I N D U S T R I A L P R O D U C T S A N D S E R V I C E S. Ron Frisard AW Chesterton

Transcription

1 I N D U S T R I A L P R O D U C T S A N D S E R V I C E S Valve Packing Challenges with Boric Acid Valve Leaks Ron Frisard AW Chesterton INPO Boric Acid Corrosion Control Working Meeting

2 Subjects Review Chesterton s boric acid valve testing Review best practices in packing programs Nuclear Power -2-2

3 Industry challenges for valve leakage Stem Friction - Create the lowest coefficient of friction from packing set with the largest operability window for the actuator Long Term Sealing - Have a packing set that will perform leak free for many nuclear plant fuel cycles without maintenance issues Consistent gland load - Packing gland load calculations that can be easily applied without complication and chance for error Nuclear Power -3-3

4 Boric Acid valve leakage High visibility Unique sealing challenges - Crystallizing fluid Need for investigation - Why leaks - What valve type / size - Concentration Nuclear Power -4-4

5 Early Work / Discussions EPRI Meeting in February (Charlotte) - Discussions from many plants on the issue of what is a leak, frequency of leaks, etc. USA/STARS Summer meeting, Boston - Had similar discussions about Boric acid valve packing testing Nuclear Power -5-5

6 Seabrook FP&L Paul Brown from Seabrook helped to work on a standard testing protocol Nuclear Power -6-6

7 Standard Testing Protocol (Open) It is important to have an open standard that is respected in the industry - Duplicates as best as possible to real life - Has agreed upon metrics (cycles, concentration, temperature, pressures etc) - Could be repeated by anyone (no proprietary testing equipment) Nuclear Power -7-7

8 Survey The best way to get a consensus on a testing protocol Chesterton sent an electronic survey to many utility engineers who deal with boric acid valves on a regular basis Topics included: - Type of valves seen with valve leakage - Concentration - Frequency - Stem materials Nuclear Power -8-8

9 Survey Thanks for everyone who participated If you did not, - See us at our booth to give us your - Take a printed version from the back of room Our final results will be given to the FLMUG group as reference data and put on the website Nuclear Power -9-9

10 Results so far IS BORIC ACID A CONCERN AT YOUR POWER PLANT NO 7.14 % YES 92.8% Nuclear Power

11 During plant operations, what is the most common method used to identify a Borated Water leak? Personnel observations, scheduled inspections, or surveillances Radiation monitors Sump level detection systems Nuclear Power

12 Of the following materials, what are most valve stems in Borated Water Systems made of? 17-4 ph SA ph ASTM A Stainless Steel Nuclear Power

13 Proposed Testing Standard Parameters Boric Acid Concentration: 2000 ppm Temperature and Pressure: (115) F & 2250 psig Stem Material: ASTM A Stainless Steel Stem Finish: 8 15 rms Valve Actuations: Installation / Consolidation Install 5-Ring Packing Set Tighten Gland Studs to Specified Torque Packing Consolidation At 2250 psig 115 F stroke full 3 Actuate valve (# OF CYCLES) Monitor gland load throughout test Visually monitor 3 times daily for leakage Collect 10 cycles Nuclear Power

14 Proposed testing equipment 3"-1500 lb ASME Class 2 Copes Vulcan Model D AOV 1 DIA ASTM A Stainless Steel Stem 3/8 Packing cross section Graphite Packing Type Data Acquisition - Thermocouples - Process Temperature - Gland Temperature - Bonnet Temperature - Pressures Transducers - Process Pressure - AOV operation - Strain Studs - Strain gauged bolts Nuclear Power

15 Proposed leakage collection and observation Using digital photography of the stem and gland area multiple times daily to see visual leakage Nuclear Power

16 I N D U S T R I A L P R O D U C T S A N D S E R V I C E S Packing Procedures Lesson s Learned

17 Presentation Objectives A review of Packing Procedures at U.S. Nuclear Power Plants shows a great disparity between the amount of detail. The lack of detail could contribute to packing failures and therefore lower plant efficiency This Presentation will review many packing issues that would benefit a review of your plants procedures Nuclear Power

18 Reasons for Good Packing Procedures Contractors During Outages - Need for Consistency in Handling Packing - Products differ from one plant to the next / Installation of those products differ and need to be detailed in Packing procedure Nuclear Power

19 Reasons for Good Packing Procedures Where to find the answer - Some packing procedures are incomplete Leave nothing to chance - yea, I know how to do that ~ don t I Nuclear Power

20 Stem Lubricants From NRC Inspection Report On July 9, 2002, as part of the Selected Issue Follow-up Inspection of Inspection Procedure 71152, the inspectors selected CAP (dated March 15, 2002) for review. Corrective Action Process documented a licensee-identified concern where N-5000, an anti-seize lubricant used in valve maintenance, had been inappropriately applied to the stem of air-operated valve AFW-2A. Used in this application, the N-5000 lubricant had become degraded such that it was causing Valve AFW-2A to stick during its operation. Nuclear Power

21 Integration with Packing Software Procedure should reflect how the Plant s Packing software is used Important to note that all packing software programs are not the same ~ Some contractors / New workers are use to using different programs. Nuclear Power Stuffing Box Depth 2 " EIN No. SAMPLE456 Arrangement: 8 In Series 1 In Parallel Journeyman Worksheet - II Rev. A Total Compressed Height * " SleeveLength " * Reference Only Plant: Unit: 1 CallawayFacility Date: 02/20/2002 System Area : System Function : System Temp : 1000 F System Pressure : 1000 psig Recommended Torque :* : 3 ft-lbs Max Torque :* : 4 ft-lbs THIS IS NOT A REAL VALV SAMPLE JOURNEYMAN W Static Friction : 258 lbs Force Dynamic Friction : 172 lbs Force OverRide Performed : Packing Installation : Completed By: Date: Torque: Journeyman Work Sheet : Prepared By: Date: Install / Config Aprroval : By: Date: Notes: 1) Drawing not To Scale: 2) Drawing may not reflect actual number of packing rings. Check Chesteron Improvement for actual number of rings/sleeves. Manufacturer: VALVE MFG Box ID Stem OD Model: SAMPLE1 Actual Valve Sizes: " " Size: 1 Type: Actuation: Wrench Size " Stud Type: GLOBE MAN Blind Stud Chesterton Improvement Ring OD Ring ID Selected Packing Sizes: " " Combined Clearance: " Packing Cross Section: " Gland Stud Diameter: " Description Item M&S Number Quantity Needed Style 5300 * Style 1-CI End Ring * Style 5100 Carbon Sleeve Style 5150 Spring Assembly w/innerguide XXXXX 2 * or use Packing Kit No Kit Comments: No Stud Quantity : 2 Calc. Stud Length : " Uncompressed Spring Height : " Min Compressed Spring Height : "

22 Example #1 Nuclear Power Plant Valve procedure - Maintenance I & C - Packing Installed & Consolidated in accordance with Packing Vendor / Engineering Specification (Torque / Stroked) Completely unloaded packing I&C re-loading packing based on instrumentation Consolidate Packing Set for the 2nd time Nuclear Power

23 Example #1 Cont Graphite Packing resiliency is diminished by unloading / reloading effecting overall packing life and performance. Recommended Procedure would have only 1 group (either Maintenance or I&C) do the packing loading and Consolidation - Clean Handoff Nuclear Power

24 Communication Packing Vendor Engineering Total Valve Ownership I/E Maintenance Nuclear Power

25 Example #2 MOV valve with damaged stem Consulted packing vendor and utilized a packing set that provided better/increased sealing capabilities for the deteriorated stem conditions. Set has performed well without any issues and the stem was not needed to be replaced. Nuclear Power

26 Cleaning out stuffing Box Leaving material in stuffing box can contribute toward packing failures by creating uneven surface for bushing and packing (uneven loading). If possible, backseat the valve to limit entry of foreign material into valve and to aid in valve stem inspection. Nuclear Power

27 Skill of Craft Leaving details to the technical skill of the Maintenance & Contractor personnel could lead to uncertainty Nuclear Power

28 Installing Packing Correctly Check with Packing Manufacturer for handling / installation of packing - Each packing style has it s own handling procedures Nuclear Power

29 Lantern Rings Issues Stack up issues - Procedures should specify which valves types still have Active Leak-off lines. - Procedure should describe which packing configuration should be used for valves with active lantern ring. - Could include full set below and full set above Lantern Ring Nuclear Power

30 BRAIDED Nuclear Power

31 Lantern Ring Cont. - Detail the proper consolidation of bottom set in the procedure. Without proper consolidation the packing set will fail Nuclear Power

32 Lantern Rings Cont. Details in the procedure should specify how to properly convert an active leak-off line to a standard packing configuration. Watch out for packing set being in line with old leak off port - Extrusion and reducing packing load over time and premature failure - Options : - 1) Normal 5 ring set with bushing in bottom - 2) Split bushing and move set lower / Higher - 3) install packing at bottom of valve and bushing on top. Nuclear Power

33 MOV Motor Issues MOV exceeds Amp Limit -I/E needs to be aware of procedure to install packing correctly Packing software program pulls all groups together Nuclear Power

34 Stack Up Issues Non standard stuffing boxes depths - Procedure should spell out what the correct packing arrangement is needed for shallow stuffing stuffing boxes - Carbon bushings installed height should not be < 1.5 x Cross Section - Need 6 ring configuration for stuffing boxes between ring depth Nuclear Power

35 Outage Timing Preparing for an outage with packing training can drastically reduce time of the outage Pre-measuring of valves to calculate/input datasheets and Pre-inventory packing planning. Allow for challenging/critical valves to take priority do not allow common valves that were planned to take valuable manpower Nuclear Power

36 Thread Inspection Procedure should give guidelines on how to inspect gland bolts - Also show where to obtain replacement studs and cut to proper length Thread condition in most cases still determines how much packing load will be transmitted Nuclear Power

37 Anti Seize Used Torque Formula calculations could be off by a significant amount if anti-seize has been substituted - For example,.2 from.1 would cause a 50% difference in torque valves ~ 50% more packing friction! Procedure should also incorporate using Antiseize with live loading assemblies - Without proper lubrication binding can occur: result improper in-service consolidation (also incorrect spring heights) Nuclear Power

38 Live Loading Issues Important to note how Valve Live Loading works from each supplier - Valve OEM and Packing manufactures do not engineer assemblies the same Procedure should spell out how to determine spring configuration (diagram or drawing) Nuclear Power

39 Carbon Spacer Procedure should specify how to calculate correct spacer height - Height should be determined by depth Procedure should specify how to cut bushing correctly (Tile Cutter works extremely well to cut bushings with excellent accuracy) Nuclear Power

40 Packing Selection Packing selection should be determined by packing software (if possible) Procedures should specify what packing is to be used on a specific valve Nuclear Power

41 Packing Selection Options 5300 (GTP) w/style one End rings 5 Cross Sections in Height Static Coef. Of Friction.15 Dynamic Coef. Of Friction.10 Minimum Gland Load 5800 Wedge Packing (Graphite) 4 Cross Sections in Height Static Coef. Of Friction.085 Dynamic Coef. Of Friction.085 Minimum Gland Load Nuclear Power PSI 1400 PSI 5800T Wedge Packing (Graphite with Small traces of PTFE) 4 Cross Sections in Height Static Coef. Of Friction.065 Dynamic Coef. Of Friction.065 Minimum Gland Load 1400 PSI

42 Torque Tables A torque table needs frequent updating because of added valves sizes Mistakes can happen in formula that results in inaccurate torque (and friction). Software Program has no mistakes Nuclear Power

43 How to calculate torque (emergency) A simple formula should be listed in the procedure to allow for the Installer to calculate a torque value if there is no access to the software program. Nuclear Power

44 Bringing data back into system A big part of an outage that is sometimes left out is taking valve information that was experienced and learned during the outage and updating the plant s packing program (the specific valve record). Nuclear Power

45 When the Friction is too high (Binding 101) Section should be dedicated on how to reduce friction (Valve Binds after installation) - Check for valve part interference - Verify if using a low Friction packing Nuclear Power

46 Valve Dynamics Common sense for Valves The valve stem and stuffing box wall should be smooth and free of any series of pits, cuts, scratches or nicks in a line that could possibly act as a path of leakage regardless of their depth. If the stem or stuffing box is excessively pitted notify the proper personnel. Stem roughness and/or high spots will destroy the packing. Scale can permit leakage through itself and thus around the packing. Nuclear Power

47 Valve Dynamics Common sense for Valves Typical acceptable Tolerances Stem diameter tolerances ±.003. Stuffing box diameter tolerances Stuffing box finish RMS. Stem Finish RMS. Normality, squareness, and parallelism within.005, not more than.015 on any single surface. Nuclear Power

48 Consolidation Issues Consolidation: - Graphite natural ability to conform - Write into procedures to properly consolidate the packing. Using measuring devices for loads great idea not everyone uses Nuclear Power

49 Thank you for your time Any Questions.. Nuclear Power