WESTERN TURBINE USERS: Arrive early, stay late to maximize involvement, benefit
2017 Conference & Expo
The 27th annual meeting of the Western Turbine Users Inc (WTUI) is only a few weeks away, March 19-22, 2017, at the South Point Hotel and Spa in Las Vegas. Make your reservations today at www.wtui.com. This is the organization’s first conference outside of California since the 2007 meeting in Phoenix and the group’s third trip to Las Vegas (1994 and 2001). Most people don’t need an excuse to extend a business trip to Nevada’s largest city by a day or two, but there’s a good reason not to rush in and rush out this year: professionally beneficial social events.
They are critical to the success of user-group meetings, enabling attendees to meet in a relaxed environment and expand their networks for problem-solving. WTUI is hosting several “not-to-be-missed” functions as part of the organization’s 27th annual conference. Most would not have been possible without financial support from the sponsors identified on signage in the exhibit hall, which will include Alan Mibab’s AGTSI. Please thank them when you have the opportunity.
The headline events are profiled below. Keep in mind that several have a participant limit and a special fee, so the sooner you contact Conference Coordinator Charlene Raaker (firstname.lastname@example.org) the better your likelihood of success.
Sunday, March 19
Golf tournament, 7:30 a.m. to 12:30 p.m., will be held at the Rhodes Ranch Golf Club, 15-20 minutes from the South Point. Golf Chairs Wayne Kawamoto and Jim Bloomquist consider this 6900-yard course, highlighted by several par 3s, “Las Vegas golf at its finest.” The tournament is arranged as an 18-hole, four-man shotgun scramble (sometimes three- or two-man). Cost is $100 per player.
Golfers love their prizes: longest drive, closest to the center line, closest to the pin on several holes, plus team awards for low score. Last year, 26 awards were presented at the Monday luncheon, with two golfers receiving two each. Beware these “ringers” when you step onto the course this year: Janice Shogren, Beth Kallaene, Gabe Golden, Jay Dunkelman, Jeff Dietz, Zack Almont, Fred Keeler, Andy Stewart, Wes Knapp, Greg Jacobs, Mike Wayne, Ray Perez, Alan Hermann, Greg Atkinson, David Ehler, Brian Hulse, Vance Manning, Wayne Feragen, “Maddog” Kawamoto, Joe Jackson, Bloomquist, Jeff Martin, Tim Ahn, and Greg Young.
Bowling tournament at the South Point starts at 10 a.m., ends at l p.m. This is WTUI’s first bowling contest; it was substituted for the tennis tourney this year given the hotel’s huge bowling center. Bowling is limited to the first 30 participants to sign up at $20 each.
Welcome hospitality from 5:30 p.m. to 8:30 in the exhibit hall. This event, which includes the opening of the exhibition, is a very special function says WTUI Treasurer Kawamoto. All conference attendees and spouses/guests are invited.
Monday, March 20
This year’s spouse tour, 9 a.m. to 3 p.m., at $75 per person (including lunch), is billed as a once-in-a-lifetime experience (The Best of Vegas) for the up to 50 participants. The lid is still on the program so you’ll have to check back at www.wtui.com for the agenda later. However, a better idea might be to sign up now; the Western Turbine all-volunteer organizers always “deliver.” Bus transportation is provided, loading outside the South Point lobby at 8:45 a.m.
Awards luncheon, from noon to 1:00, salutes recipients of the golf and bowling awards.
WTUI hoedown, from 6:30 p.m. to 10 in the Grand Ballroom. Attendance is included in the conference registration fee. This is sure to be a good time and noisy, given the live entertainment by a boot-stomping band. Monday evening receptions and dinner at Western Turbine meetings are always fun.
Tuesday, March 21
Two highlights on the Tuesday program are recognition awards and special technical presentations. The awards are presented at lunch—both for WTUI service and industry best practices. When the exhibition hall closes at 2:30, the technical presentations begin. There are three one-hour sessions in this part of the program, each consisting of three presentations conducted in parallel. Stay tuned to the Western Turbine website to get the details as they become available.
Wednesday, March 22
Highlights of the Wednesday program—going-home day—are GE’s hour-long new products update beginning at 10:45 a.m. and a special tour of the Hoover Dam powerplant arranged by WTUI Chairman Chuck Casey. Bus leaves the hotel at 1:30. The GE program offers a heads-up on developments that might facilitate operations, boost output, decrease emissions, and/or increase efficiency of your plant. The second, available only to 80 pre-registered attendees, certainly is worth staying for. There is no special fee for the Hoover Dam tour.
Built during the Great Depression in fewer than five years it was the largest dam of its time. Today, 80 years later, this National Historic Landmark is considered one of the “Seven Engineering Wonders of the Modern World.” The engineering marvel, which enabled industrial development of the Pacific Southwest, forms Lake Mead behind the 72-story structure—said to be the largest man-made reservoir in the Western Hemisphere.
John Baker chaired his last LM2500 Breakout Session at the 2016 Palm Springs meeting, supported by Garry Grimwade who takes over in the front of the room at the upcoming Las Vegas conference. Baker needed a break to recharge his batteries, having led this group for nine consecutive years, perhaps more service time than any other breakout chair in the organization’s history. He remains an active industry volunteer as a member of the steering committee for the Combined Cycle Users Group.
Both Baker’s and Grimwade’s day jobs are at Riverside Public Utilities’ Clearwater Cogeneration Facility, a nominal 30-MW LM2500-powered 1 × 1 combined cycle in Corona, Calif. A proud Baker, the plant manager, calls it “the best powerplant in America.”
The first breakout session, which ran for three hours Monday afternoon, kicked the meeting into high gear identifying/analyzing the findings in 2015 by Level 4 depots responsible for most major work on LM2500s. Air New Zealand Gas Turbines (ANZGT) was represented by Chris Martin, MTU Maintenance by Nico Brademann, and TransCanada Turbines (TCT) by Mico Madamesila.
Engine configurations covered by WTUI include the single annular combustor (SAC) and dry low emissions (DLE)—base engines as well as LM2500+/LM2500G4. These machines are used primarily to drive electrical generators and compressors, and to turn propeller shafts on naval and commercial vessels. The base LM2500 SAC dominates with about two-fifths of the units in service; LM2500+/LM2500G4 SAC account for another 30%, in round numbers.
An important lesson learned came out of the first case-history presentation and applies to all engine variations. Oversized compressor front frame (CFF) lower lug bores were found from the 4 to 8 o’clock positions. This is characteristic of some LM2500s installed onto Dresser-Rand packages, which use lower mounting lugs but have larger-diameter pin bores. The hole size is adjusted by reaming the CFF lugs.
In this case, the mod was made by the customer for its specific application. The mistake was in not letting the depot know about the custom mods. Had the shop repaired the lugs back to the OEM specific diameter without first checking with the customer, the overhauled CFF would have been incompatible with package mounts.
High-pressure compressor (base SAC and DLE machines). Heavy wear on mid-span damper pads on the first-stage blades caused an airfoil to liberate on one engine. The compressor had been borescoped beforehand with pad wear detected. Unfortunately, the owner decided to run the engine to the scheduled overhaul and failure occurred before the planned outage, putting a hard stop on the machine with damage to most all compressor parts as well as the combustor and first-stage nozzles. The old saying “pennywise and pound foolish” comes to mind.
Reminder: Periodic inspections are recommended every 4000 operating hours (refer to O&M Manual, Table 5-1) and damper pads on first-stage blades should be replaced at every depot visit.
Stage-16 HPC blades (SAC and DLE base and plus machines). Platform corner loss is a recurring issue on some engines with post SB-236 Inconel 718 blades. Stage-16 blades are known to have a resonance near the engine’s operating range, causing high vibration which results in cracking, liberation, and/or corner loss. IND-236 specified the material change for improved durability against aeromechanical excitation, but while this has eliminated blade-tip corner cracking, platform corner loss is still an issue.
The OEM recommends Stage-16 blade platforms be checked during borescope inspections; when an engine is in the depot, NDT these blades. An investigation by GE resulted in a new blade design with cropped platform corners. The new design is said to have no impact on engine performance or operability.
Vespel® strip de-bonding (base SAC and DLE machines). Particles of Vespel strip have been found on the rotor air duct and inside the Stage 2 disk as the result of strip de-bonding from the HPC-rotor air duct. Loss of the Vespel strip may allow fretting wear to both the air duct and the second-stage-disk bore and could contribute to a change in the forward HPC vibration profile. A GE representative said the OEM is replacing the current epoxy adhesive with an alternative capable of operating at a higher service temperature.
A concerned user asked if this change would cause a step change in vibration. The OEM said it would and the level could go up or down—but as long as the engine is operating within GE’s prescribed limits it should be fine.
Broken inlet-guide-vane pushrod (base SAC and DLE machines). During minor maintenance of this engine, three variable-stator-vane (VSV) pushrods were found broken and fully separated from the vane actuation lever below the spherical bearing housing on the threaded portion of each pushrod. Background facts: The unit is used for standby power, less than 50 hours/30 starts annually; compressor wash was semiannual.
Pay close attention to procedures the operator was told—specifically, proper cleaning and drying instructions in the O&M Manual. Also important is to ensure thorough hardware checks during periodic inspections and implementation of correct storage and preservation procedures when the engine is not in use.
VSV torque-shaft wear (SAC and DLE plus machines). Aft spherical bearings have experienced excessive wear on some engines post IND-169, -192, and -196. The latest thinking on the issue was published in IND-248 and -249 in July 2014. The first introduces an improved forward torque-shaft support, which consists of a new bearing bracket and a new shaft sleeve for the forward bearing. IND-249 introduces an improved aft torque-shaft bearing bracket. Another change: replacement of the slot-loaded spherical bearing to a full-contact one.
The depot speaker recommended that the latest configuration be installed in the field when the torque shaft is worn. Inspection should be to limits in WP 418. Bearings should be replaced once the radial clearances exceed the following: VSV torque-shaft forward bearing, 0.120 in.; aft bearing, 0.060 in.
DLE baffle cracking (an update for DLE base and plus machines). Baffle cracking has been discovered on disassembly of the post IND-181 design, which features profile and material changes. Speaker assured there was no impact on engine operation and no secondary damage has been found. Recommendation: Have the depot inspect and NDT DLE baffles upon exposure.
A GE investigation revealed the cracking initiates and propagates by high-cycle fatigue (HCF), starting at the bolt head. The OEM is working on an enhancement—the addition of a stiffening ring—to raise the resonant frequency above the combustor’s acoustic range.
Combustor burning was identified on the inner liner of a base SAC machine at eight locations during borescope examinations. The burning, which worsened over time, was found near the inner rivet band at the inner liner, cowl, and dome-band joint. The user was concerned about the rate of wear.
Here’s the machine history pertinent to this issue: Combustor overhauled and installed in November 2012; burning noted during borescope in July 2013 (4137 hours after overhaul); more burn holes noted in second borescope in November 2013 (hours not available); no significant change in damage found during the third borescope in May 2014 (10,727 hours after overhaul); degradation forced combustor removal and shop visit in December 2014 (15,398 hours).
Other important facts:
Engine runs on gas with no water or steam injection; however, the combustor is configured for water injection and has no thermal barrier coating on the inner and outer surfaces of the liner.
Burn holes were spaced relatively evenly around the combustor.
Temperature spreads were within limits.
Contaminant buildup on parts was found during the shop inspection, but this was not believed to cause the burning observed.
Poor fuel filtration was suspect, but data provided to the depot were good.
A user asked the OEM representative in the meeting if the gas inlet pressure fluctuated and, if so, could that have affected the flame. Reply: Unstable pressure could have affected the flame which could have caused acoustic issues resulting in cracking/damage to the combustor.
However, with no specific gremlin identified, the depot’s recommendation to this user going forward was to monitor combustor condition in accordance with the O&M Manual, and review site conditions—including fuel, filtration, fuel nozzles, etc—and maintain a watchful eye on them.
First-stage nozzle air seals (SAC base and plus machines). Seal tabs oxidized and cracked in operation, causing a potential risk for domestic object damage to the HP turbine airfoils. Vane design was found to cause overheating and oxidation of adjacent tabs. The fix: Installation of new inner and outer seals on affected machines. Another improvement: The number of tabs has been changed from 72 to 64 to match the number of vanes. Plus, the redesigned indexing tab is conducive to correct assembly and it avoids circumferential movement of seals.
Turned/broken cooling-air tubes (SAC and DLE base and plus machines).
Damage was found on second-stage blades on various engines. Plus, damaged/mission/rotated cooling-air tubes (spoolies), retainers, and spring washers were identified with missing parts/fragments fund inside nozzle segments. Side notes:
Rotation of the cooling tube allows spring washer to cut into the tube releasing debris that can migrate into the flow path. This is conducive to domestic object damage of second-stage blades and nozzles.
Vibration and the temperature difference between nozzles and HPC cooling air are thought to cause cooling-tube rotation.
Rotated spoolies do not seem to have any effect on nozzle airfoil degradation.
The spring washer has been eliminated, and removed from the IPC. Tube length and OD have been increased for a press fit to stop relative motion and wear. See IND-254 Rev 1 for details.
Inspect cooling-air tubes periodically to monitor their condition.
Implement IND-254 at the next hot-section exchange.
Breakout Chair Jason King, O&M manager at CPV Sentinel Energy LLC’s eight-unit peaking plant in North Palm Springs, Calif, reminded users in his opening remarks of this fleet’s strong commitment to information-sharing for driving continuous performance improvement. To support this commitment, the LMS100 users have established and strongly endorse these two communications channels:
Monthly conference call, conducted the first Wednesday at 1 p.m. (Pacific). Contact King via the www.wtui.com website for dial-in number and participant passcode.
Yahoo LMS100 Users Group (http://groups.yahoo.com/group/LMS100UG). Intent is to keep users current on the various technical and logistical issues challenging the fleet. It is facilitated by Karl Maier of SPS®.
Tripp DellaVilla of SPS made the first formal presentation of this breakout, focusing on LMS100 reliability and availability performance metrics and downtime contributors compiled from the company’s ORAP® database. Here are a few of the points made by DellaVilla:
Participation by LMS100 owner/operators in ORAP, now representing 67% of the 55 operating units in the fleet, should be higher to provide greatest value.
ORAP Analytics™ Portal, recently released, allows users to view their plant’s data via an Internet-based, on-demand business intelligence interface highlighting the specific KPIs of interest.
Less work for plant personnel, more accurate information. ORAP Asset Insight™, recently commercialized, is an automated data-collection solution designed to tie into the plant’s PI historian, via the Cloud, to collect without human intervention 85% of the data required by ORAP. The remaining 15%, concerning outage-event details, still requires a personal touch.
Next GE presented on fleet stats. Excerpts from those presentations follow:
Fleet consists of 55 operating units (at the time of the 2016 meeting), as mentioned earlier. In addition, three units are being installed in California, two in Texas, and two in Argentina. A dozen orders were book in the year leading up to the 2016 conference: Five each in California and Arizona, two on the East Coast.
Fleet operating hours totaled 434,000 operating hours/43,864 starts, with the high-time engine at 43,824 hours.
Twenty-eight units have reliabilities of more than 98%.
Fleet availability was said to be 98.2%.
Another presentation, one highlighting the various “field events” forcing an outage of 24 hours or more between October 2015 and February 2016, revealed nothing out of the ordinary: high-pressure-turbine first-stage blade cracks; HPT second stage blade foreign object damage; power-turbine FOD event, VSV system issue, failure to start, etc.
A later OEM presentation on asset management identified spares available to customers. Highlights:
Lease program has six PA supercores, with two currently available.
For the PB, one supercore is available.
The rotable module menu:
Five high-pressure turbines.
Three intermediate-pressure turbines.
Six power-turbine (PT) rotor/stator modules.
Three booster rotors.
A lengthy discussion of user experiences moderated by Chairman King touched on the following subjects, attesting to the breath of coverage:
Chafing of jacking-oil lines which can lead to line failure. Easy to inspect for using a borescope, the floor leader said. He referred the group to SB-134 for guidance.
Booster vane-ring replacement (SB-144). King did this at his plant and the job went well; he even showed a video to prove it.
Loose PT23 sensor. Easy fix; see SB-179.
Variable stator vanes held audience interest for significant time. SB-177 and SB-184 were focal points of the discussion.
Fuel-hose leaks. Most such problems are resolved by proper installation and tightening of joints.
Debris in oil filtration system. CCJ