Case study : welding procedures in chilled water hot-tapping works

Abstract

Due to the high demanding of steel product in manufacturing and construction, welding processes are commonly adopted to build the steels into different shapes. In one hand, the higher strength steel will help to reduce the structure weight, improve the strength and impact toughness, however, in the other hand it also leads to lower weldability.

This paper reviews the classification of the steels, the commonly adopted welding processes, basic knowledge of impact toughness. the relationship between the strength and impact toughness and the influence to the strength, weldability, impact toughness, etc.

A case study is carried out to elaborate the procedures in the chilled water pipe hot-tapping works. Hot-tapping is not referring to the water temperature in the pipe is high. It means to tap a tee-off branch from an existing main live pipeline, which means the main pipeline is in operation continuously during the hot-tapping works being carried out.