Modified WIC test: an efficient and effective tool for evaluating pipeline girth weldability

Abstract

The Welding Institute of Canada (WIC) test is a simple and standardised weldability test for hydrogen assisted cold cracking that was developed in the 80s. It has been extensively utilised by the industry to qualify safe welding envelopes but the difficult access to the weldment by instrumentation hinders its use for scientific research. Moreover the lack of repeatability arising from the traditional manual deposit and the short weld length causes industrial trials to have a low success rate. The present work proposes a modified geometry, referred to as the modified WIC (MWIC) test that shows: (1) an improved success rate of weld deposition, (2) an enhancement to instrument the weldment and (3) welding conditions in better accordance with the field pipeline girth welding conditions. The design is validated under a mechanised, shielded metal arc welding process with the cellulosic electrodes used for in-field pipeline construction.

Techno-economic Feasibility of Modified Pulse Arc Deposition on Thick Section of Quenched and Tempered Steel

“…HACC is generally accepted [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] as the phenomenological consequence of a critical concentration of hydrogen trapped in a susceptible microstructure subject to a threshold level of stress. Traditionally, hydrogen cracks have been known to manifest in the coarse-grained HAZ and are frequently described as toe cracking, root cracking or under-bead cracking, depending on the location of the crack [17].…”

“…To establish the susceptibility to HACC, multi-pass welds were deposited on the MWIC weldability test ( Fig.1 and Fig. 2) [20], using the same parameter range that was tested in Stage 1. The welded joint was removed from the MWIC specimens 24 hours after weld completion by milling the test assembly just inside the restraint length.…”

“…The anchor welds were sawed off using a Struers water-cooled precision metallographic saw. The weld zone was assessed for cracking by examining six weld metal transverse cross-sections prepared for metallurgical inspection (Figure 3) [20]. A sample is defined as cracked (Fig.4) if a planner defect is visually identified on a sample surface when magnified at x400, and the vertical length of the defect is greater than 5% of the height of the weld bead (t w ) [20].…”

“…The weld zone was assessed for cracking by examining six weld metal transverse cross-sections prepared for metallurgical inspection (Figure 3) [20]. A sample is defined as cracked (Fig.4) if a planner defect is visually identified on a sample surface when magnified at x400, and the vertical length of the defect is greater than 5% of the height of the weld bead (t w ) [20]. The weld metal microstructure was examined using Zeiss Axio Imager optical microscope on metallographically prepared weldments cross-sections, (polished to 1 μm diamond paste and etched in 2% nital solution).…”

“…Dimensions of the Single V Butt weld prep used for weldability testing. All dimensions in mm[20] Weldability test piece with the location of the 6 faces to be examined under an optical microscope at a magnification of x400 highlighted[20].…”