Sealing Systems For PumpsSealing Systems For Pumps … Sealing Systems Scott 060712.pdf · Sealing Systems For PumpsSealing Systems For Pumps Part I ... Piping Plans Sealinggg Water

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


PackingMechanical Seal Basics

Pros & Cons: Packing & SealsgMechanical Seal Elements

Basic Seal DesignsBasic Seal DesignsMaterials of Construction


AtmosphereVessel pWall

Shaft

ProcessProcessFluid Leakage


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.


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


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


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


Drive Elements Adaptive Hardware

Load Element

Primary Seal ElementsSecondary Seal Elements Primary Seal ElementsSecondary Seal Elements


Primary Ring

RetainerDisc

Drive Band

Mating Ring

O-RingSpring Adaptorat g g

Spring

Elastomer Bellows


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


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


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


SSelfelf--Cleaning Effect of Rotating SealCleaning Effect of Rotating SealResistance to packing and adhesion by the product to the rotating member


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


Part I - The End!!!

Questions???Questions???

Tom Nowak – West Region Engineering ManagerOffice # 562-802-2555

[email protected]

Roger Chavez – Sales Rep.Mobile # 562.547.6431

[email protected]


Sealing Systems For PumpsSealing Systems For Pumps Part II

Presented by:

Shelby ScottShelby ScottWestern Region John Crane IncJohn Crane, Inc


Seal TypesSeal Types Causes of Seal Failure

Piping PlansSealing Water Usageg gSafeunit Flowmeters


Type 21 Type 1


Pump TypesPump Types

Sewage PumpSubmersible Pump


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


Waste Water Applications


Waste-water pump


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


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


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


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


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


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


Circulation Pipe From Discharge to Seal Chamber

gDischarge

Discharge to Seal Chamber

SuctionSuction

Single Mechanical Seal

Flush Plan 13 - Circulation to Suction


Circulation Pipe From Seal Chamber to Suction

Discharge

Chamber to Suction

SuctionSuction


Plan 31 – Cyclone SeparatorSARBS Pump Maintenance Seminar, June 7, 2012

Discharge

Clean fluid to sealAbrasives back to suction

SuctionSuction


Plan 32 - External Source Flush Higher PressureSeal Water Is


DischargeMinimum Pressure

5 psi / 3 bar

Seal Water IsThe Seal Face

Lubricant

A

5 psi / .3 bar Above “A”

Suction

Seal Water FlowA

Suction


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


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


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.


Part II - The End!!!

Questions???

Roger Chavez – Western Region Offi # 562 802 2555Office # 562-802-2555Cell # 562-547-6431

[email protected]

Documents

Sealing Systems For PumpsSealing Systems For Pumps … Sealing Systems Scott 060712.pdf · Sealing Systems For PumpsSealing Systems For Pumps Part I ... Piping Plans Sealinggg Water