Subcommittee On Pressure Relief Systems

API CRE Update

Clark Shepard

Spring 2010

1

Standard/RP Title Current Edition DateNotes or

CommentsExpected Publication

Date

Std 520 Part 1 Sizing, Selection, and Installation of Pressure-

relieving Devices in Refineries Part I—Sizing and

Selection

8th Edition, December 2008

Work items beginning in Spring 2010

9th Edition 2013

RP 520 Part 2 Sizing, Selection, and Installation of Pressure-

relieving Devices in Refineries Part II—

Installation

5th Edition, August 2003

Ballot 1Q10 6th Edition 2010

Std 521(ISO 23251)

Pressure-relieving and Depressuring Systems

5th Edition, January 2007

Ballot August 2011 (DIS)

6th Edition November 2012 (FDIS)

Std 526 Flanged Steel Pressure Relief Valves

6th Edition, May 2009

7th Edition 2Q14

Std 527 Seat Tightness of Pressure Relief Valves

3rd Edition, July 1991

Re-affirmed July 2007

2012

Std 2000 (ISO 28300)

Venting Atmospheric and Low-Pressure Storage Tanks

Nonrefrigerated and Refrigerated

6th Edition, November 2009 (API adopt back);

ISO release 2008

DIS June 2011 December 2012

Standard/RP Issues Cost/Reliability Issues

Std 520 Part I Task Force focused on RP 520 Part II

None identified

RP 520 Part II Work on inlet pressure drop section

Potential Cost Improvement - Potential revision and inclusion of 5% into inlet pressure drop criteria

Std 521(ISO 23251)

Challenge to heat flux equations

Potential Additional Cost – Work nearing completion where detailed equations based on CFD and test data can be used to validate existing simple methodology

Std 526/527 No issues None identified

Std 2000 (ISO 28300)

1. In/Out Breathing – Working with SCAST with regards to equation revisions

2. Documenting the basis of the heat flux equations for sizing emergency venting

3. Deflagration venting

1. Potential Additional Cost – Clarifying text when to use equations in Annex A (past API 2000 equations)

2. Cost neutral - Work continues on heat flux basis

3. Potential Additional Cost – Working with SCAST to define when frangible roofs can be acceptable for venting vapors during internal deflagration

Projects

1. PERF 99-05 PRV Stability Project evaluating multiple factors that could lead to instability (chattering) including inlet pressure drop – Plans to complete during 4Q10– Data reviewed this week appeared random although not all test

information has been analyzed

2. Heat Recovery Steam Generators (Waste Heat Boiler) in Sulfur Recovery Units– Breakout team – PRS working with HTE and Sulfur Expert– Focus is on pressure relief requirements to address tube failure