Ordinance on Industrial Safety and Health
Ministry of Labour Ordinance No. 32 of September 30, 1972
Latest Amendments:
Ministry of Health, Labour and Welfare Ordinance No. 47 of March 30, 2007
In Japanese
掲載日：2008.03.28
Part II Safety Standards
Chapter IV Prevention of Explosion, Fire, etc
Section 6 Acetylene Welding Equipment and Gas Welding Equipment Using Manifold
Subsection 1 Acetylene Welding Equipmentt
Article 301 (Pressure Limit)
- (1) The employer shall, when carrying out the work welding, cutting or heating of metals using acetylene welding equipment (meaning the one listed in item (i) of Article 1 of the Order, the same shall apply hereinafter), not generate or use acetylene having a pressure exceeding a gauge pressure of 130 kPa.
Article 302 (Generator Room)
- (1) The employer shall, as regards a acetylene generator of acetylene welding equipment (hereinafter referred to as “generator”), install it in a purpose-built generator room (hereinafter referred to as “generator room”)
- (2) The employer shall, as regards a generator room, install it in a floor having no floor just above and at a place considerable distance from equipment using fire.
- (3) The employer shall, when installing a generator room out of doors, install it’s opening at a distance of 1.5 m or more from other buildings.
Article 303
- (1) The employer shall conform a generator room to the following provisions:
- (i) To be constructed with an incombustible wall, and to have the following structure or a structure with the same strength as the following or more.
- (a) To be made of ferroconcrete with the thickness of 4 cm or more.
- (b) To be made of steel or lumber on which metal lath is lined and mortar is painted through 3 cm or more in thickness or of steel on which an iron plate with thickness of 1.5 mm or more are lined.
- (ii) To use thin iron plate or lightweight incombustible materials for the roof and ceiling.
- (iii) To project an exhaust pipe having a cross-section area of one-sixteenth of the floor area or more from the roof, and place the opening of the said pipe distance of 1.5 m or more from a window, an entrance and other opening.
- (iv) To use an iron plate with the thickness of 1.5 mm or more or with structure having the same strength as the iron plate or more using incombustible materials for a door of the entrance.
- (v) To keep the space between a wall and a generator that does not hinder adjusting of the generator, or the work feeding of carbide, etc.
- (i) To be constructed with an incombustible wall, and to have the following structure or a structure with the same strength as the following or more.
Article 304 (Storeroom)
- (1) The employer shall, as regards movable acetylene welding equipment, notwithstanding the provisions of paragraph (1) of Article 302, store in an purpose-built storeroom when the said equipment is not used. However, this shall not apply to when storing the equipment after its gas bell is removed and the generator is washed.
- (2) The employer shall, as regards the storeroom set forth in the preceding paragraph, construct it by fire-proof materials such as iron plate-lined lumber and slate-lined lumber.
Article 305 (Construction Codes of Acetylene Welding Equipment)
- (1) The employer shall conform acetylene welding equipment (excluding generators and safety equipment) that generate or use acetylene of a gauge pressure (hereinafter referred to as “pressure” in this Article) of 7 kPa or more to the following provisions.
- (i) To conform the gas holder to the following provisions.
- (a) To construct the principal portion of the gas holder with steel plates or steel pipes having a thickness listed in the right column of the following table or more corresponding to the inner diameter listed in the left column of the same table.
Inner diameter (cm) Thickness of steel plate or pipe (mm) Less than 60 2 60 or more but less than 120 2.5 120 or more but less than 200 3.5 200 or more 5 - (b) The method of jointing steel plates or steel pipes of the principal portion to be welding, rivet joints or bolt joints.
- (c) To be equipped with a gas escape valve or a cock to discharge a mixture of acetylene and air.
- (a) To construct the principal portion of the gas holder with steel plates or steel pipes having a thickness listed in the right column of the following table or more corresponding to the inner diameter listed in the left column of the same table.
- (ii) For the gas holder for acetylene that is compressed by a compressor after fed from the generator, in addition to compliance with the provisions of the preceding item, to be equipped with a safety valve and a pressure gauge as prescribed in the following:
- (a) Safety valve
- i.) Those operate before the pressure in the gas holder reaches 140 kPa, and shut while the pressure lowers to a level lower than the normal pressure by 10 kPa.
- ii.) In the case that the generator generates a maximum quantity of acetylene, those have the capability of keeping the pressure in the gas holder at less than 150 kPa.
- (b) Pressure gauge
- i.) The diameter of the dial plate to be 75 mm or more for one mounted on a stationary gas holder, and 50 mm or more for one mounted on a movable gas holder.
- ii.) The maximum scale of the dial plate to indicate pressures which are 1.5 times the normal pressure or more and500 kPa or less.
- iii.) For the dial plate, to have an readily visible indication of the normal pressure.
- (a) Safety valve
- (iii) The portions of the gas holder, purifiers, acetylene distributing lines, etc., which contact acetylene not to be constructed with copper or an alloy containing 70% or more copper.
- (i) To conform the gas holder to the following provisions.
- (2) The employer shall not use copper for the portions of the purifiers, acetylene distributing lines etc., of acetylene welding equipment other than those set forth in the preceding paragraph that is liable to contact acetylene.
Article 306 (Installation of Safety Equipment)
- (1) The employer shall, as regards acetylene welding equipment, provide safety equipment for each torch. However, this shall not apply to when the said safety equipment is provided to the main pipe and each of the branch pipes most close to the torches.
- (2) The employer shall, as regards acetylene welding equipment in which the gas holder and the generator are separated, provide safety equipment between the generator and the gas holder.
Article 307 (Sludge Pit of Carbide)
- (1) The employer shall install a sludge pit at a safe place and conform its construction to following provisions. However, this shall not apply to a mobile acetylene welding equipment used during business trip:
- (i) Bricks or concrete shall be used.
- (ii) The capacity of the sludge pit shall be three times that of the carbide charging device or more.
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