(Gaseous Quench)
FSA Knowledge Series
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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
▪ Multi-phase (Steam)
> Described in this document
> Please visit FSA’s Knowledgebase for more details
> Please visit FSA’s Knowledgebase for more details
What is an API Plan 62? (Gaseous 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.
Valve Variable Area Flow Meter
Isolation
Needle
How an API Plan 62 Works (Gaseous 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 within 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
Quench fluid entry to atmospheric side of the seal 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.
How an API Plan 62 Works (Gaseous Quench)
An API Plan 62 support system is often a panel mounted group of instruments and valves that regulates the flow of gas to the quench port on the mechanical seal.
Typically plant nitrogen is used as the quench medium since it is readily available, is inert, and does not create any adverse chemical reactions with the pumped fluid.
Following the flow path of the gas through the API Plan 62 system:
Isolation Valve – Isolates the gas source from the mechanical seal to allow for maintenance.
Check Valve – Prevents back flow of process fluid in the event of an abnormal process upset or catastrophic seal failure.
How an API Plan 62 Works (Gaseous Quench)
Pressure Regulator – Reduces the supply gas pressure being delivered to the mechanical seal.
Needle Valve – Used to make fine adjustments to the quench gas flow rate.
Flow Meter – Provides an indication of the quench gas flow rate.
What does an API Plan 62 do? (Gaseous Quench)
An API Plan 62 with a gaseous quench media, typically nitrogen, is used to:
▪ Displace atmospheric oxygen to delay oxidization (coking) of leaked pump media on the atmospheric side of the mechanical seal.
▪ Displace atmospheric humidity to prevent the formation of ice in cold and cryogenic pumping applications where ice may interfere with the operation of a mechanical seal.
▪ Provide an alternative to steam quench in cold climates where the possibility of freezing of steam condensate is a risk.
What an API Plan 62 cannot do (Gaseous Quench)
An API Plan 62 with a gaseous quench media does not:
▪ Remove atmospheric coking deposits as the result of seal leakage in hot services.
▪ Remove crystallization resulting from evaporation of pump fluid leakage.
▪ Remove solids and debris from seal leakage.
▪ Provide cooling or heating of the mechanical seal environment.
▪ Eliminate atmospheric emissions.
An API Plan 62, when used in a confined space, can cause localized depletion of oxygen levels and should not be used in these services without adequate ventilation.
API Plan 62 with liquid or steam quench media may provide solutions to the above limitations of an API Plan 62 with gaseous quench media.
Optional
Features for an API Plan 62 (Gaseous Quench)
Coalescing Filter - A 2 to 3 micrometer (μm) coalescing filter traps liquids and particles that can potentially damage the mechanical seal.
Pressure Gauge – Can be provided to indicate the supply gas pressure and/or downstream pressure of the regulator.
Pressure Transmitters - Can be used to provide local and remote indication of the supply gas pressure and/or downstream pressure of the regulator.
Flow Transmitter – Can be used to provide local and remote indication of the quench gas flow rate.
Features for an API Plan 62 (Gaseous Quench)
Quench containment options
▪ Fixed bushing
▪ Solid floating bushing
▪ Segmented bushing
Optional Features for an API Plan 62 (Gaseous Quench)
Weather
enclosures – For facilities that experience extreme weather environments, an API Plan 62 can be mounted in a weatherproof enclosure protecting the instruments from extremes of cold, dust, salt exposure, and humidity. Heaters can be added in the enclosure for cold environments. Sunshades can be added to the instruments, or the entire API Plan 62, for hot environments.
Cost to Operate an API Plan 62 (Gaseous 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 source gas, carbon footprint of producing the source gas, and the flow regulation settings will govern the actual operating costs.
Cost to Operate an API Plan 62 (Gaseous 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 (Gaseous Quench)
The general rule of thumb to determine the quench flow rate
▪ 10 to 15 SCFH per inch of shaft diameter at temperatures up to 100°F
▪ Add 10 to 15 SCFH per 100°F above 100°F
▪ 10 to 15 Nl/hr per mm of shaft diameter at temperatures up to 40°C
▪ Add 10 to 15 Nl/hr per 50°C above 40°C
Pressure: ▪ 1 to 2 psig ▪ 0.06 to 0.12 barg
How to Install an API Plan 62 (Gaseous Quench)
API Plan 62 instrumentation is typically panel mounted on a stand that can be placed in a position near the pump that allows sufficient space for maintenance and inspection activities. It does not need to be mounted immediately adjacent to the mechanical seal.
The instrumentation panel is commonly constructed using tubing components but may also be constructed from pipe components or a combination of tube and pipe components. The instrument panel and stand should be grounded to earth.
The instrument panel delivering the quench gas is connected to the mechanical seal quench connection, typically labeled “Q” or “Quench”.
The drain connection, typically labeled “D” or “Drain”, should be left open.
General API Plan 62 Commissioning Guidelines(Gaseous Quench)
To commission an API Plan 62:
1) Using the mechanical seal assembly drawing, verify that the quench piping is connected to the correct port in the mechanical seal.
2) Open the pressure and/or flow control valve(s) and adjust to achieve the target flow rate.
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 starting the equipment.
5) Ensure any drain ports are unplugged.
How to Operate an API Plan (Gaseous Quench)
Operation of an API Plan 62 requires maintaining a continuous flow of quench gas to the mechanical seal.
During operation:
▪ Periodically check the quench gas flow rate.
▪ Periodically check for leaks at the connections.
During routine maintenance of the mechanical seal, inspect the overall condition and function of the quench system and replace or repair any defective components found.
General Troubleshooting of an API Plan 62 (Gaseous Quench)
Extended operation of a mechanical seal with low or no quench flow can cause premature seal failure and excessive leakage to atmosphere.
There are two main events that can reduce or eliminate the effectiveness of an API
Plan 62:
1) Loss of source gas pressure
2) Blockage or fail-closed of any flow control component
A local flow meter or remote indicating flow transmitter can detect both events indicating a flow below the target flow rate. When detected, the control components should be diagnosed and replaced or repaired as required.
Alternatives to API Plan 62 (Gaseous Quench)
Alternative piping plans that are similar:
API Plan 51 Dead-ended atmospheric blanket
API Plan 52 Dual unpressurised seal system
API Plan 62 - Steam Use steam as quench media
API Plan 62 Summary (Gaseous Quench)
An API Plan 62 with a gas quench displaces the oxygen and humidity from the atmospheric side of a mechanical seal that:
▪ Delays oxidization (coking) of leaked pump media in hot pumping services
▪ Prevents the formation of ice in cold and cryogenic pumping applications
Flow to the mechanical seal is controlled by a series of flow control devices and regulated to low pressure. These instruments can be conveniently panel mounted and installed near the pumping equipment.
