Methods for Assessment of Pipeline Girth Weld Integrity

In this section

Back to Core Research Programme AMorph – 4D Printing for Field Morphing Structures Automation of Composite and Hybrid Joining Process Coaxial Wire Additive Manufacturing Processes and In-Line Monitoring Tools Development of Coded Excitation Technique for Non-Metallic Pipes Inspection Development of Digital Twin technology as a demonstrator for real-time integrity assessment of crack growth in tensile specimens Development of Friction Stir Welding (FSW) for Hydrogen Fuel Storage Tanks Development of Leak-Before-Break Hydrogen Storage Composite Pressure Vessels With Polymeric Liner Establishing Assessment Methods for Determining Safe Service Limits of High-Temperature Materials in Extreme Environments Fracture toughness in aggressive environments: effect of crack monitoring techniques on test results In-process detection and non-destructive testing of electron beam weld imperfections Internal Bore Coatings for Applications in Corrosion and Hydrogen Environment Joining of Additively Manufactured Materials Long term behaviour of polymeric liner materials/coatings in hydrogen service Techniques for High Temperature Ultrasonic Inspection of Arc Welding Ultimate Leverage Fund

Project Code: 0901-01

Objectives

Develop and validate a strain-based failure assessment diagram (SB-FAD) procedure for girth welds.

Understand how material variability in the girth weld influences use of stress and strain-based methods.

Develop and validate material models for accurate residual stress prediction in pipeline girth welds.

Develop a procedure for including of the effects of residual stresses on crack-tip constraint for assessing girth weld fracture resistance.

Project Outline

The project will be divided into four tasks to achieve each of the objectives. The underlying theme of all of them will be the development of advanced/improved assessment procedures for girth welds in either pipelines of pipe-work. The task will cover the following subjects:

Strain-based FAD

Definition of reference strain which allows for flaw/pipe geometry.

Definition of maximum allowable reference strain.

Validation through numerical analysis and analysis of full-scale tests data.

Effect of material variability

Determination of how strength and fracture toughness vary around the pipe and through the wall thickness in both parent pipe and girth welds in modern steels.

Development of a testing and analysis procedure which best takes these variations into account for stress, but in particular, strain-based assessment methods.

Residual stress prediction

Determination of true cyclic stress history of material. Uniaxial testing under a thermal cycle simulating welding will be done in conjunction with the Dalton Institute.

Use of this information in an Abaqus numerical analysis model to predict residual stresses in girth welds.

Effect of residual stresses on fracture resistance

Experimental and numerical analysis to develop residual stresses (initially starting with uniform residual stresses) and how these redistribute during a fracture test.

Quantify how crack-tip constraint develops during loading.

Extend the simple model to a girth weld.

Relevant Industry Sectors

Oil and Gas, Pipelines, Power Generation (especially Nuclear).

Technical and Economic Benefits

The work will provide a technique that can be used to optimise the structural integrity of girth welds in pipelines and pipework with reductions in whole life costs.