Discussion of the Background of the Design Margins in API 17TR8 HPHT Design Referencing ASME VIII Division 3
There has been a significant amount of discussion of the appropriateness of the design margins from ASME Boiler and Pressure Vessel Code Section VIII Division 3 being applied to the design of HPHT equipment. A technical report has been issued with a first revision which references the use of ASME Section VIII Division 2 and Section VIII Division 3 for design of HPHT equipment above 15 ksi. Additionally, there has been recent pressure testing which attempted to validate the margins used in ASME Section VIII Division 3 and API 17TR8. There has also been a significant amount of discussion that the equipment in HPHT service may be very different from the pressure equipment which utilizes ASME Section VIII Division 3 and the design methods discussed in the standards. This paper will discuss the background of ASME Section VIII Division 3, including an overview of how the standard began, and the types of equipment which were being considered when the document was first drafted. It will also discuss the background of the design margin used in ASME Section VIII Division 3 over the years and how the current margin came into play. It will also discuss the margins used in addition to the margins on the structural capacity of a piece of equipment and how the margins interrelate within the Code. This paper will demonstrate the robust nature of ASME Section VIII Division 3, and its applicability to the design of HPHT equipment.