Can an elbow be welded directly to the head?

There seems to be no such rule; I personally am reluctant to do it, but the company does have examples of direct welding.

If the structure of the head and the flanges for butt welding is taken as a reference, the arcuate transition section of the head must be at a certain distance from the weld. It’s not ideal to weld the elbow directly to the housing, but in practice, many cases involve direct welding when the bending radius of the elbow is large.

It can be welded, but generally the straight sections of elbows are relatively short, which makes operation difficult and hinders the application of insulation material. The flow of fluid at the elbow has to change direction by a large angle, resulting in increased wear; once it gets damaged, replacing it is troublesome. If there are no special requirements, it is best not to do this

The elbow is welded directly to the head; reinforcement calculations are required for the openings. It’s not easy to determine the protrusion height – is it the straight length of the elbow? Personally, I think it’s better to have a section of straight pipe.

I agree with what was said above; although there are no regulations prohibiting it, it is still not recommended to do so.

Different industries have different regulations. For example, under the IMDG Code, tanks of type T20 do not allow for openings in the head, and therefore it is certainly not permitted to add elbows. Mobile pressure storage devices need to be classified according to a higher cargo rating; generally, a rating of 6.0 or above is not permitted. At the same time, the collision prevention principle must also be taken into account. If it is a gas tank, basically no goods are allowed; otherwise, it will be very difficult to obtain a certificate. If it’s a static tank, then it’s more complicated. It depends on your industry standards. From the perspective of actual performance, it is related to many factors such as the position of the orifices, the thickness of the tank’s walls, and the type of valve connected at the outlet end of the elbow; these factors can either enhance or weaken the strength of the tank, resulting in significant differences.

If the bending radius of the elbow is large enough, welding is possible; however, unless there is a specific requirement, it is better not to do so, as the fluid at the elbow has to change direction by a large angle, which leads to high wear, and the damaged component is difficult to replace.

Welding it directly to the head results in too complex stress conditions, so this should be avoided.

It is best not to weld directly to avoid stress concentration at the elbow.

There are no regulations on this in the standards, but you can weld a steel pipe to the cover and then weld it to the elbow; I handled similar issues in this way as well.

The elbow can, in theory, be welded to the head, but the following requirements must be met: 1. When welding the elbow, the minimum distance between the elbow and the weld on the head should be greater than 50 mm; 2. The straight section of the elbow must meet the reinforcement requirements of the head. This is just my experience from regular design work; if there are any issues, please feel free to offer your criticism and suggestions.

We once built a device of DN400, with a 325 elbow connected to its head; lol. We asked if there might be any problems with that, and the design institute said it was fine. (Because the opening is already getting close to the small diameter of the head.) We asked whether a stress analysis was needed, and the design institute said no – there would be no problem, and they wouldn’t be held responsible if anything went wrong. (There is written documentation to prove it.) Then we just went ahead and created one type of container~:lol

Under normal pressure and low pressure, the medium can generally be welded directly. However, welding should not be performed directly on hazardous media and medium/high-pressure equipment, as it involves opening for reinforcement and stress concentration.

There are no regulations in this regard, as a insulation layer needs to be added, and it seems there is a minimum length requirement for the pipes. Moreover, if the flange connection is too close to the elbow, it is also inconvenient to disassemble. So, in my personal opinion, one should not do this. Don’t cause problems in future use just to save on the cost of taking over.

There are no prohibited requirements. But we do not advocate doing this.

Under conditions that meet the design requirements, the elbow can be welded directly to the head, but generally, at least 50 mm of straight pipe is required. This is easy to operate

If the elbow radius is large enough, welding is possible; however, if there are no special requirements, it is better to add a section of straight pipe.

If the bending radius is large, R > 1.5D, there is no problem; if the bending radius is small, R = D, then there is a problem

I wonder who knows why it needs to be welded this way? There’s no rule yet that says it’s not allowed, but welding in this way looks really ugly. Are you using it as a level gauge connector?