Research Papers: Design and Analysis

Stress Intensification Factors for Fabricated Lateral Piping Connections

[+] Author and Article Information
David Mair

Level 12, 333 Collins Street,
Melbourne, Victoria 3000, Australia
e-mail: david.mair@worleyparsons.com

Contributed by the Pressure Vessel and Piping Division of ASME for publication in the JOURNAL OF PRESSURE VESSEL TECHNOLOGY. Manuscript received July 30, 2013; final manuscript received March 24, 2014; published online September 11, 2014. Assoc. Editor: Allen C. Smith.

J. Pressure Vessel Technol 136(6), 061206 (Sep 11, 2014) (7 pages) Paper No: PVT-13-1127; doi: 10.1115/1.4027319 History: Received July 30, 2013; Revised March 24, 2014

Stress intensification factors (SIFs) are published in the piping codes for tees; branch connections where the branch intersects the header pipe at 90 deg. These factors when multiplied by the nominal stress provide a measure of the increased local stresses at the junction of the two pipes. However, in cases where the branch pipe meets the header at an angle of other than 90 deg, the main piping codes do not provide a method of calculating the SIFs. This presents a difficulty for the pipe stress engineer who must determine appropriate SIFs, usually in a conservative way and then manually enter these into the pipe stress program. This paper summarizes some of the published methods of calculating SIFs for a limited range of lateral branch connections and makes recommendations based on comparisons with finite element analysis (FEA) studies. It also includes recommendations on how such FEA studies should be applied in order to provide suitable SIF values.

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Fig. 4

Typical variation of SIF with angle for branch diameter less than run diameter

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Fig. 2

Typical FEA model of reinforced lateral

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Fig. 1

Typical FEA model with mesh shown

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Fig. 8

Branch torsional SIF versus average diameter to thickness ratio

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Fig. 3

Stresses due to out-plane moment on branch

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Fig. 5

Ratio of torsional SIF on branch at 30 deg to that at 90 deg

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Fig. 6

Ratios of SIFs at different angles compared to those at 90 deg—unreinforced laterals (see Table 2)

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Fig. 7

Ratios of SIFs of reinforced laterals to those of unreinforced laterals (see Table 2)



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