2 of paragraph l, the
worker, when directed to use an air respirator, etc., shall use the said
(Measures for Prevention of Gas Leakage)
Article 22. The employer whose workers engage in work to be carried out
in a boiler, tank, reaction tower, hold, etc., where the piping for supplying
the gas designated in item 11 of Attached Table 6 of the Cabinet Ordinance
(hereinafter referred to as "inert gas") is installed, shall
take the following measures:
(1) Close cocks or valves or install shut-off plates.
(2) Lock the valves, cocks, or shut-off plates which are closed
in compliance with the provisions of the preceding item and put up notices,
stating that the valves, cocks or shut-off plates shall not be unlocked
in a conspicuous place.
2. In terms of valves or cocks installed to pipes to supply
inert gases or the switches, push buttons, etc., to operate the said valves
or cocks, the employer shall indicate the names of the inert gases supplied
through the said pipes and the direction of opening or closing of the said
valves and cocks, in order to prevent leakage of the inert gases from the
pipes, resulting from erroneous operation of the said valves, cocks, switches,
push buttons, etc.
(Measures concerning Gas Exhaustion)
Article 22-2. When the employer has workers engage in work in places where only insufficient draft or ventilation is available under conditions in which there could occur flowing of inert gases, as excreted from the safety valves, etc., installed in the containers in tanks, reaction towers, etc., into the said places, he shall assume measures to prevent the retention of the said inert gases in the said places, installing equipment, etc., by which to enable the inert gases, as excreted from the said safety valves, etc., to be exhausted directly to external sites.
(Prevention of Air from Being Rarefied)
Article 23. The employer whose workers engage in work to be carried out in a tank or reaction tower connected to the piping to draw out the inside air (not including the piping for ventilation) and facilities or equipment to be kept closed tightly while in use, shall take measure for keeping the covers or doors at the entrances of such facilities or equipment open while the workers are at work.
(Measures to Be Taken for Gas Piping Work)
Article 23-2. The employer whose workers engage in the work to install or remove the piping for supplying a gas mainly consisting of methane, ethane, propane or butane or the said gas including the air in the basement, duct or other places where the ventilation is poor, shall take the following measures:
(1) Completely shut off the supply of the gas so that the gas
will not leak into the place where the installation or removal work or
the piping is to be carried out.
(2) Ventilate the workplace so that the concentration of the
air in the workplace can be kept at least at 18% or more, or require the
workers to use the air respirators.
2. The provision of Article 7 shall be applicable with necessary modification to the air respirators
to be used conforming to the provision of item 2 of the preceding paragraph.
3. In the situation set forth in item 2 of paragraph 1, the
workers shall use the air respirators, etc., if required to do so.
(Measures for Pneumatic Caisson Method)
Article 24. In executing work by
pneumatic caisson method at a work site where the geologic formation
designated in-a) or b) of
item 1 of Attached Table 6 of the Cabinet Order or at a work
site adjacent to the said geological formation, the employer shall examine
the well or piping in the work site for possible leakage of oxygen-deficient
air and the degree of leakage if any, and measure the oxygen concentration
in the air whenever necessary.
2. When the result of the examination conducted conforming to the provision of the preceding paragraph indicates a leak of oxygen-deficient air, the employer shall notify the parties concerned to that effect, instruct what should be done for preventing anoxia and take necessary measures for preventing the workers from entering the work site where the oxygen-deficient air is leaking.
(Measures concerning Underground Rooms, etc.)
Article 25. When the employer has
workers engage in work which is carried out inside underground rooms,
pits, etc., where wells or pipes are provided which are adjacent to
the stratum as provided in the a) or b) of item
1 of Attached Table 6 of the Cabinet Order or which lead
to the said stratum, he shall provide measures thereby to prevent the
inflow of air deficient in oxygen into the places where the said work
is carried out, closing the places from which the said air deficient
in oxygen may leak, installing equipment thereby to enable the said
air deficient in oxygen to be exhausted directly to external sites,
(Works for Modification, etc., of Facilities)
Article 25-2. The employer whose workers engage in work for the modification, repair or cleaning of pumps, piping or related facilities containing or once having contained putrid or easily decomposable objects such as sewage, decomposed sediment, waste water, or pulp liquid, including the disassembling of such equipment or facilities, shall take the following measures:
(1) Decide the method and procedure of the work and notify
the workers accordingly prior to the start of the work.
(2) Designate a supervisor from among those workers who have
the knowledge of how to prevent hydrogen sulfide poisoning to supervise
the execution of the work.
(3) Remove the hydrogen sulfide completely from the facilities
to be worked on and close all the valves and cocks of the pipings connected
to the said facilities to prevent hydrogen sulfide from flowing into the
(4) Lock all the valves and cocks closed conforming to the
provision of the preceding item and put up a sign in a conspicuous place
to prohibit workers from opening such valves and cocks.
(5) Measure the concentration of hydrogen sulfide in the atmosphere
surrounding the facilities to be worked on and install a ventilator or
take other necessary measures if there is the possibility that the workers
may be subject to hydrogen sulfide poisoning.