No Turning Again

I didn’t even make it out to the shed this weekend, never mind turning anything. No. Instead of that I had to replace central heating radiators. These were bought from a subsidiary of a very large DIY chain about 7 years ago, and in the last 2 weeks 3 have suddenly burst. There was no warning, no slight leak, no rust stains, nothing. They just popped. Usually in the middle of the night, naturally.
I’m not a trained engineer, but this looks like a bodged repair to me.

I’m no expert, but this looks to my untrained eye like a previous repair has burst. The hole is slightly smaller than a No.4 Pozidrive screwdriver. Each one has been the same. One even burst in 3 places at once.
This is a gravity fed system incidentally, so no sudden pressure increases. Very strange.