Best practices for steam trap installation

A steam trap has two major functions, to remove condensate as quickly as it forms, and to prevent steam discharge. There are certain installation faults, which negatively affect the ability for traps to perform these functions efficiently.
By Kelly Paffel, Swagelok Company May 11, 2011

A steam trap has two major functions, to remove condensate as quickly as it forms, and to prevent steam discharge. There are certain installation faults, which negatively affect the ability for traps to perform these functions efficiently.

A high percentage of steam trap failures are simply due to incorrect installation. Proper installation should provide six years of maintenance-free operation. Outlined below are Best Practices for steam trap installations, to help maximize system operation:

  1. The most important rule to remember for steam trap installation is GRAVITY. Condensate must flow from the process to the steam trap by the forces of gravity. Pressure and velocity cannot be relied on to remove the condensate from the process.
  2. Determine the steam leak rate of any new steam traps purchased, per the following leak rate standards:
    1. PTC-39
    2. ISO 7841
  3. All steam traps leak a quantifiable amount of steam and the consumer should be specifying steam traps with the least amount of steam loss to prevent unnecessary energy loss.
  4. Steam traps with 1 in. or smaller connections should use tubing with tube connectors to eliminate leak points such as threaded connections. Threaded connections are obvious sources of leaks in the system due to expansion, contraction, and corrosion that occurs in a steam system.
  5. Some steam component manufacturers have tube connections available for steam trap installations. Ensure material pressure ratings are acceptable. 
  6. Never reduce diameter of the tubing/piping before the steam trap, or reduce connec­tion size of the steam trap. Piping from the process to the steam trap should always be equal to or larger than the process outlet connection. For example, a steam unit heater with a 1 in. condensate outlet would require a 1 in. or larger tubing/piping from the unit heater to a same connection size on the steam trap.
  7. Expand the tube/pipe diameter after the discharge connection of the steam trap. For example, a 1 in. steam trap discharge should connect into tubing/piping with an expanded diameter of 1.25 in. or 1.5 in.
  8. Connect steam traps with connection sizes of 1 in. or smaller to the tubing or piping with universal mounts. The universal mount provides the ability to connect the steam trap to the application with two bolts, thus dramatically reducing installation time.
  9. Install a strainer to help eliminate or reduce premature failure due to corrosion. There are three main choices for strainer installation:
    • Installation of an external strainer ahead of the steam trap
    • Installation of a steam trap with integral strainer
    • Installation of a universal mount with an integral strainer
      • When installing an external or internal strainer; always install a blow-off valve on the strainer. This allows the strainer to be blown down during operation and, more importantly, permits the steam trap cavity to be safely depressurized during servicing.
  10. Always install the steam trap in a location that is accessible by plant per­sonnel.
  11. Install a visual indication of the steam trap performance on all process ap­plications. The visual indication can be a sight glass or test valve.
  12. Locate the steam trap below the lowest condensate discharge point of the equipment.
  13. Never install a rise in the pipe ahead of a steam trap.
  14. Check valves should be installed after the steam traps in most applications.
  15. Develop and maintain installation standards for all applications.
  16. Codes:
    • Material test reports on all components (steam traps, connection devices, etc.)
    • B31.1 Piping code

For more information, visit www.swagelokenergy.com.


The above material is part of Swagelok Energy Advisors’ series of Best Practice papers, authored by Kelly Paffel. Kelly is a recognized authority in steam and condensate systems. He is a frequent lecturer and instructor on the technical aspects of steam systems. In addition, Kelly has published many papers on the topics of steam system design and operation. Over the past 30 years, he has conducted thousands of steam system audits and training sessions in the United States and overseas, which has made Kelly an expert in trouble-shooting actual and potential problems in the utilities of steam. Kelly is a member of the U.S. Department of Energy’s (DOE) Steam Best Practices and Steam Training Committees.