In today’s post, we’ll provide you with a basic understanding of the ASME code for pressure vessel designs in the chemical and process industries. This guide is applicable in the USA and most regions of South and North America. The following are the six most common shell and tube heat exchanger parts.
The fundamental building blocks of shell and tube heat exchangers are the tubes, which provide the heat transfer surface between a fluid flowing inside and a fluid passing the exterior of the tube. The tubes are often composed of copper or steel alloys and can be seamless or welded. For some applications, additional nickel, titanium, or aluminum alloys might be needed. Typically, welded tubes are more affordable.
The tubes are kept in place by being inserted into grooves cut into the tubesheets or by being welded to the tubesheet, where the tube sticks out from the surface. Consequently, the fluid on the shell side and the fluid on the tube side do not mix. The tubesheet is often made of a single round piece of metal that has been suitably drilled and grooved to accommodate the tubes (in the required design, such as square or triangle). It also holds the gaskets, the spacer rods, and the bolt circle that is fastened to the shell.
Shell & Nozzle
The nozzles serve as the entrance and exit ports, and the shell merely serves as a container for the fluid on the shell side. The shell is typically formed by rolling a metal plate that is cut into the required dimensions into a cylinder and welding the longitudinal connection. By slicing the diameter pipe to the appropriate length, smaller diameter shells can be created.
Tube-Side Channel and Nozzles
The flow of the tube-side fluid in and out of the heat exchanger’s tubes is easily controlled by the channel and nozzles on the tube side. These channels and nozzles are frequently composed of alloy materials due to the fact that the tube side fluid is typically more corrosive. Instead of solid metal, they could be made of clad.
Baffles have three purposes:
- They stabilize the tubes during assembly and usage to keep them in the right position and stop vibration of the tubes brought on by flow-induced eddies
- They increase the velocity and heat transfer coefficient by guiding the shell-side flow back and forth across the tube field
- They keep the tube spacing consistent
Tie Rods & Spacers
There are two uses for tie rods and spacers:
- Keep the baffle assembly in place
- Maintain the chosen baffle spacing.
The tie rods are fastened to the last baffle and to the other end of the tubesheet.
Maintaining Your Heat Exchanger
To ensure that all the parts of your heat exchanger are working properly, you’ll need to maintain them well. Get yourself a Torq N’ Seal® high pressure tube plug that creates a permanent, positive seal greater than 7,000 psi that can help you finish your maintenance project in an efficient and fuss-free manner. Alternatively, the condenser tube plug is the best option if you have a heat exchanger with pressure less than 250 psi, temperature below 300 deg F, and tube ID between 0.580″ and 1.200″. Get these affordable and handy tools today!