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Why a Seal Support System Water Flush Plan Matters

by Thomas Webster, on Tue, May 18, 2021 @ 09:05 AM

Process requirements are used among flush flow rate calculations to determine the appropriate seal support system water flush plan for pumps in the oil and gas industry

Flush plans aim to maintain proper lubrication, temperature, pressure, and solids management by circulating fluid to or from a seal. A suitable flush plan should create an optimal working environment for the seal to prolong the seal life, avoid unnecessary wear, and prevent seal failure. Seal support system water flush plans can provide an alternative solution to flush plans involving lubrication oil, nitrogen, hydraulic oil, and other oil-based buffer or barrier fluids. Water flush plans may be implemented in cases where the process fluid is below 93.3°C (200°F) and minor dilution of the process fluid is acceptable. If the process fluid is above this temperature, a water flush plan may not be appropriate, as this runs the risk of flashing—which can lead to significant unintended consequences.

If the wrong API 682 seal support system water flush plan is implemented, this can lead to a number of inefficiencies including: 

  1. Changes in pressure or temperature
  2. Vibrations
  3. Reduced flush flow rate 

These inefficiencies can lead to unscheduled seal repair and eventually early seal failure. Luckily, there is an extensive range of API 682 seal plans available to account for any rotating equipment seal support needs in oil and gas processes.

Seal Support System Water Flush Plans Best Practices 

Implementing the best practices for flush plans can greatly increase overall seal reliability and reduce flushing inefficiencies. To demonstrate the best practices for seal support system water flush plans, let’s take a look into a couple of water flush plans and the associated recommendations to improve flushing efficiency and seal reliability.

API 682 Plan, Location


Best Practices

Plan 32 - Process SidePlan 32


External Flush 

API 682 Plan 32 delivers a clean, cool flush fluid from an external source into the seal chamber. This plan is typically used in conjunction with a close-clearance throat bushing to maintain elevated pressure in the seal chamber. Plant water can be used as the flush fluid instead of nitrogen, but ensure it is chemically compatible with the process fluid and that dilution is not a concern.

  • External flush pressure should always be maintained at least 29 psi (2 bar) above the seal chamber pressure.
  • Flushing should be continuous, even while starting up and shutting down the system. The source of the flush fluid must be reliable at all times.
  • Flush fluid should not vapourize upon entering the chamber.

Plan 55 - Between SealPlan 55


Buffer Fluid Circulated by External System 

API 682 Plan delivers cool, clean unpressurized buffer fluid to the seal chamber that is pumped from an external reservoir. This provides cooling and lubrication to the outboard seal regardless of pump operation. 

  • This plan is not to be used with polymerizing or contaminated process fluid.
  • These systems may require the use of filters, coolers, or other components depending on the need, as well as the purity of the water being used.
  • The buffer fluid pressure should be maintained at less than 40 psi (2.8 bar) and should also be less than that of the seal chamber.
  • Implement high-quality temperature sensors at the seal inlet and outlet as well as a flow meter.

Plan 62 - Atmospheric SidePlan 62


Quench From External Source 

API 682 Plan 62 delivers quench fluid from an external source to the atmospheric side of the seal. This aims to quench or cool and clean the seal surface, and can prevent coking on seal faces by clearing any solids. This plan can be used with horizontal or vertical pumps. While steam is the most common fluid in refinery applications, water and nitrogen can also be used.

  • There must be a reliable continuous supply of fluid which should not exceed 14.5 psi (1 bar).
  • A close-clearance throttle bush should be implemented on the atmospheric side of the seal.
  • Bearings should be isolated from the quench fluid, as to not degrade the life cycle of the bearings.

These are just three examples of many other water flush plans available. Each auxiliary seal plan requires careful considerations regarding process fluid and process conditions to best integrate a water flush plan into a given process. There is a significant benefit in consulting with seal support system experts to get the most out of a water flush plan.

The Benefit of Local Experts

If you are experiencing inefficiencies with your flush plan, whether that be pressure or temperature changes, vibrations, or lower flow rates, you may want to reconsider your API 682 flush plan. Having the right seal support system water flush plan can prevent unplanned mechanical seal maintenance and unplanned downtime by providing the seal with the ideal environment for efficiency. 

Given the variety of seal support applications in oil and gas, there are a multitude of variables that come into play when choosing a seal support system flush plan. It is crucial to work with local experts who understand the ins and outs of flushing applications.

Edmonton Valve & Fitting is equipped with expert local Field Advisors who have on-the-ground experience identifying inefficiencies and recommending solutions. We can help you choose a flush plan that will maximize flushing efficiency as well as prevent unplanned seal maintenance or repair. We can provide locally fabricated, custom-configured sealing solutions that meet your requirements.

To find out more about how Edmonton Valve and Fitting can help identify inefficiencies in your seal support system water flush plan and recommend the right plan for your requirements, contact us through our website or by calling 780-437-0640.
Topics:Sample Systems

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