Section 1 General requirements

1.1.1 This Section gives the general requirements for boiler tubes, superheater tubes and pipes intended for use in the construction of boilers, pressure vessels and pressure piping systems.

1.1.2 In addition to specifying mechanical properties for the purpose of acceptance testing, these requirements give details of appropriate mechanical properties at elevated temperatures to be used for design purposes.

1.1.3 Except for pipes for Class III pressure systems (as defined in the relevant Rules), all pipes and tubes are to be manufactured and tested in accordance with the requirements of Ch 1 General Requirements and Ch 2 Testing Procedures for Metallic Materials, the general requirements of this Section and the appropriate specific requirements given in Ch 6, 2 Seamless pressure pipes, Ch 6, 3 Welded pressure pipes, Ch 6, 4 Ferritic steel pressure pipes for low temperature service, Ch 6, 5 Stainless steel pressure pipes and Ch 6, 6 Boiler and superheater tubes.

1.1.4 Steels intended for the pressure piping systems where the use of steels with guaranteed impact properties at low temperatures is required to comply with the specific requirements of Ch 6, 4 Ferritic steel pressure pipes for low temperature service or Ch 6, 5 Stainless steel pressure pipes.

1.1.5 As an alternative to Ch 6, 1.1 Scope 1.1.3 and Ch 6, 1.1 Scope 1.1.4, pipes or tubes which comply with National or proprietary specifications may be accepted provided that these specifications give reasonable equivalence to the requirements of this Chapter 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.

1.1.6 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.

1.1.7 Pipes for Class III pressure systems are to be manufactured and tested in accordance with the requirements of an acceptable National specification. The manufacturer's test certificate will be acceptable and is to be provided for each consignment of material. Forge butt welded pipes are not acceptable for fuel oil systems, heating coils in oil tanks, primary refrigerant systems and other applications where the pressure exceeds 0,4 MPa.

1.2.1 Pipes for Class I and II pressure systems, boiler and superheater tubes are to be manufactured at works approved by Clasifications Register (hereinafter referred as 'LR'). The steel used is to be manufactured and cast in ingot moulds or by an approved continuous casting process as detailed in Ch 3, 1.4 Manufacture.

1.2.2 Unless a particular method is requested by the purchaser, pipes and tubes may be manufactured by any of the following methods:

• Hot finished seamless.
• Cold finished seamless.
• Electric resistance or induction welded.
• Cold finished electric resistance or induction welded.
• Electric fusion welded.

1.2.3 Care is to be taken during manufacture that the pipe or tube surfaces coming in contact with any non-ferrous metals or their compounds are not contaminated to such an extent as could prove harmful during subsequent fabrication and operation.

1.3.1 All pipes and tubes are to have a workmanlike finish and are to be clean and free from such surface and internal defects as can be established by the specified tests.

1.3.2 All pipes and tubes are to be reasonably straight. The ends are to be cut nominally square with the axis of the pipe or tube, and are to be free from excessive burrs.

1.4.1 The tolerances on the wall thickness and diameter of pipes and tubes are to be in accordance with an acceptable National specification.

1.5.1 The requirements for the chemical composition of ladle samples and acceptable methods of deoxidation are detailed in subsequent Sections in this Chapter.

1.6.1 All pipes and tubes are to be supplied in the condition detailed in the relevant specific requirements.

1.7.1 Pipes and tubes are to be presented for test in batches. The size of a batch and the number of tests to be performed are dependent on the application.

1.7.2 Where heat treatment has been carried out, a batch is to consist of pipes or tubes of the same size, manufactured from the same heat of steel and subjected to the same finishing treatment in a continuous furnace, or heat treated together in the same batch type furnace.

1.7.3 Where no heat treatment has been carried out, a batch is to consist of pipes or tubes of the same size manufactured by the same method from material of the same heat of steel.

1.7.4 For pipes for Class I pressure systems and boiler and superheater tubes, at least two per cent of the number of lengths in each batch is to be selected at random for the preparation of tests at ambient temperature.

1.7.5 For pipes for Class II pressure systems, each batch is to contain not more than the number of lengths given in Table 6.1.1 Batch sizes for pipes for Class II pressure systems. Tests are to be carried out on at least one pipe selected at random from each batch or part thereof.

1.8.1 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.

1.9.1 All pipes for Class I and II pressure systems, boiler and superheater tubes, are to be presented for visual examination and verification of dimensions. The manufacturer is to provide adequate lighting conditions to enable an internal and external examination of the pipes and tubes to be carried out.

1.9.2 For welded pipes and tubes, the manufacturer is to employ suitable non-destructive methods for the quality control of the welds. It is preferred that this examination is carried out on a continuous basis.

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

1.10.2 The hydraulic test pressure is to be determined from the following formula, except that the maximum test pressure need not exceed 14 MPa:

1.10.3 The test pressure is to be maintained for sufficient time to permit proof and inspection. Unless otherwise agreed, the manufacturer's certificate of satisfactory hydraulic test will be accepted. Where it is proposed to adopt a test pressure other than that determined as in Ch 6, 1.10 Hydraulic test 1.10.2, the proposal will be subject to special consideration.

1.10.4 Subject to special approval, either an ultrasonic or eddy current test can be accepted in lieu of the hydraulic test.

1.11.1 Surface imperfections may be removed by grinding provided that the thickness of the pipe or tube after dressing is not less than the required minimum thickness. The dressed area is to be blended into the contour of the tube.

1.11.2 By agreement with the Surveyor, the repair of minor defects by welding can be accepted, subject to welding procedure tests which demonstrate acceptable properties appropriate for the grade of pipe to be repaired. Weld procedure tests are to be subjected to the same heat treatment as will be applied to the actual pipes after weld repair.

1.11.3 The repaired area is to be tested by magnetic particle examination, or, for austenitic steels, by liquid penetrant examination on completion of welding, heat treatment and surface grinding.

1.12.1 Pipes and 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. Identification mark for the specification or grade of steel.

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

1.12.2  It is recommended that hard stamping be restricted to the end face, but it may be accepted in other positions in accordance with National Standards and practices and meets the requirements of Ch 1, 4.8 Identification of materials.

1.12.3 Where a number of light products weighting ≤ 50 kg per meter, are securely fastened together in bundles, the manufacturer may brand only each bundle. A firmly fastened durable label containing the identification may be attached to each bundle.

1.13.1 Unless a LR certificate is specified in other parts of the Rules, a manufacturer’s certificate validated by LR is to be issued, see Ch 1, 3.1 General.

1.13.2 The manufacturer is to provide LR with the following information:

1. Purchaser's name and order number.

2. If known, the contract number for which the material is intended.

3. Address to which material is despatched.

4. Specification or the grade of material.

5. Description and dimensions.

6. Identification number and/or initials.

7. Cast number and chemical composition of ladle samples.

8. Mechanical test results, and results of the intercrystalline corrosion tests where applicable.

9. Condition of supply.

1.13.3 As a minimum, the chemical composition stated on the certificate is to include the content of all the elements detailed in the specific requirements. Where rimming steel is supplied, this is to be stated on the certificate.

1.13.4 When steel is not produced at the pipe or tube mill, a certificate is to be supplied by the steelmaker stating the process of manufacture, the cast number and the ladle analysis.

1.13.5 The steel manufacturer's works is to be approved by LR.