Case Study 1
Corroded Tee

• The CONC specified for a 10” Sch 120 (21.4mm nom.) HP 2 Phase Flowline was 15.76mm,
• A number of fittings, Tees & Elbows, were selected for inspection due to issues with solids in line and the threat of erosion,
• The Tees were ASME B16.9 Fittings and do not have specified thickness.  The thickness of the component is not uniform and varies with respect to position on the Tee due to manufacturing method and need to provide reinforcement for the opening.  The thickness of the Tees on this system ranged from approximately 22mm to 30mm.
• Reported thicknesses ranged from 18mm to 30mm
• Report was accepted by Inspector, OIE and Integrity Engineer as all values were above CONC.
• On review the 18mm reported was at the crotch corner of the tee and had lost approximately 12mm from erosion.
• Flowline was now operating at 20 bar(g) with a CITHP of 110 bar(g) with a Tmin of 9.8mm (straight pipe).
• Reinforcement check to ASME B31.3 for an extruded tee showed fitting to be Fit for Service at CITHP.

Important to understand how CONC applies to Rated Fittings (ASME B16.9) and to maintain CONC values against most up to date Operating and Design Conditions.