Section 3 Tubes

3.1.1 Provision is made in this Section for seamless copper and copper alloy tubes intended for use in condensers, heat exchangers and pressure piping systems.

3.1.2 Tubes for Class I and II pressure systems (as defined in the relevant Rules), are to be manufactured and tested in accordance with the requirements of Chapters Ch 1 General Requirements and Ch 2 Testing Procedures for Metallic Materials and the requirements of this Section.

3.1.3 As an alternative to Ch 9, 3.1 Scope 3.1.2, tubes which comply with National or proprietary specifications may be accepted provided that these specifications give reasonable equivalence to the requirements of this Section or alternatively are approved for a specific application. Generally, survey and certification are to be carried out in accordance with the requirements of Ch 1 General Requirements.

3.1.4 Tubes for Class III pressure systems are to be manufactured and tested in accordance with the requirements of a National or International Standard recognised by LR. The manufacturer's test certificate will be acceptable and is to be provided for each batch of material.

3.2.1 Tubes for Class I and II pressure systems are to be manufactured at a works approved by LR for the grade of material being supplied.

3.2.2 Tubes for Class III pressure systems are not required to be manufactured at a works approved by LR.

3.3.1 Tubes are to be clean and free from surface and internal defects and residues from manufacturing operations.

3.3.2 The tubes are to be supplied in smooth, round, straight lengths and the manufacturer is to guarantee freedom from deleterious films in the bore. The ends are to be cut clean and square with the axis of the tube and are to be de-burred.

3.4.1 The tolerances on the wall thickness and diameter of the tubes are to be in accordance with a National or International Standard recognised by LR.

3.4.2 The measurement of dimensional accuracy and compliance with the specification are the responsibility of the manufacturer, but the reports are to be made available to the LR Surveyors, who may require checks to be made in their presence.

3.5.1 The chemical composition is to comply with the requirements of a National or International Standard recognised by LR and comply with the base limits for the principal elements given in Table 9.3.1 Chemical composition of principal elements only.

3.6.1 Copper-phosphorus and aluminium brass tubes are to be supplied in the annealed condition. Aluminium brass tubes may additionally be required to be given a suitable stress relieving heat treatment when subjected to a cold straightening operation after annealing.

3.6.2 Tubes in the copper-nickel iron alloys are to be supplied in a solution heat treated condition to ensure that no iron rich phases are present.

3.7.1 Tubes are to be presented for test in batches of 300 lengths. A batch is to consist of tubes of the same size, manufactured from the same material grade.

3.7.2 At least one length is to be selected at random from each batch and subjected to the following tests:

1. Tensile test.

2. Flattening test.

3. Drift expanding test.

3.7.3 The procedures for mechanical tests and the dimensions of the test specimens are to be in accordance with Ch 2 Testing Procedures for Metallic Materials.

3.7.4 The flattening test is to be continued until the interior surfaces of the tube meet.

3.7.5 For the drift expanding test, the mandrel is to have an included angle of 45°.

3.7.6 The results of all mechanical tests are to comply with the appropriate requirements given in Table 9.3.2 Mechanical properties for acceptance purposes.

Table 9.3.2 Mechanical properties for acceptance purposes

Designation	0,2% proof stress N/mm2 minimum	Tensile strength N/mm2 minimum	Elongation on 5,65% minimum	Drift expansion test % minimum	Grain size mm maximum (see Note)
Copper-phosphorus deoxidised–non-arsenical	65	220	40	40	–
Copper-phosphorus deoxidised–arsenical	65	220	40	40	–
Aluminium brass	125	320	40	30	0,045
90/10 Copper-nickel-iron	100	270	30	30	0,045
70/30 Copper-nickel-iron	120	360	30	30	0,045
Note When a maximum grain size is specified, the structure is to be completely re-crystallised. The manufacturer is to guarantee the grain size, but testing of each batch will not be required.

3.7.7 At the discretion of the Surveyor, a modified testing procedure may be adopted for small quantities of materials. In such cases, these may be accepted on the manufacturer's declared chemical composition and hardness tests or other evidence of satisfactory properties.

3.8.1 All tubes are to be visually examined. The manufacturer is to provide adequate lighting conditions to enable an internal and external examination of the tubes to be carried out.

3.8.2 The inner and outer surfaces are to be clean and smooth but may have a superficial, dull iridescent film on both the inner and outer surfaces.

3.9.1 Each tube is to be subjected to a hydraulic test at the manufacturer's works.

3.9.2 The hydraulic test pressure is to be determined from the following formula, except that the maximum test pressure need not exceed 7 MPa:

3.9.3 The test pressure is to be maintained for sufficient time to permit proof that the tubes do not weep, leak or undergo a permanent increase in diameter. Unless otherwise agreed, the manufacturer's certificate of satisfactory hydraulic test will be accepted.

3.9.4 Where it is proposed to adopt a test pressure other than that determined in Ch 9, 3.9 Hydraulic test 3.9.2, the proposal will be subject to special consideration.

3.9.5 Subject to special approval, an automated eddy current test can be accepted in lieu of the hydraulic test. Discontinuous irregularities on the external and internal surfaces of the tubes are permitted if they are within the agreed dimensional tolerances, with the exception of cracks, which are not permitted.

3.10.1 The repair of defects by welding is not permitted.

3.11.1 Tubes are to be clearly marked by the manufacturer in accordance with the requirements of Ch 1 General Requirements. The following details are to be shown on all materials which have been accepted:

1. LR or Clasifications Register.

2. Manufacturer's name or trade mark.

3. Grade of material or designation code.

4. Identification number and/or initials which will enable the full history of the item to be traced.

3.11.2 Identification is to be by rubber stamp or stencils. Hard stamping is not permitted.

3.12.1 A manufacturer’s certificate validated by LR is to be issued (see Ch 1, 3.1 General), giving the following particulars for each casting or batch of castings which has been accepted:

1. Purchaser's name and order number.

2. Specification or grade of material.

3. Description and dimensions.

4. Cast number and chemical composition.

5. Mechanical test results.

6. Results of stress corrosion cracking test, where applicable.

7. Hydraulic test report.