Section 4 Steel Tubes and Pipes

401. Steel tubes for boilers and heat exchangers

1. The definition of heat treatment mentioned in Table 2.1.42 of 401. 3 of the Rules are as follows

(1) Low temperature annealing : An annealing treatment which is performed to eliminate internal stress or reduce quenching strain.

(2) Normalizing : Heating a ferrous alloy to a suitable temperature above or and then cooling in still air to a temperature substantially below . Is performed to refine the structure and eliminate internal stress.

(3) Full Annealing : An annealing treatment in which a steel is austenitized by heating to a tem-

perature above the upper critical temperature ( or ) and temperature.

(4) Isothermal Annealing : A process in which a ferrous alloy is

partly or wholly austenitic, and is then cooled to and held at a

then cooled slowly to room

heated to produce a structure temperature that causes trans-

formation of the austenite to a relatively soft ferrite-carbide aggregate.

2. Chemical composition

The chemical composition of R STH 33 is to comply with the requirements given in Table 2.1.7.

Table 2.1.7 Chemical composition

3. Heat treatment and mechanical properties

(1) The heat treatment of R ST H 33 is to be same as the requirement for R ST H 35

(2) The mechanical properties of R STH 33 are to comply with the following requirements.

(a) Tensile test : The tensile test of R STH 33 is to comply with the requirements given in

Table 2.1.8.

Table 2.1.8 Mechanical properties

(b) Flattening test : The flattening test of R STH 33 is to comply with the requirements given in

401. 5 (2) of the Rules. However, the value of e is to be 0.09

(c) Flanging test : A section of steel tube which is taken from its end is to be turned over

cold so as to have a flange, the outside diameter of which is not less than specified in

Table 2.1.9, at right angle to the axis without cracking or showing flaw. In this case, the flanging test specimen is to be of length L such that after testing the remaining cylindrical portion is not less than 0.5 D . But, this test is to be made only for R ST H 33 tubes having wall thickness not more than 1/10 of its outside diameter and not more than 5 mm.

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Ch 1 Materials Pt 2, Ch 1

Table 2.1.9 Outside Diameter of Flange after Flanging

(d) Crushing test : Where required by the Surveyor, a crushing test is to be made on a section of steel tube of 65 mm in length which is to stand crushing longitudinally without cracking or splitting to the height specified in Table 2.1.10.

Table 2.1.10 Height of Section after Crushing

(e) Reverse flattening test : The reverse flattening test of R ST H 33 is to comply with the re- quirements given in 401. 5 (4) of the Rules.

(f) Hydraulic test : The hydraulic test of R STH 33 is to comply with the requirements given in

401. 5 (5) of the Rules.

(3) The non-destructive inspection, substituted for the hydraulic tests, specified in 401. 5 (5), (d) of

the Rules are to be either ultrasonic tests or eddy current tests.

(a) Ultrasonic test is to comply with K S D 0250 (Ultrasonic examination for steel pipes and tubes). Steel tubes and pipes not to be detected the signal equivalent to that to be detected at artificial holes of reference block from detection sensitivity UD are accepted.

(b) Eddy current test is to comply with K S D 0251 (Eddy current examination for steel pipes and tubes). Steel tubes and pipes not to be detected the signal equivalent to that to be de-

tected at artificial holes of reference block from detection sensitivity EY are accepted.

4. Selection of test specimen

The test specimens of R STH 33 are to be taken in accordance with the following requirements, from each grade and each size which has been heat treated at the same time in the same heating fur-

nace for heat-treated tubes and from each grade and respectively.

(1) Seamless steel tubes : One sampling steel tube is to fraction thereof, and one tension, one flattening and to be taken from each of the sampling steel tubes.

(2) Electric-resistance welded steel tubes : In addition to

each size for non-heat-treated steel tubes

be selected from each lot of 100 tubes or one flanging or flaring test specimens are

the requirements in (1), one sampling steel

tube is to be selected from each lot of 50 tubes or fraction thereof for 100 and less steel tubes, and each lot of 100 tubes or fraction thereof for 100 over steel tubes, and one reverse flattening test specimen is to be taken from each of the sampling steel tubes.

402. Steel pipes for pressure piping

1. Mechanical properties

“The non-destructive inspection deemed appropriate by the Society" specified in 402. 5 (4), (d) of the Rules are dealt with according to the provisions in 401. 3 (3) of the Guidance.

404. Steel pipes for low temperature service

1. Application

In application to 404. 1 (2) of the Rules, the term "the discretion of the Society" means the ac- ceptance in accordance with Pt 1, Ch 1, 104. or 105. of the Guidance.

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