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Guideline

CONSTRUCTION CODE FOR BOILERS

Notification No. 197 of the Ministry of Health, Labour, and Welfare

In Japanese


Part 1. Steel Boilers

Chapter 1. Materials


Article 1. Main Materials
1. Main materials for steel boilers (hereinafter referred to simply as the "boiler" or "boilers" in Part 1 of this code) shall be ferrous or non-ferrous materials with chemical compositions and mechanical properties that can be used safely under the possible chemical and physical influences of the maximum allowable working pressure and working temperature.
2. The maximum working temperature in the preceding paragraph shall be equal to the maximum temperature of steam or a liquid in the boiler, while for heating surface materials, 30 (in the case of materials for the radiation superheater, 50 or more) or a certain value calculated using appropriate methods shall be added to the maximum temperature of steam inside.

Article 2. Restrictions on Use of Materials
The materials specified in each row in the left column of the following table shall not be used for any of the boilers or the parts thereof subject to exposure to pressure which are listed in the corresponding right column.:

Material Boilers and parts thereof subject to pressure
Materials with a carbon content exceeding0.35% Parts to be welded
Those specified in JIS G3106 (Rolled Steels for Welded Structure) and materials with equivalent or inferior mechanical properties Boilers or parts thereof specified below:
1. Boilers exceeding 1.6 MPa in maximum allowable working pressure
2. Shells or head plates of boilers exceeding 1 MPa but not exceeding 1.6 MPa in maximum allowable working pressure, provided that the longitudinal joints of such shells or similar joints of such head plates are welded
Those in JIS G3101 (Rolled Steel forGeneral Structure) and materials with equivalent or inferior mechanical properties Boilers or parts thereof specified below:
1. Boilers exceeding 1.6 MPa in maximum allowable working pressure
2. Shells or head plates of boilers exceeding 0.7 MPa but not exceeding 1.6 MPa in maximum allowable working pressure, provided that the longitudinal joints of such shells or similar joints of such head plates are welded
Those in JIS G3454 (Carbon Steel Pipes for Pressure Service), JIS G3455 (Carbon Steel Pipes for High Pressure Service), JIS G3456 (Carbon Steel Pipes for High Temperature Service), JIS G3458 (Alloy Steel Pipes), JIS G3459 (Stainless Steel Pipes) and materials with equivalent or inferior mechanical properties Heating tubes of boilers
Those in JIS G3452 (Carbon Steel Pipes for Ordinary Piping) and materials with equivalent or inferior mechanical properties Parts of boilers specified below:
1. Feedwater piping between the boiler body and the check valve and the blowoff piping between the body and the blowoff valve (if two or more blowoff valves are installed, the one located farthest from the body) of any boiler exceeding 0.7 MPa in maximum allowable working pressure
2. Pipings other than steam piping, feedwater piping and blowoff piping (except those specified in 1 above) of boilers not exceeding 1 MPa in maximum allowable working pressure
Those in JIS G4051 (Carbon Steels forMachine Structural Use) and materials with equivalent or inferior mechanical properties Shells and head plates of boilers
Those in JIS G4303 (Stainless Steel Bars), JIS G4304 (Hot Rolled Stainless Steel Plates, Sheets and Strip), JIS G4305 (Cold Rolled Stainless Steel Plates, Sheets and Strip) and materials with equivalent or inferior mechanical properties Headers of the economizer that are exposed to flame
Those in JIS G5501 (Gray Iron Castings),pearlitic malleable iron castings specified in JIS G5705 (Malleable Iron Castings) and materials with equivalent or inferior mechanical properties Parts of boilers (not including the economizer) coming under one of the specifications below:
1. Parts which are subject to exposure to pressure and flames
2. Box-shaped castings enclosed with flat surfaces, of which the inside of any section perpendicular to the longitudinal axis cannot be contained in a square 200 mm long on each side (except the valves and other attachments for use in a pressure range not exceeding 1 MPa)
3. Parts which are subject to exposure to pressure greater than 1.6 MPa
4. Cover plates for manholes
Those in JIS G5502 (Spheroidal Graphite Iron Castings), and blackheart malleable iron castings specified in JIS G5705 (Malleable Iron Castings), ductile iron castings and malleable iron castings specified in the Appendix 5 of JIS B8270 (Pressure vessels (General standard)) and materials with equivalent or inferior mechanical properties Parts of boilers (not including the economizer) coming under any of the specifications below:
1. Parts which are subject to exposure to pressure and flames
2. Box-shaped castings enclosed with flat surfaces, of which the inside of any section perpendicular to the longitudinal axis cannot be contained in a square 200 mm long on each side (except the valves and other attachments for use in a pressure range not exceeding 1 MPa)
3. Parts which are subject to exposure to pressure greater than 2.4 MPa
4. Cover plates for manholes
Those in JIS H3300 (Copper and Copper Alloy Seamless Pipes and Tubes) and materials with equivalent or inferior mechanical properties Parts of boilers other than the pressure gauge linking tube or some other attachments
Those in JIS H5120 (Copper and Copper Alloy Castings) Parts of boilers other than valves or some other attachments

Article 3. Allowable Tensile Stress of Materials other than Castings
1. The allowable tensile stress of materials other than castings shall be as specified below:
(1) The allowable tensile stress of ferrous or non-ferrous materials shall be the minimum of the following:
(a) 1/4 of the minimum tensile strength at room temperature;
(b) 1/4 of the tensile strength at the specified working temperature;
(c) 1/1.5 of the minimum value of the yield point or of the 0.2% proof stress at room temperature;
(d) 1/1.5 of the yield point or of 0.2% proof stress at the working temperature (90% of the 0.2% proof stress at the prescribed working temperature may apply to austenitic stainless steel if such material is used for any of the appropriate parts specified by the Director-General of the Prefectural Labour Bureau).
(2) Notwithstanding the provisions in the preceding items, the allowable tensile stress for bolts that are strengthened using such measures as heat treatment shall be the minimum of the values determined under the said items and those specified below.
(a) 1/5 of the minimum tensile strength at room temperature;
(b) 1/4 of the minimum value of the yield point or of 0.2% proof stress.
2. Notwithstanding the provisions in the preceding paragraph, the allowable tensile stress when the working temperature of materials is within their creep range shall be the minimum of:
(a) Mean value of the stress producing a 0.01% creep in 1,000 hours of service at the said temperature;
(b) 1/1.5 of the mean value of the stress producing a rupture in 100,000 hours of service at the said temperature;
(c) 1/1.25 of the minimum value of the stress producing a rupture in 100,000 hours of service at the said temperature.

Article 4. Allowable Tensile Stress of Castings
The allowable tensile stress of castings shall be as set forth in the following items:
1.The allowable tensile stress of iron castings shall be the appropriate one of the values specified in (a) or (b) below according to the categories of such castings:
(a) 1/6.25 of the tensile strength at the specified working temperature for iron castings in FCD400 and FCD450 of JIS G5502 (Spheroidal Graphite Iron Castings) and blackheart malleable iron castings in JIS G5705 (Malleable Iron Castings), or materials with equivalent or superior mechanical properties;
(b) 1/10 of the tensile strength at the specified working temperature for other iron castings.
2. The allowable tensile stress of steel castings shall be the result of multiplying the appropriate one of the values determined under the item 1 of the paragraph 1 or paragraph 2 of the preceding Article by the applicable one of the casting factors given in (a) or (b) below according to the categories of such castings:
(a) 0.8 for the steel castings in JIS G5101 (Carbon Steel Castings) with a chemical composition not exceeding any of the chemical contents specified in the right column of the following table for each type of such castings listed in the left column of the same table, and for the steel castings in JIS G5102 (Steel Castings for Welded Structure), JIS G5121 (Stainless Steel Castings) and JIS G5151 (Steel Castings for High Temperature and High Pressure Service), or materials with equivalent or superior mechanical properties (0.9 or 1.0 for those steel castings which have met the requirement of the test prescribed by the Director-General of the Prefectural Labour Bureau, depending on the category and method of the test performed):

Type of steel castings The content of chemical composition
Carbon Manganese Phosphorus Sulfur Silicon Nickel Chromium Copper
SC360 and SC410 0.25 0.70 0.04 0.04 0.60 0.50 0.50 0.50
SC450 and SC480 0.35 0.70 0.04 0.04 0.60 0.50 0.50 0.50
Remarks:
1. The chemical contents are given in percentage.
2. The manganese content may be increased by 0.04% for every 0.01% decrease in the carbon content, compared with the levels specified in the table. However, the manganese content shall never exceed 1.10% whatever the carbon content may be.
3. The nickel, chromium and copper contents shall not exceed 1.0% in combined total.

(b) Casting factor of 0.67 for other steel castings
3. The allowable tensile stress of nonferrous metal castings shall be the result of multiplying the value determined under the item 1 of the paragraph 1 of the preceding Article by a casting factor of 0.8.

Article 5. Allowable Compressive Stress of Materials
The allowable compressive stress of any material shall be equal to the allowable tensile stress for the material.

Article 6. Allowable Shearing Stress of Materials
The allowable shearing stress of any material shall be equal to 80% of the allowable tensile stress for the material.
INDEX
1-1 / 1-2 / 1-3 / 1-4 / 1-5 / 2
Supplementary Provisions


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