Ratcheting failure of pressurised straight pipes and elbows under reversed bending

Abstract Ratcheting studies were carried out on Type 304LN stainless steel straight pipes and elbows subjected to steady internal pressure and cyclic bending load. The internal pressure for all the straight pipes was 35 MPa and in the case of elbows the internal pressure was varied for different elbows, ranging from 27.6 MPa to 39.2 MPa. Cyclic bending load was applied on the specimens by subjecting them to different levels of load-line displacement. The specimens have undergone significant ratchet swelling (ballooning), ovalization and consequent thinning of the cross-section during ratcheting. The straight pipes failed either by occurrence of through-wall crack accompanied by simultaneous ballooning, or bursting with simultaneous ballooning. All the elbows failed by occurrence of through-wall crack accompanied by simultaneous ballooning. Ratcheting behaviour of straight pipes and elbows were compared and it was generally inferred that ratcheting was more pronounced in straight pipes than in elbows.

[1]  Gang Chen,et al.  Ratcheting behavior of pressurized elbow pipe with local wall thinning , 2013 .

[2]  D N Moreton,et al.  Onset of ratchetting in pressurised piping elbows subjected to in-plane bending moments , 1996 .

[3]  Bingjun Gao,et al.  Recent progresses in experimental investigation and finite element analysis of ratcheting in pressurized piping , 2013 .

[4]  Xu Chen,et al.  Ratchetting and ratchetting boundary study of pressurized straight low carbon steel pipe under reversed bending , 2006 .

[5]  K. K. Vaze,et al.  Ratcheting-Fatigue Failure of Pressurized Elbows made of Carbon Steel , 2009 .

[6]  D N Moreton,et al.  Response and cyclic strain accumulation of pressurized piping elbows under dynamic in-plane bending , 1996 .

[7]  Akihito Otani,et al.  Comparison of Failure Modes of Piping Systems With Wall Thinning Subjected to In-Plane, Out-of-Plane, and Mixed Mode Bending Under Seismic Load: An Experimental Approach , 2010 .

[8]  P. Gandhi,et al.  Fatigue ratcheting studies on TP304 LN stainless steel straight pipes , 2010 .

[9]  K. K. Vaze,et al.  Uniaxial and biaxial ratchetting study of SA333 Gr.6 steel at room temperature , 2003 .

[10]  K. K. Vaze,et al.  Ratcheting Studies on Type 304LN Stainless Steel Elbows subjected to Combined Internal Pressure and In-Plane Bending Moment , 2012 .

[11]  Bingjun Gao,et al.  Ratcheting Study of Pressurized Elbows Subjected to Reversed In-Plane Bending , 2006 .

[12]  Katsumasa Miyazaki,et al.  Failure Mode and Failure Strengths for Wall Thinning Straight Pipes and Elbows Subjected to Seismic Loading , 2008 .