Nozzle Pro – Unreinforced Tee

unreinforced branch meshed for FEA

The example will create a model in NozzlePro using minimal user input (3 clicks and 4 numerical entries) to obtain useful information.  This article will also highlight a somewhat controversial aspect of how the B31.3 code treats reducing tees (which is expected to change soon). One reason for the popularity of NozzlePro is that specified … Read more

Easy vacuum checks for piping

buckled pipe

A client recently asked us whether vacuum may be a problem for her piping system. She was aware that the piping codes pointed to the external pressure check in ASME VIII Division 1. I won’t make this out to be a simple topic and indeed there is still ongoing research in the area. But for … Read more

Improving LNG Plant Piping

This video presentation discusses challenges inherent to LNG piping, including large diameters, cryogenic temperatures, stainless steel materials, and large D/T ratios. It also covers various items which are not addressed by the B31 codes. Robert WeyerRobert has over 15 years’ experience in the mechanical engineering industry with proven expertise in mechanical and piping design. His … Read more

Piping fatigue and corrosion

ASME B31.3 contains the footnote ‘Corrosion can sharply decrease cyclic life; therefore, corrosion resistant materials should be considered where a large number of major stress cycles is anticipated’. But what happens if carbon steel with high corrosion allowance has been selected and changes are out of the question? Or you may be assessing an existing … Read more

B31.3 branch stress own-goal

image of stress at reducing branch from CAESAR II

Quick summary This article may pique your curiosity if you’re interested in the finer details of pipe stress analysis, but if you’d rather just get the overall takeaway – Sustained bending stresses in ASME B31.3 2016 calculations are underpredicted at some branches As long as the stress analyst remembers to split the branch pipe model … Read more

Salad Postprocessor for CAESAR II

Salad Postprocessor

The Salad Post-processor takes data exported from CAESAR II to do additional calculations and summaries. The software is now updated to version 1.40, and is available at no cost here. Lets go through some of the things you can do with this software . Make a summary of your stress model On one page you … Read more

Determining SIF of Non-Standard Fitting

Lateral tee with crotch plate

Background Some instances in piping stress engineering we come across fittings not defined in ASME B 31.3, due to their sheer size and/or the diameter to thickness (D/t) ratio. Without understanding the stress intensification factors (SIFs) of fittings, flexibility analysis becomes impossible. This discussion is about how a challenge for the determination of SIFs of … Read more

G’day, I’m a hoop stress engineer!

inside of pipe

For much of my career I have been involved in pipe stress analysis in some way, starting with Pipeplus by Algor, moving on to Triflex and then to CAESAR II. After I had a few years of part-time stressing under my belt, I landed a pipe stress role on a three-platform greenfields project in the Timor … Read more

‘Hot’ sustained stress – method comparison

compressor station piping

In the past few years there has been an increased focus on the so-called ‘hot sustained’ stress in piping system analyses. The ASME B31.3 2006 edition clarified that Sustained stress requirements must be met for all operating conditions of a piping system. There had always been practitioners whose view was that any stress due to change in temperature should … Read more

B31.3 Code Issue – Non-conservative Sustained Stress

I would like to highlight an issue in ASME B31.3 that’s been sitting there underneath most of our noses for several years. Depending on your interpretation of the Code (or that of your pipe stress software) this can result in significant under-prediction of sustained and occasional bending and torsional stresses at reducing intersections. [Edit March 2017: this … Read more