Task Force on Iso-23251/Std 521

MINUTESTASK FORCE ON ISO-23251/STD–521COMMITTEE ON PRESSURE RELIEVING SYSTEMS8:30 A.M. – 6:00 P.M. Hyatt Regency Monday, November 10, 2008 Los Angeles, CABrad Otis Convenor ISO 23251; E. Zamejc Chairman Project Leader ISO 23251, API STD 521I. Introductions and registration of attendance (All)Copies of meeting agenda and the current draft of ISO 23251 (after the modifications from the summer 2008 meeting at The Hague) were distributed. Registration and check of register performed.II. Appointment of secretary to keep meeting minutes (All)A. Shackelford was appointed secretary.I. Approval of Spring 2008 ISO-23251/API 521 New Orleans Minutes (All)The meeting minutes for the last meeting were reviewed. The following changes were proposed by T. Bevilacqua and accepted:  [Title] “hotel” added to Intercontinental in the title to avoid confusion that the reference was made to the location  [Section I] Indicate role for S. Crimaudo as API Staff liaison  [Section V.i] modify language to indicate that the approval was performed by ISO ballot to clarify that the committee did not approve the amendment at the meeting.  [Section V.j.ii] The action items have update dates indicating Fall 2009, and the question was posed as to whether or not this was a typographical error. E. Zamejc postponed resolution to the discussion on the action items and will update the action item list appropriately based on the current status. In addition, the first sentence should read “consists” not “consisting”.  [Section V.j.iii] Action Item 15 should refer to all production facilities, not just offshore, as this issue exists at onshore installations as well.  [Section VI.k] It was noted that the releases from PRVs discussed during the CCPS Metrics presentation by D. Eure specifically meant those to atmosphere.The following items were also noted:  [Section IV.e] Item IV.e) under TI has no number, and E. Zamejc indicated no number had yet been assigned  [Section V.i] The meeting minutes indicate that “S. Crimaudo was asked if there was a way to have API announce the amendment” and the question was raised as to what the resolution of this was. E. Zamejc responded that the API announced the amendment on their web site.Finally, feedback was provided to E. Zamejc from S. Smith regarding the distinction between low and high pressure air assisted flares [email provided in the meeting handouts]. B. Schwartz agreed to review the information and provide a proposal on whether or not additional information is required in the document.III. Approval of Summer 2008 ISO-23251 / API 521 The Hague Minutes (All)E. Zamejc gave a special thanks to D. Saile for hosting the meeting at The Hague over the summer. E. Zamejc indicated there was significant reorganization of the document, which is reflected in the current revision provided as a handout for the meeting, and that there is plenty of opportunity to provide feedback on the reorganization.The meeting minutes for the last meeting were reviewed. The last action item was assigned a number (58). A request was made to indicate the section affected by the resolution of previous action items; however, the reorganization of the document renders a reference to a specific section difficult as the section number has changed. Most agreed that simply searching the document for the phrases desired was the best option.The minutes were approved as modified. As a side note, the approval of the meeting minutes was limited to those attendees that were present at the meeting.IV. Review of inquiries / correspondence for API 521 / ISO 23251 A general question was posed regarding the work process to be used for the review of technical inquiries. C. Brooke noted that there is a presentation scheduled for the Joint Session to propose a work process, and that the work process adopted at the last meeting should continue to be used for now. a) 521-A1-2008-1 (Zamejc)It was generally agreed that the questions posed in the technical interpretation were consulting in nature; however, discussion regarding the section in question led to the agreement that the section was confusing. It was noted that the intent was likely that the sizing of a relief header having a depressuring load was controlled by that depressuring load and that the additional vapor from the relief devices protecting equipment affected by that fire would not significantly affect the sizing (or perhaps should not even be added, if the equipment being depressured are the same equipment in question). There was general agreement that the guidance in §5.18.3.2 (reference to current working draft revision) should reference guidance provided in §6.3.2.M. Porter agreed to propose language for the response to the technical interpretation as well as to clarify section 5.20.2.2 and add a reference to 7.1.2. M. Porter to send to T. Bevilacqua and H. Løvåsen (copy E. Zamejc) for review. There was general agreement that the definition of the pool size should only be in one location. C. Brooke indicated that the feedback from the technical inquiry work process to be presented during the Joint Session may be an option for this technical inquiry. b) New errorAn error on the pressure ratio in Figure 44 of the current working draft (isothermal flow chart) was discovered. D. Saile anticipates that ISO will recognize that the error is typographical in nature, and will check with ISO on how to handle correction to the figure given the lead time in issuing the next revision. c) New inquiry A new technical inquiry (not yet numbered) was received regarding §5.15.2.2.2 dealing with the effect of external pool fires on unwetted vessels. E. Zamejc has reformulated the questions into ones that can be answered ‘yes/no’ and proposed the responses to those questions. E. Zamejc to issue the responses to the technical inquiry as a ballot for the committee to respond to. d) Historical origin of flame center equation, pool fire areas (information only)E. Zamejc has provided (in the meeting handouts) some of the results of his research from an investigation into a couple of questions pertaining to the references in ISO 23251, specifically regarding the reference for the radiation calculations that define the flame center and the reference for the basis for the pool fire area.There was some discussion about how to handle reference materials, especially considering the loss of a good amount of reference material when it was managed by API. The current philosophy is that all of the information (including electronic files) is the responsibility of the task force chair, to be handed over to the new chair when elected. C. Brooke took the action item to bring up the issue of maintaining reference materials to the CRE as a concern, noting that during the CRE meeting on Sunday, subcommittee chairs were encouraged to provide the CRE with concerns instead of just providing document status.V. Old Business e) Status on CSB response amendment (published in May)The meeting handouts contained a draft of the response from API to the CSB that was supposed to have been sent in May 2008. It was noted that there has been no feedback received from the CSB executive council. There was some discussion about the contents of the response, including whether the references to blowdown drums should have been preceded with “atmospheric” and whether the language could be interpreted as still allowing atmospheric blowdown drums. The question was posed as to whether or not the issue has been closed. API has provided the committee’s response to the CSB and has published the amendment to the ISO standard in a timely manner (well within the normal five year cycle). The CSB has an opportunity to provide any technical feedback as part of the current updates for the next revision cycle. While it may have been clearer to use “atmospheric”, the term blowdown drum was specifically defined to refer to atmospheric blowdowns, and since the response has already been sent, no modifications were made. E. Addison (Inspector, NOWCC; Emergency Prevention & Preparedness Section; US EPA Region 9) noted that there is the impression that industry is not removing all blowdown drums, and the language used in the amendment still allows atmospheric blowdown drums. It was noted that the language does not allow blowdown drums where there is a vapor cloud explosion hazard, but that there are other applications where the blowdown drum is not in hazardous service (e.g., steam, heavy oil) where the committee did not want to expressly prohibit the use of blowdown drums for these installations. Many of the operating company representatives indicated that they were removing blowdowns in hazardous service; therefore, it would be good to communicate to regulators that industry is removing blowdown drums in hazardous services. E. Zamejc indicated the committee would be open to discussion on this communication and would confer with API Staff about how to proceed.The question as to whether or not some users may be ‘grandfathering’ was discussed, and it was noted that these guidelines do not specifically allow for grandfathering. f) Review action list i. Action item listThe action item list was reviewed to determine the current status of the action items (AI) and whether or not the action item would be discussed in more detail later. The current status was recorded within the action item list itself, and is not replicated here; however, some items were discussed in more detail.AI-20: The question of whether or not a reference is implicitly endorsed in its entirety was unresolved. D. Saile noted that the important factor is whether or not a specific aspect of that reference is cited in the text. If the citation is for information only, then there is no endorsement or acceptance involved. If specific aspects or portions of the reference are cited, then there is acceptance of only those portions. If an entire reference is cited as something that shall be followed, then the committee should be comfortable with accepting all aspects of that reference. It was noted that we have not been consistently differentiating between the types of references; however, a few examples extracted ad hoc were of the type that cited specific portions of the reference. T. Bevilacqua took the action item to review the citations in the standard to determine the type of citation, and to produce a list of all of those that appear to fall within the ‘entire citation’ category for further review by the committee.AI-29: Now that M. Ewanishan is no longer involved with the committee, this action item has no assignee. The action item is suspended due to lack of volunteers to carry it forward. It was noted that there has not been a general consensus reached as to how to consider liquid carryover due to factors such as entrainment from the top tray of a distillation tower.AI-32: This action item was closed as the basis for the item could not be recalled.AI-33: It was noted that the committee cannot establish acceptable risk criteria as that is the purview of governments or user companies. This action item was closed.AI-35: M. Porter volunteered to talk to R. Goodman and ensure consistencies with the updates to API 14C.AI-38: B. Friedman to provide actual examples of the case where closure of a valve would allow pressure to increase beyond normal pressure with subsequent inadvertent opening of the valve resulting in a large relief requirement.AI-52: F. Self volunteered to draft some proposed language about destruction efficiency. B. Friedman indicated that the EPA, in conjunction with a couple of other groups at different times, looked at combustion efficiency and published a couple of reports on these results in the mid-80s that could be cited. It was noted that J. Pole [sic] was the technical lead for the tests and the reports. ii. Review list of work Items for 2nd edition of ISO 23251The work item list for the 2nd Edition of ISO 23251 was reviewed to determine current status. The numbering below is retained from the work item list in the attachments: 1. Claus plant relief protection (C. Brooke) – Update Spring 2009. 2. Bypass valve inadvertent opening (B. Otis) – Update Spring 2009. 3. Fire exposure of external heat or cooling jackets (C. Eskridge) – Update Fall 2009. 4. Flare purge reduction seal configuration (B. Schwartz, J. Straitz) – Draft completed and sent to the API 537 committee for review. 5. Plate and frame heat exchanger internal failure (E. Zamejc) – Draft completed 6. Relief discharge near heliports (E. Zamejc) – Update Spring 2009. 7. Relief on inter-stage reciprocating compressors (B. Otis) – Draft completed 8. Distance piece pressure relief on reciprocating compressors (B. Otis) – Draft completed 9. Expand to cover offshore platforms on flare header, KO drum, instrumentation credits (M. Porter) – Update Spring 2009. 10. Cracking of heavy oil in fire scenario (F. Self) – Update Spring 2009. A request for any information on thermal cracking was made to the group by F. Self. 11. Coke drum vapor decay rate (F. Self, M. Ali) – M. Ali reported that the data has been deemed proprietary and could not be shared; therefore, this work list item has been closed. 12. LNG regasification, base load plants relief scenarios (H. Attal) – Draft completed 13. Practical guidance to calculate back flow through check valves (R. McMican) – Draft completed, to be revised 14. Guidance on liquid seal drum design (R. McMican) – Draft completed 15. Pressure protection of offshore platform inlet configuration (H. Løvåsen) – Draft completed 16. Blocked discharge on centrifugal pumps, other pumps (M. Ali) – Draft completed 17. Internals in flare knockout drums (T. Bevilacqua) – Draft completed 18. Guidance on acoustic and/or turbulence induced vibration effects on flare, blowdown and relief header piping (E. Zamejc) – Update Spring 2009. 19. Review 5.19.3 (D. DeMichael, T. Bevilacqua) – Update Spring 2009. 20. Dense phase expansion (F. Self, C. Brooke) – Draft completed 21. US CSB Recommendations to ISO Std 23251 (E. Zamejc) – Completed with amendment 22. Tube failure relief requirement reference (H. Rubens) – Draft completed 23. Calculation of relief rate due to external heat input for no phase change (H. Rubens) – Draft completed g) Prioritize work items for 2nd edition of ISO 23251E. Zamejc to determine the prioritization for discussion on action items and work items. h) Work on action items and work itemsE. Zamejc indicated that there was significant reorganization of the document during the meeting at The Hague that should be reviewed by all members. In addition, a proposal was made to consider merging the sections 4 and 5, noting that both sections discuss the potential causes of overpressure from two aspects – first the determination of the applicability of the cause of overpressure, then the determination of the relieving requirements. In addition, Jude Golla’s new clause on overpressure upsets during maintenance activities will be included (see Action Item 34). The following people were interested in attending a two-day session in the first quarter of 2009 to work on this merging: E. Zamejc, J. Golla, B. McMican, T. Bevilacqua, A. Aldeeb, P. Saunders, J. Kolenc, H. Attal, B. Weber, R. Thomas, and L. McDaniel. E. Zamejc to propose location/time in Houston area.Action Item 4 (Relief system design documentation reworking of §4.4 – P. Henry): P. Henry provided a strawman for the reworking of the relief system design documentation. An introduction to the section was added to provide additional guidance on the benefits of good design documentation. The proposal to have a small task force to review the document electronically and send the comments back to P. Henry for consolidation and consideration was accepted. The following people volunteered: E. Zamejc, R. Thomas, P. Saunders, Z. Kumana, A. Aldeeb, T. Bevilacqua, J. Golla, M. Porter, D. Eure, H. Løvåsen, C. Brooke, T. Baker, B. Weber, L. McDaniel, J. Barnett, F. Saint-Martin. E. Zamejc to send the proposal to the team electronically. Feedback is expected back to P. Henry by January 31, 2009. P. Henry to consolidate for Spring 2009 meeting.B. Schwartz noted that API STD 537 has some design documentation forms for the mechanical and process design aspects of a flare analogous to the relief device specification sheets that could be cited. E. Zamejc noted that there needs to be clear guidance that if a specific line item in the documentation requirements was not applicable, then it was not required as part of the design documentation. It was also noted that the scenario checklist proposed shall be consistent with the scenario list already in ISO 23251. B. Schwartz to provide.Action Item 42 (proposal on specific guidance for toxic releases for §6.3.3.1 – D. Eure): D. Eure provided a proposed strawman for the language dealing with this guidance. As an introduction to the proposed language, D. Eure provided a summary of why the changes were needed and what was being proposed. The following insertion was provided as a highlight of this summary:Background - Why new language is needed for API-521 In December 2007 API, ACC, NPRA (Nat Petrochem & Refiners Assoc) and the CCPS agreed on a set of reportable process safety lagging indicators.  This was a major accomplishment due in large part to the fact that API, NPRA and ACC committed to aligning their metrics programs.  All the organizations agreed to an "exclusion" advocated by API that releases through a pressure relief device that was properly designed, and operated per that design, would not be counted as reportable process safety incidents. o CCPS Report: Properly designed = Designed per API Standard 521 or equivalent. o This is stated explicitly in the new "API Guide to Measure Process Safety Incidents" and the CCPS document. o API's argument was that if a PSV and vent piping were designed per API 521, it should not present a hazard to the people in the plant or community. o Acceptance of this exclusion was a major concession to API.  API Standard 521 provides clear criteria for PSV discharges of flammable materials to atmosphere, but it leaves it up to a company's discretion to set what toxic conc's are acceptable.  The concern shared by ACC and CCPS is that unless the standard provides some type of guidance on design of atmospheric discharges of toxic materials similar to what is provided for flammable releases, it will be very hard to defend that PSV discharges of toxic materials did not present a safety hazard and such releases should be reported as Process Safety Incidents (PSI).  ACC and CCPS might reconsider the PSV exclusion in their definitions if new language in 521 is not going to be considered any time soon.  New language in 521 is an important issue affecting the alignment of the various associations' process safety indicators.Proposed Revision to Toxic Vapors  Require evaluation for toxicity risks.  Provides specific guidance for evaluating toxicity risks.  Why ER-3 values - focus effort on higher risk cases  Allow multiple of ER-3 for inside-the-plant screening o ER values are generally based on long duration (1 hr) exposures. o Exposure to relief discharges are typically short-term exposures o Priority for higher consequence events, higher severity for personnel. o Plant personnel are trained & are generally capable of quickly escaping. o Must be consistent with your corporate risk criteria. o Exception is necessary for "knock-down" chemicals w/ poor warning properties.  Recommend the use of an "exclusion zone" based on easily-escapable criteriaDuring discussion of the topic, it was noted that the use of “ER” was specifically intended to be generic; however, there was an impression that ER was related to ERPG. As a result, there was a proposal to change the terminology. This lead to a similar discussion as last time regarding the different types of values that could be used and what the appropriate threshold should be, noting that we need to be careful about specifying thresholds with one type of basis (e.g. not all hazards can be related to fatalities since some are based on long-term disability or other effects). The proposal to have a subtask group review the proposed strawman and provide comments was accepted. The following people volunteered: E. Zamejc, R. Thomas, R. McMican, P. Henry, M. Porter, M. Ali, H. Attal, B. Otis. D. Eure to collect the comments electronically and set up a teleconference to discuss the feedback. E. Zamejc to copy the information to the dropbox.Action Item 41 (Definition of manually actuated valve – D. Eure): D. Eure provided a proposal for the definition of a manually actuated valve. Some wordsmithing produced a definition that was added to the document.Action Item 43 (mechanical design stresses due to temperature variations during depressuring – D. Eure): D. Eure proposed language to consider integrating into §6.2.2 and will have an update for Spring 2009.Action Item 5a (ExxonMobil data regarding 25ft limit for pool fire – R. McMican): R. McMican indicated that prior to 1973, the practices had 25 ft except for spheres. After 1973, the practices also included downward facing surfaces above 25 ft in the potential fire exposure. No changes were proposed for ISO 23251, and the discussion for external pool fire height was deferred to Spring 2009 with other planned discussions on fire modeling.Action Item 12 (review depressuring philosophy – R. McMican): R. McMican indicated that the section was reviewed and that the bulleted items covered the main concerns, specifically that the effects of depressuring on the internals within the equipment being depressured be considered. If the group determined that additional guidance may be useful, some additional language was provided. A question was posed as to whether the intent was to specify criteria for evaluation, or to manage the overall risks associated with depressured equipment (some of those risks being the effect that the depressuring has on the internals), and the answer was that the intent was to manage the overall risks. The proposed language was accepted, but there was some discussion about the location for insertion and whether the two bulleted lists in §5.18.1 should be considered to be merged. R. McMican to review the section to see if the lists could be merged.Action Item 34 (Potential causes of overpressure during maintenance, startup, and shutdown – J. Golla): J. Golla provided an outline of a proposal to discuss potential causes of overpressure during maintenance procedures. There was a general consensus to include this information in the document. The work to include this was added to the scope of work for the group dealing with the merging of sections 4 and 5 during a two- day session in the first quarter of 2009.Action Item 24 (design pressure for KO with sonic flare – B. Schwartz, J. Iqbal): B. Schwartz provided some proposed language to deal with the design pressure of the knockout drum and a caution about using seal drums. It was noted that the issue centers on the current language that says knockout drums be designed for 50 psig, which was intended to ensure the knockout drum does not rupture in the event of a flashback at pressures close to atmospheric; however, the pressure at the sonic tip is greater than 50 psig. In addition, the effects on the pressure in the knockout drum should account for the hydraulics of the fluid flow from the knockout drum to the flare tip. There was some discussion about whether the design pressure for knockout drums in sonic flare systems should be designed to handle the flashback pressure, and the consensus was that there should still be a lower bound on the design pressure at 50 psig to deal with the flashback when the flare was at near atmospheric pressure (i.e. do not consider flashback when at elevated pressures during a relieving event). There was general agreement that it is very difficult to get flashback with the tip operating at sonic velocities; therefore, the potential for flashback in these cases is low. The resulting discussion centered on whether or not to add the information that the potential for flashback was low, and it was noted that the reason for the low potential was not necessarily that the flashback velocity was less than sonic velocity and that without the data the document should not indicate this. Finally, there was a question about separating guidance between onshore and offshore, and there was general agreement that the guidance was applicable regardless of the location. E. Zamejc to include the lower bound 50 psig design pressure in the proposed language.Action Item 47 (combustibility of fluid being flared – J. Iqbal, B. Schwartz): B. Schwartz provided a reference dealing with the combustibility of the fluid being flared and will send to E. Zamejc for distribution. B. Schwartz to propose language to be included and check the references for Spring 2009.Action Item 48 (factors affecting radiated fraction – B. Schwartz): B. Schwartz provided a paper [Schwartz, RE, White, JW, Predict Radiation from Flares, Chemical Engineering Progress, 7, 93 (July, 1997), pp 43-49.] that discussed this, and was already referenced in ISO 23251, although the reference was not under the fraction radiated. B. Schwartz to propose modification to §6.7.2.3.3. to include these elements.Action Item 45 (vent systems – J. Straitz): J. Straitz proposed some general language regarding vent systems to be added in §6.8.8. Some wordsmithing was conducted on the proposed language.Action Item 50 (information requirements from user – J. Straitz): J. Straitz proposed some language to add to §6.7.1. The key addition was to include the topographical information and proximity of other equipment to the disposal system.Action Item 51 (factors that affect noise – J. Straitz): J. Straitz proposed some language to discuss factors that affect noise, including the effects of injecting too much steam. It was noted that there are progressive problems with adding too much steam - noise, flare instability (on/off), then flame out. There was some wordsmithing on the proposed language.Work Item 17 (internals in flare knockout drums – T. Bevilacqua): T. Bevilacqua proposed some language for §6.7.10.2 to deal with the potential for knockout drums that have internals to block the outlet and to encourage the use of a positive means of bypassing the normal outlet if needed. There was some discussion about the utility of the outlet deflection plate, and there was some indication that the benefits may be low given the risks. There was some discussion about if the deflection plate was designed and maintained correctly whether or not a bypass was required. The proposal to take up the modified language at the next meeting was accepted (T. Bevilacqua).VI. New Business i) OtherNo new business was discussed as this line item on the agenda was not reached.VII. AdjournMeeting on Monday November 10, 2008 was adjourned at approximately 6:00 pm.

Task Force on Iso-23251/Std 521

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