I´m facing a maintenance issue related tubing cracks(subsea control valves hydraulic system tubing) and would appreciate your help for identify the main cause and solve it appling engineering best practices.
Briefly: Leaking was observed in OD 1/2" hydraulic tubing, after analyses micro-crunches was found, apparently initiate by surface exthernal corrosion.
Aditional information:
Material order inform ASTM A312TP316L
Material analysis found: %C:0,017, %Mn:1,59, %Si:0,49, %Cr:16,75,%Mo:2,18, %S:0,001, %P:0,016,%Ni:9,63.
Down hole 7500 PSI
I´m planning to replace all tubing (down hole and the others) as soon is possible for attribute reliability , cause it I need to identify the correct one. (please inform standards if possible).
Thanks in advance

consider the use of duplex materials.


Article (769KB) by Joseph W. McEnerney (P.E. Gibson Tube Inc., USA); "Experience manufacturing alloy 19D (UNS S32001) seam welded lean duplex stainless steel tubing for subsea umbilical applications"
http://www.stainless-steel-world.net/pdf/McEnerney.pdf

Application of duplex stainless steel in the offshore industry
http://www.stainless-steel-world.net/pdf/D97_208.zip

S

http://www.corrosionist.com

Define the exposure environment, including any corrosion control measures, as thoroughly as possible before selecting a material then follow the Institute Of Petroleum Guidelines For Design, Installation & Maintenance Of Small Bore Tubing Systems where appropriate.

Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdoweb/