Leaks often occur in the external coil of the equipment during use; what’s the reason?
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One of the reaction kettles in our facility is heated by external coil tubes, with 300-degree heat transfer oil as the heating source. During use, a leak occurred in the external coil tubes, at the seam area; after it was repaired and used for some time, a similar issue arose in other areas. What could be the cause? How can we prevent similar situations from happening again?
Is the material of the outer coil the same as that of the main body?
Reply to 2# 21067758: It’s different. The equipment is made of 304 stainless steel, while the coil is made of carbon steel.
The welding quality is poor, right? Next time when welding, the groove needs to be prepared first before welding, and the right welding rod must be selected.
Reply 4# nglcx2003cn: It’s not a welding issue. There’s nothing wrong with the weld itself; the cracking is at the edges of the weld.
Reply to 5# Waiter: It’s the stress generated by layer upon layer of surfacing.
Today’s half-tubes are all made of the same material as the main body; otherwise, the welds will definitely crack over time. Using welding rods made of a different steel type is also ineffective
Reply to 7# 21067758: I also suspect that it’s due to different material properties and thus different expansion coefficients; it seems impossible to resolve this issue with this equipment. If anything is missed, it has to be filled in later.
This can be repaired by welding first, and then a reinforcing plate can be welded to the joint area of the circumferential weld
Reply to 9# hannianlong: Would it be more effective if the original weld was polished flat and an additional reinforcing plate was added around the circumferential weld?
Reply to 10# Waiter: The main purpose of adding plates is to reduce deformation at the welding areas; three plates can be placed at intervals of 120 degrees to minimize overall deformation of the circumferential welds. You want to grind it flat and add another ring plate, but considering that the deformation rates of different materials vary, cracks may form between the two materials, so I disagree with this idea