Modeling Connection to Fired Heater

Modeling Fired Heater Piping Connection is a bit tricky as the pipe is not welded to a fired heater shell similar to ordinary equipment. The heater has a hole, the pipe runs through that hole inside the heater body.

There are two techniques for modeling fired heater piping connection:

  • First method: Use an anchor at the point where the piping goes inside the heater. The heater vendor must provide the allowable loads for this anchor point. Or the API 560 code may be used
  • Second Method: Model whole or part of the furnace coil that is inside the heater. The vendor should provide allowable displacements at the point where the pipe goes inside the heater (+dx, -dx, +dy, -dy, +dz, -dz). Usually, it’s the gap values between the pipe and heater shell

You can choose one of these two methods.

First Method – Allowable Loads

First method is very conservative. The loads on heater usually are very huge, but allowable loads are very small and can’t be met.

In START-PROF software the “Fired Heater” Object can be used.

Allowable Nozzle Loading Method of Fired Heater Piping Connection Model
Allowable Nozzle Loading Method of Fired Heater Piping Connection Model

Second Method – Allowable Displacements

Using the second method it is more easy to satisfy the vendor requirements. There’s no need to model whole furnace coil, just 3-4 U-Tubes is enough.

Allowable displacement model of Fired Heater Piping Connection model
Allowable displacement model of Fired Heater Piping Connection model

The supports in the furnace coil should be modeled correctly.

The following conditions should be met:

  • Pipe displacements at the point where pipe hoes inside the heater should be less than vendor’s allowable
  • All stresses both in the pipe and in the furnace coil should be less than allowable according to the selected code
  • Loads on the furnace coil supports should be less than allowable
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Alex Matveev

Alex Matveev is one of the authors of pipe stress analysis codes GOST 32388-2013 Process Piping, and GOST 55596-2013 District Heating Networks. He is also one of the developers of PASS/Start-Prof software, which is developed since 1965 and used in 95% of process, power, district heating, gas and oil transportation design companies in Russia and CIS countries; it is industry standard in that region. He is the head of the PASS/START-PROF pipe stress analysis software development team. Also, He offers technical support and training for users of their software that number already 3000+, developing since 1965, industry standard in several countries for 50+ years, translated into English in 2017, come out from their domestic market, and started sales for the international market since 2018.

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