Tensile Overload | Sub-surface Equipment | Materials And Corrosion Control
| Damage Mechanism |
|
Damage Description |
· Downhole equipment including drill pipe or production tubing/casing would suffer tensile overload failure resulting in tube parting or rupture when they are encountering an excessive loading greater than their load bearing capacity. In a tensile overload failure the pipe will stretch and “neck down” prior to rupture. One of the fracture faces will form a cup and the other a cone. This type of failure indicates that either the pipe was inadequate for the installation or it was loaded beyond the material’s yield point |
Affected Materials |
· Carbon steel and low alloy steels. |
Critical factors |
· The pipe weight
· Excessive pull during stuck pipe · Corrosion damage · Fabrication or operation (excessive tong marks) defects |
Affected Units or Equipment |
· Production elements: tubing hangers, hanger subs, R & X nipples, flow couplings, production tubing, casing, production liner, tail pipe, PBR seal and packer assemblies, sand screens, and other downhole accessories
· Drilling elements: drill pipe, heavy weight drill pipe, drill collars, drill jars, cross-over subs, tool joints, drill bits, bit subs, Kellys · Workover elements: coiled tubing, wirelines, fishing tools (over-shots, tubing/casing spears, milling tools, reverse circulating junk catchers, fishing magnets, fishing jars, wash over pipe) |
Appearance or Morphology of Damage |
· Ductile failure with cup/cone-shape (necking-down) fracture surface |
Prevention/Mitigation |
· Avoid over-pull during operation
· Screen out pipe with excessive corrosion, fatigue pre-cracks, manufacturing defects, or heat checking |
Corrosion Monitoring & Inspection Techniques |
· Visual inspection
· VT, UT and RT inspection techniques should focus on general and local loss in thickness |
Inspection Frequency |
· After job |
KPIs |
· Zero/No Failure |
Roles and Responsibilities |
· Operations/Corrosion Engineers (monitor operating parameters, ensure comply with Corrosion Control, monitoring and inspection techniques. In addition, they should keep updating the data management record) · Inspectors (perform visual examination) · Operators (support Inspection & Operations engineers as needed) |
Competencies and Training |
· Corrosion Courses
o e-COE 101 Corrosion Basics o e-COE 701 Corrosion & Corrosion Prevention o PEW 407 Corrosion Technology o COE 104 Chemical Treatment for Producing Operations |
Reference Resources (Standards/GIs/BPs) |
· B. D. Craig “Practical Oilfield Metallurgy and Corrosion” by Pennwell, 1993
· API 5C1 Recommended Practice for Care and Use of Casing and Tubing · Handling and Running Procedure for Chrome OCTG by Drilling & Workover Engineering Department, May 2003 · Field Inspection Guidelines for Sumitomo CRA Material- Saudi Aramco – Karan, Sumitomo Metal, 2008 · Offshore Running and Handling Guidelines for Sumitomo CRA Material, Saudi Aramco-Karan, 2008 |
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