BP Experiences -- Guided Wave Radar Level Instruments Rick Stanley API SOICS April 2008

2 Overview BP Inventory Overall Experience Design and Operation Issues −Configuration −Off Normal Behavior −Physical Design Wish List and Path Forward

3 BP Inventory Guided Wave Levels used at all 5 BP US Refineries −Whiting – 75 −Texas City – 50+ −Cherry Point – 40+ −Carson Services −Propane storage bullets −Cooling towers −Process levels −Interfaces Overall experience is good, but there are problem applications −Configuration issues −Post startup adjustments −Consistency and reliability of measurements

4 Understanding Configuration Many Choices – difficult to make the right ones Manufacturer guidelines haven’t been that effective −Contractors incompletely specify configuration −Deeper understanding of application requirements Understanding of what the choices mean and how they interact is experience that we are only now getting Some areas of difficulty −Null zone and hold off −Dielectric selection −Thresholds −Out of range behavior −Fault behavior

5 Some Real Examples Carson 2008 Turnaround – Installed about 40 Guided Wave Levels Shop testing – water fill Manufacturer tech support on site multiple times Some installation difficulties Several head swaps prior to startup Despite a lot of effort, we were adjusting things prior to and during startup Post TAR – Almost all GWR are reading OK and are stable – but it took a lot of work to get there We seem to have more difficulties than TxC and Whiting have had, but distance has a way of dulling experiences. Everyone has successes and problem applications

6 Hold Off, Blocking Distance and Null Zone Several heads had to be remote mounted due to clearance Extension of cable from probe to head lead to mis-interpretation of parameter adjustments required Initial operation resulted in end of probe not detected faults Faults forced output to 100% even at zero level Consultation with factory resulted in correction of parameters Problem was fixed, but at cost of operations confidence 3 Services with dual GWR – pulled one and replaced with DP

7 Dielectric Instruments require careful dielectric selection – process design basis may not be right Example -- DEA contactor −Instrument set for high dielectric (water based) −During startup hydrocarbon overfill into DEA contactor −Magnetic float indicated 4”, DP indicated 30” and guided wave indicated 0. −Guided wave had been indicating up until hydrocarbon carry over −Corrected dielectric for hydrocarbon – revealed actual level of about 50” −Left at hydrocarbon dielectric and seems to be working since Similar issues to be expected in flare KO drums and similar places why water and hydrocarbon may exist

8 Trend of Hydrocarbon onto DEA

9 Threshold Appropriate thresholds for detection of level surface aren’t always constant Auto-sense functions can lead to erroneous levels Hydrocarbon level in flash drum −Guided wave and through the air radar tracked very well −Guided wave went to 100% - Investigation found that threshold had been lost. Reset to manual threshold and they have been tracking since Empty Drum −Threshold set to automatic – result was spikes in level even though drum was empty −Set to fixed threshold, but still having issues with empty drum −Had to adjust thresholds differently on parallel services

10 Hydrocarbon – GWR vs. Through Air Radar

11 Out of Range Behavior Experiencing problems with instruments when level is outside probe range Want signal to stay at 0% when level falls below probe or configured range and 100% when level increases beyond probe or configured range Having difficulty getting reliable behavior in empty vessels Instruments appear to be going into fault, which drives the signal to its configured fault output – this means a low level can indicate as a high level Need reliable and predictable out of range performance.

12 Installation External Chambers −GRW manufacturers were generally not planning on getting into the chamber business. −Users view has been to buy these like displacers – complete assemblies with chambers Attempts at response have been mixed. Design development and fabrication quality −Materials −Basic design −Welding quality Recent projects have resorted to piping fabricators or local fabrication

13 Installation Guided wave installations often don’t have platforms View of heads is limited or not possible – operations hasn’t been happy about that Need a means of relocating display to grade without affecting radar path Long rods are subject to being bent when being removed or re-installed.

14 Documentation Guided wave specific specification form Baseline configuration for common applications −Hydrocarbon level −Mixed service level −Interface −Water −Dry vessel Configuration data storage −Manufacturer’s programs −AMS or similar systems

15 We Know What These GWR’s areDoing :-)

16 Wish List – Path Forward Use of GWR has generally been quite successful and well accepted Some services still need work and have impacted the attitudes of those who own them Effectiveness of manufacturer support is still spotty −On site support is needed for commissioning of any quantity −Even with on site support we have still had performance issues Successful implementation requires careful attention to device applications and post startup review and adjustment. Not particularly tolerant of error. Right now the commissioning labor per installation is high Steep learning curve, but we think we are over most of it. Still concern over some services, especially dry vessels or widely varying process conditions.

17 Conclusions Guided Wave Radars are not simple but they do work (eventually) They aren’t always predictable when first commissioned They take more work than Specific Gravity based devices We will be developing much more defined practices −Specification and configuration requirements −Checkout and commissioning procedures We will continue to use the technology, but will run into resistance if we try to eliminate traditional SG based devices −Operations doesn’t always understand SG devices will be inaccurate −But….. It does give them a signal even if its wrong. It will take time to develop comfort that people have with the old technologies