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Ordinance on Safety of Boilers and Pressure Vessels

Ministry of Labour Ordinance No.33 of September 30, 1972
Latest Amendments:
Ministry of Health, Labour and Welfare Ordinance No. 171 of July 16, 2001

In Japanese

Chapter I. General Provisions

(Definitions)

Article 1. In this Ministerial Ordinance, the terms listed in the following items shall be defined as set forth in the corresponding items:

(1) Boiler shall be defined as the boiler specified in item 3 of Article 1 of the Enforcement Order of Industrial Safety and Health Law (hereinafter referred to as "Cabinet Order").

(2) Small-sized Boiler shall be defined as the boiler specified in item 4 of Article 1 of the Cabinet Order.

(3) First Class Pressure Vessel shall be defined as the first class pressure vessel specified in item 5 of Article 1 of the Cabinet Order.

(4) Small-sized Pressure Vessel shall be defined as the small-sized pressure vessel specified in item 6 of Article 1 of the Cabinet Order.

(5) Second Class Pressure Vessel shall be defined as the second class pressure vessel specified in item 7 of Article 1 of the Cabinet Order.

(6) Maximum Allowable Working Pressure shall be defined as the maximum gauge pressure (hereinafter referred to as "pressure") allowed for use in steam boilers, hot water boilers, first class pressure vessels and second class pressure vessels according to their construction.



(Heating Surface)

Article 2. The calculation of heating surface as set forth by the Ministry of Health, Labour and Welfare Ordinance based on a) of item 3 of Article 1 of the Cabinet Order shall be done for the surface specified in the following items according to the boilers described in the respective items:

(1) Boilers other than water tube boilers and electric boilers: Surface of boiler itself in contact with fire, burning gas and other high-temperature gas (hereinafter referred to as "burning gas, etc.") and in contact on its other side with water or other heat mediums (in the case of boilers having fins, studs, etc., on the surfaces contacting with burning gas, etc., the surfaces calculated by the corresponding application of b) to f) of the following item for the fins, studs, etc., concerned shall be added).

(2) Water tube boilers other than once-through boilers: The total of the following surfaces of the water tubes and headers.

a) For water tubes (excluding those specified in b) to h)) and headers in contact with burning gas, etc., totally or partially, the surfaces in contact with burning gas, etc.

b) For water tubes having fins longitudinally and for which both sides of the fins are in contact with burning gas, etc., the total of the surfaces obtained by multiplication of the surface of one side of the fins and the coefficient shown in the right column of the following table according to the classification of fins shown in the left column of the same table and the surface of the outside circumference of the tubes.

Classification of fins Coefficient
Fins receiving radiation heat on both sides 1.0
Fins receiving radiation on one side and convection heat on other side 0.7
Fins receiving convection heat on both sides 0.4

c) For water tubes having fins longitudinally and for which one side of the fins is in contact with burning gas, etc., the total of the surfaces obtained by multiplication of the surface of one side of the fins and the coefficient shown in the right column of the following table according to the classification of fins shown in the left column of the same table and the surface of the parts in contact with burning gas, etc., of the outside circumference of the tubes.

Classification of fins Coefficient
Fins receiving radiation heat 0.5
Fins receiving convection heat 0.2

d) For water tubes having fins around their circumference or helically, the total of twenty percent of the surfaces of one side of the fins (in the case of spiral fins, the surface calculated on the assumption that fins are fixed around the circumference and the number of their windings equal to the number of sheets of fins around the circumference) and the surface of outside circumference of the tubes.

e) For water tubes covered by firebricks, the projected surfaces to the outside walls of the tubes.

f) For stud tubes covered by fireproof materials and arranged on walls, half of the surfaces of the outside circumference of the tubes. In the case of the tubes of which all circumferences of covering materials are in contact with burning gas, etc., the surface of the outside circumference of the tubes.

g) For stud tubes in contact with burning gas, etc., the total of fifteen percent of the side surfaces of the studs and the surface of the outside circumference of the tubes.

h) For bailey style water walls, the surfaces in contact with burning gas, etc.


(3) Once-through boilers: Of the surfaces of water tubes from the entrance of the combustion chamber to the entrance of the superheater, those in contact with burning gas, etc.

(4) Electric boilers: The surface equivalent to the maximum capacity of the electric facilities on the assumption that 20 kilowatts of the capacity of electric facilities is equal to one square meter.
INDEX
I / II / III / IV
V / VI / VII / VIII


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