Preliminary Piping Principles
Preliminary Piping Principles

خانه Preliminary Piping Principles

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Preliminary Piping Principles

Preliminary Piping Principles

Piping is used in various industrial fields, for example, in factories that supply and operate a special chemical process such as refineries, refineries, etc.

Related standards for refineries and petrochemical units are:

1-Process Piping ANSI B31.3

2-Power Piping ANSI B31.1

Process piping is used to transfer fluids between storage units and process units and other units.

Service piping, to transfer steam, air, water, etc. to provide facilities for the process to be carried out optimally

Is used. The service piping is called Utility piping.

Planning, designing and building a (Plant)


When an employer decides to build a new plant, or to develop an existing plant, hire a design engineering company to design and build, or if the company’s engineering department grows to design and control itself. Projects and employs one or more contractors. Designing and building an industrial plant is a complex responsibility that is usually done by specialized companies as consultants.

Piping Required Items:


Pipes are one of the main parts and components that make the connection between devices and create a path. Pipes are usually made by “Nominal pipe size or NPS and wall thickness according to Schedule No. is.

It should be noted that in the article definitions of pipes and tubes, this section is fully described.

The choice of type and material of pipe will depend on the conditions of placement in that service, including (type of process, working class, temperature and pressure).

Material Selection is one of the most important tasks of a process engineer.

The method of selecting the pipe material according to the desired service is also mentioned in the ANSI standard in a table (table below).

Pipes are usually produced in lengths of 6 or 12 meters. If the end of the length of this pipe is flat, it is called Plain End or PE. If the chamfer is applied at the end (for welding), it is called Bevel End or BE, and if the thread is applied, it is called Threaded & Coupled or T&C.

Pipe connection methods:

The connection methods used for most carbon steel and stainless steel pipes are:

1-Butt Welded

2-Socket welded


4-Bolted Flange

5-Bolted Quick Coupling

Butt Welded fittings are used for sizes larger than 2 inches. This method is very important for thick pipes.

Socket Weld connectors are commonly used for sizes smaller than 2 inches. This method guarantees their sealing in these sizes. This is a valuable factor when transporting flammable, toxic or radioactive fluids.

Screw flange fittings are used to connect flanged tanks and equipment, valves and process lines that require intermittent cleaning.

Piping Fitting connections

Fittings are important components of piping that we will thoroughly review and describe. Also, fittings are used to change the process path, change the diameter of the pipe, branch from the main pipe and …..

1-Elbow (knee)


Tees are devices used for branching and in some cases to change the direction of fluid in pipes. These tees have two main parts: 1- Header and 2- Branch

There are four types of TEE:

1- Equal Tee In this type of three-way, all three heads have the same size.

2-Reducing Tee, in this type of tee, the branch diameter is smaller than the main diameter. The main point about these reducing tees is that usually the diameter of the branch can not be less than half the diameter of the main pipe. Like Tee6 * 4.

3-Equal Lateral Tee This type of tee is the same as item number 1, except that the angle between the branch and the main is no longer 90 degrees. This type of tee actually allows for branching at desired angles where low current resistance is important.

4-Reduce Lateral Tee, this type of tee is the same as item 2 with the same angular difference between the branch and the main diameter, which is not 90 degrees.

Tee standard can be found ANSI / ASME B16.11.


Crossroads are devices for branching. Crossroads are built in both Equal and Reduce forms. General applications are places where we face a lack of space.


There are devices that are used to connect two pipes with different diameters. If we are going to connect a large diameter pipe to a small diameter pipe, it is called a reducer. If we want to connect a small pipe to a large pipe, we call it Expander.

Reducers themselves are divided into two categories, which are:

1- Concentric Reducer: which is the input and output axis of the same and in fact the Reducer reduces the diameter equally on both sides. For example, Safety Valves mostly use this type of reducers.

2-Eccentric Reducer (eccentric reducer): that the inlet and outlet axis are not the same and in fact the reducer starts to reduce the diameter on one side. Is used.

5-Swage Nipple:

Depending on the type, this connection can be used for two purposes. As we know, these are devices that are used to connect two pipes of different sizes in sizes of 2 inches and less.


These and other tools are usually used to connect pipes smaller than 2 inches. In fact, the user system of these items is used in Socket Welds and Thread, and depending on their application, they are used in both Half Coupling and Full Coupling.

The standard used for these items is ANSI / ASME B 16.11.


Usually used for maintenance and connection. This is a screw connection designed for use in Socket Welded systems.


A reducing device is used to connect a smaller pipe to a nozzle or screw connection.

Used larger. Its main application is in instrument connections. By drilling and hammering the vulva parts, reducing joints can be produced with any reduction rate. These tools are not used on high pressure lines. Their types are divided according to their shape, such as Round, Hexagonal, etc.

9- Olets:

And are a means of branching out. (90 degree or perpendicular to the main pipe). Olets are generally used when the size (diameter) of the branch pipe is less than half the diameter of the main pipe.

Olets are generally divided into four categories: Weldolet, Sockolet, Threadolet, and Sweepolet.


Items are like Olets, except that the branch is taken at a 45 degree angle.


Piping is one of the most important components. In terms of material, flanges, like pipes, have a specific material, and they can be made of carbon steel, monel, etc. Flanges can be connected to pipes like Butt Weld, Socket weld, Thread. The types are:

11-1-Welding Neck Flange: These flanges are suitable for places with high temperature, shear stresses and high vibration pressure.

11-2-Flange Slip-on :

These flanges are less resistant to shock and vibration. It is also easier to center these flanges than welding neck flanges.

11-3-Reducing Flange:

These types of flanges are suitable for resizing. However, in case the rapid transfer of current causes unwanted turbulence, they should not be used like pumps. Reducing flanges are also available in non-centric type.

11-4-Expander Flange:

It is similar to Welding Neck flanges but connects to a larger pipe, turning the pipe into one or two larger sizes.

11-5-Lab-Joint Flange: If expensive pipes such as SS are used, it is economical to use this type of flanges, because the flange can be made of carbon and only the Stub End can be made of pipe and used. Let us.


Used to block the end of the pipe.

Author: persian / Date: 2017-10-26
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