FCL have, for many years now, provided engineering support services to a major supplier of subsea flanges in the oil & gas industry. This has included a full flange design capability which is made available to their clients on all projects.
As a result of this relationship our client can provide fully detailed calculations for weld neck and swivel ring flanges to satisfy requirements of all major design codes including DNV-OS-F101 using rules in PD5500 and ASME Section VIII Division 3.
Calculations are regulary provided for weld neck flanges to API 6A (6BX) and swivel ring flanges to API 17D (17SV) and both flange types to ASME B16.5.
The calculations provide assurance that the flanges can accommodate the applied design loads and that the prescribed bolt make-up stress (bolt pre-load) is sufficient to avoid flange leakage in service.
The use of traditional design methods are supplemented by both linear and non-linear finite element stress analysis, particularly when it is necessary to demonstrate that the design of flanges in duplex materials comply with the requirements of DNV-RP-F112 to avoid hydrogen embrittlement resulting from the cathodic protection system employed.