Full-Size Testing And Analysis of X120 Linepipe

A new high-strength steel with a specified minimum yield strength of 120 ksi has been developed for linepipe applications. Because existing specifications were not originally intended for the X120, and no service experience exists for this grade, fullsize pipe tests and finite element analyses were conducted to evaluate structural performance. The full-size testing included burst, pure bending, collapse, bending + collapse, ring expansion, curved wide plate and crack arrest tests. In addition to these tests, bending trials were performed on the X120 using commercial pipeline construction equipment to verify cold deformability. This paper presents the burst and fracture arrest studies. Results from burst tests and analyses demonstrate sufficient pressure containment capacity. For crack arrest, full-size tests were conducted to evaluate the intrinsic arrestability of the material and the effectiveness of crack arrestors. Although the X120 pipe did not have sufficient toughness for intrinsic arrest for the prescribed test conditions, tight-fitting sleeve crack arrestors were shown to be effective in stopping propagating fractures.