Session: MF-24-02 Matls & Fabrication for Refining-Design & Fabrication Issues Affecting Design Life

Paper Number: 122443

122443 - Evaluation of Corrosion Resistance of Stainless Steel Piping With Fillet Weld on External Side in Comparison to Back Shielding Condition 

Back shielding by inert gas is required to not only single sided butt joints but also fillet joints of piping in accordance with specification or standard such as API RP582 where chromium content of base metal is high, e.g., greater than 2.5 %, and wall thickness is thin, e.g., 1/4” (6.5 mm) or lesser, for preventing oxidation in atmospheric environment by welding heat input.

However, volume of back shielding space on inside piping by fillet welding, such as joints between run pipe and piping support or reinforcing pad, are sometimes too large to purge oxygen out with economical rationality due to limitation of place of back shielding isolations, especially piping erection period at construction site.

Recently non-backing gas practices with GMAW-S and GTAW are implemented to single sided butt joints of stainless steel (SS) process pining in oil and gas industries with successful results. Therefore, oxidation of fluid contacting side can be considered as not matter from corrosion resistance viewpoints because heat affected zone of SS welds on fluid contact side is inevitable without back shielding regardless of welding method.

This paper presents corrosion resistance of fillet welds on SS piping in comparison to back shielding conditions and introduces possibility of omission of back shielding for fillet welds.

Presenting Author: Atsushi Takahashi JGC CORPORATION

Presenting Author Biography: Atsushi Takahashi has been working for JGC CORPORATION since 2006 and assined as Chief Engineer Welding since 2019.
He is a deputy chirman of Chemical Plant Welding Research Comitee in Japanese Welding Engineering Society since 2022.

Authors:

Atsushi Takahashi JGC CORPORATION
Takahiro Tsuda JGC CORPORATION