A-TIG Welding Technology for Double Tube Sheet Heat Exchangers

Literature Overview

This 2012 study by Diao Zhifeng, Yang Shubiao, Huang Renlong, Ji Qinghe, Yan Hua, and Gu Zhimin, conducted jointly by the Jiangsu Special Equipment Safety Supervision and Inspection Institute and Jiangsu Shuangliang Boiler Co., Ltd., addresses the welding technology for double tube sheet heat exchangers using the A-TIG (Arc-Tungsten Inert Gas) welding process. Double tube sheet heat exchangers are critical components in chemical processing, petrochemical, and pharmaceutical industries where isolation between process fluids is essential. The welding of these components requires high-quality, leak-tight joints that can withstand high pressures and corrosive environments.

Technical Background

A double tube sheet heat exchanger consists of two tube sheets separated by a spacing, with tubes passing through both sheets. The annular space between the two tube sheets provides an additional barrier against leakage, making this design suitable for applications where fluid cross-contamination must be prevented. The welding of the tube sheets to the shell, the tubes to the tube sheets, and the annular chamber seals all require high-quality welds.

The A-TIG welding process, also known as plasma TIG or constricted arc TIG, is a variant of conventional TIG welding in which the arc is channeled through a constricted nozzle, creating a more focused and higher-energy-density arc. This results in deeper penetration, narrower weld beads, and improved arc stability compared to conventional TIG welding.

Welding Procedure Development

The researchers developed welding procedures for several critical weld joints in the double tube sheet heat exchanger, including the tube sheet to shell weld, the tube to tube sheet weld, and the annular chamber seal weld. The procedures were qualified according to applicable standards and verified through non-destructive testing and mechanical testing.