Feb 2013
Gas Transmission
Study to determine Stress Concentration Factors (SCF) for alternative design on branch connections
Feb 2013
Jul 2014
National Grid Gas Transmission
Robert Bood (box.GT.innovation@nationalgrid.com)
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Network Innovation Allowance
Gas Transmission Networks
A number of major manufacturers are now producing variations of the insert weldolet for use as branch connections to transmission pipe work replacing the conventional sweepolet design. The insert weldolet would offer the following benefits over the traditional version:

  • Shorter Installation time, and hence reduced costs

  • Simpler design and reduced manufacturing costs

  • Reduce reliance on a small number of suppliers, improving lead time.

Before National Grid can adopt the use of the insert weldolet , there needs to be clear evidence as to the mechanical viability of these designs. This analysis is to be addressed by this programme.

This study will seek to establish whether the stress concentration factors (SCF) of a number of alternative designs of branch connections are bounded by those used in the pipe work stress analysis code IGEM/TD/12. If so it will provide National Grid with a broader range of potential designs and suppliers of branch connection pipe work than are currently available increasing construction efficiency and reducing costs.

If the 3D FEA SCFs are comparable with those determined by the methodologies given in the IGEM/TD/12 standard, it will provide evidence that the standard (non FEA) methodologies of SCF determination are appropriate for the newer designs of WICI such as insert weldolets. This will assist in their adoption and use.