Section 3 Welded pressure pipes
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules for the Manufacture, Testing and Certification of Materials, July 2022 - Chapter 6 Steel Pipes and Tubes - Section 3 Welded pressure pipes

Section 3 Welded pressure pipes

Parent topic: Chapter 6 Steel Pipes and Tubes

3.1 Scope

3.1.1 Provision is made in this Section for welded pressure pipes in carbon, carbon-manganese and low alloy steels.

3.2 Manufacture and chemical composition

3.2.1 Pipes are to be manufactured by the electric resistance or induction welding process and, if required, may be subsequently hot reduced or cold finished.

3.2.2 Where it is proposed to use other welding processes, details of the welding processes and procedures are to be submitted for review.

3.2.3 In all cases, welding procedure tests are required. Test samples are to be subjected to the same heat treatment as the pipe.

3.2.4 The method of deoxidation and the chemical composition of ladle samples are to comply with the appropriate requirements given in Table 6.3.1 Chemical composition of welded pressure pipes.

3.3 Heat treatment

3.3.1 Pipes are to be supplied in the heat treated condition given in Table 6.3.3 Heat treatment: welded pressure pipes.

3.4 Mechanical tests

3.4.1 All pipes are to be presented in batches as defined in Ch 6, 1 General requirements.

3.4.2 Each pressure pipe selected for test is to be subjected to tensile and flattening or bend tests.

3.4.3 The results of all mechanical tests are to comply with the appropriate requirements given in Table 6.3.2 Mechanical properties for acceptance purposes: welded pressure pipes.

3.5 Mechanical properties for design

3.5.1 The mechanical properties at elevated temperature for carbon and carbon-manganese steels in Grades 320 to 460 and 1Cr½Mo steel can be taken from the appropriate Tables in Ch 6, 2 Seamless pressure pipes.

Table 6.3.1 Chemical composition of welded pressure pipes

Type of steel Grade Method
of
deoxidation 		Chemical composition of ladle samples %
C Si Mn S max. P max. Residual elements
Carbon and carbon- manganese 320 Any method
(see Note) 		≤0,16 – 0,30– 0,70 0,050 0,050 Ni 0,30 max.

Cr 0,25 max.

Mo 0,10 max.

Cu 0,30 max.
360 ≤0,17 ≤0,35 0,40– 1,00 0,045 0,045
410 Killed ≤0,21 ≤0,35 0,40– 1,20 0,045 0,045
460 ≤0,22 ≤0,35 0,80–1,40 0,045 0,045 Total 0,70 max.
1Cr1/2Mo 440 Killed 0,10 – 0,18 0,10 – 0,35 0,40–0,70 0,040 0,040 Ni Cr Mo Cu Sn Al
0,30 max. 0,70– 1,10 0,45– 0,65 0,25 max. 0,03 max. ≤0,020

Note For rimming steels, the carbon content may be increased to 0,19% max.

Table 6.3.2 Mechanical properties for acceptance purposes: welded pressure pipes

Type of steel Grade Yield stress
N/mm2 		Tensile strength
N/mm2 		Elongation on 5,65% minimum Flattening test constant
C
Carbon and carbon-manganese 320 195 320 – 440 25 0,10
360 215 360 – 480 24 0,10
410 235 410 – 530 22 0,08
460 265 460 – 580 21 0,07
1Cr1/2Mo 440 275 440 – 590 22 0,07

Table 6.3.3 Heat treatment: welded pressure pipes

Type of steel Condition of supply
Carbon and carbon-manganese, see Note Normalised
(Normalised and tempered at the option of the manufacturer)
1Cr1/2Mo Normalised and tempered

Note Subject to special approval, electric resistance welded (ERW) pipes and tubes in grades 320 and 360 may be supplied without heat treatment for the following applications:

Note (a) Class 2 piping systems, except for liquefied gases or other low temperature applications.

Note (b) Class 3 piping systems.

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