Discussion on the issue of oxygen pipeline branch connections

Article 1 specifies steel seamless reducers, which include pipe sockets, branch pipe supports, instrumentation connections, etc. In other words, venting, temperature measurement, pressure measurement, and backwashing do not belong to the branch head. The term \"branching point\" here should refer to a branch or a side pipe. These are the two main requirements: the inner wall must be smooth, without any sharp edges, burrs, weld beads, or protrusions; furthermore, when manufacturing tees, they can only be fitted in place, not inserted.

Highlight one point. . Welding through holes cannot be performed when installation is not on-site. . As long as the following uncontrollable factors exist: the quality of the openings, the grinding of burrs, and the quality of the inner surface of the welds. The first point mentions steel seamless reducers, which include pipe sleeves, branch pipe supports, instrument connections, etc. In other words, venting, temperature measurement, pressure measurement, and backwashing do not belong to the branch head. The term \"branching point\" here should refer to a branch or a side pipe. I disagree with this view. These are the two main requirements: the inner wall must be smooth, without any sharp edges, burrs, weld beads, or protrusions; furthermore, when manufacturing tees, they can only be fitted in place, not inserted. I disagree with the view that it can only be placed in a fixed position. .

What do you think would be a more reasonable approach?

Do the design, supervision, and inspection parties approve this plan? How can we ensure good welding quality on the inner surface – with proper fusion, a smooth surface, and no burrs? Solve it in this direction.

Analysis of oxygen pipeline explosion accidents (especially those involving ultra-high pressure oxygen) suggests that they are often caused by defects on the inner surface of the pipeline welds. Mainly smoothness, burrs, weld beads, as well as high levels inside the welds.

In construction, branches that are at a certain angle to the main pipe – whether vertical or inclined – as well as instrument connections and drain/bleed fittings, are generally considered to be branches. For the reducer fitting mentioned in the first point, a steel butt-welded seamless reducer fitting is used. The key is whether this steel butt-welded seamless reducer refers to the reducer itself or the welding method between the reducer and the main pipe. If confirmed by the reducer itself, this clause can be understood in that way, right? In Article 2, standard steel butt-welded seamless tees should be used for the branch ends; in this case, finished seamless tees are employed to be welded to the main pipe. If it is a pressure gauge branch, then a tee such as DN400×25 might be required. This type of tee is not common in construction drawings or design plans.

Article 2 originally stated that openings must not be made for insertion. This interpretation is also ambiguous: A: No openings are allowed, and plugging in is even less permitted ； B: Holes can be made, but connections are not allowed. Under the latter interpretation, welding cannot be performed, so it can only be installed in a fixed manner. Either it’s a finished product

That’s the problem: when using a tee together with an elbow for DN400X25, more elbows are required, which seems inappropriate.

The butt-welded branch pipe supports should also be finished components, and do not fall under the category of plug-in types.