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Mastering API 682: your guide to mechanical seal and auxiliary system excellence 

API 682: Ensuring reliability and safety

Developed by the American Petroleum Institute (API), API 682 sets the standard for designing, selecting materials and operating mechanical seals and their auxiliary systems in pumps, compressors and other rotating equipment. Recognised in the petroleum, natural gas and petrochemical industries, this standard improves mechanical seal reliability in fluid-processing applications by addressing leak prevention, maintenance and efficiency to reduce environmental risks and enhance plant safety.

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Key components of API 682

API 682 addresses crucial elements to maintain seal and system efficiency.

  • Mechanical seals: Specifies requirements for single, dual-unpressurised and dual-pressurised seals, ensuring compatibility with processed fluids.
  • Auxiliary piping plans: Details the necessary configurations and components for cooling, flushing and pressure control systems.
  • Installation, operation and maintenance: Offers recommendations to extend service life and reduce downtime.
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Supporting sustainable operations

API 682 contributes significantly to global sustainability goals by promoting environmentally responsible practices.

  • Environmental impact: Reduces industrial emissions and spillages by promoting advanced sealing technologies.
  • Resource efficiency: Extends seal lifespan, reducing material and energy consumption and lowering operational costs.
  • Energy conservation: Optimises seal performance, reducing friction and energy use in pumps and rotating equipment.

John Crane’s API 682 piping plan booklet

This essential reference guide provides expert insights and practical guidance for effortlessly navigating the complexities of 32 different piping plans. Keep it handy for quick, reliable support whenever you need to select or understand a piping plan.

Read Booklet

FAQs

What is API 682 and why is it important?

API 682 is a global adopted developed by the American Petroleum Institute that defines recommendations for the design, selection, testing and operation of mechanical seals and seal support systems for centrifugal and rotary pumps used mainly in oil and gas, and chemical industries.

API 682 standardises:

  • Mechanical seal design categories
  • Seal arrangements (single, dual-unpressurised, dual-pressurised)
  • Seal chamber dimensions
  • Piping plans (flush/support systems)
  • Material selection
  • Testing and qualification

What’s the difference between API 682 and API 610?

API 610 covers pump design, while API 682 covers mechanical seals and seal support systems used on those pumps.

Key distinction:

Standard

Focus

API 610

Centrifugal pumps

API 682

Mechanical seals plus seal systems

Many projects require both standards together.

Are API 682 seals zero-emission?

All mechanical seals allow some leakage across the seal faces.

Arrangement 3 seals are able to achieve zero-emissions to atmosphere during normal operation by employing a barrier fluid at higher pressure between the process and the atmosphere. This makes them the preferred solution for volatile or hazardous fluids.

What are Category 1, 2 and 3 seals in API 682?

These categories classify seal construction and service severity:

  • Category 1 → General refinery service
  • Category 2 → Higher reliability and instrumentation
  • Category 3 → Severe service with highest robustness

What changed in API 682 4th Edition?

Key updates include:

  • New piping plans added (e.g., 03, 55, 65A, 65B, 66A, 66B)  
  • Instrument changed from switches to transmitters
  • Floating alarm added for Plan 53B to track changing effect of temperature
  • Improved standardisation of seal systems

Is API 682 mandatory?

Not legally mandatory — but often required by:

  • Oil and gas operators
  • EPC specifications
  • Corporate engineering standards
  • Insurance / risk management policies

What industries use API 682?

  • Oil and gas
  • Petrochemical
  • Refining
  • Chemical processing
  • LNG

Its adoption continues to grow outside refining due to reliability gains.

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