Purpose of Piping Plans
�Create a more favorable environmentfor the mechanical seal
• Flushing to remove heat
• Lowering fluid temperature
• Altering the seal chamber pressure
• Cleaning the process fluids
• Control atmospheric side of seal
Purpose of Piping Plans
�Provide a means of detecting andcontrolling seal leakage
• Capture and/or prevent leakage
• Detect leakage
• Route leakage to appropriate collection
or disposal system
• Provide fluid other than process fluid for
the seal environment
Requirements of Mechanical Seals
�Liquid seals
• Stable fluids
• Good lubricating properties
• Fluids do not flash or vaporize in seal
chamber
• Free from contamination and solids
• Moderate viscosities
Requirements of Mechanical Seals
�Gas seals
• Gas or vapor suitable for sealing
• Constant supply of external buffer/barrier
gas
• Process fluids free from contamination
from both liquids and solids
• Process fluids which are not adversely
affected by gas leakage
Methods of Achieving Goals
�Piping or routing of process fluids
�Introduction of external fluids
�Auxiliary equipment
• Seal coolers
• Cyclone separators
• Reservoirs
�Instrumentation
Plan 52What• Unpressurized buffer
fluid circulationthrough reservoir.
• Fluid is circulated bya pumping ring in thedual seal assembly.
Plan 52Why• Outboard seal acts
as a safety backupto the primary seal.
• Zero to very lowprocess emissions.
• No processcontamination isallowed.
Plan 52Where• Used with dual
unpressurized seals(“tandem”).
• High vapor pressurefluids, lighthydrocarbons.
• Hazardous or toxicfluids.
• Heat transfer fluids.
Plan 52Preventative
Maintenance
• Piping loop mustself-vent to vaporrecovery/flaresystem nearatmosphericpressure.
• Process vaporpressure is generallygreater thanreservoir pressure.
• Buffer fluid must becompatible withprocess leakage.
Plan 52Preventative
Maintenance
(continued)• Primary seal leakage
is indicated byincreased ventpressure.
• Reservoir level gageindicates outboardseal leakage.
Plan 53AWhat• Pressurized barrier
fluid circulationthrough reservoir.
• Fluid is circulated bya pumping ring in thedual seal assembly.
Plan 53AWhere• Used with dual
pressurized seals(“double”).
• High vapor pressurefluids, lighthydrocarbons.
• Hazardous or toxicfluids.
• Heat transfer fluids.
• Dirty, abrasive orpolymerizing fluids.
• Mixers or agitators.
• Vacuum service.
Plan 53APreventative
Maintenance
• Piping loop mustself-vent to reservoirlocated at highestelevation.
• Pressurize reservoirat all times,maximum gascharge 150 - 200 psi(10 - 14 bar)
• Barrier fluid must becompatible withprocess.
• Reservoir level gageindicates both IB andOB seal leakage.
Plan 53BWhat• Pressurized barrier
fluid circulation witha bladderaccumulator.
• Fluid is circulated bya pumping ring in thedual seal assembly.
Plan 53BWhere• Used with dual
pressurized seals(“double”).
• High vapor pressurefluids, lighthydrocarbons.
• Hazardous or toxicfluids.
• Heat transfer fluids.
• Dirty, abrasive orpolymerizing fluids.
Plan 53BPreventative
Maintenance
• Piping loop must befully vented beforestarting.
• Accumulator must bepressurized at alltimes, usually by gascharge.
• Barrier fluid must becompatible withprocess.
• Regularly monitorbarrier pressure –manually add barrierfluid when pressuredecays.
Plan 53CWhat• Pressurized barrier
fluid circulation witha pistonaccumulator.
• Fluid is circulated bya pumping ring in thedual seal assembly.
Plan 53CWhy• Isolate process fluid.
• Zero processemissions.
• Higher pressure thanPlan 53A.
• Dynamic tracking ofsystem pressure.
Plan 53CWhere• Used with dual
pressurized seals(“double”).
• High vapor pressurefluids, lighthydrocarbons.
• Hazardous or toxicfluids.
• Heat transfer fluids.
Plan 53CPreventative
Maintenance
• Piping loop must befully vented beforestarting.
• Reference line musttolerate processcontaminationwithout plugging.
• Barrier fluid must becompatible withprocess.
• Reservoir level gageindicates bothinboard andoutboard sealleakage.
Plan 54Where• Used with dual
pressurized seals(“double”).
• High vapor pressurefluids, lighthydrocarbons.
• Hazardous or toxicfluids.
• Heat transfer fluids.
• Dirty, abrasive, orpolymerizing fluids.
• Mixers or agitators.
Plan 54Preventative
Maintenance
• Piping loop must befully vented beforestarting.
• Circulating systemmust be pressurizedand energized at alltimes.
• Barrier fluid must becompatible withprocess.
• Circulation systemlevel gage indicatesboth inboard andoutboard seal leakage.
Plan 72What• Unpressurized buffer
gas control system.
• Containment sealsupport typically withnitrogen buffer gas.
Plan 72Where• Used with dual
unpressurizedcontainment seals(“tandem”).
• High vapor pressurefluids, lighthydrocarbons.
• Hazardous or toxicfluids.
• Clean, non-polymerizing, non-oxidizing fluids.
• Used in combinationwith Plan 75 and/orPlan 76.
Plan 72Preventative
Maintenance
• Clean, reliable, lowpressure gas must besupplied to seal at alltimes.
• Bottled gas supply isnot recommendedexcept as part of anemergency backupsystem.
• Primary seal leakage isindicated by pressurein the vent line.
Plan 72Preventative
Maintenance
(continued)
• Vent or drain areusually connected tolow pressure vaporrecovery/flare system.
Plan 74What• Pressurized barrier gas
control system.
• Gas seal supporttypically with nitrogenbarrier gas.
Plan 74Where• Used with dual
pressurized gas seals(“double”).
• High vapor pressurefluids, lighthydrocarbons.
• Hazardous or toxicfluids.
• Services that do nottolerate barrier fluids.
• Clean, non-polymerizing fluids.
• Moderate temperaturefluids.
Plan 74Preventative
Maintenance
• Clean, reliable,pressurized gas mustbe supplied to seal atall times.
• Barrier pressure istypically at least 25 psi(1.75 bar) above sealchamber pressure.
• Flow meter indicatesboth inboard andoutboard seal leakage.
Plan 74Preventative
Maintenance
(continued)
• Bottled gas supply isnot recommendedexcept as part of anemergency backupsystem.
Plan 75Why• Leakage collection for
zero to very lowprocess emissions.
• Safety indicator forprimary seal.
Plan 75Where• May be used alone or
with Plan 72 oncontainment seals.
• Fluids that condense atambient temperature.
• High pressure fluids,light hydrocarbons.
• Hazardous or toxicfluids.
• Clean, non-polymerizing, non-oxidizing fluids.
Plan 75Preventative
Maintenance
• Collection reservoirmust be located belowseal drain anddownward-slopedpiping.
• Continuously ventcollection reservoir tolow pressure vaporrecovery/flare system.
• Drain collectionreservoir to liquidrecovery system asneeded.
Plan 75Preventative
Maintenance
(continued)
• Primary seal leakage isindicated by increasedvent pressure.
• Monitor regularly forliquid level, valvesettings, and low ventpressure.
Plan 76Why• Leakage collection for
zero to very lowprocess emissions.
• Safety indicator forprimary seal.
Plan 76Where• May be used alone or
with Plan 72 oncontainment seals.
• Fluids that do notcondense at ambienttemperature.
• High vapor pressurefluids, lighthydrocarbons.
• Hazardous or toxicfluids.
• Clean, non-polymerizing, non-oxidizing fluids.
Plan 76Preventative
Maintenance
• Continuously vent tolow pressure vaporrecovery/flare system.
• Vent piping shouldinclude a condensatedrain.
• Primary seal leakage isdetected by increasedvent pressure.
• Monitor regularly forvalve settings, blockedlines, and low ventpressure.
Good Piping Practices
�Minimize line losses
�Large diameter tubing
�Upward sloping lines
�Long radius bends
high point vent
Vertical
Equipment
Horizontal
Equipment
18 - 24 in.
(0.45 - 0.6 m)
3 ft. (0.9 m) max
low point drain
Plan 23 Example
Good Piping Practices
�Minimize line losses
�Large diameter tubing
�Upward sloping lines
�Long radius bends
Vertical
Equipment
Horizontal
Equipment
18 - 24 in.
(0.45 - 0.6 m)
4 ft. (1.2 m) max
low point drain
Plan 53A Example
Review
�Intended to create a more favorableenvironment for the seal
�Collect and detect seal leakage and providesafety backup
�Documented in several API, ASME, and ISOstandards
�May require auxiliary equipment or externalsources of fluids
�Necessary to improve seal reliability/Safety