Basic concepts of Piping header in chemical plant

pipe header
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I will introduce how to use piping header, which are often seen in batch chemical plants.

A pipe header is ” a collection of multiple pipes “.

piping header

It can be considered that the number of pipe headers x the number of pipes is stretched around.

Are you just lining up the pipes? You may think that, but the function is divided depending on the place where it is installed.

Especially when switching pipes are considered, such as in a batch plant, or where facilities are frequently expanded or remodeled, the concept of headers alone will affect the design cost.

There are many parts that will be helpful in knowing how to use the factory.

header is deep

Where to use piping header

Headers are used in various places in chemical plants.

I will explain each location separately.

Piping header around pump

The pump header is the header at the pump outlet.

pump header

Batch chemical plants often use only one pipe even if there is a pump header.

In a continuous factory, it may be sent to multiple pipes at the same time.

  • Using the same pump to separate the oil layer and the water layer (liquid separation)
  • Transfer the liquid to another location after circulating for sampling
  • Transfer the liquid to another place while circulating to make the slurry concentration, temperature, liquid composition, etc. uniform

This usage is common.

In either case, the destination is switched several times a day.

That’s why most header valves are on-off automatic valves instead of manual valves.

Having people go to the site several times a day to operate the valves sounds easy, but it’s hard work when the numbers pile up.

In batch chemical plants, we often see headers with 5 or more pipes.

Not all of this piping is used during one production.

Maybe 2 or 3 at most.

Remaining pipes are used for other production and cleaning.

This is a way of thinking unique to batch-type chemical plants, which have a lot of switchover production.

Piping header around tank

A tank header is a header attached to the top of a tank.

piping header

A tank may receive liquid from multiple locations.

If you attach a nozzle to each tank, no matter how many nozzles you have, it will not be enough.

Header for that.

It does not receive liquid from multiple pipes at the same time.

This is because the liquid may flow backwards.

  • Occasionally receive from multiple locations such as outdoor tanks
  • receive fluids from specific locations at specific times of the day

The latter case is particularly common in batch-type chemical plants.

The former case will be limited to waste oil tanks, etc. In that sense, it is treated the same as an outdoor tank.

There are several patterns for accepting liquids in the headers of batch chemical plants.

  • Pump from another tank
  • Gravity intake from another tank
  • Reflux is applied in the same tank to receive the liquid
  • Circulate and receive liquid in the same tank with a pump

An on-off automatic valve is required if each is on the same header.

Piping header around the flow meter

A flowmeter header is a header for one flowmeter outlet.

piping header

It is used when sending a constant amount with a flow meter when sending a liquid from one tank with a pump.

It is used for utility factors such as water and organic solvents.

A common flow meter is used when a certain liquid is sent to multiple locations in one day.

These headers often have a dedicated location in the factory.

Conversely, neglecting this location in the plant design will cause major problems in the medium to long term.

  • water
  • vapor
  • nitrogen
  • Air
  • organic solvent

It is only during the plant construction phase that we think about where these utilities will come from and how they will be distributed.

Even if you try to add it later, there is no suitable place, and you will have to forcibly add the header in a strange place.

piping header

Branch headers may be attached along the route of piping.

piping header

This is used for branching pipes in high places.

Rarely used for long-distance piping.

Batch-type chemical plants rarely have long-distance piping, so there are not many opportunities to be aware of this.

If you attach the header to a high place, it will be difficult to work on the valve, so you will have to lower it to the floor.

There are many patterns.

If it’s a continuous plant, I think the situation is a little different…

Ingenuity in the connection layout of piping headers

This section describes the layout of headers and connecting pipes.

It is a pretty maniac category even in plumbing design.

If you have checked so far, you are quite advanced as an owner engineer.

Each factory has its own concept of piping design.

Under these conditions, I will introduce what I think about when considering piping diagrams and piping layouts.

I say it many times, but it’s a maniac content.

P&ID of piping header

I will introduce the P&ID of the header assumed this time.

PID (piping header)

P&ID has no line specs and no destination, so please think of it as a mere image.

Headers are assembled in low places to divide a single pipe in high places into multiple destinations.

This is the image.

In batch-type chemical plants, there are many cases where the number of destinations increases and decreases like this.

Headers are placed near the piping stand even within one plant, but there are many headers even when connecting through plants.

This is because there are cases where one plant does not complete everything from raw materials to finished products, but intermediates are made and completed in another plant.

The larger the factory, the more choices there are in the production process, so the number of headers tends to increase.

Piping header layout

Let’s consider the case where the P&ID in the above example is put into a piping diagram.

piping header

It’s hard to call it a “piping diagram” either, because it doesn’t include line specs, directions, or levels.

Still, there are many things to think about just with the shape of the piping.

lower once

The first point to note is to lower the piping once .

Many factories do not follow this rule. In that case, it becomes a form of “horizontal bending”.

There’s only one reason to drop it. Allow room for future expansion .

Many pipes are arranged on the pipe stand.

If a pipe is bent horizontally here, the surrounding pipes will interfere with the horizontal bend.

In order to avoid horizontal bends in the piping, the height has to be changed, which causes pooling of liquid and gas.

As long as there is such a possibility, it is reasonable to lower it once.

I think that horizontal bending is permitted only when “the place to bend is at the end of the piping stand and there is no possibility of extending the piping any further”.

In the first place, if it is a simple plant that does not have room for extension or renovation, horizontal bending is OK.

It may be a thought unique to a batch plant that often undergoes extensions and renovations.

Left is left, right is right

Route the pipes on the left side of the header to the left route , and the pipes on the right side to the right route.

This means that the arrangement of piping headers may depend on the destination.

The alignment of the pipe headers is likely determined by the process application (line cleaning, etc.), but it also influences the destination.

Conversely, if the pipe group on the left is to be passed through the right route, and the pipe group on the right is to be passed through the left route, the pipe groups must be bent so that they intersect.

The number of elbows does not increase and the DB does not increase, but the piping distance will increase in the first place, and the standing position on the piping stand will lose a sense of unity.

The main purpose is to minimize the piping distance and reduce the amount of construction work.

enough height

The height of the header must have a margin.

Handle operation of the header valve. The handle operation of the liquid drain valve and the installation height of the bucket.

This area is roughly ergonomically determined and standardized by each company.

The reducer is the secondary side of the header valve

Place the reducer on the secondary side of the header.

For example, if the header is 50A and the pipe ahead of the header is 40A, a 50A/40A reducer is required.

This is installed on the secondary side of the header valve.

It means that the header is composed of 50A same diameter tee and not 50A/40A different diameter tee.

Is this also unique to batch-type chemical plants?

This is because there is a possibility to extend the header.

In some cases, a blind flange is added at the end of the header, but this depends on the internal solution.

In order to reduce pooling, the end of the header may be completed with an elbow.

Even in such a case, there is a possibility that the header will be expanded at some point, and there is no choice but to modify the secondary side of the existing header valve.

Therefore, 50A piping may be required.

If you have used a different diameter cheese on the header, you have to modify the header itself.

If you don’t use the header for a long time, there is no problem.

Because there is a need to use piping somewhere in the header.

For times like this, I would like to be able to freely modify the secondary side of the header valve without modifying the header.

For times like this, I would like to be able to freely modify the secondary side of the header valve without modifying the header.


Discrete designs like piping headers are difficult to learn from a book.

The following books can be used as a reference, so those who are in charge of piping design should read them.

Related information

Related information

trace and jacket


piping diagram


vent line


expansion joint

liquid expansion


I introduced how to use the header of a batch chemical plant.

It is classified into four types: tank, pump, flow meter, and branch.

Detailed designs such as header layout, left/right/height, and reducers are possible.

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.