Abstract

The role of residual stress in the performance properties of tubular products is increasingly coming under renewed interest. A historical review shows how tubular manufacturing standards have added straightening and stress relief requirements to minimize residual stress. International technical reports focusing on performance equations have included a residual stress term for tubular collapse performance. Research summaries concerning full size testing of casing in saturated H2S liquid environment have reported the significant impact of tensile residual stress in the propagation of surface notches.

Recent technology advancements in the aviation, medical and nuclear industries have resulted in effective ways to strategically place deep, stable residual stress fields into metal structures to greatly improve damage tolerance and to mitigate fatigue cracking and environmental-assisted cracking. Engineered placement of residual stress fields in oil country tubular products, drill pipe, and line pipe has reached the research and testing phase.

This paper also presents a review of residual stress formation during manufacture and as a factor in tubular performance, a review of advanced processing techniques in managing residual stress, and a review of recent performance testing on tubular components incorporating near yield strength compressive residual stress fields.

Introduction

The combination of deeper drilling programs, horizontal drilling, cyclical hydraulic fracturing, and recent increases in well design safety by government regulators has pushed the needed performance of oil country tubular products to their natural limits. In order to enhance tubular performance and consistency, a renewed interest in understanding and managing residual stress is stirring within the industry. This paper reviews the complexities of the various manufacturing processes that add components of residual stress as the tubes are being manufactured so that the reader has an appreciation for the many heating and cooling and plastic deformation processes that are required to produce a finished tube. Also, a historical review of how tubular standards activity has brought about manufacturing requirements that result in a level of control over residual stress is provided. Appendix 1 further provides the user with some key historical excerpts of standardization work related to residual stress beginning in 1938 and links residual stress to pipe performance. To improve management of residual stress will require the use of management tools that can either minimize these stresses or engineer specific beneficial orientations of residual stress that will enhance performance. One new residual stress controlling technology, Low Plasticity Burnishing or LPB, has entered the research and testing phase for tubular products and the 5,656 hours of preliminary test results related to mitigating sulfide stress cracking in a high strength P-110 coupling material are provided.

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