Thread Failure | Sub-surface Equipment | Materials And Corrosion Control
| Damage Mechanism | Thread Failure |
Damage Description |
· Drill pipe, production tubing and casing with thread connections are required to provide proper sealing, corrosion resistance and mechanical properties to withstand internal/external pressure or tensile loading or torsional bending, during transportation and operations. Any mechanical or chemical damages to thread connections would result in losing their seal-ability. |
Affected Materials |
· Carbon steel, low alloy steels, corrosion-resistant-alloys |
Critical factors |
· Handling with care during transportation to avoid any mechanical damages on threads.
· Application of a proper storage compound and using thread protectors during transportation to mitigate any typed of corrosion attack on threads. · Proper lubrication with thread compounds to avoid washout during operation. · Mismatching between pin and box would upset the shoulder. · Shoulder damage: from tong or using sharp-edged wrench for jacking. · In sufficient make-up torque would result in washout. · Excessive torque may result in swelled and split tool joint box. |
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: Coiled tubing, 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 |
· Improper selection of storage compound could promote pitting corrosion at threads.
· Washout from in-sufficient make-up torque. · Mishandling on thread connections results in washout, pin cracking, galling. · Mechanical damage could occur on thread connections from improper use of thread protectors, bumping of box shoulder by pin-end, mismatching of box and pin, tong marks. |
Prevention/Mitigation |
· Use proper storage compound during transportation and storage
· Handling with care during transportation and operations · Avoid over/under torque · Avoid any direct mechanical damage to the threads · Avoid heat checking |
Monitoring & Inspection |
· Visual examination and dimensional check before commissioning |
Inspection Frequency |
· After each job |
Key Performance Indicators (KPIs) |
· # Thread failures per year
· # Leaks due to thread failure |
Plant Integrity Windows (PIWs) |
· Not Applicable |
Competencies and Training |
Corrosion Courses
· e-COE 101 Corrosion Basics · e-COE 701 Corrosion & Corrosion Prevention · PEW 407 Corrosion Technology · COE 104 Chemical Treatment for Producing Operations |
Reference Resources (Standards/GIs/BPs) |
· H. J. Choi, “Understanding Heat Checking, an Overlooked Failure Mechanism of Drilling Components,” JPT Drilling Technology, pp-34, February 1998
· 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 SMI CRA Material- Saudi Aramco – Karan, Sumitomo Metal, 2008 · Offshore Running and Handling Guidelines for SMI CRA Material, Saudi Aramco-Karan, 2008 |
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