Selection of inner and outer grooves for equipment manufacturing

This post was last edited by ztr1118 on 2012-6-5 20:45. The inner groove is convenient, and it’s easy to clean the root area. :victory::victory::victory:

So, if it’s a very small device, how can it be made more conveniently? Like those with a diameter of 500 mm? Should an internal groove or an external groove be chosen?

This post was last edited by ztr1118 on 2012-6-5 20:48. 1. The purpose of grooving is to obtain a weld joint that meets the design requirements, while minimizing the amount of weld filler metal as much as possible, ensuring thorough welding. 2. As for the type of groove to be used, it mainly depends on the thickness of the plates of the container that needs to be welded and on your welding methods. 3. When selecting the groove shape and dimensions, factors such as the welding method, minimizing the amount of weld filler metal to avoid defects, reducing residual welding deformation and stress, facilitating welding protection, and ensuring ease of operation should be taken into consideration. 4. In practical work, generally speaking, there are roughly the following points: (1) Using an internal groove can reduce the amount of weld metal deposited, which is equivalent to an X-groove ； (2) For containers with a diameter of less than 800 mm, if manual welding is used and an internal groove is created, the construction process becomes more difficult; therefore, an external groove is generally chosen ； (3) For containers ranging from 800 to 1600, since there is ample space for construction, either an internal groove or an external groove can be chosen; since the root can be cleaned externally with an internal groove, and considering aesthetic appearance, an internal groove is generally preferred. (4) For fillet welds, it is of course better to use an internal groove, as this reduces the amount of weld metal used while ensuring good quality at the root of the weld. When an external groove is used for fillet welds, the root area often fails to be fully welded in many cases.

This post was last edited by ztr1118 on 2012-6-5 20:49. The situation varies from one manufacturing plant to another. Generally, for containers under 800mm in size, it is advisable to use external grooves (as welding inside is difficult); single-sided welding with free formation on the back side is sufficient, and there is no need for root cleaning； However, some of the automatic welding equipment used by manufacturing plants is equipped with special attachments that can be inserted into such containers to carry out welding, thereby allowing for the creation of internal grooves ； For values over 800, it is recommended to use an internal groove; as mentioned above, this makes it easier to clean the outer area and results in a better appearance

These days, many manufacturing plants use submerged arc automatic welding for basic Class A and B welds with a diameter greater than 1200 and a thickness of 6 layers or more; moreover, no beveling is required for welds with a thickness of 14 layers or less! As for joining the pipe to the WN flange, since the flange already has an external bevel, the pipe is generally also processed to have an external bevel~ As mentioned by others above as well, hehe~

Can full penetration be ensured with free forming behind single-sided welding without root cleaning?

I’m not very familiar with submerged arc welding. Are there any requirements regarding the diameter of the container? What about containers with a small diameter? May I ask how containers with small diameters (diameters less than 800 or even smaller) are manufactured these days, and how full penetration of the welds is ensured?

Because submerged arc welding is carried out using the machine’s cross arm; if the inner diameter is too small, it’s difficult for the cross arm to rotate. Welding longitudinal seams may not present too many problems, but it’s not easy to do so. In our factory, for small diameters, we usually use TIG welding for the root pass and manual arc welding for the finish pass. I’m new to this field, so my explanation might not be very clear haha~

Back to floor 7: Single-sided welding with free forming on the back side, without thorough root cleaning; I believe this does not guarantee full penetration. However, full penetration is not required for all weld joints. For structures that require full penetration, double-sided welding or TIG welding for root pass is necessary

Using TIG welding for the root pass ensures full penetration, just like in the case of butt welding between flanges and pipes. It’s such a small area – how is it possible to clean the root inside? Should an external groove still be used?