Section 12 Fabrication and testing requirements
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Construction & Classification of Submersibles & Diving Systems, July 2022 - Part 3 Pressure Chambers - Chapter 1 General - Section 12 Fabrication and testing requirements

Section 12 Fabrication and testing requirements

Parent topic: Chapter 1 General

12.1 General

12.1.1 The manufacturer’s works are to be approved in accordance with the requirements specified in Materials and Qualification Procedures for Ships, Book A, Procedure MQPS 0-4.

12.1.2 All manned chambers under internal and external pressure require the following to be carried out;
  1. 100 per cent radiography on all major welds. Welds not subjected to radiography shall be examined by other approved non-destructive testing methods. The use of gamma ray examination may be used only if specifically approved;
  2. in general, ‘tell-tale’ holes should not be drilled in compensating plates which will be subjected to external pressure. Where ‘tell-tale’ holes have been drilled in compensating plates, they are to be fitted with taper-screw plugs and seal welded prior to the hydrostatic pressure test, and are to remain efficiently plugged and sealed during service;
  3. post weld heat treatment may be required. Each case will be considered individually based on applicable Pressure Vessel code;
  4. diving bells/chambers subject to external pressure are to be subjected to an external test pressure of 1,3 times the maximum agreed working pressure when tested in open water and to an external test pressure 1,4 times the maximum agreed working pressure if tested in the test chamber. Test pressures other than the foregoing will be given consideration;
  5. after hydrostatic test, all pressure retaining welds and / or seal welds shall be examined in accordance with the requirements for either magnetic particle examination or liquid penetrant examination;
  6. intermediate heads for the pressure chambers should be designed and attached using the adopted national or international pressure vessel design code. In the case where the intermediate heads' attachment are not covered by the adopted code, the heads may be attached based on the guidance given in ASME PVHO-1. The basic allowable stress will be as per the applicable design code/ standard;
  7. spherical shell and spherical segment head shall be post weld heat treated irrespective of thickness. Heat treatment of the formed heads and the testing of the formed heads material will be considered individually;
  8. production tests will be carried out in line with the requirements of the code being followed in agreement with the attending Surveyor;
  9. the lifting block or the reinforcement plate for attaching the lifting block on the top of the diving bell are to have through thickness properties and be subject to appropriate NDE (UT & MT). The attachment welds are to be subject to UT & MT to Surveyor's satisfaction.
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