Sealing with pressure and pipe fitting are two kinds of sealing methods commonly used in pipeline engineering, they have some differences in practical application. The following is a detailed explanation of both methods.

Hot Tapping refers to the maintenance, replacement, addition or reduction of branch pipes in the pipeline system, without stopping the operation of the entire system, but only by opening holes in the pipeline for operation. This method is usually suitable for high pressure, high temperature and large diameter pipeline systems. Pressure plugging requires the use of a commonly used pressure plugging device, which can form a temporary seal inside the pipeline to prevent media leakage. Pressure plugging can improve work efficiency, reduce downtime losses, and reduce the impact on the system.

The main advantages of sealing with pressure are:

1. There is no need to stop the operation of the entire pipeline system, reducing production interruptions and downtime.

2. Branch pipes can be added or reduced in the pipeline system.

3. Suitable for high pressure, high temperature and large diameter pipeline system.

4. It can reduce installation cost and maintenance time.

However, pressure plugging also has some limitations and shortcomings:

1. Sealing with pressure requires the use of special equipment and technology, and has high requirements for operators.

2. For some special piping systems, pressure plugging may not be applicable.

3. Ensure the sealing performance of the sealing device to prevent media leakage when performing the sealing operation with pressure.

Pipe fittings are commonly used in pipe systems to connect pipes of different diameters, materials or functions. They can be rotated, bent or branched as needed to achieve the design requirements of the piping system. Pipe fittings are usually made of metal, plastic or composite materials and have certain strength and sealing properties.

The main advantages of pipe fittings are:

1. Pipe fittings can connect pipes with no diameter or material function to facilitate the layout and adjustment of the system.

2. Pipe fittings can be rotated, bent or branched to achieve the design requirements of the pipeline system.

3. The pipe fittings have certain strength and sealing performance, which can ensure the normal operation of the pipeline system.

However, pipe fittings also have some limitations and shortcomings:

1. The installation and disassembly of pipe fittings is more complicated and requires the use of commonly used tools and techniques.

2. The connection point of the pipe fittings may have the risk of leakage, and it needs to be tightly sealed.

3. The material and specifications of pipe fittings are limited, and may not be able to adapt to special working environments and media.

In general, pressure plugging and pipe fitting are the two commonly used plugging methods in pipeline engineering. Pressure plugs are used to repair, replace, add or subtract branches without ceasing production, while fittings are primarily used to connect pipes of different diameters, materials or functions. The choice of which method to use should be determined according to the specific engineering requirements and conditions to ensure the stable operation and efficient maintenance of the pipeline system.