mechanical seals

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Mechanical Seals

Firas Al-Zayadneh

PPT Course

Borg-Warner Mechanical Seals

Prepared By:

Firas M. Al-Zayadneh

Mechanical Skills Training Unit SAITD

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Mechanical Seals

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Mechanical Seals

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Objective

Develop the skills and theoretical knowledge required to remove, inspect, troubleshoot, and refit the Borg-Warner mechanical seal in accordance with

manufacturer’s standard procedures.

Course Objective

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Mechanical Seals

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1. The various methods of sealing rotating equipment

2. Classification of Mechanical Seals

3. The Borg-Warner Seals

4. The Bellows seals

Overview

5. Mechanical seals-special parts

6. The installation of a mechanical Seal

7. Environmental Control

8. Why Seals fail?

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Chapter

The various methods of sealing rotating equipment1

Introduction

1.1 Stuffing box packings

1.2 Condensate injection sealing

1.3 Floating seal rings

1.4 Labyrinth Bushings

1.5 Wind back scroll or wind back seal

1.6 Lip Seals

1.7 Mechanical Seals

a. Principles of operation

b. Comparison with other types

c. Advantages

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Mechanical Seals

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Chapter

Classification of Mechanical Seals2

Introduction

2.1 Balanced and unbalanced

2.2 Rotating and stationary

2.3 Single and double seals

2.4 inside and outside seals

2.5 Seals placed on the shaft or cartridge mounted

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Chapter

The Borg-Warner Mechanical Seals3

3.1 U-type mechanical seal

3.2 Some design features of the U-type seal

3.3 W-Seals (double seals)

3.4 Tandem Seal type UT

3.5 D-Type mechanical Seals

3.6 GS mechanical seals

3.7 GU-mechanical seal

3.8 The QL and QBL mechanical seals

3.9 The inverted seals UHT and DHT

3.10 Borg-Warner model numbering system

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Chapter

The Bellows Seals4•Welded Metal bellows seals

•Advantages

•The advantages of stationary bellows seals comparing to rotating bellows seal

•Potential Problems

•Borg-Warner Bellows seals

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Chapter

Mechanical Seals – Special Parts5

•The seal flange and seal flange bushing

•Shaft sleeve

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Chapter

The Installation of a Mechanical Seal6

•Determine if the pump or unit is in good enough condition to use a mechanical seal (pre-installation checks)

•Place the seal at its correct position (seal setting with respect to the seal manufacturer instructions)

•Assemble all components of the mechanical seal in correct manner and in correct sequence

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Chapter

Environmental Control7• Environmental controls are necessary to control dirt and heat, or to cool the seal area and, under certain conditions, to keep the product away from the seal entirely

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Chapter

Why Seals Fail?81. The main reasons of seal failures

2. Seal failure due to faulty installation

3. Seal failure due to lack of auxiliaries

4. Pump condition as a cause of seal failure

5. Changed conditions

6. Wrong choice of materials

7. Fault in the seal parts from the manufacturer

8. Some shapes of failure in the mechanical seal parts

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We hope you would enjoy this course

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Introduction

• Commercially developed 50 years ago

• They are the predominant type of seals found on centrifugal pumps, compressors, and similar machines

• They present a significant improvement over former sealing devices

• Despite their widespread use, there has been a growing concern amongst users about their performance in service

• The behavior of mechanical seals is unpredictable, and their mean time between failures appears to be between 8 to 13 months, but some times they might live up to 3 to 5 years

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Introduction

•Studies have shown that failures come in the following distribution

•The major cause of failure is often beyond the scope of the seal designer’s responsibility, springing from possible lack of knowledge and training; certain from a lack of real appreciation of those factors which can clearly cause failure

•The other major component which can cause a pump outage is the bearings

40%

24%

19%

9%

8%

operating problems Mechanical difficultiesFaulty fluid circuit designSeal component selection inadequateMiscellaneous

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Chapter

The various methods of sealing rotating equipment1

Introduction

1.1 Stuffing box packings

1.2 Condensate injection sealing

1.3 Floating seal rings

1.4 Labyrinth Bushings

1.5 Wind back scroll or wind back seal

1.6 Lip Seals

1.7 Mechanical Seals

a. Principles of operation

b. Comparison with other types

c. Advantages

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Mechanical Seals

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The function of a seal

• The basic function to a seal is to prevent or to reduce to a minimal level the leakage from high pressure areas to low pressure areas

• Seals come in two main categories: Static seals and dynamic seals

• Also seals serve to prevent entry of foreign materials into an operating medium

• In some rotating machines, like multi stage centrifugal compressors, shaft seals are normally used to achieve one of the following:

• Reduce or prevent in-leakage of gas

• Reduce or Prevent out-leakage of gas

• Reduce or prevent both in- and out-leakage

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The various methods of sealing rotating equipment

The following methods are commonly used for sealing rotating shafts:

1. Conventional packings

2. Condensate injection sealing

3. Floating seal rings

4. Labyrinth seals

5. Wind back scroll or wind back seals

6. Lip seals

7. The mechanical seals

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1 Conventional packings

• In pumps, packings must leak to perform properly, they are used to control leakage and not to stop it

• This controlled leakage along the shaft allows the fluid being handled to send lubricant into the packing

• Many packings contain a built in lubricant, it is intended only for initial start up or as temporary protection

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• Stuffing boxes come in three basic forms:

• Where pressure is above atmospheric

• Where pressure is below atmospheric

• When used for slurries

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• Where pressure is above atmospheric

P>atm atm

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• Where pressure is below atmospheric

P<atm atm

Flow from pump discharge

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• When used for slurries

Slurry atm

Clean Flow from external source

(pressure should be 10-25psi more than pump pressure)

Slurry atm

Clean Flow from external source

(pressure should be 10-25psi more than pump pressure)

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Disadvantages:

1. It requires regular adjustment of the gland

2. It will score the shaft or shaft sleeve

3. the packings require a generous amount of lubrication, that means wastage and pollution

4. It requires relatively more power, because rings around the shaft acts as brakes

5. Can’t cope with increasing pump sizes and stuffing box’s pressures

6. If used on abrasive materials, a packing offers a short lift together with increased power consumption resulting from frictional drag

1 2 3 4 5 6100

200

300

400Pres

sure

(psi

)

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Advantages:

1. Initial cost is relatively low

2. Easily replaced in the field

3. Available in wide range of materials

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2 Condensate injection sealing

• A serrated breakdown bushing replaces the packing and the pump sleeve runs within the said bushing with a narrow radial clearance (0.0014”)

• Cold condensate at higher pressure must be available and introduced to this breakdown bushing

• A small part of the injected condensate flows into the pump, the reminder flows outward into a cavity called a collecting chamber which is vented to the atmosphere, and from here the leakage is piped back to condenser

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2 Condensate injection sealing

Drawbacks of condensate injection sealing:

1. It requires a lot of piping and auxiliary equipment with energy to keep it going

2. Pressure monitoring is of great importance

3. The radial clearance is also of great importance between the breakdown busing and the shaft sleeve

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3 Floating seal rings

• In this type a number of individual solid rings are used, each ring is mounted in a specially constructed holder and it is spring loaded to produce an stationary seal in axial direction, the assembly is locked against rotation

• The radial clearance between the above described rings and the shaft sleeve is relatively small

• The principle of work is similar to the condensate injection seal

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3 Floating seal rings

Advantages:

1. The individual rings are able to float to a certain degree, thus allowing then to find their own relative position t the shaft

2. This seal is cheaper to maintain as individual portions of the seal may be replaced when damaged

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4 Labyrinth Seal

• They are controlled clearance seals, there are no rubbing parts

• The basic idea behind this type is to make it as difficult as possible for the fluid to get out

• A small leak is tolerated

• Because of the narrow axial and radial clearance, installation and maintenance has to be well taken care of

• They are well suited for shafts that rotate at high speeds

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4 Labyrinth Seal

There are several types of these seals:

• Straight seal

• Stepped

• interference

Straight sealStepped sealinterference seal

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5 wind back scroll or wind back seal

• In its simplest form, it is a sleeve with helical grooves, when the pump is running; it provides a reverse pumping action thus slowing down the flow of the liquid trying to get out

• Wind back does not prevent leakage but reduces it depending on the shaft running speed and its design

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5 wind back scroll or wind back seal

Disadvantages:

• It is less effective when shaft is running at low speeds

• If the machine is completely stopped then this seal wont work and it will act as a regular throat bushing

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6 Lip seals

• It is used primarily to keep lubricant in

• They are called oil seal or shaft seals

• Advantages:

• Fit into small space• Fairly low cost• Easy to install• Handle many variables while

sealing

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Mechanical Seals

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6 Lip seals

Operation:

An interference fit exists between the lip and the shaft, a spring is usually fitted to insure uniform pressure and contact around the shaft.

The lip should ride on a thin film of lubricant, the film does the sealing so it must be controlled precisely by the mechanical pressure of the sealing element and the shaft finish

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7 Mechanical Seals

• A system consists of a rotating element attached to the shaft, that turns against a stationary face attached to a flange.

• Continuous contact between faces is maintained by the hydraulic pressure of the pump and the loading of the spring or bellows

• The two mating faces are made from dissimilar materials and with finely lapped smooth surfaces

• Enough pressure between faces is there to exclude all foreign materials except a thin film of lubricant between the faces

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7 Mechanical Seals

The function of the spring in the mechanical seal:

• To compensate the shaft play in the axial direction, and to keep mating faces in contact all the time

• Also the spring pressure maintain contact while the machine is not working

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7 Mechanical Seals

How it works?

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7 Mechanical Seals

Comparison between mechanical seal and conventional packings:

Conventional packings Mechanical seals

Large sealing areas Small sealing areas

Leakage from run out No Leakage from run out

Leakage from endplay No Leakage from endplay

Can be packed in place Installed over shaft end

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7 Mechanical Seals

Reasons why many companies are using mechanical seals more than conventional packings:

1. Pollution

2. Cost of product

3. Power consumption

4. Cost of bearings

5. Vertical pumps

6. Cost of shafts or sleeves

7. Vacuum service

8. High pressures

9. Self Adjusted

10. Housekeeping costs

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Mechanical Seals

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Chapter

Classification of Mechanical Seals2

Introduction

2.1 Balanced and unbalanced

2.2 Rotating and stationary

2.3 Single and double seals

2.4 inside and outside seals

2.5 Seals placed on the shaft or cartridge mounted

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Introduction

Mechanical seals can be classified into four types:

1. Balanced or Unbalanced

2. Rotating seal or stationary seal

3. Single seal or double seal

4. Inside seal or outside seal

And we can also classify them whether any of the previous types can be mounted on the shaft or cartridge mounted

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Balanced and Unbalanced Mechanical seals

The forces acting on the mechanical seal:

1. The force of the spring, and it acts mainly when the machine is off

2. When the pump is running, the pressure inside the stuffing box will increase, this pressure acts on the total area of the rotating face forcing it against the stationary face Fluid pressure

spring pressure

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3. The third force is the force of the liquid film coming in between the faces as a lubricant, we have to remember that this film is essential for correct operation of the seal. This film produces a pressure gradient across the faces, and this tends to force the faces apart

Fluid pressure

Film wedge

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So, in general we have 3 forces:

1. A Spring force Fs pushing the faces towards each other (closing force)

2. Hydraulic force Fh pushing the faces towards each other (closing force)

3. Film wedge force Fw which tend to force faces apart (opening force)

The resultant force Fr which is trying to close the faces will be:

Fr = Fs + Fh - Fw

BAFh

Fs

Fw Fw

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• In practice, the spring force Fs is very small and we can ignore it

• We try to make Fw very close to Fh or a little smaller

• As a conclusion we find out the following:

• If Fh = Fw, we call this seal a balanced seal

• If Fh is bigger than Fw, we call this seal unbalanced seal

• If Fh is smaller than Fw, the seal in this case doesn’t work

BAFh

Fs

Fw Fw

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Unbalanced Mechanical seal

This figure describes a typical unbalanced mechanical seal where the pressure of the stuffing box is 100 lb/in2 and face area of 2 in2

The pressure at the outside diameter of the seal faces is 100 psi and at the inside diameter is atmospheric (0 psi), the average pressure across the faces is (100+0)/2=50 psi

As mentioned before Fw=Area x pressure, that means Fw=2x50=100 lbs , this force tends to open the faces

At the same time, Fh=Area x pressure = 2 x 100 = 200 lbs , and this force tend to close the faces

BA

100 lb/in2

100 lb/in2

50 lb/in2

0 lb/in2

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Unbalanced Mechanical seal

In this case, the mechanical seal is unbalanced, and the excessive closing force can cause excessive heating of the seal faces. Because there is no way to form a lubrication film, and this is why this type is not used frequently, and used only for low pressure applications and small sizes, the limit is usually set for 100 psi

200 lbs 100 lbs

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Balanced Mechanical seal

Here, the closing force is reduced by reducing the closing area, and the easiest way to do this, is by using a stepped sleeve onto the shaft

Now only 1 sq.in. is exposed to the pressure, so the closing force is reduced to 100 lbs

When the forces are perfectly balanced, there would be a danger of opening up the faces, if the force increased due to any reason or due to sudden shaft play

1 sq.in.

1 sq.in. Stepped sleeve

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The following image shows the principle behind the balanced mechanical seal

Diameter A is called the balance diameter

This seal is actually over balanced, and would be forced apart by the pressure gradient between faces

This is not a correct way to balance a seal

A

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To overcome this problem, we must create a pressure area by increasing the contact area above the balance diameter, and we increase the resultant closing force

The balance in mechanical seals is given in %

The balance diameter divides the contact area of the stationary face in two parts, when we say: a seal is 75% balanced, we mean that 75% of the contact area lies above the balanced diameter, and the remaining 25% lies beneath the balance diameter

A

A

75%25%

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Stationary and rotating sealsRotating Seals

It is called rotating because the spring rotate with the shaft, and it represents 95% of the seals

Advantages:

• It is suitable to be used in chemical solutions where solids may precipitate, and because of centrifugal forces, this seal has a tendency to free its self

• Low cost seal and available in a wide variety of materials and designs

Disadvantages:

• The centrifugal forces will cause additional stress on the rotating parts

• This design is seldom used for high speed applications because of the centrifugal forces affecting the flexible seal-ring

• This type has a tendency to vibrate at high speeds and big shaft diameters

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Stationary and rotating seals

Stationary seals

It is called stationary because the spring doesn’t rotate with the shaft

Advantages:

• Centrifugal forces do not work on the flexible seal ring and springs

• Used on shafts that travel at 15000 fpm (feet per minute) or higher and shaft diameter more than 3 inches

• It is a logical choice for use on mixers, because it can handle misalignment problems

Disadvantages:

• If used with chemical solutions where solids may precipitates and tend to foul the sliding faces

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Single or Double seals

Mechanical seals are not zero leakage devices, they work based on a fluid film existing between the mating faces, and therefore a small amount of leakage is there (might be as low as 1 drop per minute), and the flow is often invisible. In cases where zero leakage is required for any reason, a single seal is not suitable, and a double mechanical seal is generally selected

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Inside or outside seal

If the rotating face is mounted inside the stuffing box holding the fluid, it is referred to as an inside seal

When the rotating face is mounted outside the stuffing box, then it is known as outside seal

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Advantages of Inside seal:

• The rotating face is surrounded by liquid, and the hydraulic forces are acting with the springs to keep the faces in contact

• Flushing and lubrication can be designed to be more positive for better cooling

• It take advantage of centrifugal forces to throw dirt and solid particles away

Disadvantages:

• The metal parts are subjected to chemical attack from liquid inside the stuffing box

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Advantages of outside seal:

• Preferred for ease of maintenance

• They permit the metal parts to be isolated from corrosive environment

Disadvantages:

• Hydraulic forces tend to open seal faces

• Lubrication and flushing is restricted

• Abrasive, dirt particles in the fluid can pack in the annular opening, these are then pushed between the faces and cause rapid wear

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Chapter

The Borg-Warner Mechanical Seals3

3.1 U-type mechanical seal

3.2 Some design features of the U-type seal

3.3 W-Seals (double seals)

3.4 Tandem Seal type UT

3.5 D-Type mechanical Seals

3.6 GS mechanical seals

3.7 GU-mechanical seal

3.8 The QL and QBL mechanical seals

3.9 The inverted seals UHT and DHT

3.10 Borg-Warner model numbering system

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U type mechanical seal

U type mechanical seal is the most widely used Borg-Warner seal, it is a single seal widely used in refining processes and chemical industries and in pipeline and general purpose field

It is a balanced seal for pressures up to 1000 psi, and its temperature range is limited by the type of gasket material used. It can handle temperatures up to 220 C

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Basic seal parts include:

• Seal drives

• Drive pins

• Coil spring

• Spring holder

• U-cup

• Rotating face

• Stationary face

• Seat gasket

Special parts consist of:

• Seal flange

• Shaft sleeve

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Some design features:

• Gaskets fully confined

• Positive drive

• Single coil spring

• Uniform spring pressure

• Flexibility of the faces

• Ease of dismantling

• Protection against damage

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Special arrangements

As we know before, mechanical seals can’t prevent leakage completely. So, if the product is toxic or dangerous; then we can use two mechanical seals in one stuffing box

There are two arrangements for this case:

1. The rotating face of the inboard seal in opposite direction of the rotating face of the outboard seal (back to back) and we call this double seal or W-Seal

2. The two rotating faces are in the same direction. And we call this arrangement Tandem seal

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Double

Seal (W-Seal)

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Tandem Seal

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The difference between Tandem seal and Double seal (W-Seal):Tandem Seal Double Seal (W-Seal)

Both seals are faced in the same direction The rotating faces in opposite direction (back to back)

Both seals are running in two different environments Both seals are running in the same environment

Fluid in the seal cavity is used as a barrier fluid. And is at pressure lower than that in the stuffing box. Therefore, leakage will be from stuffing box into the seal cavity containing the barrier fluid

The seal liquid (buffer liquid) must be at a pressure above the operating pressure of the stuffing box in order for the seal to function

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Double seals (W-Mechanical Seal)

A seal liquid (buffer liquid) whose temperature and pressure are controlled is circulated through this cavity to provide good seal life and to prevent completely any leakage of the product outside the pump

The seal liquid must be at a pressure above the operating pressure of the stuffing box in order for the seal to function. The liquid going across the inboard face will enter the stuffing box and mix with the pumped fluid, the liquid going across the outboard face will go to atmosphere

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Double seals (W-Mechanical Seal)

In case the inboard seal leaks, the seal liquid (buffer liquid) will leak into the pump, and because of this the buffer liquid must be compatible with the pumped liquid

The seal liquid (buffer liquid) in most cases is either oil or water

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Tandem Mechanical Seals

Both seals are running into two different environments. The inboard will be sealed against the pumped product and the outboard seal will be running in an environment of its own. (this can be oil, methanol, or in fact, air)

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The UT mechanical seal is tandem mechanical seal used especially for unattended product pipe line pumps

The stuffing box is divided into two chambers. The inner chamber contains a single balanced type U seal which seal pumped product exactly same as the conventional single seal. The outer chamber is filled with lubricating oil and is connected to a control tank with piping

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How control tank works:

• The control tank is partially filled with lubricating oil on level higher than the stuffing box of the pump

• The pumping ring takes suction from the tank and discharges into the tank. Creating a constant flow of lubricating oil to and from the tank while the pump is in operation

• Normal product leakage from the inner seal is carried to the tank in the oil stream, where it separates and flows to the drain through orifice B

• If the inner seal fail, product flow to the tank will exceed carrying capacity of orifice B and the level in the tank will rise, actuating the high level control

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• If the outer (oil) seal fails, oil level in the tank will lower until it actuates the low level control

• Additional control (orifice A and pressure switch) is included for units handling Butane or propane in addition to other products

• Normal leakage vents through orifice A, if the product seal fails, pressure will be created in the tank because of low gas carrying capacity of orifice A and B. A tank pressure of 1.5 psi will actuate the pressure switch

• Level controls and pressure switch can be connected to a warning system or can be used to shut down the pump

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D-Type mechanical seal

• It is a special seal design for boiler feed pump

• The maximum allowable temperature on the D seal is 80 C

• There are two main differences between D-type and U-type in the shape of the parts:

1. the flange design incorporates a volute and has an inlet and outlet tap (Port) completely like the pump casing

2. The rotating face has a number of slots in its outer diameter

• When the pump running, the rotating face acts as an impeller, forcing the liquid to leave the flange via outlet port. The liquid is then lead through a cooler and returned to the seal via flange inlet

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• By circulating and thus cooling the product as described, it is possible to run D-Type seal on pumping temperatures much higher than the maximum allowable temperature

• As leakage across the seal faces will automatically be made up by water (product) from the pump it will be obvious that a too high leakage rate cause stuffing box temperature to increase

• The use of the stuffing box neck bushing is a must with D seals. This is not to build up pressure in the box but to act as a kind of heat barrier

• A vent valve is very important at the highest point in the system

• The piping system should be as short as possible, and bends should be avoided to reduce the pressure drop

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• The cooler should be mounted approx 18-24” above the shaft center line. The reason for this is that very often boiler feed pumps can be on standby, fully primed and ready to run. The pump is then full of hot water. By placing the cooler as mentioned above, the natural circulation will happen. Thus the liquid surrounding the seal is always relatively cool

• Usually D seals use tungsten carbide faces, and this material doesn’t accept sudden change in temperature. So we have to remember: Coolers above Shaft Center Line

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Type GS Mechanical Seals

• This is a special design to be used as the secondary seal in tandem with the standard U type

• The tandem combination is of type GU seal

• Also it can be used in tandem with a Q seal (called GQ), and with QB seal and called (GQB) or UZ seal and called GUZ

• The GS seal can be used as a single gas seal for a compressor or any other machine handling gases such as Air, Helium, Nitrogen, Carbon dioxide, propane, butane, hydrogen sulfide, and oxygen or in wet gas vapors

• In general, it can be used on compressors handling corrosive or non-corrosive gases up to 1000 psi and at surface speed up to 400 ft/second

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Type GU Mechanical Seals

• The GU seal is a combination of two standard seals ( U and GS) and is a typical example of a tandem arrangement

• Used for unattended pipelines where a backup seal is required

• Any leakage from the U seal enters the GS seal cavity, as long as this is a normal leak this will be drained off through the orifice, installed in the GS flange drain tap

• In case the leakage on the U seal increases beyond the capacity of the orifice, the GS cavity will fill up and finally pressure will start to build up. When the pressure reaches a certain setting a pressure switch is activated sending an alarm signal to control room

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Type GU Mechanical Seals

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GS type Seal ( BORG WARNER GAS SEAL)

• Designed to seal dry gases such as Helium, nitrogen and oxygen that contain no lubrication properties

• It is a conventional mechanical seal with a bearing included to carry load imposed by the spring and hydraulic forces

• Rotating face is made usually from hardened alloy steel, stationary face is made from graphite carbon

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Chapter

The Bellows Seals4•Welded Metal bellows seals

•Advantages

•The advantages of stationary bellows seals comparing to rotating bellows seal

•Potential Problems

•Borg-Warner Bellows seals

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Chapter

Mechanical Seals – Special Parts5

•The seal flange and seal flange bushing

•Shaft sleeve

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Chapter

The Installation of a Mechanical Seal6

•Determine if the pump or unit is in good enough condition to use a mechanical seal (pre-installation checks)

•Place the seal at its correct position (seal setting with respect to the seal manufacturer instructions)

•Assemble all components of the mechanical seal in correct manner and in correct sequence

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Pre-installation checks

1. Shaft run out

Run out shouldn’t exceed 0.002” 0.05mm

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2. Concentricity of shaft sleeve:

Shouldn’t exceed 0.002” 0.05mm

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3. Lateral or axial shaft movement:

For roller type bearings: normally not exceeds 0.002” 0.05mm

For plain thrust bearings:

This can range from 0.010” to 0.025”

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4. Radial Bearing tolerance:

Max allowable value is 0.002”

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Mechanical Seals

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5. Measuring of stuffing box:

1 Stuffing box face run out:

acceptable run out is 0.001” per 1” of shaft diameter to a max of 0.005”

2 Concentricity of shaft in the stuffing box:

Shouldn’t exceed 0.001” per 1” of shaft diameter up to a maximum of 0.005”

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6. Impeller Run-Out:

Allowable is 0.001” per 1” o impeller diameter

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Chapter

Environmental Control7• Environmental controls are necessary to control dirt and heat, or to cool the seal area and, under certain conditions, to keep the product away from the seal entirely

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Chapter

Why Seals Fail?81. The main reasons of seal failures

2. Seal failure due to faulty installation

3. Seal failure due to lack of auxiliaries

4. Pump condition as a cause of seal failure

5. Changed conditions

6. Wrong choice of materials

7. Fault in the seal parts from the manufacturer

8. Some shapes of failure in the mechanical seal parts

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Why seals fail?

The main reasons of seal failures

Seal failure due to faulty installation

1. Improper seal setting

2. Gasket failure

3. Meeting faces not matching properly

Seal failure due to lack of auxiliaries

1. Cyclone separator

2. Orifices

3. Heat exchanger

4. Drain and venting lines

Pump condition as a cause of seal failure

1. Misalignment of faces

2. Shaft endplay

3. Abrasive particles

Changed conditions

1. Vaporizing and flashing across faces

2. Stuffing box pressure, temperature and gravity of product

Wrong choice of materials

Fault in the seal parts from the manufacturer

Some shapes of failure in the mechanical seal parts

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Thank you

mechanical seals

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