Hot tap tees of the full encirclement split tee design are currently used in the UK gas industry to provide connections onto existing high pressure gas transmission pipelines and above ground installations. The fitness-for-purpose of this type of tee is not covered by the UK design code for above ground gas installations, IGE/TD/9. A fitness-for-purpose methodology has been developed by Advantica Technologies to determine the integrity of the fitting and attachment welds. The fitness-for-purpose assessment addresses the following: • The compliance of the fitting to plastic collapse, shakedown and fatigue design criteria. • The integrity of the attachment welds onto the carrier pipe. • The use of Engineering Critical Assessments in conjunction with existing procedures to ensure overall integrity.

Parametric formulae derived for offshore structural tubular joints have been assessed for potential use for estimating stress intensification factors for pipe stress analysis. The background to these equations is given and comparisons made for a range of typical geometries. Despite the absence of a "plug" of material in a pipe joint, the tubular joint equations appear suitable for the estimation of stress intensification factors for fabricated tees subjected to moment loading of the branch. It is considered that this approach should be investigated further by code developers.