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  1. JT100

    B31.8 Hydrotest- Allowable Hoop Stress?

    Thanks again BigInch.
  2. JT100

    B31.8 Hydrotest- Allowable Hoop Stress?

    So for hoop stress during hydrotest the allowable stress is 1.25 x MAOP = 1.25 X 0.72 X SMYS = 0.9 SMYS? What is then the allowable longitudinal or combined stress during hydrotest, is that also 0.9xSMYS?
  3. JT100

    B31.8 Hydrotest- Allowable Hoop Stress?

    Cheers BigInch. Thanks for clarifying, I was a little confused by a statement in Appendix N- N-5(c): "If the hoop stresses during the test exceeds 100% of SMYS then ..." Will post future questions to the pipeline forum.
  4. JT100

    B31.8 Hydrotest- Allowable Hoop Stress?

    Can anyone guide me to an allowable hoop stress value for the hydrotest case for subsea piping to ASME B31.8 (Offshore Code?). I have read through the code and can see no clear definitions. In offshore code (VIII) A847.2 makes reference to at least 1.25 times the maximum allowable operating...
  5. JT100

    Wall thickness according API5L

    Thanks Steve, I thought that may be the case.
  6. JT100

    Wall thickness according API5L

    I have a similiar question here, apologise for hijacking thread, I found some of this usefull though and thought it may be relevant. Can DNV codes be used against ASTM-A-106 materials? I've had a look in the codes and cannot find anything definitive, F101 lists the API material requirements...
  7. JT100

    CP Calculation- Coating Breakdown Factors

    Thanks Steve.
  8. JT100

    CP Calculation- Coating Breakdown Factors

    ok but how would i treat it as 100% 'broken down'? do you know whether it can be taken as an equivalent coating in the standards, i have previously taken the 'a' and 'b' constants that are referenced in the DNV standards and then calculated a cbf using: cbf = a + b*t where t is the design...
  9. JT100

    CP Calculation- Coating Breakdown Factors

    thanks steve, yeah the end fittings are duplex and they plan on coating them with this nickel kanigel for hisc etc reasons. so can i treat it as having no current reducing properties?
  10. JT100

    CP Calculation- Coating Breakdown Factors

    I am currently designing some anodes for cathodic protection of flexible pipe. I am trying to calculate the mean current requirement and I have the current density and the surface area however I am struggling to find the coating breakdown factors for the end fittings. They are coated in a Nickel...
  11. JT100

    Subsea Gaskets

    i think the standard is API 17D that covers SBX and SRX ring gaskets
  12. JT100

    Trench and Natural Backfill

    On a recent project we said to the client that we plan to trench an umbilical but leave it to naturally backfill, i have been asked to confirm that the wave and current data supports the natural backfill. has this been addressed in any standards? or does anyone know of any papers written...
  13. JT100

    Pipeline Bends- Tangent Lengths

    Thanks to both above, cleared it up for me. jt
  14. JT100

    Pipeline Bends- Tangent Lengths

    Could anyone please explain exactly what these are? I believe it is something to do with extra length for welding and it tends to have been approx 500mm whenever I've come across it however I am not 100% sure exactly what they are. Thanks. jt
  15. JT100

    Offshore Pipeline Leak : Preservation Method

    i came across a company called brinker technology that uses platelets to locate and block leaks using the difference in pressure, dont know too much about it but might be worth looking into. they can inject platelets of various sizes into the pipeline, and if required inject a radioactive...
  16. JT100

    Offshore Riser Design

    I don’t think its something that gets taken into account in riser design, the pressure required to get the pig up the riser is going to be lower than the operational pressure (most of the time anyway) so its not really worth considering.
  17. JT100

    pipeline anode temp

    thanks for the reponses, and the spreadsheet, thats very helpfull- the Film coefficient is just another name for heat transfer coefficient yeah?
  18. JT100

    pipeline anode temp

    yes i am working to DNV RP F103, and taking the protection potential from is0 15589-2. it is a short pipeline (2km) and so i plan on placing 1/2 anodes at each end of the route, the pipeline is to be trenched and rock dumped however the anodes will be exposed on the seabed. i'm assuming that...
  19. JT100

    pipeline anode temp

    the pipeline has a five layer coating so would there be any value in applying an insulating sheath? i have calculated an ohtc for the pipe wall and the coatings however i didnt think the anode should be included as i want to find the temperature at the outer surface of the coating to know what...
  20. JT100

    pipeline anode temp

    how can i calculate the temperature at the external surface of a coated pipeline on the seabed? pretty dure i'm missing something basic here, i've calculated the ohtc but unsure of next step. its for a CP design, i usually just assume the temp of inner product of the pipeline, however this is to...

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