Session: CS-08-02 ASME Code Section XI Activities-2

Paper Number: 123337

123337 - Proposed New Guidance for the Design of Fillet Welded Patches 

Fillet welded lap patches may be applied to pressure vessels and piping that have suffered local wall thinning due to corrosion, erosion, and other damage mechanisms in the oil and gas, and petrochemical industries.  This type of repair is considered temporary until there is an opportunity for permanent repair or replacement.  The guidance provided in ASME PCC-2 Article 2.12 is widely used to design the fillet welded patches.  The article provides a design procedure for determination of required thickness of the repair patches considering the bending stress due to eccentricity (thickness offset).  However, ASME PCC-2 guidance results in significantly higher thickness for the fillet welded patches for most pressure vessel applications, especially when the required thickness of the vessel shell is close to its nominal thickness.  In this paper, conservatism associated with ASME PCC-2 guidance is discussed and an alternative, simplified, and less conservative procedure is proposed based on results from a parametric study of different design parameters using ASME Section VIII Division 2 Design By Analysis methodologies.  Both two-dimensional (2D), and three-dimensional (3D) elastic-plastic finite element simulations were performed by varying lap patch-to-vessel shell thickness ratio, lap patch angle and length, etc.  The differences between the trends from the 2D and 3D simulations is discussed.  Two examples are also presented showing the application of the proposed methodology and how it compares with the current ASME PCC-2 guidance.

Presenting Author: Seetha Ramudu Kummari The Equity Engineering Group, Inc.

Presenting Author Biography: Dr. Kummari is an engineer within the Advanced Analysis Group at E2G | The Equity Engineering Group, Inc. and provides engineering consulting services to the oil & gas, chemical, and nuclear industries on a wide variety of consulting projects. His areas of specialization include Fitness-For-Service using API 579, high temperature assessments, fatigue and fracture mechanics, and advanced stress and heat transfer analysis using Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD).

Dr. Kummari earned his Ph.D. in Mechanical Engineering from Case Western Reserve University, Cleveland, Ohio. As a part of his Ph.D. dissertation, he developed experimental and computational methods to assess fracture risks of bones in elderly people. He earned both his Bachelor’s and Master’s degree from a reputed educational institute in India, Indian Institute of Technology (IIT) Kharagpur.

Authors:

Seetha Ramudu Kummari The Equity Engineering Group, Inc.
Brian Macejko The Equity Engineering Group, Inc.
Michael Bifano The Equity Engineering Group, Inc.
Ryan Jones Canatus Engineering Group Ltd