MINUTES OF MEETING Technical Committee on Fundamentals of Combustion Systems Hazards January 29-30, 2013 GE Corporate Headquarters Houston, TX I. Attendance: Principal Members/Staff: Dale Evely, Technical Committee Chair, Southern Company Services, AL Denise Beach, NFPA, MA Bryan Baesel, Eclipse/CEC Combustion Safety Inc., OH Barry Basile, Babcock Power, MA Michael D. Cazabon, The Dow Corning Company, TX John Eley, GN Electronics Inc., IL Joseph E. Fehr, Sega, Inc., MO James Franks, XL Global Asset Protection Services, TN Richard Gallagher, Zurich Services Inc., DE Ted Jablkowski, Fives North American Combustion., CT John Kane, The DuPont Company, NC David King, American Electric Power Corporation, OH Randy Kleen, General Electric Co., TX Gail Lance, Babcock & Wilcox Company, OH Carlos Lasarte, Combustion, Energia & Ambiente, C.A., Mexico (Nonvoting) Dennis Mason, AEGIS Insurance Services, MI Glenn Raney, Invensys Operations Management, TX Mark Ratcliffe, BP Americas, Inc., TX Roy Reeves, Emerson Process Management, PA Celso Schmidt, UTC/Forney Corporation, TX Bill Smith, Exothermic Engineering LLC, MO William A. Smith, Global Risk Consultants Corp., GA Franklin Switzer, S-afe, Inc., IN Mike Walz, Burns & McDonnell Engineering Co., MO Harold (Skip) Yates, HRY, Inc. Boiler Systems Consulting, MI (via teleconference) Allen Zadiraka, OH (via teleconference) Alternates : Joseph Bittinger, American Electric Power, OH Steven Graf, Emerson Process Management, PA Farshad Hendi, Invensys, TX William Rucki, Fives North American Combustion Inc., OH (via telecon., 1/30 only) Guests : Robert Dobbins, Zurich Services Inc. Brian Moore, Hartford Steam Boiler Mike Polagye, FM Global (via teleconference) Daniel Lee, ABB Incorporated
II. Minutes of Meeting: 1. Call to order. The meeting was called to order at 8:05 a.m. CST on Jan. 29, 2013. 2. Introduction. The Committee members and guests introduced themselves and identified their affiliation. 3. Minutes Approval. The minutes from the May 2012 meeting were approved as written. 4. NFPA Staff Report. The NFPA Staff Liaison reviewed the new document revision process and tools, including the new terminology, the revision cycle timeline, and the online public input submittal process. (Attachment A) NFPA Staff reminded the committee that committee actions related to document revisions and public input will be available in the First Draft Report, which will be posted on the NFPA 85 document information page no later than Sept. 6, 2013. 5. Old Business. A. Gas Line Purging Task Group. Members of the task group are: B. Baesel; R. Gallagher; T. Jablkowski; R. Kleen; D. Mason; and F. Switzer. The task group submitted recommendations to the committee to designate a single equipment isolation valve and identify it in annex A figures. The committee adopted these recommendations as First Revisions. Mr. Switzer noted that the next edition of NFPA 56 will be issued in August 2013. B. Vent Valve Sizing. NFPA Staff submitted a Code Fund Request to the Fire Protection Research Foundation. NFPA Staff will update the committee once the funded projects have been announced. In addition, Mr. Zadiraka reported that he has interacted with industry participants who misunderstand the purpose of the vent valve, particularly in the SIS user groups. Mr. Zadiraka recommended that a definition or annex text be developed to clarify the purpose of the vent valve. C. Referenced Documents in Fundamentals Chapters. Mr. Switzer reported that he does not have access to the latest editions of ASME codes. Mr. Switzer and Mr. Mason will be at NFPA headquarters later in 2013 and can view copies of the documents in the NFPA Library. NFPA Staff noted that if any issues are identified, further action could be taken by the correlating committee. In addition, the ASME Boiler and Pressure Vessel Code committee is working on a new section 7 on combustion systems. Sections 6 and 7 are recommended practices for maintenance of boilers, mainly focused on commercial/institutional sized boilers. Mr. Moore will inform NFPA Staff when ASME goes out for review with these sections and NFPA Staff will issue a notice to the BCS-FUN committee. D. Requirement for burner management system to be limited to a single boiler or HRSG. NFPA has not received permission to distribute the draft recommended practice, API 538. Mr. Lasarte was able to provide an overview comparing NFPA 85 and API 538 (Attachment B), noting that the API document refers to NFPA 85 in several locations. Mr. Polagye noted that API is working on a new draft of the recommended practice, and will inform NFPA Staff when the document is released for public review. NFPA Staff will then issue a notice to the BCS-FUN committee.
E. Glossary Update. The committee reviewed the request by NFPA Staff to remove definitions from chapter 3 if the term is not used in the mandatory text of NFPA 85. The committee took action on many definitions. Committee actions will be available in the Report, which will be posted on the NFPA 85 doc info page no later than Sept. 6, 2013. In addition, the committee requests staff to submit a request to the secretary of the NFPA Standards Council to incorporate the NFPA Glossary of Terms in boilerplate paragraph 3.1. The committee is optimistic that the Standards Council can respond before the Second Draft meeting. Finally, the committee noted that the term fluidized bed is identified inconsistently throughout chapter 7 and requests the BCS-FBB committee to adopt an action that would make all occurrences consistent. 6. New Business A. Document Revision. The committee reviewed the public input and other requests and created First Revisions in chapters 1-4 and related annex text. B. Recognition of NFPA 85 in Latin America. Mr. Lasarte presented a report of a recent survey of Latin American countries regarding recognition and use of NFPA 85. The report showed that only a small percentage of industry participants in those countries are aware of or have used NFPA 85 in their jobs. NFPA Staff will work with Mr. Lasarte to increase awareness of NFPA 85, perhaps through NFPA Journal Latinoamericano. NFPA Staff will contact the NFPA International Department to identify additional resources. C. Fuel gas piping maintenance and purging task group. The committee established a task group to look at possible purging requirements downstream of the equipment isolation valve. The committee created Committee Input (CI) 125 to solicit public comments and support revision of NFPA 85. The task group scope is to recommend new minimum safety requirements for opening and recharging a fuel gas system for maintenance or inspection. The task group is asked to report back in the Second Draft meeting. Task group members are: B. Baesel (chair); T. Jablkowski; J. Kane; D. Mason; and A. Zadiraka. D. Interlock requirements task group. M. Polagye agreed to request that the Correlating Committee establish a task group to make recommendations regarding the interlock issues described by Mr. Dan Lee in Public Input 44. 7. Other Items. There were no other items to discuss. 8. Next Meeting. The Second Draft meeting will be hosted by Southern Company on December 4-6, 2013 in Atlanta, Georgia. The meeting will be 2 ½ days. Additional details will be forwarded as they become available. 9. Adjournment. The meeting adjourned at 5:15 pm CST on Jan. 30, 2013.
Attachment A: NFPA Staff Presentation
Welcome TCs on Fundamentals of Combustion Systems Hazards Jan 29-30, 2013 GE Headquarters, Houston TX At this and all NFPA committee meetings we are concerned with your safety. If the fire alarm sounds, please proceed to an exit. Use of tape recorders or other means capable of reproducing verbatim transcriptions of this or any NFPA meeting is not permitted Guests All guests are required to sign in and identify their affiliations. Participation is limited to those individuals who have previously requested of the chair time to address the committee on a particular subject or individuals who wish to speak to Public Input they have submitted. Guest chairs are located around the room as a courtesy. Members categorized in ANY interest category who have been retained to represent the interests of ANOTHER interest category (with respect to a specific issue or issues that are to be addressed by a TC/CC) shall declare those interests to the committee and refrain from voting on any Public Input, Comment, or other matter relating to those issues. 1
General Procedures Follow Robert s Rules of Order. Discussion requires a motion. Motions for Ending Debate Previous Question or Call the Question Not in order when another has the floor Requires a second This motion is not debatable bl and DOES NOT automatically stop debate A 2/3 affirmative vote will immediately close debate and return to the original motion on the floor. Less then 2/3 will allow debate to continue. Committee member actions: Member addresses the chair. Receives recognition from the chair. Introduces the motion. Another member seconds the motion. Committee chair actions: States the motion. Calls for discussion. Ensures all issues have been heard. Takes the vote. Announces the result of the vote. 2
Overview What s New? Still basically 4 steps: (Report on Proposals) Second Draft (Report on Comments) NITMAM/CAM Issuance NEW opportunities to skip steps: If no public comments are received, the committee can request immediate issuance NITMAMs will only be certified based on public comments. Changes in Terms: New Term Input Stage Public Input Meeting Committee Input Committee Statement (CS) First Revision (FR) Report Old Term ROP Stage Proposal ROP Meeting Trial Balloon (or later, FR that fails ballot) Committee Statement Committee Proposal or Accepted Public Proposal ROP ROP Draft What s New? Flowchart Changes in Terms: See page 4 for flowchart overview New Term Comment Stage Public Comment Second Draft Meeting Committee Comment Second Revision Second Draft Report Second Draft Old Term ROC Stage Public Comment ROC Meeting Comment that Failed Ballot (Second Revision that failed ballot) Committee Comment or Accepted Public Comment ROC ROC Draft 3
NEW Committee Actions and Motions: Resolve Public Input Create a First Revision Create a Committee Input (Trial Balloon) Resolve a Public Input (PI) o Committee develops a Committee Statement (CS) to respond (resolve) a Public Input. o Committee must clearly indicate reasons for not accepting the recommendation in CS and/or point to a relevant First Revision o PI does not get balloted Create a First Revision (FR) o Committee wants to make a change to a current section or add new text. o Committee develops a Committee Statement (CS) substantiating the change. (do not refer to PI as the reason) o Ensure any associated PIs get a committee response, often simply referring to the relevant FR. o Each FR gets balloted Create a Committee Input (Trial Balloon) Committee wants to receive Public Comment on a topic, but not ready to incorporate it into the draft Need to have a Committee Statement Does not get balloted 4
Committee Statements (Substantiation): All Public Input must have a Committee Statement Must include a valid technical reason No vague references to intent Explain how the submitter s substantiation is inadequate Committee Statements (Substantiation): Should reference the First Revision if it addresses the intent of the Submitter s Public Input Formal voting Voting during meeting is used to establish a sense of agreement (simple majority) Secured S d by letter ballot (2/3 agreement) Only the results of the formal ballot determine the official position of the committee on the Ballots are on the First Revisions (FR) ONLY Public Input and Committee Input not balloted Reference materials are available:, PI, CI, CS, etc Ballot form allows you to vote: Affirmative on all FR Affirmative on all FR with exceptions specifically noted Ballot form provides a column for affirmative with comment Note: This box only needs to be checked if there is an accompanying comment. Reject or abstain requires a reason. 5
Initial ballot Circulation of negatives and comments Members may change votes during circulation First Revision that fails letter ballot becomes Committee Input (CI) just like the trial balloon version of CI so as to solicit Public Comment Balloting Ballots will be an online format Alternates are strongly encouraged to return ballots NFPA Overview No New Material after the Public Input Stage What constitutes new material is to some extent a judgment call Online submittal of comments through Terra Comment phase works similar to old process HOWEVER, comments that do not contain specific action will no longer be accepted NO Reverse committee action NO I agree with the committee action NO Use submitter s original material No new material after the Public Input Stage What constitutes new material is to some extent a judgment call NITMAMs will be certified ONLY on comments Nitmammers must participate in the entire process 6
Legal Patent: Disclosures of essential patent claims should be made by the patent holder, but others may also notify NFPA if they believe that a proposed or existing NFPA standard includes an essential patent claim. Antitrust: the single most important provision- Federal law prohibits contracts, combinations, or conspiracies which unreasonably restrain trade or commerce. Section 1 of the Sherman Act Legal Activities Disapproved by the Courts Packing meetings Hiding commercial interest throwing the committees out of balance No final decision-making authority to unbalanced Task Groups; include all interested parties. Hiding scientific or technical information from committees Doc Info Pages Document Information Document scope Current/Previous Edition information Issued TIAs, FIs and Errata Archived revision information Standard Council Decisions Articles and Reports Read only document Next Edition Meetings and Ballots ROP/ROC or First Draft Report and Second Draft Report NITMAM and Standard Council Decisions Submission of Public Input/Comment Private TC info Ballot circulations, informational ballots and other committee info Technical Committee Committee name, responsibility and scope Staff liaison Committee list Private committee contact information Current committee documents in PDF format Committees seeking members and committee online application Thank you for participating! Any yquestions? 7
Attachment B: C. Lasarte Presentation on API 538
2/14/2013 NFPA 85 BCS-FUN TC API RP 538 Vs. NFPA 85 Technical Committee on Fundamentals of Combustion Systems Hazards January 29-30, 2013 GE Corporate Headquarters 1333 West Loop South, 8th floor. Houston, TX As far as an approach to comparing the two documents I would simply start with the document scopes. Do they overlap? As an API document, I assume it is application specific to petrochemical plants. Is that correct? Is there a min/max heat input? As a Recommended Practice, NFPA would not consider anything in API RP 538 to conflict with NFPA 85. However, if there are major, specific discrepancies, such as independence of the burner management system, they would be significant to note. NFPA staff has not received permission from API to distribute the draft document to the BCS-FUN and BCS-MBB members. Committee members were encouraged to submit public input on this subject after reviewing the relevant materials.. Have any of you checked the API RP 538? INDUSTRIAL FIRED BOILERS FOR GENERAL REFINERY AND PETROCHEMICAL SERVICE 1 Scope 1.1 This recommended practice specifies requirements and gives recommendations for design, operating, maintenance, and troubleshooting considerations for industrial fired boilers that are used in refineries and chemical plants. It covers waterside control, combustion control, burner management systems, feedwater preparation, steam purity, emissions, etc. 1.2 This recommended practice is not intended to apply to firetube boilers, gas turbine exhaust boilers, or fluidized bed boilers. 1.3 This recommended practice does not cover a boiler s mechanical construction. Purchaser or Owner shall specify codes such as ASME, ISO, etc. The API RP 538 in its Point 4.5 IGNITER MANAGEMENT SYSTEM indicates: Given the extensive acceptance of NFPA 85 in the boiler industry it seems logical that we should use extreme care in correlating these two important safety standards such that engineers and operators that work with boilers may not be confused by terminology used in this API 538 standard and in NFPA 85 2011 or previous editions. In many cases confusion will arise from time of the original boiler design, where a clear decision has to be made by the end user of what standard to apply for his power boilers. To this effect, the NFPA 85 igniter classifications used for many years are used in RP538 in order to clearly address the ways igniters can be used. Summarizing these igniter classes as per NFPA 85 2011 section 3.3.85 to 3.3.85.4 is as follow: 1
2/14/2013 The API RP 538 Copy textually the description of the Igniters Classification: a. Igniter. A permanently installed device that provides proven ignition energy to light off the main burner. b. Class 1 Igniter. An igniter that is applied to ignite the fuel input through the burner and to support ignition under any burner light off operating conditions. Its location and capacity are such that it will provide sufficient ignition energy, generally in excess of 10 percent of full load burner input, at its associated burner to raise any credible combination of burner inputs of both fuel and air above the minimum ignition temperature. c. Class 2 Igniter. An igniter that is applied to ignite the fuel input through the burner under prescribed conditions. It is also used to support ignition under low load or certain adverse operating conditions. The range of capacity of such igniters is generally 4 percent to 10 percent of full load burner fuel input. d. Class 3 Igniter. A small igniter applied particularly to fuel gas and fuel oil burners to ignite the fuel input through the burner under prescribed light off conditions. The capacity of such igniters generally does not exceed 4 percent of the full load burner fuel input. e. Class 3 Special Igniter. A special class 3 high energy electrical igniter capable of directly igniting the main burner fuel. Introduce a summary table: Table 1 - Igniter properties summary table The API RP 538 in its Point 4.6 BURNER MANAGEMENT SYSTEMS indicates: For those that apply NFPA 85 to Industrial Fired Boilers for their burner management systems, RP 538 provides supplementary guidance for the unique boiler and combustion system hazards particular to the refinery and petrochemical plant environment. RP538 First Edition should not be applied exclusively as a basis for Burner Management Systems. It should be used in conjunction with NFPA 85 Boiler and Combustion Systems Hazards Code. As indicated in NFPA 85 Chapter 1, The purpose pose of this code shall be to contribute to operating safety and to prevent uncontrolled fires, explosions, and implosions in equipment. This code shall establish minimum requirements for the design, installation, operation, training, and maintenance of pulverized fuel systems, boilers, HRSGs, combustion turbine exhaust systems, and their systems for fuel burning, air supply, and combustion products removal. This code shall require the coordination of operating procedures, control systems, interlocks, and structural design. This code shall not be used as a design handbook. A designer capable of applying more complete and rigorous analysis to special or unusual problems shall have latitude in the development of such designs. In such cases, the designer shall be responsible for demonstrating and documenting the validity of the proposed design.ǁ NFPA 85 is not a mandatory requirement by all local governing authorities. The API RP 538 in its Point 4.6.1 Hazard Analysis indicates: With the current release of NFPA 85 (2011), Annex 4.11 has been updated to include hazard analyses that are consistent with current practices in the refining and petrochemical industry. Selected paragraph references that follow are in current release of the referenced industry documents, e.g. NFPA 85 (2011) Annex 4.11 Utilizing the equivalency provision in Section 1.5, an alternative design to meet the requirements of the code can be accomplished where all the following are provided: a. Approval of the authority having jurisdiction. b. A documented hazard analysis that addresses all the requirements of this code. c. A documented life-cycle system safety analysis that addresses all requirements of this code and incorporates the appropriate application-based safety integrity level (SIL) for safety instrumented systems (SIS). One methodology for achieving a life-cycle system safety analysis is to use a process that includes SIL determination and a SIS design and implementation consistent with the ISA 84 standard series. As an industry consensus document, RP 538 may assist in defining Recognized and Generally Accepted Good Engineering Practice (RAGAGEP) for the application of instrumentation, control, and protective functions to boilers. The API RP 538 in its Point 4.6.2 Documentation for Defensible Basis indicates: NFPA 85 is a prescriptive, minimum safety standard to be used by competent designers and is not a design handbook. Competent designers are given the latitude to address special or unusual problems provided they document the validity of the designs where such problems exist (NFPA 85, Section 1.3). Additionally, none of fthe requirements in NFPA85 are intended dto preclude the use of systems that provide equivalent or superior safety over that prescribed (NFPA 85, Section 1.5). In contrast, RP 538 is a performance based recommended practice that provides options to mitigate specific process hazards and forms a basis for justifying special designs to the authority having jurisdiction when these designs deviate or diverge from the prescriptive requirements in NFPA 85. 2
2/14/2013 The API RP 538 in its Point 4.6.3 The Impact of Loss of Steam to Critical Process Equipment indicates: Implementation of NFPA 85 requires a competent designer to properly integrate the individual components of a protective function (input sensors, logic solver, and final elements) into a comprehensive protective system. The startup permissive and tripping interlocks specified in NFPA 85 are limited to those directly associated with the steam generator and combustion system. However, additional steam generator interlocks that are site or process specific may be required to ensure safe operation and prevent damage to the steam generator, associated equipment (e.g. outlet piping, and superheaters), or critical process equipment. When designing the burner management system and safety interlocks for a steam generator in general refinery or petrochemical service, the overall impact (e.g. safety, environmental, financial) to the plant for loss of steam should be evaluated. Depending on the consequential damage to process, some equipment protection interlocks that are typical for steam generators (e.g. low drum water level trip) may not represent good engineering practice for a specific application. In those cases, a high priority alarm may represent best practice, recognizing that failure to correct the condition may sacrifice the steam generator for the benefit of critical production processes and/or critical process equipment. For additional clarification on Process Hazards Protection, see Section 7.4.4. The API RP 538 in its Point 7 Instrumentation, Control Systems, and Protective Systems indicates: One of the primary objectives of RP 538 is to provide guidance for addressing the unique boiler and combustion system hazards present within the refining and petrochemical industry. 7.1 APPLYING RP 538 TO BURNER MANAGEMENT SYSTEMS For those that apply NFPA 85 to industrial fired boilers in the refinery and petrochemical industry, RP 538 provides supplementary guidance for boiler and combustion system hazards. RP538 First Edition should not be applied exclusively as a basis for Burner Management Systems. It should be used in conjunction with NFPA 85 Boiler and Combustion Systems Hazards Code. API RP 538 7 Instrumentation, Control Systems, and Protective Systems On this Section the API RP 538 do a comparative analysis with the NFPA 85 related to the following subjects: 7.1.1 Hazard Analysis (Repeat the same indicated on 4.6.1 Hazard Analysis insisting on: While many in the industry regard NFPA 85 as a document that needs to be strictly followed, it was never intended to be applied as a design handbook or checklist. Within the requirements of NFPA 85, it is recognized that a competent designer and/or hazard assessment team should evaluate the hazards and allocate protective functions to mitigate the hazards. Where special problems arise, a competent designer is given the latitude to resolve these issues with a documented defensible basis API RP 538 7 Instrumentation, Control Systems, and Protective Systems On this Section the API RP 538 do a comparative analysis with the NFPA 85 related to the following subjects: 7.1.2 Documentation for Defensible Basis 7.1.2.1 Burner Management System Logic Solvers 7.1.2.2 Watchdog Timer 7123Master 7.1.2.3 Fuel Trip (MFT) Relay 7.1.2.4 Emergency Shutdown (ESD) Pushbutton - Hardwired 7.1.2.5 One Boiler per Logic Solver 7.1.2.6 Switches vs. Transmitters including Low Water Cutoffs 7.1.2.7 Flame Proving 7.1.2.8 Bypassing of Interlocks 7.1.2.9 Provisions for Online Testing of Safety Shutoff Valves (SSVs) 7.1.2.10 Valve Proving Systems 7.1.2.11 Atmospheric Vent Valves Between Burner Safety Shutoff Valves (SSVs) 3
2/14/2013 API RP 538 7 Instrumentation, Control Systems, and Protective Systems On this Section the API RP 538 do a comparative analysis with the NFPA 85 related to the following subjects: 7.1.2 Documentation for Defensible Basis.Cont. 7.1.2.12 BMS Supervision of Light-Off Conditions 71213Restricting 7.1.2.13 Control Valve Movement until Release-to-Modulate 7.1.2.14 Purging a Single Burner Boiler Limiting Purge Rate 7.1.2.15 Purging Multiple Burner Boilers (9 burners or less) 7.1.2.16 Miscellaneous Prescriptive Trips 7.1.2.17 Limitations of the Interlock System 7.1.2.18 Timing Sequences 7.1.2.19 Valve Stroke Time vs. Time to Safe State 7.1.2 Documentation for Defensible Basis NFPA 85 is a prescriptive, minimum safety standard to be used by competent designers and is not a design handbook. Competent designers are given the latitude to address special or unusual problems provided they document the validity of the designs where such problems exist (NFPA 85, Section 1.3). Additionally, none of the requirements in NFPA 85 are intended to preclude the use of systems that provide equivalent or superior safety over that prescribed (NFPA 85, Section 1.5). In contrast, RP 538 is a performance based recommended practice that provides options to mitigate specific process hazards and forms a basis for justifying special designs to the authority having jurisdiction when these designs deviate or diverge from the prescriptive requirements in NFPA 85. In the next slides are examples of how the comparative analysis is handled: 7.1.2.1 Burner Management System Logic Solvers The API RP 538 Copy textually the following points: a. NFPA 85 (2011) Fundamentals 4.11.5 Fundamentals 4.11.6* To indicate that: b. RP 538 These issues may be resolved with the installation of a safety certified logic solver (i.e. per IEC 61508) and mitigates the requirement for an independent watchdog timer, master fuel trip relay, and hardwired operator-initiated emergency trip as noted below. 7.1.2.2 Watchdog Timer The API RP 538 Copy textually the following points: a. NFPA 85 (2011) 1. Definitions 3.3.169 2. Fundamentals 4.11.6(10)* A.4.11.6 (10) To indicate that: b. RP538 - With safety certified logic solvers, the use of external watchdog timers do not provide an improved level of safety or reliability and are not necessary. 4
2/14/2013 7.1.2.5 One Boiler per Logic Solver The API RP 538 Copy textually the following points: a. NFPA 85 (2011) Fundamentals 4.11.7.4: The logic system shall be limited to one boiler (or HRSG). To indicate that: b. RP 538 - More than one boiler per logic solver is permissible when using safety certified logic solvers (i.e. per IEC 61508) and critical equipment grouping within the protective system. The primary justification is that within the refining and petrochemical industry, much higher risk than that presented by a boiler is managed across multiple operating units within a single safety certified logic solver. In practice, however, most facilities will opt for one boiler per logic solver with rare exception. For example, a consideration may be to combine two adjacent standby boilers into a common logic solver. During proof testing, however, this would require online testing protocol for the offline boiler which would increase the potential to nuisance trip the online boiler. Additionally, software and firmware upgrades to the logic solver cannot be performed without taking both boilers out of service. 7.1.2.6 Switches vs. Transmitters including Low Water Cutoffs The API RP 538 Copy textually the following points: a. NFPA 85 (2011) 1. Definitions 3.3.159.11 2. Definitions 3.3.159.12 3. Fundamentals 4.11.3 4. Fundamentals 4.11.3.1 5. Fundamentals 4.11.3.2 6. Multiple Burner Boilers 6.4.2.2.14 7. Annex A.6.4.2.3.1 (last paragraph) 8. Multiple Burner Boilers 6.4.3.2.24 To indicate that: b. RP 538 - The use of transmitters rather than switches for interlocks enhances safety system reliability. With the 2011 edition of NFPA 85, the use of transmitters in lieu of switches is permitted. The use of the term switch in the definition chapter of NFPA 85 is a carry-over from earlier editions of that code and the use of switches is not a requirement for either single or multiple burner boilers. 7.1.2.7 Flame Proving The API RP 538 Copy textually the following points: a. NFPA 85 (2011) - Fundamentals 4.12.3.5 Flame Proving 1. 4.12.3.5.5 2. 4.12.3.5.6 To indicate that: Within the context of NFPA 85, section 4.12.3.5.5 applies to tangentially fired boilers. For a tangentially fired boiler in "fireball" mode, individual flame detectors may sense flame even when the corresponding burner is not in operation. However, if the boiler load drops below the minimum fireball threshold, the flame monitoring philosophy reverts back to individual burner flame detection. b. RP 538 Section 4.12.3.5.5 in NFPA 85 (2011) shall be applied exclusively to tangentially fired boilers. Since greater than 95% of boilers in the refining and petrochemical industry are wall fired with 9 burners or less, the capability to discriminate flame between individual burners independent of boiler load is practical, reasonable, and achievable. 7.1.2.10 Valve Proving Systems The API RP 538 Copy textually the following points: a. NFPA 85 (2011) 1. Single Burner Boilers - 5.3.2.3* 2. Single Burner Boilers - 5.3.2.3.1* 3. Multiple Burner Boilers - 6.6.5.1.3.1 A.6.6.5.1.3 To indicate that: NOTE - As of 2011 all listed automatic valve-proving systems use aluminum body safety shutoff valves. This does not typically meet the piping specification in refining and petrochemical facilities. b. RP 538: An upstream manual isolation valve should be used to shut-off the fuel supply during shutdowns for plant maintenance outages. Where boiler operation is steady state during normal plant operation, this arrangement coupled with operating procedures and trained operators adequately protects against the hazard of valve seat leakage. For boilers or boiler burners that cycle during normal operation, the owner/operator may elect to implement a valve proving system to verify seat integrity; however, it is recommended that the safety shutoff valves be proven at shutdown or scheduled outage instead of waiting until the startup sequence.. 5
2/14/2013 7.1.2.14 Purging a Single Burner Boiler Limiting Purge Rate The API RP 538 Copy textually the following points: a. NFPA 85 (2011) - Single Burner Boilers 5.5.2.6.1 Prefiring Cycle. accomplish the following steps in the listed order (8) Prove the purge airflow by satisfying one of the following items: a. Air pressure and open damper b. Airflow interlock (9) Purge airflow must reach no less than 70 percent. (10) The purge must be for at least eight air changes.. To indicate that: b. RP 538 For single burner boilers, the purging requirements stated within NFPA 85 do not address high velocity burners with narrow throats and/or swirlers which have the potential to jet stream a narrow cross section of high velocity air through the center of the firebox rather than purging the boiler with a broader, slower air pattern. While there is a prescribed minimum purge rate at 70% MCR airflow, there is no upper limit. In practice, too high a purge velocity may inhibit the capability to clear dead spots or inactive pockets and sweep the combustion chamber free of combustibles. 7.1.2.17 Limitations of the Interlock System The API RP 538 Copy textually the following points: a. NFPA 85 (2011) - 6.4.2.1.6* A.6.4.2.1.6 To indicate that: b. RP 538 - While prescriptive trips are typically associated with operational or flame stability limits, it is important to understand that the burner may be subject to loss of flame inside of those operational limits. Thus, there is a requirement for flame scanners on boilers. However, flame scanners may not provide sufficient protection on low NOX multistage burners. At a minimum, multi-stage burners need dedicated scanners to cover each stage of the burner. Where impractical or difficult to achieve, the combustion control system (CCS) may independently monitor combustion status and alarm or trip upon combustion difficulty. Final Comment: The API Recommended Practice 538 has made a very critical analysis, very detailed and maybe severe of the NFPA 85. Recommendation: Establish a detailed review of the comparisons made by the API RP 538 Take all the criticisms made in the API RP 538 and analyze within BCS FUN NFPA 85 committee potential improvements for future revisions. Evaluate how the image of the NFPA could be affected by an analysis like this Could it be considered an approach to this API Task Group? From now based on the API RP 538 the Manufacturers will do a different instrumentation for the refineries and petrochemical boilers? 6