Which is better Branching of piping | “upper” and “lower”

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I will explain the concept of branching piping.

When removing a branch from a pipe in a chemical plant, I am a little confused as to whether it is upper or lower.

trade-in trade-in

If you are an engineer who is just looking at a piping diagram randomly or entrusting it to a piping drawing shop, you may not even have a chance to worry about it.

We will consider whether it is a upper or lower in several cases.

Just by doing this idea properly, you can extend the life of the equipment and reduce troubles.

It’s a little trick!

Branching of the main pipe is top up for gas and trade-in for liquid

If the content of the main pipe is gas, it should be upper . If the content is liquid, it should be lower.

The reason for this is simple.

get rid of buildup

That’s all.

Gas is the top and liquid is the bottom.

Main piping is an image of common piping outside the plant.

For example, this applies to utility piping leading from a chiller outside the plant to inside the plant.

This applies to both gases and liquids. Gas is steam and air, liquid is water.

Nitrogen, organic solvents, etc. are excluded because they are utilities.

Accumulates when gas is lower.

Accumulates when liquid is upper.

If there is accumulation, it will cause trouble such as resistance to piping and clogging of rust drain.

Sub-main branching is upper

Submain is basically upper.

Put simply, this idea.

do not bring in foreign objects.

Clogging of pipes and equipment with rust hinders heat transfer in heat exchangers and causes.

Structure of main and submain

The sub-main is an image of the main piping on each floor in the plant.

The point is to use different ways of thinking between main and sub-main. It’s a source of confusion

Main and sub-main configuration for liquid flow Let’s think about it with the following image.

sub-main branching

The pipe traded in from the main pipe is connected to the sub-main pipe.

There is always a liquid pocket between the main pipe and the sub-main pipe.

Let’s put some liquid here.

It has a function to remove rust from lower piping when water is flowing in the main piping and rust is generated.

There is also the idea of ​​​​installing a strainer and removing it.

After the sub-main piping, the piping sent to the user is upper.

The sub-main pipe also has a rust drain at the end.

This is the basic idea.

What if submain is lower?

From a slightly different point of view, what happens if sub-main pipe branching is lower?

The same is true in this case.

sub main branching

When sub-main piping is lower branching, the rust in the sub-main will clog the nearest part of the lower.

The idea of ​​removing the drain or performing automatic liquid separation here is good, but the cost will go up.

Frequent drainage, installation of an automatic liquid separation device, and pressure loss are costs.

It is wise to avoid sub-main lower branching unless there is a serious reason.

Branching of collecting pipe is upper

Collective piping is better to upper.

Drainage pipes are common for collecting pipes. This also applies to solvent waste oil piping.

Drainage up and down (branching)

Install a check valve in front of the connection by upgrading the collecting pipe.

The reason for attaching a check valve is, of course, to prevent mixing due to backflow.

The reason for reverse flow is that the working pressure of each connecting pipe is different.

Not all connecting pipes have the same height, they are not pumped, and the specifications of the pumps are not standardized.

If water accidentally flows into the connecting pipe from multiple lines, it can backflow from the higher pressure side to the lower pressure side.

Add a check valve to minimize this.

It is dangerous if the check valve is installed in lower piping.

The secondary side of the check valve is always filled with liquid.

As a result, the pump may not start and the water cannot be drained.

Let’s take upper as a basis . Install a non-return valve.

Although it is not written in the picture, if possible, attach a shutoff valve.


Ingenuity such as pruning of piping will appear as one of the plumbing troubles.

There is no guarantee that there will be books on plumbing problems that apply to you, but the more you read, the more likely you are to get hits.

created by Rinker
¥2,420 (2024/02/29 11:29:29時点 Amazon調べ-詳細)

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I explained how to separate the top and bottom of the debranched pipe.

The main piping is top-up for gas, bottom-up for liquid, top-up for sub-main, and top-up for collecting pipe.

They are used depending on the place of use and conditions, but it is possible to discuss general characteristics such as whether they are gas or liquid, and whether rust and drain are included.

Please feel free to post your worries, questions, and questions about the design, maintenance, and operation of chemical plants in the comments section. (The comment section is at the bottom of this article.)

*I will read all the comments and answer them seriously.