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  1. Eyeoftheneedle

    differences between DNV RP E305 and DNV RP F109

    You should read the first sentence of the Introduction: "DNV-RP-F109 will replace the existing offshore design code, DNV-RP-E305 "On-Bottom Stability Design of Submarine Pipelines"." NB this text was taken from the 2007 version.
  2. Eyeoftheneedle

    Critical Buckling Force

    Not a problem. Don't forget to keep in mind that whatever equations you are using are based on very specific shapes for the imperfections.
  3. Eyeoftheneedle

    Critical Buckling Force

    DNV-RP-F110 - GLOBAL BUCKLING OF SUBMARINE PIPELINES is a good place to start to explain how it all works. If, as you say, you have all the equations then I'm guessing you have the already looked at Hobbs R. E. (1984): “In-Service buckling of Heated Pipelines”, ASCE Journal of Transportation...
  4. Eyeoftheneedle

    Upheaval Buckling of Buried Pipeline

    Membrane stresses...elastic limit..come on..step out of NON-Limit State Codes for a second...help this guy out with something that can actually help him, don't scare him with issues that are overly conservative. Pipelines these days are (and should be) designed specifically to limit states...
  5. Eyeoftheneedle

    DnV RP-E305 Soil data

    DNV-RP-E305 (now superseded by DNV-RP-F109) is very specific in that if you are using the Simplified Design Method then you must use 0.7 for sand and Figure 5.11 for Clay. The reason for this is because it is not just a friction factor, it is also a calibration factor that helps you get...
  6. Eyeoftheneedle

    Upheaval Buckling of Buried Pipeline

    Johnreb, The 'standard calculations' mentioned by others will be Hobbs-type formulation checks, which in themselves give you an idea of what's going on but are not detailed enough for what you need. Your best bet is to go to a reputable Design House and get them to do the calcs for you using...
  7. Eyeoftheneedle

    How do I count non-zero entries in a vetor matrix

    frogger79, just re-read what you were looking for; i.e. non-zeros... To do this you need to change the 'n' in the (n vn) term within the loop to 'length(Space)-n' and then you'll have the number of non-zero terms in your data set. Uploading MathCad died for some reason, hence the long-hand...
  8. Eyeoftheneedle

    How do I count non-zero entries in a vetor matrix

    frogger79 The attached file does it for you - hope this helps you. You needed to setup a loop (similar to what ishvaaag suggested). http://files.engineering.com/getfile.aspx?folder=56f5fc8b-9951-43ad-a037-c23363052c28&file=help_needed_Eyeoftheneedle.xmcd
  9. Eyeoftheneedle

    Subsea Pipeline - HSS disbondment - CP shielding

    BigInch - that's what I suspected (hoped) so glad you confirmed that for me. Thanks. SJones - good clarification, part of my confusion was getting my head around the fact that if there is water flow then how can there be no conductive path - thanks for helping me with my sanity. ILI (in-line...
  10. Eyeoftheneedle

    Subsea Pipeline - HSS disbondment - CP shielding

    During recovery of an installed pipeline it was noted that there had been some disbondment of some of the Heat Shrink Sleeves (HSS) at the field joints. This had led to some seawater entrapment, which could have potentially been in contact with the steel. As the HSS are noted for their high...
  11. Eyeoftheneedle

    SUBSEA WATER PIPELINE BUCKLING DURING PIPE LAY WORKS.

    Looking again at your system, the stress concentration due to the outer concrete alone is about 1.6 (DNV-RP-F105 will give you guidance on this) so combined with your thin wall it is more than likely to be the discontinuities at the field joints that is your problem. Suggest towing out long...
  12. Eyeoftheneedle

    SUBSEA WATER PIPELINE BUCKLING DURING PIPE LAY WORKS.

    It buckled in 8m water depth (0.8bar), so it can't be collapse driven - it's critical collapse depth is probably around 100m or so.
  13. Eyeoftheneedle

    SUBSEA WATER PIPELINE BUCKLING DURING PIPE LAY WORKS.

    SLT option looks expensive, time-consuming (10km per day...yeah right!) and it is currently untested so probably not a great option for a Project in trouble. It's also for deep water applications. Sorry to rain on your parade...
  14. Eyeoftheneedle

    Automatic welding and DNV Supplementary D

    Supplementary Requirement D means there are enhanced dimensional tolerances for the linepipe supplier to contend with. In terms of AUT, the tolerances applicable because of the D are just used as input to setting up the work. The tighter the tolerances though, the easier it is to line up for...
  15. Eyeoftheneedle

    Subsea Pipeline Free Span Survey (As Laid & As Built Surveys)

    In my experience it is always good practice to keep checking the situation of the pipeline in all conditions as-laid empty, following flooding, etc. Indeed most clients insist on it as the pipeline is their money-maker so they want to be happy that by the time the installation contractor has...
  16. Eyeoftheneedle

    DYNAMIC Soil Stiffness for Free Span Analysis

    subsealinepipe (Amir) 1) It's worth checking this one with DNV as normally they have a good reason for removing tables when they update codes and quite often you will find that previous tables and previous equations will yield the same results as the new equations. In any event, it would be...
  17. Eyeoftheneedle

    SUBSEA WATER PIPELINE BUCKLING DURING PIPE LAY WORKS.

    Absolutely BigInch - more tension or buoyancy or davits, etc. Adding buoyancy got you another few hundred metres, so you're heading in the right direction ;) Seems pretty thin wall for a 26inch line - D/t of 70 combined with X52 (and spiral pipe) would likely have problems being installed...

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