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  1. robb4

    Offshore Pipeline routing - straight section before bend

    Which are the main parameter to decide the straight length of a pipeline at the starting point, before any bend? How to determine the minimum feasible length? As far as I know this length is connected to the friction of soil and should be at least one catenary length. Any help will be appreciated...
  2. robb4

    Free Span Full Fatigue

    Finally, I found a reference paper for the minimum gap ratio below that no VIV occurs. It is " 1997 OMAE, Volume V, Pipeline Technology, ASME 1997 (Mark, Vitali, Velley) – The multispan project: design guideline for free spanning pipelines". In this paper it is stated "In general it can be...
  3. robb4

    Free Span Full Fatigue

    Hi Big", maybe there is a misunderstanding because with free span clearance/External Pipeline Diameter I meant a different thing (see attached). Anyway I agree with you that a very important thing is the other ratio (free span length/external diameter). Thank you...
  4. robb4

    Free Span Full Fatigue

    Hi guys, Regarding free span analysis according DNV RP F105 I've the following question: Is there a minimum gap ratio (free span clearance/External Pipeline Diameter) that lead to VIV onset (i.e. below that limit no VIV occurs)? I found in a document that with gaps ratio below 0.3 no VIV...
  5. robb4

    Pipelines On bottom stability

    Hi, I'm involved in on bottom stability study of a offshore pipeline. Due to extreme enviromental loads we are thinking about use of mattresses to ensure the stability during design life. Since the DNV codes (RP 305 and RP F109) don't consider this situation, do you have any reference or...
  6. robb4

    Offpipe software

    Hi, My Company has bougth an Offpipe (http://www.offpipe.com/) license and I found that it use a DOS interface. Anyone knows a software that can interface with Offpipe to avoid to use the Dos interface? Thanks
  7. robb4

    Offshore Pipeline: soil liquefaction

    Thanks for your reply. Of course the wave is another aspects to be considered in liquefaction study but considering my water depth (60m) maybe it wouldn't be an issue. Regarding the return period the only one reference I find is on DNV OS F101 that states the following (Sec 4 C500): C 500...
  8. robb4

    Offshore pipeline coatings

    SFLM, Thanks for your reply. when you need to reach high value of thermal insulation (below 4W/m2K), the concrete cannot be used as insulation so you would need to add a proper layer. After the post of SJones I got in contact with that Company and they states that is possible to do that...
  9. robb4

    Offshore Pipeline: soil liquefaction

    Hi, I'm collecting input data for a Detail offshore pipeline project. Regarding the soil liquefaction analysis due to seismic hazard I'm collecting data regarding Peak Ground Acceleration assosiaceted with return period of 200, 500 and 1000 years. My question is which is return period to be...
  10. robb4

    Allowable Lateral Distance between Pipelaying Barge and Platform

    At least the minimum lateral displacement (and pipeline heading) should be enough to allow the barge to deploy dead man anchor (so the dimension of barge plus some meters could be enough). Consider that anchor pattern can be adapted to pass over that zone. It's not a good idea to have a lot of...
  11. robb4

    Pipeline Load Reduction Due to Trenching

    Yes, it's correct. In this case you've three different options: - don't consider the trench (very conservative approach) - use another standard like Danish Submarine Pipelines Guidelines (very old standard) - use a software to simulate hydrodinamic flow inside tranch (like AGA).
  12. robb4

    Offshore pipeline coatings

    Hi, my question is about pipeline coatings. In particular I would know if it is possible to put concrete coatings above thermal insulation coatings. The main pipeline data are: Pipeline 8" Insulation Thickness 40 mm Concrete coating thickness 40 mm Thank you.
  13. robb4

    Buckling detection in deep water

    For atedionyahoo. Do you mean the standard buckle detector (like a gauge plate)? I know that for deep water application it's not a standard to use it because the risk of rupture of buckle detector itself.
  14. robb4

    Buckling detection in deep water

    Hi Guys, I'm involved in a deep water project (1400 m WD), and I'm writing a functional specification for installation of rigid pipeline. My question is what are the most suitable methods for buckle detection in such deep water (either in j-lay and reeled pipeline)? Of course the gauging plate...
  15. robb4

    Unbounded flexible risers - Dropped Object

    Dearl all, I'm writing a specification for the purchase of unbounded flexible riser (about OD 16", ID 8" in a water depth of 1400m). I'm thinking about the protection from dropped object, how can I fix the requirements in terms of Impact Energy and Object Diameter? The only reference I found...
  16. robb4

    Line Pipe MTO

    Dear all, I have to prepare a material take off for line pipe to be used offshore. My question is regarding spare quantities: is there any standard, guidelines or recomended practice I could use to estimates occurency of wet buckle, spare for welding qualifications, damage due to pipe...
  17. robb4

    Offshore pipeline: Bends

    Dear all, I'm writing a SoW for a FEED Design of a pipeline system and I'm listing the standards to be used for design. My question is about 5D induction bends: Is there any standard that covers this item (for example in terms of desing, material, construction and testing)? In particular I'm...
  18. robb4

    Wall thickness according API5L

    Thank you Big Inch Unfortunately I cannot decrease pressure because I need that one for other reasons, but if there are major problems with these thickness we can change the grade material and go to X70 or X80. Considering that our design temperature are -10°C and 80°C do you think it's...
  19. robb4

    Wall thickness according API5L

    Dear all, I'm designing a 32'' gas pipeline and according specification of my client I've to choose wall thickness according API5L 2004. The problem is that wall thickness I've calculated (39.1mm) is above the maximum wall thickness reported on standard (31.8). As far as you know, is it...
  20. robb4

    two pipeline in the same trench

    StephenA The owner is the same for both pipelines. Another issue for this project is that the work area is swamp one, so we could have some problem during installation. Anyway according to your reply to investigate the possibility to land both pipelines in the same trench we have to see...

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