Tubing cracks 2

[angelmar]

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

 

[strider6]

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

 

[SJones]

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/