Not my artery

We had another leaking water pipe in our boiler room. Quite close to where we had one just some weeks before. But this time more water was spitting out of the pipe (leaking is just understating, the bucket to hold the water was full in no time). This morning it was repaired, a part of the pipe replaced.
What was a surprise was the extremely big lump of limescale inside the pipe. Luckily it was just one lump, the rest of the pipe was almost clean. The plumber said this was probably due to the dosing pump of our water softening system just before this part. Our water is terribly hard. He mentioned 26 °dH (which is about 31 °Clark/English degree).