AGENDA

TASK FORCE ON ISO-23251/STD–521

COMMITTEE ON PRESSURE RELIEVING SYSTEMS

8:00 A.M. – 5:30 P.M. Sheraton SeattleMonday, May 16, 2011 Seattle, WA

Brad Otis Convenor ISO 23251;

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

I. Introductions and registration of attendance (All)

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

III. Approval Fall ISO-23251/API 521 Nashville Meeting Minutes (Pages 2-6)

IV. Review of inquiries / correspondence on API 521/ISO 23251a) Old inquiries out for ballot (5)

i. Sent to API (Stephen Crimaudo) (Page 7)ii. Status of interpretations website? (Pages 7-8)iii. How does API document/handle responses to inquiries that are not

balloted (e.g., consulting, check vendor)?b) TI: Flare gas heat value inquiry (Pages 9-10)c) TI: Hot Oil /water two phase / DIERs (Pages 11-12)d) TI: Exceed design temperature of LP side during tube break (Page 13-14)e) TI: Flare F factor (Page 15)f) TI: Solar radiation – include /exclude (Page 16)g) TI: Noise levels on letdown valve and distant vent stack (Page 17)h) TI: Insulation temperature limits (Pages 18-19)

V. Old Businessa) Ballot resultsb) Path forward on addressing commentsc) Summer meeting to address comments?

VI. New Businessa) US Chemical Safety Board (CSB) Discussionsb) Update on Waste Heat Boiler Task Groupc) Update / Status of API 14C (ISO 10418)d) Work list for Next Edition (Page 20)e) Other

VII. Adjourn

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Meeting Minutes (Rev. 0)TASK FORCE ON ISO-23251/STD-521

COMMITTEE ON PRESSURE RELIEVING SYSTEMS

8:00-5:30 p.m. Nashville Sheraton Music City HotelTuesday, November 16, 2010 Nashville, Tennessee

Brad Otis Convenor ISO 23251Mike Porter, Chairman API STD 521E. Zamejc Project Leader ISO 23251

I. Introductions and registration of attendance (All).

The meeting started at 8:05. Ed Zamejc, Std-521 Master Editor, led the meeting standing in for Mike Porter, Task Force Chairman. Those present introduced themselves around the room. The yellow registration sheet was signed, and the distribution list was updated by those present. The number of attendees was 55.

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

Sorin Lupascu volunteered to keep the minutes.

III. Review of meeting minutes

It was noted that members who do not have access to the online SharePoint site should contact Steve Crimaudo (crimaudos@api.org). It was noted that the SharePoint site contains a large number of files making it difficult for members to identify and access relevant files prior to the meeting. Reorganization of the SharePoint content was suggested (e.g., move old documents to a specific folder, group documents in ZIP files, modify file names to include “open” or “completed” designations).

a) Spring 2010 ISO 23251/API 521 New Orleans Meeting

Acronyms incorporated into minutes: RAGAGEP = Recognized and Generally Accepted Good Engineering Practices; BAM = German Federal Institute for Materials Research and Testing. Minutes approved.

b) July 2010 ISO- 23251/API 521 Aberdeen Meeting

Acronym incorporated into minutes: BRL = Ballistics Research Lab. Minutes approved.

c) July 2010 ISO- 23251/API 521 Houston Meeting

It was noted that the presentations by Freeman Self on thermal cracking during a fire and dense phase relief in a fire were uploaded to the SharePoint site as were the attendance lists. Minutes approved.

IV. Review of inquiries / correspondence on API 521/ISO 23251

Ed Zamejc noted that Mike Porter addresses inquiries on the STD-521 document. Mike Porter has submitted to API several inquiry responses for balloting that were previously reviewed by the committee. They require a minimum number of votes to pass and Mr. Zamejc asked attending members to vote. The topics of these old technical inquiries are:

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a) Insulation credits in a fire (reballot)b) Concentration term in purge requirement equationsc) Air requirements (relative to steam) to prevent smoke formation while flaringd) Fire relief of fractionating columnse) Fire zone sizesf) Tube rupture where the pressure differential exceeds 69 bar (1000 psi) but the low

pressure side hydrotest pressure is not exceeded

There were no new inquiries.

Ed Zamejc received question from ISO on how API is handling documentation of inquiries. It was noted that this question was taken to API staff but a response had not yet been received. A point of interest to the attendees was the manner in which the inquiry answers are made available to the public.

Brad Otis asked about the status of a technical inquiry on insulation credits for fire in the absence of stainless steel sheeting. Ed Zamejc noted that the inquiry had three parts with only the first part balloted. The other two parts were addressed as action items as part of the document update. The ballot had passed but with a comment that required reballot. It is one of several inquiries that will be balloted. It was noted that the modified equations for multilayer insulation heat transfer coefficients to be incorporated into the document had not yet been received. These equations were to be prepared by Abdul Aldeeb. Because of timing constraints they may not be included in the document.

V. Old Business

a) Review Action Item List

Ed Zamejc noted that incomplete items were withdrawn but they can be reopened in the next version – they are not carried over automatically. The committee proceeded to review items in the action item list:

# 1-56: Items are completed.

# 57: Withdrawn - revised drawing (drawing D1) was not received.

# 66: Withdrawn - proposed change to definition of hydrotest to specifically mention the corroded state pressure not yet available.

# 92: E Zamejc revised and incorporated relief rate calculation using the wetted wall temperatures instead of the unwetted wall temperatures.

It was asked if the document changes are made using an auditable trail that identifies records associated with comments and with changes to paragraphs and section numbers. E. Zamejc noted that the current draft document shows changes made on the previous edition. The earlier drafts would need to be used to track the changes made with time. However, the minutes would not be of the level of detail to capture all of the discussion on each item.

It was suggested to reference text in action items noting the dated version of the standard for easy identification. E. Zamejc noted that the original action item text is almost always modified to some extent during the committee review meetings. It is necessary to attend these meetings to understand who proposed modified words and the background discussion as to why the change was made. It is not practical to record or include in the minutes all of this background.

E. Zamejc noted that the ISO process of reviewing a draft international standard (DIS) involves collecting comments and noting the country and clause number in the published DIS. Note that the API process involves noting the person rather than the country that commented. It was noted that if sections are

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rearranged keeping track of the section where the action items and work list items were included can become difficult and that there is a need to cite version and edition.

b) Work Item List / Carryover List

The committee proceeded to review items in the work item list:

Withdrawn: #2, #11, #13, #19.

Completed: #4, #5, #7, #8, #9, #10, #14, #15, #16, #20, #21, #22, #23.

#1) Claus Plant Relief Protection reassigned to Mike Porter who initiated a task group assigned to complete this item. It is deferred until the next edition.

#3) Withdrawn due to work/time constraints – topic is fire exposure external heat and cooling jackets. It was noted that it is a topic that warrants inclusion in API 521 and should be included in the next edition's work list.

#6) Withdrawn – no feedback received.

Carryover items from the ISO 23251 first edition are all completed.

c) Work on Action Items and Work Items

E. Zamejc noted again that document drafts will not be sent via email but will be available on the API PRS Committee SharePoint Site. The remainder of the meeting was spent on resolving any major issues in the current draft's clauses or wording that could prompt a negative vote. E. Zamejc noted that the entire document will be open to comment when it is issued as an ISO DIS (Draft International Standard).

Over-steaming flares

The first discussion topic was the steam requirements for flares. There was background discussion on EPA's concern that excess of steam in flares can lead to incomplete combustion of hydrocarbons. It was noted that API 521 steam ratio guidance (e.g., 0.25 to 1 lb steam/lb hydrocarbon) is intended for smoking prevention but does not address combustion efficiency. The maximum steam ratio for efficient destruction is an open question.

E. Zamejc noted that the document is ready to be issued as a DIS. Because this issue is complex and still under discussion, it was noted that the committee needs to focus on developing a near-term solution to the document wording recognizing that some aspects may need to be deferred until the next edition.

K. Leary and S. Reed pointed out that it is difficult to meet targets for smokeless flaring at low turndown and to avoid over-steaming, and that a lower steam ratio at turndown conditions involves a need for more purge gas and more maintenance. It was noted that flare operation at turndown surfaces is a key issue in this context and that a document change addressing this topic would not provide a steam ratio table for efficient combustion but a statement drawing attention to the need for additional design considerations.

P. Eichamer made a presentation on over-steaming and flare efficiency and the following points were discussed:

a) EPA has focused on flare efficiency during the last 2 years

b) US Federal Regulations cover pilots, smokeless flaring and BTU/MMSCF lower limits but does not cover flare combustion efficiency

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c) Flare efficiency concerns are focused on turndown operation where the flows are well below the design capacity

d) EPA enforcement divisions asked certain plants to do remote sensing and add instrumentation to measure flow & composition

e) EPA is citing Table 11 in API 521 (5th Edition) on steam/hydrocarbon ration, using a 3.5x factor

f) B. Dickens (from EPA) set an upper limit for efficiency, based on testing that did not take place at subsonic velocity at steam ports and that did not make distinctions between turndown and large flow rate.

g) P. Eichamer noted that the source of calculated efficiency values is very important and that efficiency values vary based on the flared gas and flare design; meeting participants commented that efficiency does not fall down gradually, but drops quickly as conditions change.

h) It is unclear how EPA applies Table 11 for citations and there is also uncertainty on the source of Table 11 (included in the 1st version of the standard). It was noted that the table contains same hydrocarbons and similar numbers as published in Hydrocarbon Processing based on results from the 1980s.

After the presentation there was discussion in the meeting around the 3.5x multiplier. S. Reed pointed out that using this factor acts as a means of establishing a boundary for efficient combustion while acknowledging that at low turndown the need for steam increases. He also noted that TCEQ (Texas Commission on Environmental Quality) is now looking at educating operators to prevent over-steaming from procedures aimed at keeping the flame invisible during the day.

It was also noted that D. McGregor and a group from an API environmental committee are working this issue and that they have asked C. Shepard to bring it to the API 521 committee. There was discussion in the meeting about the need to form a group to work this item and on the formation of a technical task force. Coordination of this potential group was assigned to C. Shepard. Regarding the API 521 document, E. Zamejc suggested as path forward to build consensus around the proposed wording B. Otis prepared to provide temporary guidance and wait until the next version to provide more detailed guidance.

B. Otis's proposal involves revision to §6.4.3.2.3 (now §5.3.2.4) on “Steam Injection” to alert users of this issue. The committee discussed potential changes to the document based on this proposal:

a) Comments were made that the Table 11 header should be modified to specifically call out “smokeless flaring” but it was agreed not to implement this

b) The note from Table 11 (on the suggested amount of steam and smokeless burning) was moved to a text paragraph along with the equation adjusting for hydrocarbon content

c) Language was included noting that vendor should be consulted for detailed steam requirements and that multiple factors including pressure, steam velocity and gas velocity can lower the combustion efficiency of the flare

It was noted that there is insufficient information available to provide specific guidance on an upper steam ratio limit for efficient combustion, that Table 11 is not intended to specify maximum steam rates for combustion requirements, that there is a need to focus on separating guidance on smokeless combustion from guidance on combustion efficiency, and that users should be alerted over-steaming can lead to an abrupt loss in combustion efficiency and that the manufacturers need to be consulted on this topic.

On-Demand Ignition

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The current proposed revision would allow some flares to use on-demand (non-continuously lit pilots). R. Schwartz and K. Leary noted that the probability for this type of system failing is significant, that there is a need to monitor the flame continuously or to test the pilot daily. It was commented that flares without continuously lit pilots are operated offshore where low molecular weight gas does not represent an issue based on dispersion analysis. There was discussion whether requirements for pilots belong in ISO-23251. A proposal was made to lift the paragraph in total and send it to ISO-25457 (API STD-537). E. Zamejc will forward the paragraph, with background discussion, to the ISO 25457/API 537 chair.

Liquid Seal Selection

There was discussion around providing a caution on “seal drums that overflow to atmosphere” (§5.7.8.5) which was also modified to read “seal drums that overflow to open sewer”.

Seal and Knockout Drum Design Details

There was discussion around the validity of the statement that with the specified design pressure that the vessel “should not rupture if a deflagration occurs” (§5.9 (h)) and whether detonation should be addressed as well. The guidance was recast in §5.9 (i) indicating the design gauge pressure of 345 kPa (50 psi) is suggested “where appropriate precautions are to ensure that the oxygen concentration is maintained below that required to support combustion”. A reference to §5.5.2 was also added to §5.9 (i) for effects of backpressure on pressure relief device. A question was raised on why §5.9 (j) indicates that liquid seals should be avoided; it was suggested to change language to “liquid seal should be used with caution” and “ensure the downstream system can handle liquid slug impacts”. It was commented that a possible concern is that a sudden impulse of gas on the liquid seal could carry water up to a restricted orifice at the flare tip.

It was noted that §5.9 (h) and (i) address the same topic for subsonic and sonic systems respectively. The two paragraphs were merged as suggested with guidance restated for both sonic and subsonic flare tips. Paragraph (i) was created to mention liquid-seal concern in sonic flare application. A note was added to §5.9 (h) that NFPA 69 (Explosion Prevention Systems) provides guidance on designing vessels for deflagration resistance.

Other Concerns

There was discussion on statement in §4.4.13.2.3.2 that “Where adequate drainage and firefighting equipment do not exist, equation (7) should be used”. Decided that wording should be” adequate drainage or firefighting equipment do not exist”.

Moved first sentence from §5.7.9.8 (knockout drums for offshore installations) to §5.7.9.1 (general paragraph on knockout drums) because the sentence applies beyond offshore: “If a demister pad or other liquid extraction device is used, then a properly designed by-pass around the device shall be installed to ensure an open path to the flare”.

VI. New Business

The path forward for the document was discussed. E. Zamejc indicated that there are a number of editorial and fixes required before the document is sent to ISO. For example, the definitions and equations need to be numbered properly. Once these are completed, the document will be sent to the ISO group responsible for issuing a Draft International Standard (DIS) via AFNOR in France in late December/early January. It is expected the DIS will be issued for voting no earlier than late January / early February. There is a 90 day period from the date of release for comment and voting. The entire document will be open for comments.

The meeting was adjourned at 5:30 pm.

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Inquiries Submitted to API for Ballot

521-I-06/07: Tube break @ high pressure but within hydrotest 521-2009-1: Insulation credit when jacket integrity is compromised 521-2009-New (unnumbered): Flare steam ratio revision 521-A1-2009-2: Fractionating column exposed to fire 521-A1-2008-1: Fire zone size

Location of Interpretations?

http://rfi.api.org/ - allows new interpretation and status if the number is known but no list of interpretations

From: Ed Zamejc [ezrelief@sbcglobal.net]Sent: Monday, July 26, 2010 8:23 AMTo: 'Stephen Crimaudo'Subject: FW: Interpretations ISO 23251/API STD 521Attachments: RE: Interpretation ISO 23251 (12.9 KB)

Stephen: I received the following question where the Technical Interpretation responses are located.  I checked the API website and can find the following link where you can submit an RFI:

http://www.api.org/Standards/reqint.cfm

Where all the answered RFIs kept?

Ed

From: Dominguez Santisbon, Manuel J.R. [mailto:Manuel.Dominguez-Santisbon@lr.org] Sent: Monday, July 26, 2010 3:13 AMTo: ezrelief@sbcglobal.netSubject: Interpretations ISO 23251/API STD 521

Dear Zamejc

I have been referred to you by Miss Jubeau as I have sent to her an e-mail relating to ISO 23251 Interpretations which I’m trying to find; I remember a few time ago I saw API RP 521 Interpretations, however they have been taken off from the API website, I’m wondering if those interpretations still applicable for the ISO 23251 or if new ones have been added and where I could find them.

Thanks in advance for your help.

Kind Regards

MANUEL DOMINGUEZ SANTISBONSr Process & Piping Specialist

Lloyd's Register EMEA60 Lombard StreetLondon UK

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EC3V 9EA Direct Dial: 0207 4231561Fax Number: 0207 4232889 Email: Manuel.Dominguez-Santisbon@lr.org

Dear Mr Santisbon,

You can find some informations about the scope at http://www.iso.org/iso/catalogue_detail.htm?csnumber=41414 but not interpretations.

A revision of this standard is at this time being ongoing for the 2006 version.

To get more informations about interpretations, you should contact the project leader of this standard Mr Zamejc ezrelief@sbcglobal.net .

Should you require more information, do not hesitate to contact me.

Kind regards,

Alice JUBEAUISO/ TC67/ SC6 SecretaryAFNOR Normalisation+33 (0)1 41 62 84 07 ASSISTANTE : Marie BOURBIGOT+33 (0)1 41 62 87 20| marie.bourbigot@afnor.org

De : Dominguez Santisbon, Manuel J.R. [mailto:Manuel.Dominguez-Santisbon@lr.org] Envoyé : lundi 26 juillet 2010 08:49À : jubeau aliceObjet : Interpretation ISO 23251

I’m trying to find any interpretations related to the ISO 23251, is there any web page available to search.

Kind Regards

MANUEL DOMINGUEZ SANTISBONSr Process & Piping SpecialistLloyd's Register EMEA60 Lombard StreetLondon UKEC3V 9EADirect Dial: 0207 4231561Fax Number: 0207 4232889

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Conversion Error

From: Ed Zamejc [mailto:ezrelief@sbcglobal.net] Sent: Thursday, February 17, 2011 3:49 PMTo: Stephen CrimaudoSubject: RE: Correction with API 521 - Section 6.4.3.2.8They appear to be correct:

200 BTU/ft^3 * (3.281 ft/m)^3 * 1055.1 J/BTU * 1 MJ / 1,000,000 J = 7.45 MJ/m^3.

Note that the API publication API MPMS Chapter 15 [“Manual of Petroleum Measurement Standards Chapter 15—Guidelines for the Use of the International System of Units (SI) in the Petroleum and Allied Industries Measurement Coordination FORMERLY API PUBLICATION 2564 THIRD EDITION, DECEMBER 2001”], page 15, the conversion is BTU/ft^3 * 0.3725895 = MJ/m^3 which is probably where the 74.5 came from.  It looks like API MPMS Chapter 15 should be checked too.

At this point, I suggest we include this as a DIS comment.

Ed 

From: Stephen Crimaudo [mailto:crimaudos@api.org] Sent: Tuesday, February 08, 2011 11:56 AMTo: Ed ZamejcSubject: FW: Correction with API 521 - Section 6.4.3.2.8Ed, looks like a potential revision for 521 -

Stephen CrimaudoSenior Associate, StandardsAmerican Petroleum Institute1220 L Street, NW Washington, DC 20005-4070Phone:  202-682-8151Fax:  202-962-4797crimaudos@api.org

From: Arappalli, Chandrasekar [mailto:Chandrasekar.Arappalli@petrofac.com] Sent: Thursday, January 20, 2011 9:27 AMTo: StandardsSubject: Correction with API 521 - Section 6.4.3.2.8

API 521 / ISO 23251 - Pressure-relieving and depressuring systemsFIFTH EDITION, JANUARY 2007(INCLUDES ERRATA JUNE 2007)ADDENDUM, MAY 2008

“Section 6.4.3.2.8 All of the preceding descriptions have been for flare equipment to dispose of exothermic flare gases; that is, gases that have a high enough heating value [usually greater than 74,5 MJ/m3 (200 Btu/Scf) for unassisted flares and 112 MJ/m3 (300 Btu/Scf) for assisted flares] to sustain combustion on their own without any auxiliary fuel additions. Endothermic gases can be disposed of in thermal incineration systems; however, there are situations where the preferred approach is to use a special flare design.”In the above section from API 521, the 74.5 MJ/m3 does not corresponds to 200 BTU/scf & same for 112 MJ/m3 with 300 BTU/scf. It should be 7.45 MJ/m3 & 11.2 MJ/m3.Please correct me if I have misunderstood. For your perusal.

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Regards,

Chandrasekar ArappalliPetrofacEngineering ServicesChester House, 76-86 Chertsey Road,Woking, GU21 5BJ, UKEmail: chandrasekar.arappalli@petrofac.comTel: +44 (0)1483 738561 (direct line)Tel: +44 (0) 1483 738500 (switchboard)Web: www.petrofac.comRegistered office: Petrofac Engineering Ltd., Chester House,76-86 Chertsey Road, Woking, GU21 5BJ, UKRegistered in England No. 2615887

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Oil/Water Foaming in a Fire

From: Ed Zamejc [mailto:ezrelief@sbcglobal.net] Sent: Wednesday, April 06, 2011 10:54 AMTo: Stephen Crimaudo; 'Porter, Mike K'Subject: RE: API RP 521 Water into Hot Oil

Steve:  Thanks for getting the clarification.  The foaming potential of fluids in a fire scenario is already discussed in 5.15.3.4 entitled “Mixed phase”. This directs the user to other resources (e.g., DIERS). The inquirer indicates they are unsure whether the DIERS method would suffice.  I do not know of any alternatives and suggest they take this up with the DIERS committee.  If they are aware of another method, please have them send us a reference for review. Otherwise, I do not believe their scenario has anything  special that should be included in the document.

Ed

-----Original Message-----From: Marc Young [mailto:Marc.Young@oilgassol.com]Sent: Tuesday, April 05, 2011 9:50 PMTo: Stephen CrimaudoCc: Marty RosettaSubject: RE: API RP 521 Water into Hot Oil

Yes they are. 

We have done an extensive investigation including both a study of using the first and second law of thermodynamics,  depressurizatioon using Honeywell Unism (Hysys derivative) Depressurization module and dynamic simulation depressurization to more clearly define the levels of water, crude andf vapor and have satisfied ourselves that any adiabaitc depressurization would react the same as a normal hydrocarbon depressurization.  i.e. not enough energy to vaporize much water.

However, I am still concerned about a fire case with additional heat input. If nucleated boiling occurs, the water vapor would form bubbles up through the hydrocarbon layer and would tend to generate intense foaming.  Relief valves would need to be sized for the two phase relief of the hydrocarbon foam entrained with water vapor.  Not sure the current recommended API 521 method (which only suggests using Diers method) would suffice.  If so the the vessel could overpressure and possibly rupture.       ________________________________________From: Stephen Crimaudo [crimaudos@api.org]Sent: Tuesday, April 05, 2011 12:22 PMTo: Marc YoungSubject: FW: API RP 521 Water into Hot Oil

Hello.  I forwarded your request to the committee members and I have a follow up question:

Can you ask the inquirer if the water and crude oil are already mixed together and at the same temperature?

Stephen CrimaudoSenior Associate, StandardsAmerican Petroleum Institute1220 L Street, NWWashington, DC 20005-4070Phone:  202-682-8151Fax:  202-962-4797crimaudos@api.org

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From: Marc Young [mailto:Marc.Young@oilgassol.com]Sent: Monday, March 07, 2011 4:45 PMTo: Stephen CrimaudoSubject: API RP 521 Water into Hot Oil

I have been reviewing API RP 521 with respect to steam generation on depressurization in a hot crude oil separation system operating at above the normal boiling point of water. I am reviewing this because of a concern by one of my client’s safety engineers in which he references Section 5.9.1  of the Fifth Edition. His concern is that this section is stating that vapor generation is too quick to handle with normal relief. My interpretation of “hot oil” in Section 5.9 of API RP 521 is that this risk is normally associated with the mixing water with a hot oil heating media and is normally handled by operating the heat media at a higher pressure than the water being heated.  In essence the risk of a steam explosion is due to the lack of vapor space in the heating media system and the remote nature of the expansion tank.  My interpretation of the risk of steam generation in a crude oil separation vessel is one of 1) is there sufficient vapor space in the vessel to handle the increase in volume of the rapid transition of pressurized hot water to steam and 2) if the water is emulsified can the system handle the foam generation that can result?

5.9.1 Water into hot oilAlthough the entrance of water into hot oil remains a source of potential overpressure, no generally recognized method for calculating the relieving requirements is available. In a limited sense, if the quantity of water present and the heat available in the process stream are known, the size of the pressure-relief device can be calculated like that of a steam valve. Unfortunately, the quantity of water is almost never known, even within broad limits.Also, since the expansion in volume from liquid to vapour is so great (approximately 1:1 400 at atmosphericpressure) and the speed of vapour generation is essentially instantaneous, it is questionable whether the pressure-relief device could open fast enough to be of value. Normally, a pressure-relieving device is not provided for this contingency. Proper design and operation of the process system are essential in attempts to eliminate this possibility. The following are some precautions that can be taken:a) designing the water side to be at a lower operating pressure than the hot oil side;b) maintaining minimum circulation of hot oil through equipment on stand-by in order to minimize collection of water;c) avoiding water-collecting pockets;d) installing proper steam condensate traps;e) installing heat tracing to eliminate condensation;f) installing double-block and bleed valves on water connections to hot process lines;g) installing interlocks to trip sources of heat in the event of water-contaminated feedstock.

Can you provide me with some clarification as to the scenario that the API RP 521 Committee envisioned when added this language to API 521?  Was this intended to stated that relief valves could not react fast enough to handle water vaporization if a hot crude system depressurized and caused the water in the system to flash?  Or is this the limited exception noted, e.g. “In a limited sense, if the quantity of water present and the heat available in the process stream are known, the size of the pressure-relief device can be calculated like that of a steam valve.”

Your prompt assistance in this matter would be most appreciated.

Marc S. Young, PEChief Process Technical Advisor832.327.7799 - Main832.327.8221  - Direct832.327.7789 -  Fax713-417-6147 - Cellwww.oilgassol.comOil & Gas Solutions10255 Richmond Ave., 4th FloorHouston, TX  77042 - USA[Proof_OGSLogo]

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Exceeding Design Temperature During Tube Rupture

From: Ed Zamejc [mailto:ezrelief@sbcglobal.net] Sent: Wednesday, April 06, 2011 10:45 AMTo: 'Porter, Mike K'Cc: Stephen CrimaudoSubject: RE: RFI submitted - Publication [STD 521]

Mike:  Here is a technical interpretation involving tube ruptures.  Exceeding the design temperature of the low pressure side is not currently discussed in the document.  I think we should have a few words on this given we mention the potential for brittle fracture if it gets too cold. If you agree, I’ll provide a comment on the DIS which can then be discussed/modified by the entire committee. I think that may save some time. We can tell the inquirer that the committee is reviewing this with the intent to provide some limited guidance in the document.

Ed

From: Stephen Crimaudo [mailto:crimaudos@api.org] Sent: Thursday, March 10, 2011 12:55 PMTo: Ed ZamejcSubject: FW: RFI submitted - Publication [STD 521]

Ed,

Another question on 521, thanks,  Steve

Stephen CrimaudoSenior Associate, StandardsAmerican Petroleum Institute1220 L Street, NW Washington, DC 20005-4070Phone:  202-682-8151Fax:  202-962-4797crimaudos@api.org

From: donotreply@api.org [mailto:donotreply@api.org] Sent: Monday, March 07, 2011 5:48 AMTo: Standards OnlineAppSubject: RFI submitted - Publication [STD 521]

A user has submitted a RFI via the RFI website on 03/07/2011 at 5:47 AMPublication Type:  API  

Publication Number:  STD 521 

Edition:  Fifth 

Addendum/Errata:   Number:   

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Section Referenced:  5.19 

Subject:  Design temperature consideration for equipment experiencing high temperature during tube rupture 

Background:

 My company is working on basic engineering of a petroleum refinery project. We refer to section 5.19 of API 521 5th edition wherein relief requirement for tube rupture is specified. We need a clarification regarding relief temperature exceeding design temperature of equipment / system during tube rupture situation. 

Question:

 Sometimes Low Pressure (LP) side Design Temperature (DT) is lower than High Pressure (HP) side DT. In some such cases, Relieving Temperature (RT) during tube rupture is also often worked-out to be significantly higher than DT of LP side, where PSV is mounted. Further, in some cases it is economically unviable to increase LP side DT to be at least same as RT during tube rupture. We noticed that industry’s common practice is to “ignore” RT during tube rupture while considering DT for LP side equipment / system. What is API’s recommendation for design temperature of LP equipment / system during such scenario?  

First Name:  Brijesh Last Name:  Trivedi 

Email:  btrivedi@ltcis.ltindia.com Company:  L&T Chiyoda Limited 

Phone:  +91-265-3991203 

 

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Flare F Factor

From: donotreply@api.org [mailto:donotreply@api.org] Sent: Thursday, April 21, 2011 2:11 AMTo: Standards OnlineAppSubject: RFI submitted - Publication [521]

A user has submitted a RFI via the RFI website on 04/21/2011 at 2:11 AMPublication Type:  API  

Publication Number:  521 

Edition:  fifth 

Addendum/Errata:  A Number:  1 

Section Referenced:  6.4.2.3.3 

Subject:  Fraction of Heat radiated, F Factor 

Background:

 The flare designers invariably consider much lower F factor than that calculated by API method. In some casess the F factor estimated by API method is 2.6 times that of Flare designer. Moreover there are many different methods available like Kent, Cook, Tan, Chamberlian etc providing a range of F factor values.  

Question:  Which is the best method to estimate the F factor? Is the approach different for New design and Expansion case? 

First Name:  Jatin Last Name:  Dudeja 

Email:  jatin.dudeja@ril.com Company:  Reliance Industries Limited 

Phone:  +91-22-44783487 

 

15

Flare – Solar Radiation

From: donotreply@api.org [mailto:donotreply@api.org] Sent: Thursday, April 21, 2011 2:15 AMTo: Standards OnlineAppSubject: RFI submitted - Publication [521]

A user has submitted a RFI via the RFI website on 04/21/2011 at 2:15 AMPublication Type:  API  Publication Number:  521 

Edition:  fifth Addendum/Errata:  A 

Number:  1 Section Referenced:  6.4.2.3 

Subject:  Solar Background Radiation 

Background:

 Some companies include solar radiation in the radiation levels (table 9) specified in API 521 while some others don’t. When sizing the new stack or assessing the existing the stack, the solar radiation can have a significant impact on the flare design when low radiation constraints are considered. This will result in the stack being oversized for those situations with less or no sun contribution (at night and during cold seasons). 

Question: What should be the correct approach (should solar radiation be considered in mentioned limits or not) for Designing a flare Stack or while debottlenecking for the expansion case? Can approach be different in both scenarios? 

First Name:  Jatin 

Last Name:  Dudeja Email:  jatin.dudeja@ril.com 

Company:  Reliance Industries Limited Phone:  +91-22-44783487 

 

16

Noise from 2 Sources

From: donotreply@api.org [mailto:donotreply@api.org] Sent: Thursday, April 21, 2011 3:53 AMTo: Standards OnlineAppSubject: RFI submitted - Publication [521]

A user has submitted a RFI via the RFI website on 04/21/2011 at 3:53 AMPublication Type:  API  

Publication Number:  521 

Edition:  JANUARY 2007 

Addendum/Errata:   

Number:   

Section Referenced:  section 7.3.4.3 

Subject:  Noise 

Background:

 Saipem (Fano premises, ITALY) is involved in North Stream project, a project which foresee the construction of a gas pipeline from Russia to Germany. In the German shore approach a “cold” vent can operate, in upset conditions, for 40 continuous days emitting methane. The emission data are as follows: Hs = 15 m (stack height); Qs = 55.6 kg/s (Source mass rate); Ts = -68 °C (Source Temperature); ps = 1 barg (Source pressure); Ds = 12 inch (Stack Diameter); Ws = 410 m/s (Source Velocity) 

Question:

 About 250 metres before the vent stack there is a valve where the gas pressure drop from 110 to 5 barg. Therefore we have a source located approximately at ground level (the valve) and the second source to a height of 15 metres (the vent outlet). Considering that no mention of ground effects has been quoted in API formulation, we think that the computation of Lp(30) in not correct in our case. What methodology we can apply to estimate the noise emission of valve and vent? Thank you for the assistance. 

First Name:  giorgio 

Last Name:  carizi 

Email:  giorgio.carizi@saipem.com 

Company:  Saipem  

Phone:  +39 0721 168 2603 

17

Insulation Temperature Limits

From: Ed Zamejc [mailto:ezrelief@sbcglobal.net] Sent: Wednesday, December 15, 2010 11:53 AMTo: Stephen CrimaudoCc: portemk@chevron.comSubject: RE: RFI submitted - Publication [521]

Stephen: We have included a revision in the next edition of the document on this topic. Please find attached the excerpts from the latest draft.  The revision indicates that the temperature endurances of the insulations are dependent not only on the types listed in Table 6 but could also vary between manufacturers and grade of insulation. Hence, the following eternal guidance is give:

“Therefore, the user should consult with the insulation material supplier as to the actual temperature limits for the insulation material.”

Mike: I suggest responding with the above and indicating we are planning on including this in the next edition.

Ed

From: Stephen Crimaudo [mailto:crimaudos@api.org] Sent: Tuesday, December 14, 2010 3:54 PMTo: Ed ZamejcSubject: FW: RFI submitted - Publication [521]

Ed,

Greetings.  Another interesting one for you -

Stephen CrimaudoSenior Associate, StandardsAmerican Petroleum Institute1220 L Street, NW Washington, DC 20005-4070Phone:  202-682-8151Fax:  202-962-4797crimaudos@api.org

From: donotreply@api.org [mailto:donotreply@api.org] Sent: Monday, December 13, 2010 8:11 PMTo: Standards OnlineAppSubject: RFI submitted - Publication [521]

A user has submitted a RFI via the RFI website on 12/13/2010 at 8:11 PMPublication Type:  API  

Publication Number:  521 

Edition:  5 

18

Addendum/Errata:   Number:   

Section Referenced:  5.15.5.2 

Subject:  External Insulation 

Background:  Fire insulation, or insulation that is part of a composite system, should be capable of withstanding an exposure temperature of 900 °C (approx. 1 660 °F) for up to 2 h. 

Question:

 Table 7 of API 521 5th Ed. lists the thermal conductivity values for typical thermal insulations. Are all the insulating materials listed in this table are capable of withstanding an exposure temperature of 900 degC for up to 2 hours? I believe they are, simply because they are listed in Table 7. Some of my colleagues , in my opinion incorrectly, think that only Calcium silicate type II and Dense cementitious types of insulation are capable of withstanding an exposure temperature of 900 °C by looking at the "Maximum temperature for use as insulation" values listed in the same Table 7. We are however in general agreement that stainless steel cladding/banding is strictly required in addition to the proper selection of insulating material type to reduce the value of the environment factor F to below one (1.0). 

First Name:  Kursad Last Name:  Ulusoy 

Email:  ulusoyk@vistaimvjv.com Company:  Vista Projects Limited 

Phone:  1-403-5380852 

 

19

3rd Edition of ISO 23251 Work Item ListMay, 2011

1. (New task group formed – next edition) Claus plant relief protection (Mike Porter)

2. Withdrawn - Bypass valve inadvertent opening (Brad Otis)

3. Withdrawn - Fire exposure of external heat or cooling jackets (Chip Eskridge)

4. Withdrawn - Relief discharge near heliports, e.g., offshore platform and airports (Reassigned to Jeff Sawchuk) – revised draft not yet available for review

5. Withdrawn - Coke drum vapor decay rate (Freeman Self). Determined to be proprietary and cannot be shared.

6. LNG regasification, base load plants relief scenarios (Hari Attal) - NFPA 59A is US only so deleted; if clause only contains references to two other standards, then this sets precedence whereby other clauses are required for LPG (NFPA 58, etc.) and other commodities.

7. Withdrawn - Practical guidance to calculate back flow through check valves (Bob McMican) – revised draft not yet available for review

8. Withdrawn - Review the third paragraph of 5.19.3 as it suggests dynamic analyses is required if a smaller than full-bore tube failure is used as the design case (Denis Demichael, Tom Bevilaqua)

9. Action Item 57: The seal drum drawing (drawing D1) in Annex D is inadequate. Ed Zamejc to send the drawing in DWG format to John Straitz, Javaid Iqbal and Bob McMican. Bob McMican to update the drawing, incorporating comments and help from John Straitz and Javaid Iqbal. (reassigned to Clark Shepard)Bob McMican received DWG and review by John Straitz, Javaid Iqbal – reassigned to Clark Shepard Withdrawn – next edition?

10.Action Item 66: P. Henry and R. Danzy agreed to propose a change to the definition of hydrotest pressure to specifically mention the corroded state (see inquiry 521-2009-4). Withdrawn, next edition

11.Hot/oil water mixtures – additional guidance (Ed Zamejc)

12. ...

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