When connecting small fittings to a pipe, is it necessary to use fittings or pipe supports?

I see that the installers at my company just weld directly; I’m not sure if that’s correct

1. Large-diameter pipes have sufficient thickness, so the weakening effect of the small connections on the strength of these pipes is minimal; therefore, they can be welded directly. 2. In practical applications, the issue isn’t the weakening of the large pipes themselves, but rather the fact that if the small connections are not properly supported after being installed, factors such as pipe vibration and external forces can cause high stresses at the base of those connections, leading to fatigue fractures. 3. When the medium is at a slightly higher or high temperature, temperature differences arise due to uneven heat transfer between the pipe wall and the connections, and these temperature stresses can cause the weaker connections to crack. 4. When small connections are used for bottom drain purposes, corrosion caused by the medium and the surrounding environment can easily deplete the remaining strength of those connections. 5. The examples mentioned above do not necessarily mean that direct welding is prohibited; however, it is more reasonable to use reinforcing fittings such as pipe supports.

There are many proper nouns; I don’t quite understand them, but it seems what you say makes sense

Flanged pipe collars can be used; make sure to request the manufacturer to provide a saddle-shaped groove for use in conjunction with the pipe when placing the order； It is also possible to make direct openings during pipeline welding, provided that there are one’s own stress analysis results to support it

Once the strength calculation has been done, it’s not necessary to use it. Low pressure seems to not be necessary.

When installing pipes without fittings, a reinforcement plate is generally still needed

There are standards; the difference between the main pipe and the branch pipes determines whether to use a tee

Each design institute has its own pipeline grade table, and the sizes of main pipes and branch pipes are used to make selections; there is also a table that indicates what type of connection can be used.

GB50316 specifies that for pipes with a nominal pressure greater than 10 MPa and subject to vibration, direct welding after making an opening is not allowed. There are also various types of welding methods, and some of these cannot be used in certain situations.

It’s possible; using fittings and pipe supports is done to address reinforcement issues. If the strength of the structure is sufficient, I think it’s okay. However, some standards require the use of pipe supports for reinforcement under certain pressures. If welding is used directly, discrepancies may arise during inspection, so it’s best to consider this carefully or communicate with the design team in advance.