Design Consideration for the Erection of Heavy Wall and Large Diameter Pressure Vessels

Abstract

Heavy wall reactors and large diameter pressure vessels usually face unique challenges in their erection onto their foundations at the jobsite. Today, 800 ton to 1,500 ton reactors and or large diameter vessels with diameters ranging up to 15 meters are common in the refining industry. These pressure vessels are usually fabricated in shops dispersed globally and require unique heavy duty equipment for their safe handling, transportation and erection.The challenge is to find a safe, efficient and cost effective solution based upon the limitations of the equipment, job site and the lift equipment available for erection. Equipment for the handling heavy reactors and large diameter pressure equipment is usually scarce, expensive. Planning well in advance of the lift date is required.Careful consideration must be given to the choice and design of attachment to the pressure vessels used for the lift to ensure that the vessel and lifting components are not overstressed during the lifting process. This paper identifies the types of evaluations that must be performed to determine the stresses in the vessel and lifting attachments during the lifting. The paper also discusses different types of lifting lugs that may be attached to each end of the vessel either by bolting or welding and discusses the pros and cons of each. The paper also provides an example of a finite element analysis (FEA) of a top nozzle, a FEA of a pair of lifting trunions and a FEA of welded on lifting lugs for buried pipe. The intent of the paper is to outline the effects on the vessel due to different types of lifting configurations in combination with the lifting parameters. This paper is not intended to provide guidance on how to design lifting lugs.