Correct method to weld a MS Channel to MS I-beam

[S.Chakraborty]

Hi,
A MS Channel has been welded to I-beam such that the face of the channel web and flange is directly welded to the bottom flange of an I-beam. I need to know if it is okay to weld it in this way. If it is not okay please help me understand what can go wrong and how should i weld it to the I-beam to fabricate this hanger? It will be very helpful if someone can provide me with a hand sketch.
Thanks in advance. I have attched a picture for your review.

 

[Ron]

In theory, if the weld is adequately sized and properly executed, there would not be a problem if the only loading were vertical. That is not the case and here are the considerations I would make:

1. The pipes are heavy, so they exert a high load on the hangers. This increases the friction between the pipe and the bearing channel. Thermal expansion and contraction will cause the pipe to move across the bearing channel. There are no rollers under the pipe to accommodate this so a moment will be introduced into the weld.

2. This is an industrial application so I would expect at least some vibration will be introduced in the pipe system. This will transfer to the hangers and exert a fatigue consideration in the welds.

I would look at proprietary pipe hangers that would clamp to the bottom flange of the beam instead the configuration shown.

 

[CANPRO]

There is nothing wrong with welding a hanger on the underside of a beam like this if designed and installed properly. You would need a local structural engineer to determine if this is acceptable.

It appears that the beams are aluminum. If that is the case, it is likely that you have lost approximately 1/2 of the material strength in the heat affected zone (HAZ) of the weld. I would be very concerned if this wasn't taken into account in the original designed.

 

[kostast88]

You will need a structural engineer to properly assess this, based on the loads and site conditions. It's not a big job but nobody here is in a position to guess the loads and steel condition. Also, If I were you I wouldn't take their advice for granted. Not worth the risk.

As for the weld itself, it is do-able, probably adequate (if designed in the first place) check with the fabricator who did the job if he run any calculations or if there was an engineer on the job.

 

[KootK]

If the beam is an existing element, give some thought as whether or not welds placed transverse to the flange might temporarily compromise flexural capacity. The transverse welds are short and close to the end of the beam so you're probably okay on this. If not, consider temporary beam shoring.

 

[HTURKAK]

This is typical hanger type support frame . In oil and gas industry, there are standard drawings used for in house purposes . I looked one of them , in case of 60X60x 8 L and the span of trapez 1.0 m, and welds are 6 mm fillet, the max load is 5 kN.
The expected practice is the pipe stress analysis is performed and the pipe support are designed as per the stress analysis. In most case,the supports can be pre engineered .

I will suggest you to look Process Industry Practices PIP PNFS0001 Pipe Supports Details to get the concept.

 

[S.Chakraborty]

Thank you everyone for sharing your valuable inputs to my thread. Much appreciated for your help!