(171b) Fracture Toughness and Brittle Failure – a Pressure Vessel Case Study
AIChE Spring Meeting and Global Congress on Process Safety
Wednesday, March 29, 2017 - 10:45am to 11:15am
Control of the manufacturing and fabrication process to maintain high fracture toughness remains a challenge for the Oil & Gas Industry. In this paper, a case study of a pressure vessel failure due to low fracture toughness is examined. The head of the pressure vessel detached about its circumference at a low operating pressure (<50 psi), a pressure much less than the vesselâs maximum operating pressure. A root cause analysis of the event identified factors from the vesselâs service conditions, manufacture, and fabrication that combined to cause the brittle failure.
The causal factors from manufacture and fabrication of the vessel head will be discussed. These include: (a) stress relief or normalization of the mill plate; (b) cut-out of the blank from the mill plate; (c) residual stresses from dishing and flanging the head; (d) residual stresses from welding of the head to the shell; and (e) stress relaxation of the fabricated vessel. Discussion of the factors will include review of guidelines in the ASME Boiler & Pressure Vessel Code (BPVC).
The effect of the manufacturing process on the vessel steelâs mechanical properties will then be examined. These include strength, ductility and fracture toughness. Finally, deficiencies in these properties will be used to explain failure of the vessel head at the low operating pressure.
This paper has an Extended Abstract file available; you must purchase the conference proceedings to access it.
Do you already own this?
Log In for instructions on accessing this content.
|AIChE Pro Members
|AIChE Graduate Student Members
|AIChE Undergraduate Student Members
|AIChE Explorer Members