basic sealing principles-ebi (hand-out version)

8/19/2019 Basic Sealing Principles-EBI (Hand-out Version)

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Basic Sealing Principles

Mechanical seals

Basic parts

Function of a mechanical seal

Types of mechanical seals

Arrangements

Materials

Operation of seals



Mechanical seals in Pumps

Stuffing Box

Motor

Coupling

Shaft

Basic Parts

Rotating Sealface (1)

Stationary sealface (3)

Secondary sealingelements (2+4)

Spring element (5)

Torque transmission(6)

12 35 46



Features of Sealfaces

Solid, homogen materials

Surface roughness(polished , lapped)

Hardness

Facewidth

Good heat dissipation

Rotating faces

Solid faces

Inserted faces



Rotating faces

Composite faces

Shrunk in

Bonded

Brazed

Supported

Stationary faces

Solid

Composite type



Stationary faces

Mounting 0 Ring mounted

single 0 ring

double 0 ring

elastomer cup

rigid clamped

Secondary sealing elements

0-rings

Enveloped rings

Rubber cups

Wedge designs

Quad rings



0-rings: location and compression

Dynamic 0-ring

7 %

Stationary 0-ring

10 - 12 %

Static 0-ring

20 %

Dynamic 0-ring Stationary 0-ring

Springs

helical springs

wave springs

metall bellows



Torque transmissions

Form locked transmission

Friction locked transmission

Function of a seal 1

Closing forces Static closing force

Hydraulic closing force

Media

Spring



Media as a lubricant and coolant

Media

Lubrication

Cooling


Acceptable minimal leakage


Medium

Leakage



Function of a mechanical seal

Closing forces

Static closing force

Hydraulic closing force

Lubrication

friction

cooling

Leakage

Media

lubrication

cooling Leakage

friction

Spring

Unbalanced / balanced seals

Balance ratio of a seal

k =

necessary to reduce the face load of a seal

sliding face area

hydraulic loaded area



Unbalanced seals

k >1 = unbalanced seal

Balanced seals

k <1 = balanced seal



Heat developement of a seal

Heat dissipationFace friction

The sealing gap

Media

Frictional heat

Pressurereduction



The sealing gap

high temperaturemedia

Boiling point

Frictional heat

Leakage

minimal = is acceptable

is influenced by many parameters

is neccessary for proper seal operation



Leakage effecting parameters

finish of the sliding facesrunning in process

flatness of the faces

face deflections caused by thermal and pressure loads

conditions of the secondary seals

vibrations and stability of the maschine

operation mode of the plant

characteristics of the sealed fluids

accuracy of the seal mounting and assembly

condition of the equipment

Types of seals

0-ring seals

(pusher type seals)

Bellows type seals



Single seal arrangement 1

Externally pressurized

springs inproduct contact

springs without

product contact


Internally pressurized

Springs facing away

from the product




Stationary seals

springs withproduct contact

springs without product

contact

Seal arrangements

Multiple seals

Back to back

face to face

tandem



Double acting seal arrangerments

Double acting seals

Multiple seal

Faces barrierfluid lubricated

Back to back or face to face

Pressurized barrierfluid( P1 + 2..3 bar

resp.+10% over P1)

No product leakage

For aggressive media

For solid loaded media

For polimerising, sticky media

Environmental safe operation

Tandem arrangement

Tandem seal

Multiple seal

Function as single seal with

safety seal

Quenchmedia

pressureless ( standard )

Surveyance possibility of seal

Leakagecontrol and drain

QuenchmediaProduct



Seal materials

Face materials

Secondary seals

Spring element

Construction parts

depending on theseal type

Seal face materials

Ideal characteristics

resistence to corrosion

resistence to wear

geometrical stableness

thermal conductivity

emergency running capability

price competitiveness

A selection is always a compromise



Burgmann standard materials

Soft faces

Buko 1 = resin impregn.carbon graphite

Buko 03 = antimony impregn.carbon graphite

Hard faces

Bume 5 = stainless steel

Buke 5 = ceramic (99%)

Buka 22 = silicone carbide

Buka 20 = silicone carbide

Buka 16 = tungsten carbide

With hard / hard face pairing

Buka 22 and /or Buka 16 is used

Thermal Conductivity of Sliding Materials

0

20

40

60

80

100

120

[ W / m K ]

B-carbon A-carbon S-Bume5 V-Al-Oxide 99,5% U2-WC Q1-SiC

Thermal

conductivity

= Cartex Standard



Chemical Resistance of Sliding Materials

0

2

4

6

8

10

12

14

B - c

a r b o n

A - c

a r b o n

S - B

u m e

5

V - A

l - O x

i d e

9 9

, 5 %

U 2

- W C

Q 1

- S i C

a l k a

l i n e

a c i d

Chem.

Resistance ofsliding

materials

= Cartex Standard

Hardness of Sliding Materials

0

100

200

300

400

500

600

700

800

[ H B ]

B-carbon A-carbon S-Bume 5 V-Al-Oxide 99,5% U2-WC Q1-Sic

Hardnessof

sliding

materials

= Cartex Standard



Secondary seals materials

Elastomers

P = Nitril Butadien Kautschuk ( Perbunan )

E = Ethylen-Propylen-Dien Kautschuk, EPDM

V = Fluor-Kautschuk, FPM, (Viton )

K = Perfluor-Kautschuk, (. Kalrez, Chemraz )

Elastomers, wrapped ( enveloped )

M1 = TTV, Viton double PTFE enveloped

M2 = TTE, EPDM, double PTFE enveloped

Produkt

Secondary sealing elements

Non-Elastomers

G = Statotherm, pure graphite

T = PTFE (Polytetrafluorethylen)

Y1 = Burasil, gasket asbestos free



Springs and construction

Springs

1.4571 = stainless steel, 316 Ti

2.4610 = Hast. C4

Construction

1.4571 = Stainless steel, 316 Ti

2.4610 = Hast. C4

1.4462 = Duplex SS, 329

Operation I

Operation with productcirculation

Flushing into the stuffingbox

from discharge or

external source

to the seal face



Operation I : Flush

Flush

- Increase of pressure in the stuffingbox

- Temperaturreduction

- Avoiding of deposits

- Reduction of solids content

Operation II

Packing

Throttlebusch

Lipseal

Mechanical seal



Operation II Quench

Operation with an external quench with different

medias

liquid steam gas

Collection of leakage

Prevent air contact

Cooling / heating

Additional lubrication

Prevent icing

Vacuum operation

Leakagecontroll

Burgmann Seals A Convincing Seal Concept for All Industries

Pulp and Paperindustry

Chemical industry

Refinery

Mining

Food IndustryWaste Water

Ph rmacy

basic sealing principles-ebi (hand-out version)

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