The most feared thing in winter is pipeline freezing! Heat tracing is not optional, but a crucial part of ensuring production and safety. Electric heat tracing or jacket heat tracing?
Anyone who has worked on the scene knows, what is the most feared thing in winter?
It's not cold, it's the pipes freezing.
Especially for some materials, they become thicker, crystallize, and even block directly as soon as they cool down.
At this point, heat tracing is not an optional auxiliary measure, but a crucial link in ensuring production and safety.
There are currently two mainstream methods: electric tracing and jacket tracing.
Which one to choose? You can't just look at what others are using, you have to look at what's going through your own pipe, how much temperature you need, and whether the on-site conditions allow it.
Electric heat tracing: convenient, but don't try to save time
Nowadays, many people's first reaction when they hear about heat tracing is to "stick an electric heating belt".
Indeed, electric heat tracing has fast installation and flexible control, making it particularly suitable for small-diameter pipelines, instrument pressure pipes, or those that are particularly sensitive to overheating - such as certain organic solvents, which can decompose and even smoke and catch fire at high temperatures.
But there are several pitfalls to avoid:
Don't believe the manufacturer's claim that "up to 120 ℃" can actually be used
It depends on the maximum temperature allowed by your medium. For example, if a certain material starts to deteriorate at 60 ℃, even if the electric heating belt can withstand 150 ℃, you still need to choose a low-temperature type and add temperature control.
Insulation layer must be included
I have seen too many people entangle electric heating belts and turn them on for "emergency situations", only to burn them out a few days later. Without insulation, all the heat dissipated into the air, and the electric heating belt worked hard to heat it up, eventually failing due to overheating.
Don't make do with the power supply
Special junction boxes should be used in damp and explosion-proof areas, and it is best to separate the power supply circuit and not mix it with other equipment, otherwise the cause of tripping cannot be found.
In addition, many electric heat tracing manufacturers can now provide a complete solution - if you give the drawings, they will calculate the heat loss, provide a list, and even clearly mark how to bend.
But you still need to coordinate the electrical interfaces and distribution boxes yourself. Don't think that just because you turn the key, you really don't have to worry.
Jacket heat tracing: an old method, but stable
For some media that cannot flow in winter, electric heat tracing is often inadequate.
At this point, it is necessary to install a jacket pipe - another layer of pipe should be placed outside the main pipe, and steam or hot water should be evenly heated in the jacket, resulting in a much more stable effect.
However, there are also many troubles with jacketed pipes:
Be careful when matching materials
If the expansion coefficient difference between the inner tube and the outer tube is too large, it is easy to crack the weld seam when cooled and heated. There was once a project that used carbon steel inner pipes with stainless steel sleeves. After driving for three months, several flanges leaked.
Don't be too long in length
It is generally recommended that each section should not exceed 6 meters, and a spacing plate should be added in the middle to straighten the inner pipe. Otherwise, if the inner pipe is skewed, the steam will short circuit and the local area will still be cold.
Drainage should be unobstructed
The steam in the horizontal pipe enters from above, and the condensed water is discharged from below. Cut off valves should be installed at both the inlet and outlet. Otherwise, the entire line will have to stop during maintenance.
There is another detail: the steam crossover pipe between the jackets should be connected with flanges as much as possible. Although it may be more expensive, it will be easier to dismantle and repair in the future. If the whole welding is done at a low cost, it will be difficult to cut the pipe if it leaks one day.
The 'little cleverness' in installation is often a major hidden danger
Companion pipes cannot be directly welded to the main pipe
This is repeatedly emphasized in the old regulations, but there are always construction teams on site who plan to do it quickly. consequence? One is the concentration of thermal stress, and the other is that in the future, when changing pipes, they will have to be cut together with the main pipe.
Bracket saving
Especially for centralized positions such as distribution disks and collection disks, a fixed bracket and a sliding bracket are the basic configurations. Otherwise, when there is thermal expansion and contraction, the pipe will shift and the joint will crack.
Don't ignore anti-corrosion isolation
For example, when carbon steel companion pipes are tied to stainless steel main pipes, electrochemical corrosion occurs quickly in humid environments.
Putting a plastic sheet or wrapping tape in the middle can save a lot of trouble for less than a few yuan.
The heat tracing system may seem unremarkable, but every winter, there are many incidents of parking, leaks, and even safety accidents caused by unreasonable heat tracing design and construction cutting corners.
Don't treat it as an 'ancillary project' and deal with it casually. The heat loss that needs to be calculated, the verification that needs to be done, and the money that needs to be spent cannot be saved.
After all, when it reaches minus ten degrees, no one will praise you for "saving costs", they will only ask, "Why did it freeze again.
