Sealing Systems For PumpsSealing Systems For Pumps … Sealing... · Sealing Systems For...
Transcript of Sealing Systems For PumpsSealing Systems For Pumps … Sealing... · Sealing Systems For...
SARBS Pump Maintenance Seminar, June 7, 2012
Sealing Systems For PumpsSealing Systems For Pumps Part I
Presented by:
Shelby ScottShelby ScottWestern Region John Crane IncJohn Crane, Inc
SARBS Pump Maintenance Seminar, June 7, 2012
PackingMechanical Seal Basics
Pros & Cons: Packing & SealsgMechanical Seal Elements
Basic Seal DesignsBasic Seal DesignsMaterials of Construction
SARBS Pump Maintenance Seminar, June 7, 2012
AtmosphereVessel pWall
Shaft
ProcessProcessFluid Leakage
SARBS Pump Maintenance Seminar, June 7, 2012
Pump Housing
Atmosphere
Pump Housing
Impeller Packing
LeakageShaft
gProcessFluid Note: Leakage occursNote: Leakage occurs
in a direction parallel to the shaft
Clean Process Fluid Acts as Lubricant Between Packing & Sleeve
Atmosphere
Between Packing & Sleeve
Atmosphere
TargetPumped
Fluid TargetLeakage:
30 -60 dropsper minuteel
ler
Fluid
Stuffing Box
Gland
Cooling and Lubrication
per minute
Imp
g
Typical Packing SupportTypical Packing SupportFlush Water Pressure
Higher Than "A"Atmosphere
Higher Than "A"Pumped
FluidTarget
Leakage:30 60 drops
mpe
ller Stuffing Box
30 - 60 dropsper minute
Gland
L t
Im Gland
Lantern Ring"A"
Often Clean Flush Is Used To Cool &Often, Clean Flush Is Used To Cool & Lubricate Inboard & Outboard Packing Rings
AlternateSealing Methodsg
& SupportppPackingPacking
Die-Formed Packing Ring SetsDie Formed Packing Ring SetsPre-Consolidated In Die Press To Final Shape Fast installation, minimal leakage at start-up Rings Cut With Bevel Seams Eliminates leak path Eliminates leak path
Cut To Exact Shaft Diameter Ensures maximum performance Minimal leakage
Packaged In Complete 5 Or 6 Ring Sets Ensures all old rings are removed – no left overs
Minimize Packing Water UsedStaggered Seam Locations
Start at one o'clock, stagger joints 90 degrees, and set firmly.
90º
No Support Packing CombinationPacking Combination
1625G / G57 Mixed set for no water support applications
G57 flexible graphite with corners of carbon G57 - flexible graphite with corners of carbon yarn, provide sealability, self lubricating
1625G - graphite yarn with PTFE, act as bull rings k fl ibl hi f dito keep flexible graphite from extruding
1625G G57
Packing vs. Mechanical SealsPacking vs. Mechanical SealsIs not a seal but rather a restricting device. Requires leakage or it will burn
Will seal with invisible leakage. On difficult applications theleakage or it will burn.
Will groove and wear shafts and sleeves.
On difficult applications the leakage ratio between seals and packing is 1 to 100 or better.
S l h b k 8High horsepower load to overcome friction.
Product loss
Seals have been known to run 8 to 10 years without failure.
Monetary savings from little toProduct loss.
Requires large amounts of water for cooling.
Monetary savings from little to no product loss, water savings and energy savings.
Requires maintenance time and downtime for installations and packing adjustments.
Little maintenance required after initial installation.
Seals offer better safety whenEquipment damaged and destroyed from leakage.
Seals offer better safety when sealing potentially hazardous materials.
SARBS Pump Maintenance Seminar, June 7, 2012
Pump
Leakage
AtmospherePump
Housing
Shaft
Leakage di l t
ProcessFluid
perpendicular to shaft centerline
Mechanical Seal Face LubricationMechanical Seal Face LubricationSurfaces in ContactSurfaces in Contact Fluid Migrates Through ‘Low’ Areas
Provides Lubrication to Reduce Heat Absorbs Heat Generated
Surface Wears as ‘Peaks’ Broken Off
Fluid Migration
Magnified Surface AHeated Fluid Migration
Magnified Surface B
Vapor
Magnified Surface B
1. Primary Sealing Elements
Minimizing Leakage
SARBS Pump Maintenance Seminar, June 7, 2012
Close clearance = less leakage and increased wear
g g
g
Greater clearance = more leakage and less wearleakage and less wear.
Typical seal face film thickness isTypical seal face film thickness is 10-50 -in (micro-inches).
A typical piece of paper is 5,000 -in thick!
Without Lubrication, S l F R D A d O h tSeal Faces Run Dry And Overheat
S lStuffing Box
No Fluid or Dry Running
SealGland
Stuffing Box
o u d o y u g
Rotating Face Stationary Face
Lack Of Lubrication Causes,Contact, Heat Generation & Wear
Seal Face Damage: Heat CheckingSeal Face Damage: Heat Checking
Seal FaceWearFront ViewGroove
Cracks DueTo InadequateCooling
SARBS Pump Maintenance Seminar, June 7, 2012
Mechanical Seal Elements
1. Primary sealing elements
2. Secondary sealing elementsy g
3. Drive elements
4 L d l4. Load elements
5. Adaptive hardware elements
SARBS Pump Maintenance Seminar, June 7, 2012
Drive Elements Adaptive Hardware
Load Element
Primary Seal ElementsSecondary Seal Elements Primary Seal ElementsSecondary Seal Elements
SARBS Pump Maintenance Seminar, June 7, 2012
Primary Ring
RetainerDisc
Drive Band
Mating Ring
O-RingSpring Adaptorat g g
Spring
Elastomer Bellows
SARBS Pump Maintenance Seminar, June 7, 2012
Two Basic Seal Designs Exist: Bellows seals: more flexible, no dynamic O-ring, clog-resistant
O-ring seals: compact, higher pressures, wide chemical range
bellows made from rubber, metal or PTFE
O-ring SealBellows Seal
O-ring slidesin process fluid
static sealhere
flexible bellowshead here
SARBS Pump Maintenance Seminar, June 7, 2012
The Ideal Material for Mechanical Seals: corrosion resistant wear resistant wear resistant rugged design – non deflecting
Waste Water Seal: Silicon Carbide / Silicon Carbide or Tungsten Carbide / Tungsten Carbide
Cl W t S l C b / Sili C bid C b /Clean Water Seal: Carbon / Silicon Carbide or Carbon / Tungsten Carbide
SARBS Pump Maintenance Seminar, June 7, 2012
O i M i l f Effi i S liOptimum Materials for Efficient Sealing Hard Face
Silicon Carbide Ceramic ( Al-Oxide)Ceramic ( Al Oxide) Tungsten Carbide
Soft FaceC b Carbon
Bellows Viton Buna EPDM
Metal Parts and Spring Metal Parts and Spring 304 SS ( 18-8) or 316 Stainless Steel
SARBS Pump Maintenance Seminar, June 7, 2012
SSelfelf--Cleaning Effect of Rotating SealCleaning Effect of Rotating SealResistance to packing and adhesion by the product to the rotating member
SARBS Pump Maintenance Seminar, June 7, 2012
Seal Survival Depends on Cooling / Lubrication
Heat Generated at Faces due to Friction S Liquid Around Seal Provides Lubrication Liquid Also Removes Heat Dry-Running Will Result in Quick Failure
SARBS Pump Maintenance Seminar, June 7, 2012
Part I - The End!!!
Questions???Questions???
Tom Nowak – West Region Engineering ManagerOffice # 562-802-2555
Roger Chavez – Sales Rep.Mobile # 562.547.6431
SARBS Pump Maintenance Seminar, June 7, 2012
Sealing Systems For PumpsSealing Systems For Pumps Part II
Presented by:
Shelby ScottShelby ScottWestern Region John Crane IncJohn Crane, Inc
SARBS Pump Maintenance Seminar, June 7, 2012
Seal TypesSeal Types Causes of Seal Failure
Piping PlansSealing Water Usageg gSafeunit Flowmeters
SARBS Pump Maintenance Seminar, June 7, 2012
Type 21 Type 1
SARBS Pump Maintenance Seminar, June 7, 2012
Pump TypesPump Types
Sewage PumpSubmersible Pump
SARBS Pump Maintenance Seminar, June 7, 2012
Dual Seal Arrangement
• Inboard Seal• Prevents Leakage of
Process Water
• Outboard Seal• Prevents Leakage
Into MotorInto Motor
• Oil Between Seals• Provides OutboardProvides Outboard
Seal Support
SARBS Pump Maintenance Seminar, June 7, 2012
Waste Water Applications
SARBS Pump Maintenance Seminar, June 7, 2012
Waste-water pump
SARBS Pump Maintenance Seminar, June 7, 2012
Mechanical Seals for Waste Water Applications
Mainly Single Springs Mainly Single Springs Self-Cleaning Effect Due to Rotating Spring Face Materials Need High Resistance
Chemicals Chemicals Abrasion
Elastomers to be Chemical Resistant
SARBS Pump Maintenance Seminar, June 7, 2012
Factors influencing leakage
Seal face condition Running-in process Process influences Stability of seal face Condition of the secondary seals Face deformation caused by temperature and
pressure Vibration and stability of the machine Operating mode of the plant Characteristics of the sealed fluids Accuracy of the seal mounting and assembly Condition of the equipment
SARBS Pump Maintenance Seminar, June 7, 2012
Failure Causes at Mechanical Seal
Insufficient venting at Li id Gas ring
Liquid/ Gas mixture
Insufficient venting at Mechanical Seal
Vaporization of media in seal gap
Liquid g
Negative pressure in stuffing box
Air bubbles in piping t f b ff
rotierend stationärrotating stationary
system of pump or buffer fluid system
Hindered heat transfer due to gas ring
SARBS Pump Maintenance Seminar, June 7, 2012
Failure of Mechanical Seal
Dry running at start up of pump, insufficient ventingFaces are dull and slightly shiny, Bellows at seal face melted and withcracks
Cause of failure: Observations:
Vent pump sufficientChecklist for start up
Solution:
Train staff
Waste water
10 PSIPressure
Media
90 F
Speed
Temperature
1750 RPM
SARBS Pump Maintenance Seminar, June 7, 2012
Failure of Mechanical SealFailure of Mechanical SealCause of failure:
Dry running at start up of pump, insufficient ventingFaces dull and with traces, selective corrosion
Observations:
Fill and vent Pump before start upCheck material selection,
at pH-Value <7 use SiC
Solution:
p
Waste Water with 3% Solids
45 PSIPressure
Media
75 - 90 ºF
1780 RPMSpeed
Temperature
SARBS Pump Maintenance Seminar, June 7, 2012
Th l l d f f d t i ti f
Failure of Mechanical SealCause of failure:Thermal overload of faces due to vaporization of media in seal gap, Operation near boiling point
Observations:
Faces dull and with clear running traces and blistering. Elastomers brittle.
Solution:increase pressurelower temperature
WastewaterS
Media
190ºF
Approx 25 PSI
3500 RPM
PressureSpeed
Temperature
Flush Plan 11 - Circulation from Discharge
SARBS Pump Maintenance Seminar, June 7, 2012
Circulation Pipe From Discharge to Seal Chamber
gDischarge
Discharge to Seal Chamber
SuctionSuction
Single Mechanical Seal
Flush Plan 13 - Circulation to Suction
SARBS Pump Maintenance Seminar, June 7, 2012
Circulation Pipe From Seal Chamber to Suction
Discharge
Chamber to Suction
SuctionSuction
Single Mechanical Seal
Plan 31 – Cyclone SeparatorSARBS Pump Maintenance Seminar, June 7, 2012
Discharge
Clean fluid to sealAbrasives back to suction
SuctionSuction
Single Mechanical Seal
Plan 32 - External Source Flush Higher PressureSeal Water Is
SARBS Pump Maintenance Seminar, June 7, 2012
DischargeMinimum Pressure
5 psi / 3 bar
Seal Water IsThe Seal Face
Lubricant
A
5 psi / .3 bar Above “A”
Suction
Seal Water FlowA
Suction
Single Mechanical Seal
Sealing Wate UsageSealing Water Usage
Packing / Seals Typically Supplied 5 - 10 gpm
Packing Typically Needs Only 1 gpm
S l T i ll N d O l ½Seals Typically Need Only ½ gpm
Supply Only The Amount That’s Needed!Supply Only The Amount That s Needed!
Safe nit Sealing Wate S stemSafeunit Sealing Water SystemComplete System ToComplete System To Control Sealing Water Flow & PressureMonitors Water Supply &Monitors Water Supply & Indicates TroubleUsed With: Packing Single seals Quench seals Double seals
Quick Cleaning Without Interrupting Water Flowp gOptional Alarm
Safe nit T pesSafeunit Types
SFPPacking orSingle Seal FlushSingle Seal Flush
SFQSFQQuench Seals
SFDD bl S lDouble Seals
Plan 32 - External Source FlushType SFP
SARBS Pump Maintenance Seminar, June 7, 2012
Discharge Safeunit ToReduce UseTo ½ gpm
Minimum Pressure
5 psi / 3 bar
Type SFPSafeunit
To ½ gpm
A
5 psi / .3 bar Above “A”
Seal Water Flow
Suction
A Seal Water Flow
Suction
Single Mechanical Seal
Plan 54 - External Source BarrierSARBS Pump Maintenance Seminar, June 7, 2012
Hot BarrierOut (Top)
Minimum Pressure
20 psi / 1 2 bar
Discharge Type SFDSafeunit
A
20 psi / 1.2 bar Above “A”
Suction
A Seal Water Flow
Suction
DoubleMechanical Seal Cool Barrier In (Bottom)
O-Ring Style Split SealO Ring Style Split Seal
Fast Easy InstallationFast, Easy Installation Cartridge Split SealDowntime ReducedTo A MinimumFor Typical PumpsN l Fi S iNon-clog Finger SpringsPreinstalled O-ringsVacuum To 200 psiVacuum To 200 psi Pressure RangeUp To 3600 rpmp p
Bellows Style Split SealBellows Style Split Seal
Bellows accommodates large shaft runout (~.125”)
N i t l i No o-rings or metal springs to clog or hang up.
SARBS Pump Maintenance Seminar, June 7, 2012
Part II - The End!!!
Questions???
Roger Chavez – Western Region Offi # 562 802 2555Office # 562-802-2555Cell # 562-547-6431