STRAIN ANALYSIS OF HOT TAP BRANCH CONNECTIONS UNDER EXTERNAL LOADINGS

Branch connections made onto operating pipelines, known as hot taps, were evaluated under bending loads. A full encirclement reinforcing saddle, which is incorporated into the hot tap assembly, was examined in terms of its ability to reduce the stress concentration at the branch to mainline junction. External loads were applied to an ex-service hot tap and the resulting stress network was measured. The strain distribution across the joint was established and the effectiveness of the reinforcing saddle was ascertained by applying further loadings after the reinforcement was removed. The results have shown that the incorporation of a reinforcing saddle produces a significant reduction in the stress concentration at the mainline to branch junction.