Why MESH convergence in DNVGL – RP – F112 is dangerous
Does not give consequent results Can easily be manipulated without breaking any code rules In several cases give confidence to bad mesh and bad results Adds 0 value and increase runtime Favorites bad engineering by Lower runtime and better results Mesh convergence setup from the code: Non-linear Analysis: A mesh convergence is considered reached with […]
HISC – Automatic Strain Criteria
Hydrogen Induced Stress Cracking (HISC) is a problem that duplex and super duplex material may experience when cathodic protected in seawater. The hydrogen of the seawater may diffuse into the material and may lead to cracking. DNVGL-RP-F112 describes diffusion rates, acceptance criteria for both stress and strain levels. HISC is often one of issues that […]
Stressman Enhanced Flange Method
Stressman Engineering has over the time analyzed plenty of ASME B16.5 flanges in accordance with ASME VIII and the patented flange leakage criteria developed by Coade (now Hexagon). We are working on structuring the findings. Our aim is to generate a simple lookup table that should be used with the Kellogg’s flange method. Sing up […]
White paper – Stresses in bends – Rev 2
NIRAS and Stressman has performed a joint study to better understand induction bends. In the study we have performed several parametrical analyses and benchmarked a non-linear analysis against a real burst test. The general conclusion is that simple hand calculations per ASME B31.3 Chapter II is sufficient for many topside applications, as well as subsea […]
SIFs and stresses in branch connections at different branch angles
This rough and shallow analysis studies the correlation between stresses, SIFs and connection angles of a 4″ND (WT=5mm) Tee component due to in-plane and out-of-plane bending moment. The reason for the initialization of the report was discussion thread in the LinkedIN community and our curiosity. Click here to download.
SIFs and stresses in bends at different bend angles
This rough and shallow analysis studies the correlation between stresses, SIFs and bend angles of a 4″ND (WT=5mm) pipe bend due to in-plane bending moment. The reason for the initialization of the report was discussion thread in the LinkedIN community and our curiosity. More details on SIFs are also given in the whitepaper about induction […]
Vortex Induced Vibrations on Complex Piping Structure
Sondre Luca Helgesen at Stressman Engineering performed a study in the spring of 2011 of how vortex induced vibrations does impact on complex subsea piping structures. The aim of the study was to compare DNV’s standards that are mostly based on long riser geometries. The study was performed as a Master’s Thesis at Telemark University […]
Adaptor Fitting in accordance with ASME VIII division 2
The aim of this project was to evaluate the stresses in an adaptor fitting made of stainless steel 316L. The stresses in the threads were calculated based on hand calculations. The stresses in the fitting was calculated based on finite element analyses (FEA). SCLs are drawn through the areas with the highest stresses. Several locations […]
Atmospheric tank calculation
The water tank shown below was analyzed with ANSYS Enterprise Mechanical. Load factors and acceptance criterions was taken from Eurocode and NORSOK. The hydro testing case uses an overpressure of 0.01bar (1m water) in addition to the hydrostatic water pressure and weight. The hydro testing analysis did also include 50% of 100 year return period […]
Pressure vessel calculation – ASME VIII Division 1
The pressure vessel shown was analyzed in accordance with ASME VIII Division 1 (2015-edition). Local nozzle calculations was performed with WRC537 (also known as WRC107). All calculations and analyses are done by using the software PVElite from Intergraph. The software uses the Design-By-Rules approach. The maximum allowable working pressure (MAWP) of the shell and heads […]
