Residual stresses distribution in long seam-welded offshore catenary riser of high-manganese steel

ABSTRACT

In recent years, oil and gas pipes and risers in deep sea reservoirs are required to have high resistance to collapse. This paper reports the comprehensive investigation of the residual stress distributions in a recently developed seam-welded offshore gas transmission riser of high-strength steel. Experimental hole drilling methods are applied to understand the residual stress distribution in the real scaled riser. Then, FE modelling on double-V groove is performed for a systematic parametric residual stress analysis of the riser components with consideration of parameters including the ratio of component radius to wall thickness (r/t), joint preparation, pass size, and heat input. Through the use of a residual stress decomposition technique, the thickness-through-thickness residual stress is partitioned into membrane and bending stresses. According to the results of the parametric study, a method for prediction of residual stress in circumferential direction is developed based on simplified empirical formulas for existing riser configurations with varying welding conditions.

KEYWORDS:

• Residual stresses
• steel catenary (drilling) riser
• seam welds
• empirical formulas
• radius to wall thickness ratio

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Myung Su Yi http://orcid.org/0000-0002-6984-5146

Jung Kwan Seo http://orcid.org/0000-0002-3721-2432

Jung Min Sohn http://orcid.org/0000-0002-6495-479X