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This Fluid Sealing Association Knowledge Series training presentation introduces API Piping Plan 62. A description is provided on:
▪ What is an API Plan 62?
▪ How an API Plan 62 works
▪ What does an API Plan 62 do?
▪ What an API Plan 62 cannot do
▪ Optional Features for an API Plan 62
▪ Cost to Operate an API Plan 62
▪ How to Size an API Plan 62
▪ How to Install an API Plan 62
▪ General API Plan 62 Commissioning Guidelines
▪ How to Operate an API Plan 62
▪ General Troubleshooting of an API Plan 62
▪ Alternatives to an API Plan 62
What Are Piping Plans?
▪ 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.
▪ 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.
▪ 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 62?
Plan 62 options
Quench media
▪ Gas
▪ Liquid
> Please visit FSA’s Knowledgebase for more details
> Please visit FSA’s Knowledgebase for more details
▪ Multi-phase (Steam) > Described in this document
What is an API Plan 62? (Steam Quench)
API Plan 62 is the most common atmospheric flush plans in use across the industry. This flush plan provides a delivery of quench fluid to the atmospheric side of a mechanical seal, typically injected between the mechanical seal and an atmospheric bushing.
How an API Plan 62 Works (Steam Quench)
An API Plan 62 works by injecting an external quench fluid to the atmospheric side of a mechanical seal. The quench fluid is contained withing the atmospheric quench cavity by a containment device, typically a close clearance bushing, or other device.
The flow and pressure of the external quench fluid is controlled through
auxiliary devices. Pressure is regulated to within a few fractions of an atmosphere and is always less than the seal chamber pressure. The quench fluid exits the atmospheric chamber via an atmospheric drain port and via leakage past any quench containment device.
Quench fluid entry to atmospheric side of the seal
How an API Plan 62 Works (Steam Quench)
An API Plan 62 support system is often a panel mounted or in-line piping instruments and valves that regulates the flow of steam to the quench port on the mechanical seal.
Steam is used as the quench medium as it is effective at removing hydrocarbon deposits and inorganic crystals from seal leakage, reduces oxygen concentration at the atmospheric side of the seal, and is readily available.
Following the flow path of the steam through the API Plan 62 system:
Isolation valve – Isolates the steam source from the mechanical seal and downstream instrumentation to allow for maintenance.
How an API Plan 62 Works (Steam Quench)
Tee – Splits the steam flow to direct condensate free steam to continue towards the mechanical seal and allow any entrained condensate to collect in the lower leg of the piping below the Tee.
Flow Control Valve – Used to adjust the steam quench flow rate. Typically, a needle valve or globe valve.
Steam
Trap
and Isolation Valves
– The steam trap ejects condensate to a closed sewer or condensate collection system. Isolation valves are provided to bypass the steam trap to allow repair or maintenance of the steam trap.
What does an API Plan 62 do? (Steam Quench)
An API Plan 62 with a steam quench is used to:
▪ Remove atmospheric coking deposits as the result of seal leakage in hot hydrocarbon services.
▪ Provide heating or cooling to the mechanical seal environment in temperature sensitive pumping applications.
▪ Displace atmospheric oxygen to delay oxidization (coking) of leaked pump media on the atmospheric side of the mechanical seal.
▪ Dissolve and remove crystallization resulting from evaporation of pump fluid leakage.
An API Plan 62 steam quench is commonly used in high temperature hydrocarbon services.
What an API Plan 62 cannot do (Steam Quench)
An API Plan 62 with a steam quench does not:
▪ Wash away solids and debris from seal leakage in slurry services.
▪ Prevent the formation of ice in cold or cryogenic pumping applications.
▪ Function correctly when freeze risks are present.
▪ Eliminate atmospheric emissions.
API Plan 62 with gaseous or liquid quench media may provide solutions to the above limitations of an API Plan 62 with steam quench.
Optional Features for an API Plan 62 (Steam Quench)
Pressure Regulating Valve – Replaces the flow control valve for more precise control when the steam supply pressure is high.
Pressure Gauge – Can be provided to indicate the supply pressure and/or downstream pressure of the flow control valve.
Pressure Transmitters - Can be used to provided local and remote indication of the supply pressure and/or downstream pressure of the flow control valve.
Optional
Features for an API Plan 62 (Steam Quench)
Orifice – Small diameter orifice placed downstream of the flow control valve to improve sensitivity of flow adjustments.
Strainer – Provides a filter to catch scale and deposits in the steam supply.
Check Valve – To prevent process fluid entering the steam source piping in the event of a mechanical seal failure.
Optional Features for an API Plan 62 (Steam Quench)
Optional Features for an API Plan 62 (Steam Quench)
Drain options
▪ Low point drain to prevent bearing contamination/corrosion
Optional Features for an API Plan 62 (Steam Quench)
Bearing isolators
▪ Install robust bearing isolator (such as labyrinth or face seal style) to prevent contamination of bearings
Image courtesy of Sepco
Cost to Operate an API Plan 62 (Steam Quench)
There is a cost associated with operating an API Plan 62 as the quench media is constantly being consumed whether the pump is operating or not. The operating costs can vary as the cost of the steam, carbon footprint of producing steam, and the flow regulation settings, will govern the actual operating costs.
Cost to Operate an API Plan 62 (Steam Quench)
With adequate flow control instrumentation, the cost to operate an API Plan 62 is relatively low.
Refer to the Fluid Sealing Association’s Lifecycle Cost Calculator (LCC) for a more detailed analysis.
How to Size an API Plan 62 (Steam Quench)
When sizing the flow rate for steam, there are two commonly employed methods:
Visual method
▪ Adjust the flow regulating valve until a slight wisp of steam is visible escaping to the atmosphere
Quantitative method
▪ Adjust the flow regulating to {0.02 kg/hr (1 lb/hr) up to 200°C (400°F) plus 0.02 kg/hr (1 lb/hr) for each additional 50°C (100°F)} multiplied by the seal size (mm or inches)
Example: 90 mm seal at 350°C = {0.02 + (3 x 0.02)} x 90 = 7.2 kg/hr
3” seal at 600°F = {1 + (2 x 1)} x 3 = 9 lb/hr
How to Install an API Plan 62 (Steam Quench)
Steam Header
Connection to the steam header should be from the top of the pipe to prevent any condensate from migrating down into the steam quench supply lines
Isolation Valve
Steam Header Pipe
Insulation
Condensate
How to Install an API Plan 62 (Steam Quench)
Connecting to the mechanical seal
How to Install an API Plan 62 (Steam Quench)
Burn Protection - Uninsulated pipes and steam trap should be fitted with guarding to prevent contact burns of personnel.
Optional Steam Superheating – Wrap steam quench supply tubing around suction piping, discharge piping, or pump casing of a hot pump to decrease the condensate content in the steam.
Steam Traps – Best practice is to select a steam trap that will fail in the open position.
Debris separation – A sharp change in flow direction can help separate debris and condensate from the steam supply by using a 45° Tee.
General API Plan 62 Commissioning Guidelines (Steam Quench)
To commission an API Plan 62:
1) Using the mechanical seal assembly drawing, verify that the quench and drain piping are connected to the correct ports in the mechanical seal.
2) Open the pressure and/or flow control valve(s) and adjust to achieve the target flow rate. Note when the steam is superheated, it is invisible.
3) Check all the connections on the API Plan 62 piping for leaks. Correct any if found.
4) The plan 62 must be operational before commencing preheating the pump. Starting the steam quench after preheating can lead to thermal shock and damage to the mechanical seal.
5) Ensure any drain ports are unplugged and quench flow is directed to a closed sewer or condensate collection system.
How to Operate an API Plan 62 (Steam Quench)
Operation of an API Plan 62 requires maintaining a continuous flow of steam to the mechanical seal.
During operation:
▪ Visually check steam flow is present and is not excessive.
▪ Check steam traps are functioning correctly
▪ Check that there is minimal condensate coming out of the drain connection.
During routine maintenance of the mechanical seal, inspect the overall condition and function of the steam quench system and replace or repair any defective components found.
General
Troubleshooting of an API Plan 62 (Steam Quench)
Extended operation of a mechanical seal with low or no quench flow can cause premature seal failure and excessive leakage to atmosphere.
Symptom Potential causes
▪ No flow
Loss of steam supply pressure
Blockage or fail-closed of any flow control component
Isolation valve closed
▪ Low flow rate Incorrect flow control valve setting
Partial blockage flow control valve
Excess condensate in steam supply
Inadequate insulation
General Troubleshooting of an API Plan 62 (Steam Quench)
Symptom Potential causes
▪ High flow rate Incorrect flow control valve setting
Blockage of drain connection
▪ Excess condensate Inadequate insulation at mechanical seal Failed steam trap drain connection Incorrect piping connection / sloping pipes
Steam trap isolation valve closed
Alternatives to API Plan 62 (Steam Quench)
Alternative piping plans that are similar:
API Plan 62 - Gaseous
Use inert gas as quench media
API Plan 52 Dual unpressurised seal system
API Plan 62 Summary (Steam Quench)
An API Plan 62 with a steam quench flowing on the atmospheric side of a mechanical seal will:
▪ Remove atmospheric coking deposits as the result of seal leakage in hot hydrocarbon services.
▪ Provide heating or cooling to the mechanical seal environment in temperature sensitive pumping applications.
▪ Displace atmospheric oxygen to delay oxidization (coking) of leaked pump media on the atmospheric side of the mechanical seal.
▪ Dissolve and remove crystallization resulting from evaporation of pump fluid leakage.
