SEAL SUPPORT SYSTEM OPTIMISATION (2)

OPTIMISATION OF

SEAL SUPPORT SYSTEM

For, Mechanical Seal

-- G. K. Pandey

GKP Sealing Solutions

SEAL SUPPORT SYSTEM OPTIMISATION API PLAN 11 to 13 (if st. box pressure is more than

suction pressure). API PLAN 21 to 23 (if pumping ring is capable of

providing proper circulation and design does not become too much complicated)

Change Plan 02 to any other plan that provides forced circulation.

Change water cooled heat exchanger to Air cooled heat exchanger for hot services.

API PLAN 12, API PLAN 31 to API PLAN 13 (if st. box pressure is more than suction pressure).

API PLAN 32 – change stationary throat bush to rotating throat bush.


SEAL SUPPORT SYSTEM OPTIMISATION

API PLAN 32 to API PLAN 53C (If double seal is required for safety) or even otherwise if possible.

For double ended pump connect one seal to other instead providing Plan 11 from first or second stage.

API PLAN 52, 53A and 53 B to API PLAN 53 C. Face to Face seal for API PLAN 53 C. Convert Single Seal to Double Seal and stop steam

quenching Select Stationary seal instead of Rotating seal. Provide proper size orifice.



API PLAN 11 to 13 (if st. box pressure is more than suction pressure).

Plan 11


OrificeOrifice size 3 mm min.Use of multiple orifice recommended for high

pressure difference.General observation is only one orifice

irrespective of pressure difference between discharge pressure and stuffing bos pressure.

Only one orifice causes erosion on seal face.Recommended flush rate – about 5 lpm

Provide proper size orifice

Plan 13


API PLAN 11 to API PLAN 13

PLAN 11 PLAN 13

Impingement on seal face

Liquid moves away from seal face

St. box gets prssurised St. box gets de pressurised

Logically seal life will be more with Plan 13



API PLAN 21 to 23 (if pumping ring is capable of providing proper circulation and design does not become too much complicated)

PLAN 21


Plan 21

A line with orifice is connected from the discharge side of the pump through a flow control orifice and cooler into the seal chamber.

It provides cool flush to the seal. This plan is the best for liquids at self ignition temperature. In the event of seal leakage, cool liquid will continue to reach seal faces as long as the pump is running ,ensuring that hot liquid does not come out.

The disadvantage is that heat loss is more, also cooling water requirement is high.


PLAN 23


Plan 23

In this plan process fluid is re-circulated with the help of a pumping ring in the seal chamber through a cooler and back in to the seal chamber.

A Plan 23 flushing system is most effective way of providing a cool flush to the seal faces. In this arrangement fluid in seal chamber is isolated from that in the impeller area of the pump by a throat bush. Use of an internal circulating device to circulate the fluid through a closed loop cooler allows the cooler to continuously cool a re-circulated stream rather than a continuous (hot) stream from discharge to seal (Plan 21). The cooler is required to cool the liquid in the loop. Therefore cooler size reduces drastically as compared to Plan 21 cooler. Also the cooling water requirement is much less than Plan 21.


PLAN 21 to PLAN 23

PLAN 21 PLAN 23Large cooler requirement – more initial cost

Small size cooler required – less initial cost

More heat loss – product to be cooled from pumping temperature to desired temperature.

Only heat soaked plus heat added by seal needs to be removed

Water requirement more Water requirement less



Change Plan 02 to any other plan that provides forced circulation.

Replace Plan 02 by any other plan

Due To Scale Formation Cooling Becomes Ineffective.

In Majority Of Pumps Cooling Jacket Is Integral With The St. Box. Due To This Removal Of Scale Becomes Very Tedious.

Also Stuffing Box Wall Thickness Reduces In Scale Removal, Making St. Box Weak.

St. Box Jacket Cooling Can Be Eliminated By Changing The API Plan 02 To Any Alternative Plan



Change water cooled heat exchanger to Air cooled heat exchanger for hot services.

Water cooled heat exchanger by air cooled

WATER COOLING – DISADVANTAGES SCALING Heat Transfer Poor. Scale Should Be Removed

Periodically. The Material Becomes Weak In Scale

Removing Process. Cost Of Scale Removal. Cost Of Shut Down. Cost Of Water Cost Of Recirculation Of Water


Plan 02


Plan 21- Water Cooled Heat Exchanger


API Plan-21

Shandilya Energy


API PLAN 12, API PLAN 31 to API PLAN 13 (if st. box pressure is more than suction pressure).

Plan 12 and Plan 31 to Plan 13

If stuffing box pressure is more than suction pressure

Change Plan 12 to Plan 13Change Plan 31 to Plan 13

In both the plans finer particle (approx

150 micron and less go to seal area)


PLAN 12


PLAN 31


Centrifugal force will throw away heavier particles

Only smaller particles less than throat bush clearance can go to seal area


API PLAN 32 – change stationary throat bush to rotating throat bush.

Fixed throat bush to Rotating Throat bush

Fixed throat bush was being provided to support gland packing.

Now Mechanical Seal is standard selection so it can be replaced with rotating throat bush


Plan 32

Large amount of flushing liquid is recommended to keep dirty liquid away from seal area.

Thumb rule is to maintain 5m/sec (15 ft/sec) velocity at throat bush.

Plan 32liquids dilutes the product. Should be used only when there is no alternative.


Throat bush supports gland packing


Fixed Throat bush


Rotating Throat bush



API PLAN 32 to API PLAN 53C (If double seal is required for safety) or even otherwise if possible.


For double ended pump connect one seal to other instead providing Plan 11 from first or second stage.

Multi Stage pump

In multi stage pumps change 11 to

Plan 13 and Plan 11 combination

Advantages: Non drive end seal will have plan 13 Drive end seal will get flushing from relatively

low pressure area thus seal life will increase. Flushing fluid requirement half – more

volumetric efficiency


API PLAN 11


API PLAN 13 and 11


TANDEM SEAL

Stagnant liquid

Flushing required to remove heat


BACK TO BACK

Better heat removal.

But inboard seal is at the end so heat removal less effective.


FACE TO FACE

Face heat removal excellentAlso stationary seal advantage


Plan 52


PLAN 53 A


PLAN 53 B


PLAN 53 C


Shandilya Improved 53C

Shandilya Energy

Bellow Tracker

Shandilya Energy

53C

Shandilya Energy

Plan 52 and Plan 53 C


Plan 53A, Plan 53 B and Plan 53C

General Recommendations

Face to Face seal for API PLAN 53 C.


Convert Single Seal to Double Seal and stop steam quenching

Convert Plan 11,52 or Plan23,52 to API Plan 53 C with face to face seal

Inboard seal needs flushing for heat removal as barrier fluid is stagnant on the ID of inboard seal.

In face to face seal heat removal is ideal, so inboard seal flushing can be avoided.

Between Plan 52 & Plan 53A,Plan 53 B and Plan 53 C, Plan 53 C is the best plan



API PLAN 52, 53A and 53 B to API PLAN 53 C.

PLAN 62

Quenching

KEEPS ATMOSPHERE AWAY TOXIC FLUIDS CRYSTALLIZING PRODUCTS CRYOGENIC APPLICATIONS HIGH FREEZING POINT FLUIDS HIGH TEMP. FLUIDS WHICH DECOMPOSE IN CONTACT

WITH ATMOSPHERE FLUID HAVING TENDENCY TO BECOME VISCOUS IN

CONTACT WITH ATMOSPHERE

ADDITIONAL ADVANTAGES

KEEPS AREA OUTSIDE SEALS CLEAN PROVIDES HEATING / COOLING TO SEAL FACES.

Problems with quenching

Quenching fluid leaks towards bearing side and causes premature bearing failure.

Cost of quenched fluid.

Stop Steam Quenching

By going for Double Seal atmosphere is kept away. Therefore no need of steam quenching


Provide proper size orifice

MONITORMONITOR Auxiliary systems :-

Orifice dia ( minimum 3.2 mm). Use multiple orifice for high differential pressure.

Flushing fluid quantity and pressure (In Plan 32 it is must)

For double back to back seal pressure on downstream side. Maintain proper pressure in API Plan 53 pots.

For heat exchangers out let temp. of product i.e inlet to seal quantity and outlet temperature of cooling water.

Regular cleaning of filters

Quenching fluid pressure, temperature and quantity


Select Stationary seal instead of Rotating seal.

Rotating seal

Shaft Movement

ROTATING SEAL


IN THIS CONFIGURATION THE SPRING MEMBER IS ROTATING

ADVANTAGESCentrifugal action keeps particles away from flexible members

Generally requires less axial envelope particularly outside seal chamber

Smaller radial section for a given shaft size Generally lower cost.

Stationary Seal


STATIONARY SEAL

In this configuration spring member is stationary.

Advantages-Capable of higher speeds above 23m/sec.Able to take more st. box non

perpendicularity. Can take more vibrationCan accept media with higher viscosity

Thank You.


http://www.pressure-drop.com/Online-Calculator/index.html

PLAN 53 C


Documents

SEAL SUPPORT SYSTEM OPTIMISATION (2)