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Reg. 16
MATERIALS OF CONSTRUCTION

STEEL PLATES, RIVETS, SECTION AND BARS IN CARBON STEEL

Tensile tests

(a) The tensile strength of different grades of material shall be within the limits specified in regulation 9 (d).

(b) – The upper yield point at room temperature shall be not less than 50% of the specified minimum tensile strength at room temperature.

(c) – The breaking elongation in percentage shall be not less than ( N-Rm)/C   

                                                                                                        

Where Rm = Tensile strength at room temperature in kgf/mm2

 

N = a quality index of 100 for plate thickness upto 50 mm or  95 for plate

 thickness over 50mm.

 

C = 2.2 for only gauge lengths of L=5 do or L=5.65/ Ao      

 

 Where Lo = gauge length             

                                                             

Ao = original cross section of the rectangular test piece.

                             

 

do = original diameter of the round test piece.

 

NOTE: C= 1.9 for gauge lengths of 4 Ao for test piece of Appendix-B.   

(d) – The minimum values of the stress at proof limit 0.2% at elevated temperature (Et) may be calculated by multiplying the minimum specified tensile strength at room temperature (R20) by the value of the ratio (Et/R20) given in the table below:

TABLE

Minimum values for the ratio of the stress at proof limit 0.2% at elevated temperature (Et) to the minimum specified tensile strength at room temperature (R20) of carbon steel boiler plates.

Temperature 250°C *275°C 300°C 325°C 350°C 375°C
Et/R20 0.40 0.38 0.36 0.34 0.33 0.32
Temperature 400°C 425°C        
Et/R20 0.31 0.30        

*For temperatures lower than 300°C any test required for acceptance purposes (in the absence of records of previous tests at these temperatures) shall be made at 300°C, in which case the proof stress shall be not less than value obtained by calculation from the specified minimum tensile strength at room temperature and the above proof-ratio of 0.36 for 300°C.

 
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