Checking The Residual Stresses In Carbon Steel Pipe Girth Welds Before And After Heat Treatment

Abstract

This study investigates the effectiveness of post-weld heat treatment (PWHT) in relieving residual stresses (RS) in ASTM A53 Grade B carbon steel pipe girth welds. Two sample pipe spools were fabricated using metal gas welding techniques. Residual stresses were measured in both the as-welded condition and after PWHT using the Xstress 3000 G3 Portable X-ray Diffractometer, which employs non-destructive X-ray diffraction and the d–sin²ψ method for high-precision stress analysis. PWHT was applied to assess its influence on residual stress distribution across various depths and locations within the weld zone. The measured stress profiles were compared with residual stress guidance provided in BS 7910 and the UK nuclear industry's R6 procedure. Results indicate that PWHT significantly reduces the magnitude of residual stresses, thereby enhancing the structural integrity and expected service life of the welded joints.