Section 1 General

1.1.1 This document provides guidance for approval, manufacturing, inspection and certification of high manganese austenitic steel as intended for use in the construction of cargo tanks, storage tanks, fuel tanks and process pressure vessels for liquefied gases.

1.1.2 This document is intended to provide guidance for steel plates with thickness between 6 mm and 40 mm. For greater thickness, special consideration will be given by LR.

1.1.3 High manganese austenitic steels with alternative chemical composition, deoxidation practice, condition of supply and mechanical properties may be considered, subject to the special approval of LR.

1.2.1 High manganese austenitic steel means steel containing a high amount of manganese in order to retain austenite as its primary phase at atmospheric and service temperature.

1.2.2 Piece means the rolled product from a single slab, billet or ingot if this is rolled directly into plates, sections or bars.

1.3.1 High manganese austenitic steels are to be manufactured at steelworks which have been approved by LR. The suitability of steel for forming and welding should be demonstrated during the initial approval test at the steelworks. Approval of the steelworks should follow a scheme given in Ch 3 Approval of a Works for the Manufacture of High Manganese Austenitic Steels.

1.3.2 It is the steelmaker’s responsibility to assure that effective quality, process and production controls during manufacturing are adhered to within the manufacturing specifications. The manufacturing specification should be submitted to LR at the time of initial approval.

1.3.3 Where non-conformities arise, the manufacturer is to identify the cause and establish countermeasures to prevent their recurrence. The non-conformities and the countermeasures are to be documented and reported to LR.