API Plan 53A

API Piping Plan 53A FSA Knowledge Series

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Abstract This Fluid Sealing Association Knowledge Series training presentation introduces API Piping API Plan 53A. A description is provided on: ▪ What is an API Plan 53A? ▪ How an API Plan 53A Works ▪ What does an API Plan 53A do?

▪ What an API Plan 53A cannot do ▪ Optional Features for an API Plan 53A ▪ Cost to Operate an API Plan 53A ▪ How to Size an API Plan 53A ▪ How to Install an API Plan 53A ▪ General API Plan 53A Commissioning Guidelines ▪ How to Operate an API Plan 53A ▪ General Troubleshooting of an API Plan 53A ▪ Alternatives to an API Plan 53A 3

What are Piping Plans?

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Piping plans collectively are different piping arrangements of fluid used to improve the conditions the mechanical seal operates in with the objective of improving the mechanical seal’s life.

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The American Petroleum Institute adopted numbers and created definitions for each piping plan configuration, thereby allowing a common language across the industry to simply describe a particular configuration.

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The American Petroleum Institute standard API-682 is where the definition of each piping plan can be found and where they may periodically be updated.

What is an API Plan 53A? API Plan 53A is one of a series of piping plans that provide a pressurized liquid barrier fluid to a dual liquid lubricated mechanical seal.

An API Plan 53A provides: ▪

Zero emissions of the pumped fluid to the environment

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A method to pressurize the barrier fluid

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A reservoir of barrier fluid to replace fluid consumed by the mechanical seals

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A heat exchanger to dissipate heat generated by the mechanical seal and absorbed from the pump

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Instrumentation to monitor seal performance and detect early onset of seal performance deterioration

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Containment of pumped fluid in the event of seal or support system failure

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What is an API Plan 53A? API Plan 53A consists of the following components: Pressure Transmitter

Pressurized Gas Supply PIT

Barrier Fluid Refill LI

Mechanical Seal LIT

Level Transmitter

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Reservoir with Optional Cooling Coils Drain

How an API Plan 53A Works Dual liquid lubricated mechanical seals contain a pumping device within the mechanical seal that circulates barrier fluid in a loop from the mechanical seal, through a reservoir, and returning to the mechanical seal. An API Plan 53A uses gas directly in contact with the barrier fluid in the reservoir to pressurize the barrier fluid circulation loop. The reservoir supplies a volume of barrier fluid to replace fluid consumed by the mechanical seal through normal leakage.

Seal Face Heat Generation

Heat Exchanger

Mechanical Seal

Barrier/Buffer System

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Heat Soak

Heat transported by barrier/buffer fluid flow

Natural Convection

How an API Plan 53A Works To move the barrier fluid through the circulating loop, a pumping ring is incorporated into the mechanical seal design. There are various styles and shapes of pumping rings, however they are all driven by the rotating shaft of the equipment.

Radial flow pumping ring

With higher shaft speeds, the pressure and flow generated by the pumping ring will increase.

Axial flow pumping ring Barrier fluid Process fluid

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Atmosphere side

How an API Plan 53A Works Pressure is generated in an API Plan 53A within a reservoir, where a pressurized gas blanket acts directly on the barrier fluid.

The pressure of the barrier fluid will typically be constant and equal to that of the gas supply.

For hot process fluids, the reservoir may contain a cooling coil to remove heat absorbed into the system.

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How an API Plan 53A Works During operation of a liquid dual pressurized mechanical seal, barrier fluid is consumed as a result of normal leakage. Stored liquid volume in the reservoir will exit the reservoir to the barrier loop to replace the lost fluid.

When the liquid volume in the reservoir reaches a minimum, an alarm is triggered for the operator to refill the reservoir with fresh barrier fluid.

The refill alarm can be simply based on a minimum liquid level in the reservoir.

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What does an API Plan 53A do?

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Provides a large recirculating volume of barrier fluid

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Maintains a constant barrier fluid pressure equal to that of the gas supply ▪ Barrier pressure is not affected by environmental temperature changes, if the pressure control valve is self-relieving

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Provides a visible liquid level of barrier fluid Can aid in monitoring the health of the mechanical seal

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Has a small installed footprint

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Provides a method to remove heat soak and seal generated heat

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Isolates the process fluid from the atmosphere

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In the event of catastrophic seal failure, can provide contingent sealing

What an API Plan 53A cannot do An API Plan 53A cannot:

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Guarantee any pumped fluid will not reach the environment

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Predict when a mechanical seal will fail

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Provide continuous process containment with loss of pressurized gas supply

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Support high pressure applications

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Operate for extended periods of time after a seal failure

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Support more than one seal installation at a time

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Be used with a single seal

Optional Features for an API Plan 53A Pressure Transmitter

Valves and Instrumentation: ▪

Options to monitor barrier fluid level in the reservoir ▪ ▪ ▪

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Options to monitor barrier fluid pressure ▪ ▪ ▪

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Level Transmitter (recommended) Level Switch Sight Glass Pressure Transmitter (recommended) Pressure Switch Pressure Gauge

Valves to allow isolation of reservoir from the mechanical seal for maintenance and barrier fluid refilling/draining.

Cooling Coil Connection Ports

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Level Indicator

Level Transmitter

Optional Features for an API Plan 53A Valves and Instrumentation: ▪

Temperature measurement – Addition of thermowells and local temperature indicators to measure barrier fluid temperature in and out of the mechanical seal

Temperature indicator

Thermowell

Eccentric Reducers

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Optional Features for an API Plan 53A Barrier fluid circulation: Internal to the mechanical seal ▪

Radial flow pumping ring

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Axial flow pumping ring

Radial flow pumping ring 15

Axial flow pumping ring

Optional Features for an API Plan 53A Reservoir Cooling Coils API Plan 53A allows the selection of a variety of different size reservoirs. While reservoirs with internal cooling coils are typically used, natural convection or forced convection heat exchangers external of the reservoir may also be used.

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Natural convection heat exchanger

Forced convection heat exchanger

Reservoir with internal cooling coils

Optional Features for an API Plan 53A Reservoir Design Features ▪ Pressure vessel code and certification ▪ ▪ ▪ ▪ ▪ ▪

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Materials of construction ▪ ▪

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ASTM (American Society for Testing and Materials) PED (Pressure Equipment Directive) GOST (Gosudarstvennyy Standard) UL (Underwriters Laboratory) CR (Canadian Registration) Region-specific design regulations Reservoir material choices for barrier fluid compatibility and/or environment compatibility Customer-specific surface coatings and colors

Optional Features for an API Plan 53A Barrier Fluid Refilling Options Portable ▪ Portable wheeled cart with reservoir and pump Wheeled Cart with Hand (hand or pneumatic) Pump ▪ Local reservoir with pump (hand or pneumatic) ▪ Central reservoir with pump refilling multiple API Plan 53A reservoirs ▪ Reservoir with automated refill control system (digital or pneumatically actuated)

Local Reservoir with Pneumatic Pump 18

Cost to Operate with an API Plan 53A Cost of barrier fluid Barrier fluid is consumed during the normal operation of the mechanical seal. Consumption rate will vary with mechanical seal design, shaft speed, pressure, and barrier fluid.

Cost of utilities Utilities are required to maintain a constant supply of pressurized gas during normal operation of the mechanical seal, typically nitrogen or compressed air. The method of capturing or generating the gas supply will require utilities as well.

A method to remove heat soak absorbed into the barrier fluid requires utilities either in the form of cooling water (for a water-cooled reservoir) or electricity (for a forced convection heat exchanger). Natural convection heat exchangers do not require any utilities.

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Cost to Operate with an API Plan 53A Cost of energy balance Heat is removed from the process via heat soak into the API Plan 53A system. This energy needs to be replaced within the pumping system and there is an associated cost for the energy to achieve this.

Friction losses The operation of a dual mechanical seal results in friction being generated by the seal faces.

This friction creates a drag on the rotation of the shaft which the driver needs to overcome.

There is a cost for the energy needed to overcome this frictional drag

Labor costs An API Plan 53A system requires routine maintenance to: 1) Monitor the performance of the API Plan 53A system and mechanical seal 2) Periodically replenish the consumed barrier fluid

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Cost to Operate with an API Plan 53A Typically, the initial investment for an API Plan 53A system is high, however the ongoing operational costs are low after the system is installed.

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Energy to operate

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$$$$

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Carbon footprint

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Initial investment

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$$$$

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Cost of operation

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$$$$

Refer to the Fluid Sealing Association’s Lifecycle Cost Calculator (LCC) for a more detailed analysis.

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How to Size an API Plan 53A Reservoir size ▪

Typical sizes: 11.3 or 18.9 liters (3 or 5 gallon) total volume with a working volume equal to 20-30% of the total reservoir volume.

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API 682 reservoir sizing guidelines: ▪ ▪

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Shaft diameter < 60 mm = 3 Gallon reservoir Shaft diameter > 60 mm = 5 Gallon reservoir

Example: Leakage rate of outer seal: Leakage rate of inner seal: Total barrier fluid consumption: Safety Factor 2 x 2 mL/hr: Leakage per day = 24 x 4: Leakage in 28 days = 28 x 96: Min. Working volume: Total Reservoir volume :

1.5 mL /hr 0.5 mL/hr 2 mL/hr 4 mL/hr 96 mL 2688 mL 2.7 liters (0.7 Gal) 9 to 13.5 liters (2.4 to 3.6 gallons)

How to Size an API Plan 53A Alarm Set Points Alarms are established to notify the operator that actions are required.

There are a few critical set points: Low Liquid Level (LLL) / Refill Alarm This alarm notifies the operator to add barrier fluid to the reservoir

Normal Liquid Level (NLL) / Fill Set Point This notifies the operator to stop adding barrier fluid to the reservoir

High Liquid Level (HLL) / Over Fill Alarm This alarm notifies the operator that the reservoir is overfilled 23

HLL NLL

Working volume LLL

How to Size an API Plan 53A Barrier fluid circulation The barrier fluid flow produced by the mechanical seal pumping needs to be sufficient to enable transfer of the heat absorbed into the barrier fluid to the cooling coils in the reservoir (or heat exchanger). The energy absorbed into the barrier fluid is a combination of seal generated heat and heat soak from the equipment.

Seal Generated Heat

Barrier Fluid Circulation

Seal Heat Soak from Equipment 24

Natural Convection Heat Loss

Heat Dissipated by Cooling Coils

How to Size an API Plan 53A ▪

For barrier pressures up to 10 barg (150 psig) ▪

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Pressure limit is to prevent gas absorption into barrier fluid

Typically not used for pumping temperatures above 176.6˚C (350˚F) due to heat dissipation capacity Mechanical seal must have an integrated pumping device.

Sometimes, an external circulating pump is used (then considered as an API Plan 54.)

How to Size an API Plan 53A

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An insufficient flow rate will result in large differential temperatures between the barrier fluid in and out connections at the mechanical seal and an increase in the overall temperature of the barrier fluid.

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Excessive barrier fluid temperatures affect the performance and reliability of the mechanical seal and the life of the barrier fluid.

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Mechanical seals with internal pumping devices (pumping rings) have a strong correlation to shaft speed. Flow can dramatically reduce when shaft speeds are low.

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The reservoir cooling capacity should be matched to the heat load placed on the barrier fluid.

How to Install an API Plan 53A Reservoir location The position of the reservoir relative to the mechanical seal is important. It should be located as close as possible and a short distance above the mechanical seal centerline (without obscuring access for pump maintenance activities).

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How to Install an API Plan 53A Interconnection piping/tubing ▪ Pipes or tubes connecting the mechanical seal to the reservoir should be selected to produce minimal resistance to barrier flow. Large diameter bores, smooth radius bends, short distances, minimal ancillary equipment added into the circulating loop all help lower the resistance to barrier fluid flow.

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High point vents must be installed to allow removal of air from the system during commissioning. Lines should slop upwards to the vent point with a minimum slope of 40 mm per meter (0.5 inches per foot)

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Low point drains should be provided to remove barrier fluid when decommissioning the equipment.

General API Plan 53A Commissioning Guidelines Commissioning must occur with the pump depressurized!

Filling the Reservoir Typically, the reservoir is filled from a portable cart containing barrier fluid and a pump. The pump is often a hand pump or a pneumatically driven piston pump. Use clean, fresh barrier fluid to fill the reservoir.

Continue adding barrier fluid until the normal liquid level has been reached.

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General API Plan 53A Commissioning Guidelines Venting the System When possible, the shaft should be rotated by hand to assist purging the mechanical seal barrier cavity of air.

Bleed all instrument block and bleed valves.

Continue venting until a solid stream of liquid with no bubbles is flowing from the vent valves.

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General API Plan 53A Commissioning Guidelines Alarm Set Point Verification During the filling cycles, the changes in liquid level can be used to confirm the alarm set points and to validate communication between the instrument, the data acquisition system, and the local readout.

Leak Checks Check all connections and fitting for visible leakage. Tighten any fittings if leakage is found.

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General API Plan 53A Commissioning Guidelines Reservoir Cooling Commissioning Depending on the style of reservoir and cooling in use, any required utilities, such as cooling water or electrical fan, should be activated and verified that cooling water or air is flowing.

Barrier Loop Pressurization Barrier fluid should be pressurized as the final step prior to pump commissioning to avoid reverse pressurization and contamination of the inner seal with process fluid. Open the valve to the pressurized gas supply and check for leaks or drops in pressure or barrier fluid level.

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General API Plan 53A Commissioning Guidelines Pump Commissioning The pump is now ready to be flooded with process fluid, and the equipment operator’s standard commissioning procedures should be followed.

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How to Operate an API Plan 53A Periodic Barrier Fluid Refilling Barrier fluid is consumed as mechanical seal leakage during normal operation. This will require periodic replenishment of barrier fluid into the reservoir to make up for the fluid consumed. Barrier fluid is added to the reservoir until the normal liquid level has been reached.

The barrier fluid consumption rate is a strong indicator of the health of the mechanical seal. A decrease in the refill interval is an early warning of declining mechanical seal performance.

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How to Operate an API Plan 53A Periodic Inspection of Utilities Periodic measurement of the barrier fluid temperature into and out of the reservoir (or heat exchanger) should be performed to monitor heat exchange efficiency.

An increase in the differential temperature across the heat exchanger inlet and outlet is an indication of a decrease in efficiency that can be caused by insufficient cooling flow or fouling of the heat exchanging heat transfer surfaces.

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General Troubleshooting of an API Plan 53A Symptom

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Potential causes

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Decreasing refill interval

Increasing mechanical seal leakage Leaking fittings

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Elevated temperature

Insufficient barrier fluid circulation Cooling coil fouling Insufficient cooling flow Undersized cooling Inadequate venting Change in process pressure or temperature

General Troubleshooting of an API Plan 53A Symptom

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Potential causes

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Rapid decrease in pressure

Major mechanical seal failure Delayed maintenance refilling of pressurized gas canister supply (for non-header gas systems)

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Increase in reservoir liquid level

Major inner seal mechanical seal failure Delayed maintenance refilling of pressurized gas canister supply (for non-header gas systems)

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Rapid decrease in reservoir liquid level

Major mechanical seal failure Major leak in barrier fluid loop

Alternatives to an API Plan 53A Alternative piping plans that are similar: DPIT

LI LT

API Plan 53B Pressurized bladder accumulator system 38

Plan 53C Piston accumulator pressurized system

Alternatives to an API Plan 53A Alternative piping plans that are similar:

PIT

Plan 54 Fluid from an external system

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FIT

Plan 74 Dual pressurized non-contacting gas seal

API Plan 53A Summary API Plan 53A pressurized seal systems offer a safe and reliable solution for a wide range of applications.

These systems maintain a constant barrier pressure independent of environmental temperature and pressure decay, offering significant advantages over other dual seal systems.

The correct sizing of the reservoir for cooling and the barrier fluid flow rate, together with best installation & operational practices are the keys to years of reliable performance from an API Plan 53A system.

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THANKS!

www.fluidsealing.com

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