How to remove seized tap backnut

[boilingpoint]

Hello all,

Can anyone suggest a good way of relieving this hot water tap of its backnut? The nut's quite firmly seized to the thread.

Have so far tried scraping the crud out of the nut then spraying with WD-40, tapping with a hammer, applying with a heat gun and, of course, brute force (spanner and slip-joint pliers in opposing directions).

It might be time for something more drastic.

Need to avoid damaging the tap, although some damage to the thread would be fine but only as long as it won't prevent reuse. The backnut can go, of course.

 

[Deleted member 120897]

If backnut is going, you could try carefully cutting it off, eg hacksaw, or drummer type tool? Or apply some heat (again being careful not to burn yourself).

 

[snowhead]

Junior hacksaw and cut into the nut flange and as far into the nut without causing damage to the thread.
Then hammer a flat blade screwdriver or thin chisel into the slot and the nut will split.

 

[PETE 123]

Blowlamp if metal bath i have drilled brass backnut in a line then sharp chisel to split.

 

[boilingpoint]

Thanks, Undertrained, snowhead and PETE 123.

Panic over!

In the end, I drilled into the nut, fully intending to crack it open, but used too big a bit (4 mm) to gain leverage. However, it did weaken the nut's grip enough to allow it be slowly unscrewed with what leverage I had.

Some damage sustained to the thread.

Yes. A hacksaw or a Dremel would've been the graceful way to go about it. I know for next time.

Thanks again.