All you need to know about process plant winterization

by Engineering Geek Expert in industrial engineering including piping,
Large processing plants such as refineries, petrochemical plants and more require winterization systems to protect equipment, instruments, and piping components. It helps prevent interruptions of plant operations due to the effects of changing ambient temperature conditions. It also provides workers safety from the combined effect of wind, lower temperatures, hot & cold surfaces and dangerous falling frozen debris. Winterization is generally achieved by using steam tracing, steam jacketing, electrical tracing, or process heating.

Minimum Data Requirements for the Basic Winterization Systems Design 

Data to be used for the design of winterization should be obtained from the following documents:

  • Process Flow Diagram (PFD)
  • Plot plan
  • Equipment datasheet
  • Basic Engineering Design Data (BEDD)
  • Piping & Instrument Diagram (P&ID)
  • Piping material specification

Which Process do Plants Need to be Winterized?

Winterization for process fluids shall be considered in all circumstances. It must be appropriate for the fluids and local ambient conditions.

Water and steam condensate piping winterization.

Consider the following criteria for winterization based on the lowest ambient temperature:

≥ -5 °C – Winterization is not required
-5 °C – 10 °C – Winterization of pockets or dead-legs in piping is required
≤ -10 °C – Winterization is required

Process Piping Winterization

  • Process piping where the pour point or solidifying point of the internal fluid is more than the lowest ambient temperature shall be winterized. The fluid temperature shall be maintained exceeding the solidifying point or at least 10 °C above the pour point.
  • Steam jacket piping or electric heat tracing shall be utilized to central the fluid temperature between 118 °C – 158 °C for liquid sulfur lines.

Utility Piping Winterization

Main pipes should be buried below the freezing depth. Aboveground piping or underground piping buried above the frozen depth. It should comply with the “Winterization of Process Piping” requirements.

Air and Nitrogen Piping 

  • Instrument air and nitrogen contain very little moisture. So, they are not required to be hot insulated. Such piping should be built of materials for low-temperature services considering the lowest ambient temperature.
  • When plant air is dry, its piping may be bare. When it is not dry, it should be steam traced and insulated.

Steam Piping

Steam traps should be mounted in lines where condensate is likely to accumulate. For instance, in pockets or control valve bypass lines.

A steam trap should be fitted at the inlet of each block valve to avoid freezing for the lines, not infrequent use.

Steam Condensate Piping

  • 1½” or lesser steam condensate piping should be heat traced and hot insulated.
  • 2” or higher steam condensate piping should be hot insulated.


When the winter months arrive, they carry with them brutally cold temperatures and moisture. Both can adversely affect your plant and facility’s components. With this article, you now understand carefully planning for the inevitable issues of wet weather, cold and more to minimize your plant disruption.

By carefully planning for the inevitable cold, wet weather issues, your plant can experience minimal disruption. Consider outsourcing a reliable engineering design partner if you’re looking for piping engineering services for your EPC project.

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About Engineering Geek Junior   Expert in industrial engineering including piping,

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Joined APSense since, November 20th, 2019, From Seattle, United States.

Created on Apr 1st 2021 08:41. Viewed 102 times.


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