Meeting Minutes

TASK FORCE ON ISO-23251/STD–521

COMMITTEE ON PRESSURE RELIEVING SYSTEMS

8:30 A.M. – 4:30 P.M.Grand Hyatt Denver

Monday, April 27, 2009Denver, CO

Brad Otis Convenor ISO 23251;

E. Zamejc Chairman Project Leader ISO 23251, API STD 521

  1. Introductions and registration of attendance (All)

Copies of meeting agenda were distributed. Registration and check of register performed.

  1. Appointment of secretary to keep meeting minutes (All)

A. Shackelford was appointed secretary.

III. Approval of Fall 2008 ISO-23251/API 521 Los Angeles Minutes (All)

The meeting minutes for the last meeting were reviewed. The following changes were proposed and accepted:

  • Name corrections
  • AI-32: delete redundant “could be closed as the specific items”
  • AI-42: Clarify discharge location in fourth major bullet point “API Standard 521 provides clear criteria for PSV discharges of flammable materials to atmosphere…”
  1. Review of inquiries / correspondence on API 521/ISO 23251

a) Technical inquiry 521-A1-2009-1 ballot results

The response to the technical inquiry was balloted as agreed upon during the last meeting. The ballot process approved the technical inquiry response; however, there was one negative vote. In response to the comment associated with the negative vote, there is a new form for Technical Inquiries that is being used that indicates the proper format and such, and the TI was discussed during the fall 2008 meeting [Section V.a) of the Fall 2008 minutes]. There was also an additional comment regarding a reference to the applicable paragraph, and it was decided that the reference was not needed.

b) Old inquiries

  1. TI-521-I-06/07 [521-2007-06]

The response drafted by M. Porter and reviewed by R. McMican and E. Zamejc was discussed. There was a concern that using the hydrotest implies the use of ASME, while one should ensure compliance with the appropriate pressure vessel code. It was noted that §5.16.2 indicates that the user may choose other pressures, and that §4.2.2 indicates some pressure vessel design codes do not address hydrotest.

The question was posed whether the user is required to evaluate transient conditions if the high pressure side (HPS) pressure does not exceed the corrected hydrotest of the low pressure side (LPS). The answer was “No” because the maximum pressure developed in the LPS, ignoring the hydraulic surge, could not exceed the HPS pressure. There was general agreement that the maximum pressure developed solely by the acceleration of the fluid could not exceed the HPS pressure; however, the question was posed as to why the hydraulic surge can be excluded. The response was that the hydraulic surge is so fast that the localized response of the metal experiencing the surge pressure wave does not result in the loss of containment. It was noted that on-site experience validates this.

M. Porter agreed to determine if his program evaluates the effects of hydraulic surge. If so, then C. Brooke, H. Løvåsen, and R. McMican to determine if they have any systems that meet the criteria questioned (HPS pressure less than LPS corrected hydrotest, yet pressure differential between HPS and LPS is greater than 1000 psi) and provide to M. Porter for evaluation. Detailed information regarding the heat exchanger design and configuration of the LPS system is needed for the evaluation.

  1. 521-AI-2008-1

The technical inquiry and the discussion from the previous meeting minutes were reviewed. The general consensus was that the inquiry was a consulting request and could not be answered. E. Zamejc to close the inquiry on this basis. M. Porter still has the action item to propose clarification to §5.20.2.2.

c) New inquiry

  1. [TI number not yet assigned]

A new technical inquiry (not yet numbered) having three parts dealing with §5.15.5 was received. Question 1 asks whether credit can be taken for insulation to reduce the heat input from fire if the user can demonstrate that the fire-grade insulation is intact regardless of the state of the sheathing and banding. It was noted that the general experience has been that if the sheathing and banding are compromised, then the application of water from the fire monitor will generally knock off the insulation (e.g., due to erosive action or thermal shock); however, there could be some installations where the insulation integrity will remain after the sheathing/banding is degraded. There was general consensus that credit could be taken if one could demonstrate the insulation, in the absence of the sheathing and banding, would retain its integrity and not be dislodged when it is subjected to the high-pressure water streams used for fire fighting. It was noted that credit for the water spray could not be taken when sizing relief devices on pressure vessels. There was also agreement that the wording in §5.15.5.2 is confusing as it states the jacketing and coatings can burn off or disintegrate, and E. Zamejc took the action item to update the wording to clarify the intent. Answer to Question 1 is “Yes” and will be balloted.

Question 2 deals with the application of equation 13 for multiple layers of insulation having different materials. The intent is that equation 13 is applicable to any number of layers of the same material. It may be possible to come up with an equivalent thermal conductivity for use in the equation for multiple layers of different materials.

Question 3 deals with the information presented in Table 7 and the implication that if the insulation is not rated for a maximum temperature greater than 904°C (1660 °F) then it needs to be used in conjunction with other insulation that is rated for that temperature. There was general consensus that the insulation manufacturer may have data to show that specific installations are capable of meeting the requirements for appropriate fire-grade insulation regardless of the results of the ASTM tests that are presented in the table. It was noted that the intent of the information in the table is not clear to the user. A. Aldeeb agreed to review the basis for the information in the table and to propose language to clarify the intent, ensuring that the recommendation was made to consult with insulation manufacturer. E. Zamejc noted that he sent API the ASTM references used as the basis material for Table 7. A. Aldeeb agreed to survey operating companies to find out if the maximum temperatures are used as a limitation or if the insulation vendors are consulted. Some representatives present indicated that they use the insulation manufacturer’s information, while some representatives indicated that they were not responsible for the actual selection of the insulation.

  1. 521-2009-4

A new technical inquiry was received regarding the definition of the corrected hydrotest pressure with respect to the corrosion allowance. The referenced paragraph should be §5.19.2. It was noted that the definition of hydrotest pressure in ASME NMA M deals with the corroded state, and that the definitions in API 521 has a note (Note 2) that refers the user to the design code to obtain an appropriate definition. The general consensus was to answer the inquiry with ‘No’; however, P. Henry and R. Danzy agreed to create a proposal to change the definition of the hydrotest pressure to specifically mention the corroded state (noting that the inquirer provided a proposed modification).

d) New errors/inconsistencies/suggestions for improvement

  1. Inconsistency in the fire environment factor

C. Brooke identified a report from UK Health and Safety Laboratory (RR-682 “Development of fire protection measures for vessels containing reactive chemicals”) that identified situations where the environment factor accounting for fire-grade insulation could be calculated to be greater than 1. A proposal was accepted to limit the calculated value to no greater than 1.0 was accepted.

  1. Inconsistency in fire vapor expansion equations

J. Salunkhe (email) indicates there are potential issues with the use of the compressibility factor (Z) of 1 used to derive the equations. A. Shackelford agreed to propose a response.

  1. Inconsistency in fire vapor expansion with F’ < 0.01

D. Cobb noted that the minimum value constraint on F’ of 0.01 leads to inconsistent results for the required relief area. D. Cobb agreed to propose an update to make the equations consistent by adding caveats on the use of the minimum value for F’.

  1. Improving depressuring

The proposal was made to ensure that the information provided by K. Vishwanath be considered as part of the update to the fire relief and depressuring guidance that is being addressed this summer. Specifically, the update is to resolve the issues with the draft proposed in light of the various considerations already raised (e.g. presentations by B. Otis, H. Løvåsen, et.al. on the subject).

  1. Improving flare steam to hydrocarbon ratio

There were a couple of questions and suggestions generated independently regarding the information about the steam-to-hydrocarbon ratio for flaring provided. The current language implies a precise calculation for the amount of steam needed to promote smokeless burning; however, the intent was to provide an estimate. C. Brooke’s proposed modifications were reviewed and accepted. E. Zamejc to provide the CMA work referenced by P. Eichamer in order for group to review proposed modifications.

e) ISO 25457 / API Std 537 [Co-branded] Published

E. Zamejc announced that ISO 25457 has been published and was adopted back as API Std. 537 in its entirety (i.e., identical standard).

  1. Old Business

a) Review action list

  1. Action item list

The 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-5d: It was noted that the intent was to compare the flame height calculations to see if there was justification for the 25’ limit; however, there was already general consensus that the height of the flame is approximately the diameter of the pool. A note has already been added that the 25’ limit is not necessarily representative of the maximum flame height, just a limit of the effect of the radiation from the flame to the vessel. C. Brooke’s proposal to close the action item as not needed and no further work to be done was accepted.

AI-8: E. Zamejc to contact G. Kiese for update.

AI-10: D. Saile agreed to write a proposal to 764-7 to consider referencing 23251. He noted that 764-7 was reaffirmed and was not a work item.

AI-35: M. Porter indicated his solicitations to 14-C received no response. J. Sawchuk agreed to follow-up.

  1. Review list of work Items for 2nd edition of ISO 23251

The work item list for the 2nd Edition of ISO 23251 was reviewed to determine current status. The current status was recorded within the work item list itself, and is not replicated here; however, one item was discussed in more detail.

WI-1: C. Brooke indicated that a proposal was made to the chair of the subcommittee for heat exchangers and that he should know whether that was successful at the end of this API meeting.

WI-13: R. McMican indicated he would resubmit the draft with slightly modified language.

WI-18: E. Zamejc indicated this item was reassigned to J. Baker, who provided proposed language, which was included in the handouts for the task force meeting.

b) Prioritize work items for 2nd edition of ISO 23251

E. Zamejc to determine the prioritization for discussion on action items and work items.

c) Work on action items and work items

Action Item 3 (Corrected hydrotest pressure example – C. Brooke): Example was moved to §4.2.2. C. Brooke to review current draft versus proposed text to determine if any further update is needed.

Action Item 4 (Relief system design documentation reworking of §4.4 – P. Henry): P. Henry provided the draft for the reworking of the relief system design documentation based on the review of the strawman performed by the volunteers identified during the Fall 2008 meeting (E. Zamejc, R. Thomas, P. Saunders, Z. Kumana, A. Abdeeb, T. Bevilacqua, J. Golla, M. Porter, D. Eure, H. Løvåsen, C. Brooke, T. Baker, B. Weber, L. McDaniel, J. Barnett, F. Saint-Martin). He noted that the team had not been able to review the compiled document and that there were some conflicting responses, some of which did not make it into the proposal. The proposal was then reviewed to identify the controversial items.

The suggestion was made that the documentation guidelines be placed in 520 or in an appendix. There was a general agreement that it should be in 521, but may be put into an appendix.

There was significant discussion regarding how §4.4.3 implied that following the design guidelines constituted compliance with regulations the committee may not know about, and that the language regarding compliance should not be present. C. Krause took the action item to propose a rewording of the section that highlighted the benefits of having the detailed documentation without the specific reference to compliance with regulations.

§4.4.4 indicated that the documentation was the minimum requirement, yet this was in conflict with the intent that these be general guidelines that do not fit every situation and may need to be adjusted for a particular situation. A comment was made that the “minimum requirement” statement was interpreted as a ‘shall’. The headings were modified to reflect the intent. Z. Kumana recommended the introduction to the lists be consistent, and agreed to propose language to P. Henry.

§4.4.4.2 was questioned as to why the philosophy documentation was needed, and the response was that there are multiple places within the standard that are purposefully left to the user to decide how to proceed without indicating minimum requirements, and this section was intended to ensure those decisions were recognized and documented. Some additions to the section were proposed for review, and the section was wordsmithed.

§4.4.4.3 was noted to be related to the work process, and it was noted that many of the items that are listed are required as part of the input for analysis and are generally maintained separately. It was agreed that some reference should be made to that documentation, but not necessarily be required to be included in an individual file. Plot plans were proposed to be added to the list.

Review of §4.4.4.5 raised the question about where the depressuring information should go. L. McDaniel took the action item to propose a new section dealing with depressuring information.

Issues regarding the specification sheet requirement was identified in §4.4.4.7 because the specification sheet is primarily a procurement document, and there may not be a need to have the specification sheet until one desires to procure a relief device. An example of the pressure relief devices on vendor skid units was cited. D. Eure had provided some proposed language that P. Henry will incorporate in the current proposal for the group’s review.

It was reiterated that the scenario checklist proposed shall be consistent with the scenario list already in ISO 23251 and should be in the same order.

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; however, P. Henry indicated that was not in the scope of §4.4.

E. Zamejc agreed to forward the wordsmithed copy of the proposed text to P. Henry. P. Henry will compile the proposed text from C. Kraus, the previous recommendations of D. Eure, and send to the same volunteers to review again – E. Zamejc, R. Thomas, P. Saunders, Z. Kumana, A. Abdeeb, T. Bevilacqua, J. Golla, M. Porter, D. Eure, H. Løvåsen, C. Brooke, T. Baker, B. Weber, L. McDaniel, J. Barnett, F. Saint-Martin.

Action Item 5a (ExxonMobil data regarding 25’ limit for pool fire – R. McMican) – Provided for informational purposes only, no suggestions are made to modify the document.

Action Item 11 (Depressuring activation information – H. Løvåsen): H. Løvåsen provided draft language in fulfillment of the action item. The draft language was accepted to be added to the document.

Action Item 12 (review depressuring philosophy – R. McMican): R. McMican to review the section to see if the lists could be merged.

Action Item 15 (cooldown during depressuring – H. Løvåsen): H. Løvåsen provided draft language which was reviewed and wordsmithed. A question arose about the gas leaks in the flare system, and it was noted that the intent was that if the depressuring system was activated by gas leaks and that gas leak originated in the flare system, then activating the depressuring system should be avoided because it could exacerbate the problem; therefore, the proposal is to have a reset or bypass. A disadvantage of having the reset would be the potential to override the emergency response that may affect the integrity of the depressuring system. There was general agreement that the gas leak from the flare may be too special of a case to be included as a specific example. The list of items that may activate depressuring was expanded. Z. Kumana took the action item to propose a modification to the text that would clarify the depressuring time considered in the third paragraph. The proposed text would be incorporated into the draft.