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Features• Designed to provide a safe, efficient
method of switching from an activepressure relief device to a standby,maintaining system overpressureprotection regardless of Safety SelectorValve position.
• Provides high Cv values, resulting in lessthan 3% pressure drop to the active PRV inlet, when used with the largest APIorifice available in a given valve size, inaccordance with the recommendations ofAPI RP520 Part II and ASME Section VIII,Division 1, Appendix M, helping reduce thepossibility of destructive chatter of the PRV.
• Requires only one minimally sizedpenetration into the vessel or pipe, reducing costs.
• Reduces field installation costs and spacerequirements through preassembled andcompact design.
• Provides process isolation of standbypressure relief device.
• Allows pressure relief device maintenancewithout process shutdown.
• A bleed valve is provided under each safety relief device as an effective andsafe means of venting entrapped processunder an isolated pressure relief valveprior to removal for maintenance.
• Bright red indicator for positive indication of active pressure relief device.
• Meets all mandatory requirements of ASME Section VIII, Division 1, UG-135 (b).
• Foolproof provisions for dual padlocking in either pressure relief valve position, inaccordance with the recommendations ofASME Section VIII.
• Packing design has been tested to ASTM E427, Method A halogen leak test,reducing probability of fugitive emissions.
• No seat lapping required for maintenance.Only recommended spare parts are softgoods which reduces cost of ownership.
• Meets standard temperature applicationsfrom -423°F to 800°F [-252.8°C to 426.7°C].
• Offers materials of construction compatiblewith pressure relief devices. Duplex and6MO material available.
• Helps deliver a reduced number of leakpoints to atmosphere, reducing probabilityof fugitive emissions.
• Isolates a standby pressure relief valve inaccordance with joint recommendation ofAPI Subcommittee on Pressure RelievingSystems and Subcommittee on RefineryInspection.
• Type approval by Det Norske Veritas (DNV).
• Simplicity of operation with built-in seatequalization and no special toolsminimizes total time to operate valve.
Recommended SpecificationsChangeover device inlet connection is to bethe same size and rating as the pressurerelief valve inlets.
• Pressure drop through the changeoverdevice’s active side cannot exceed 3%with pressure relief valve fully open.
• Changeover device is to have externalindicator, showing which side is active.
• Provisions for double padlocking in eitherposition are required.
• A valve bleed port must be located undereach pressure relief valve connection forpressure venting under the inactivepressure relief valve.
Anderson Greenwood Safety Selector ValveDual Pressure Relief Device System
Anderson Greenwood is either a trademark or registered trademark of Tyco International Services AGor its affiliates in the United States and/or other countries. All other brand names, product names, ortrademarks belong to their respective holders.
Flow Control
ANDERSONGREENWOOD
The Safety Selector Valve is designed specifically tofunction as an effective “switchover” device.
Anderson Greenwood Safety Selector ValveDual Pressure Relief Device System
Section I Steam ServiceSafety Selector Valves can be utilized forcertain Section I Boiler applications.Per ASME Section I Boiler and PressureVessel Code Case 2254, a switchover valvesuch as the Safety Selector Valve can beinstalled to provide a back-up safety valve forboilers with a maximum allowable workingpressure (MAWP) of 800 psig or less.
The code case requires that the followingcriteria be met by the switchover device:
The Safety Selector Valve will provide thehighest flow efficiency (Cv) of any otherswitchover device in the same nominal pipesize. These Cv values allow the Safety SelectorValve to be used with most manufacturers’flanged Section I Boiler valves and meet thecode case requirements. Please provide themodel number and set pressure of the safetyvalves to be used to ensure completecompliance with the code case.
Operation
Dual Pressure Relief Device SystemsAnderson Greenwood developed the SafetySelector Valve in response to the growingdemand for cost-effective, dual pressurerelief valve and/or rupture disc installations intoday’s process industries. The SafetySelector Valve is designed specifically tofunction as an effective “switchover” devicethat permits routine or emergency servicingof redundant pressure relief devices with noprocess interruption, thus providingcontinuous system overpressure protection.Until recently, bulky and expensive pipingfabrications or total shutdown were the onlymethods for servicing the pressure reliefdevices. These systems required either twoseparate vessel penetrations withmechanically linked block valves or a 3-wayblock valve that commonly resulted in highinlet pressure loss, excessive turbulence tothe active pressure relief device and multipleleak points.
The Anderson Greenwood Safety SelectorValve solves these problems. It is easy toinstall, requiring only one vessel penetrationin the same size as the pressure relief valveinlet. The unique design provides less than3% pressure drop to the active pressurerelief valve inlet when used with the largestAPI orifice available in a given valve size, inaccordance with API RP520, Part II andASME Section VIII guidelines.
Interlocking BlockValve with Two Vessel
Penetrations
3-Way Block Valve with Pipe Elbows
(see Pressure Drop Comparison Below)
Interlocking BlockValve with Pipe Tee
and Elbows
Traditional Dual Pressure Relief Device Systems
Using API Standard 526 direct acting spring loaded valves, the comparative pressure dropthrough the Safety Selector Valve versus the same size 3-way ball valve is as follows:
2" 3" 4" 6" 8"2J3 3L4 4P6 6R8 8T10
SSV 1.50% 0.86% 1.42% 1.37% 1.31%
3-Way Ball 6.36% 5.65% 9.30% 10.6% 8.69%
Liquid/Two Phase ServiceSafety selector valves can be used ingas/vapor, steam, or liquid service. Safetyselector valves can also be used in twophase service. The picture on the left is of anAnderson Greenwood Series 400 pilot valverelieving on liquid only. The picture on theright shows the same valve transitioning totwo phase flow as gas is becoming entrainedin the relief stream.
Anderson Greenwood Safety Selector ValveDual Pressure Relief Device System
The Anderson Greenwood Safety SelectorValve body houses a uniquely designedswitching mechanism. The internal rotorsmoothly diverts flow to either pressurerelief device. Either direct spring operatedvalves, pilot operated valves or rupturediscs may be used. The inactive device istotally isolated by external adjustment(Figures 1 and 5). To begin switchover, the
padlocks or seals are removed, the lockhasp is opened, and the retraction bushingis rotated to its stop (Figure 2). This lowersthe isolation disc from nozzle under thestandby valve and temporarily “floats” it inthe main valve cavity. The index shaft isthen rotated 180 degrees to the alternatechannel (Figures 3 and 4). The retractionbushing is then raised, securely seating
the isolation disc beneath the valve to betaken out of service (Figure 5). A redpointer indicates which device is in serviceand double padlocking provisions allowthe Safety Selector Valve to be locked ineither position. The padlocks or car sealscan only be installed with the internals inthe proper position. No special tools arenecessary for switching.
Retreaction Bushing Red Pointer Nozzle
Isolation Disc Lock Hasp Index Shaft
Note:1. Temperature range is limited according to
body material of construction as follows:
CS -20°F to 800°F [-28.9°C to 426.7°C]
SS -423°F to 800°F [-252.8°C to 426.7°C]
Anderson Greenwood Safety Selector ValveDual Pressure Relief Device System
possibility of inadvertently closing a block valve either upstream ordownstream of the intended activepressure relief valve.
• Overpressure protection of processmaintained at all times duringswitchover.
• Compact and low weight.
• Lower installation costs than withconventional methods. No fieldfabrication or multiple crane liftsrequired.
• Single, minimally sized penetrationinto vessel, single discharge headerconnection.
• Anderson Greenwood offers acompletely coordinated, tested, and assembled package consisting of the pressure relief devices and inlet and outlet Safety Selector Valves.The installed interconnecting linkageensures that both inlet and outlet Safety Selector Valves switchsimultaneously.
• Ease of Engineering: No need to use oversized piping and valves toprevent excessive pressure loss. Safety Selector Valves in tandem are of the same line size as thepressure relief valve flanges.
• Assurance of less than 3% pressuredrop to the pressure relief valve inletwhen used with the largest API orificeavailable in a given valve size.
Tandem Safety Selector Valve
The Anderson Greenwood TandemSafety Selector Valve System allows forsimultaneous selection of pressure reliefvalve and corresponding dischargeoutlet piping of dual pressure reliefdevices discharging into a closedheader system.
These redundant pressure relief device systems can be heavy and bulky, requiresignificant field fabrication, installationtime and expense, and can be difficultand confusing to operating personnel.
The Anderson Greenwood TandemSafety Selector Valve System provides abetter, safer alternative.
Redundant pressure relief valvesdischarging into a closed header systemutilize all of the inherent advantages ofthe Anderson Greenwood SafetySelector Valves. The two pressure reliefvalves, two safety selector valves, and asimple linkage are pre-assembled at thefactory. Only one flanged inlet and oneflanged outlet connection are required tobe made up in the field. The linkagebetween the inlet and outlet pressurerelief valves is simple, foolproof, andprovides positive and simultaneousswitching of the Selector Valves.
End your concern about closing off thewrong outlet block valve. Overpressure protection is available 100% of the time.
Anderson Greenwood Safety Selector ValveDual Pressure Relief Device System
Inlet Flange Outlet Flange Tandem SSV Envelope API Inlet by ANSI Pressure Face ANSI Pressure Face Dimensions, inches [mm]Orifice Outlet Size Class Type Class Type A B
Note:1. Calculated using 1/16" thick gaskets for RF connections and the
spacing listed in Table 5 of ANSI B16.5 for RJ connections.
Tandem SSVwith PRVsA
B
Anderson Greenwood Safety Selector ValveDual Pressure Relief Device System
Inlet Flange Outlet Flange Tandem SSV Envelope API Inlet by ANSI Pressure Face ANSI Pressure Face Dimensions, inches [mm]Orifice Outlet Size Class Type Class Type A B
Note:1. Calculated using 1/16" thick gaskets for RF connections and the
spacing listed in Table 5 of ANSI B16.5 for RJ connections.
Tandem SSVwith PRVsA
B
Anderson Greenwood Safety Selector ValveDual Pressure Relief Device System
Inlet Flange Outlet Flange Tandem SSV Envelope API Inlet by ANSI Pressure Face ANSI Pressure Face Dimensions, inches [mm]Orifice Outlet Size Class Type Class Type A B
Tandem SSVwith DSOPRVs
A
B
Anderson Greenwood Safety Selector ValveDual Pressure Relief Device System
Dimensions and Weights – Tandem Safety Selector Valve with Direct Spring Valves
Tandem Safety Selector Valve with API 526 Direct Spring Operated PRVs
Notes:1. Calculated using 1/16" thick gaskets for RF connections and the spacing listed in Table 5 of ANSI B16.5 for RJ connections.
2. Dimensions using Crosby JOS-E/JBS-E/JLT-E pressure relief valves. A = 47.30 [1201.42] B = 56.69 [1439.93] Expanders are required onboth the inlet and outlet Safety Selector Valves. Contact your sales representative for details.
Inlet Flange Outlet Flange Tandem SSV Envelope API Inlet by ANSI Pressure Face ANSI Pressure Face Dimensions, inches [mm]Orifice Outlet Size Class Type Class Type A B
Tyco Flow Control (TFC) provides the information herein in good faith but makes no representation as to its comprehensiveness or accuracy. This data sheet is intended only as a guide to TFC products and services. Individuals using this data sheet must exercise their independent judgment in evaluating product selection and determining product appropriateness for their particular purpose and system requirements. TFC MAKES NO REPRESENTATIONS OR WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE WITH RESPECT TO THE INFORMATION SET FORTH HEREIN OR THE PRODUCT(S) TO WHICH THE INFORMATION REFERS. ACCORDINGLY, TFC WILL NOT BE RESPONSIBLE FOR DAMAGES (OF ANY KIND OR NATURE, INCLUDING INCIDENTAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES) RESULTING FROM THE USE OF OR RELIANCE UPON THIS INFORMATION. All Patents and Patents Pending in the U.S. and foreign countries are property of their respective owners. Tyco reserves the right to change product designs and specifications without notice. All registered trademarks are the property of their respective owners. Printed in the USA.
Connection TypeF – Raised Face Flange (1" to 8")J – Ring Joint Flange (1" to 8")T – Threaded (1" to 3")X – Special
Body MaterialA – Aluminum M – Monel®C – CS N – Inconel®D – Duplex S – SSH – Hastelloy® X – Other (note type on order - contact your sales representative)
Trim MaterialS – SS D – DuplexH – Hastelloy® N – Inconel®M – Monel® X – Other (contact your sales representative)
OptionsO – Standard (Inlet Valve)T – Tandem (Outlet Valve)B – Built per ASME Boiler and Pressure Vessel Code Section I, Code Case 2254 (see page 2)X – Special - note on order required options