Chromatography Forum

I'm using Alltech/Grace Peek finger-tight fittings and have no problems up to about 300 bar. I prefer the black reinforced ones to the pure peek, but have used both. For higher-pressure applications, I'm using finger-tight things from Optimize technologies; they have a steel finger-tight bit, and a ferule that is half peek, and half split-metal-collet. I've used them up to 800 bar and find them completely reliable. No idea where to get them from, though; I got a few with an instrument and have been relying on them ever since.

I recently ran into the same problem of the ferrule being broken in the column. Upon taking it to the metals department, they were not able drill in the ss part? What type of drill bits did you use? Please help.. I am in big trouble as the column was borrowed from another chemistry department.

Upon taking it to the metals department, they were not able drill in the ss part?

Is the tube still there or did it pull out of the ferrule? If it's still there, try one of the tricks described earlier in the thread (my suggestion was to gently heat the fitting (and then possible cool the stub of tubing with an ice cube).

If the tube has pulled out, leaving the ferrule stuck in the fitting, then a *good* machine shop should be able to tap the hole in the ferrule so that you can use a threaded insert to pull it out -- but it ain't easy (this should give you some idea of the complications involved: https://www.practicalmachinist.com/vb/c ... ds-362684/) and there is a high probability of damaging the fitting.

Tom's spot-on (as usual). Keep in mind the financial value of the column (and how many injections you've got out of it). There is no point in spending £450 to save a column worth £500 that's already done 2000 injections (though I understand that in a university environment it may be difficult to find the replacement cost).
In event of total emergency, you have, of course, got the option of undoing the other end of the tube, and accepting that this piece of tubing is now part of the column...

The tubing had been cut off and I think while trying to drill, the ferrule had been pushed more in and possibly more damaged. They even tried cobalt bit which is now flat. The column end now looks like this



I don't think sonication or heating will help now.

lmh wrote:
Tom's spot-on (as usual). Keep in mind the financial value of the column (and how many injections you've got out of it). There is no point in spending £450 to save a column worth £500 that's already done 2000 injections (though I understand that in a university environment it may be difficult to find the replacement cost).
In event of total emergency, you have, of course, got the option of undoing the other end of the tube, and accepting that this piece of tubing is now part of the column...

I totally agree with you. I am sure its an old column but it was still working fine. Its a prep column and they are extremely expensive. I have contacted the manufacturers if the end fitting can be replaced...fingers crossed..

ouch, yes, being a prep column makes it rather more worthy of rescue. Good luck!

I took it to another University and they had the correct tools and they were able to remove the broken part safely. Thanks all for the suggestions.

Please remember to address one of the most important questions of all. The fitting got stuck in the column head because someone incorrectly swaged that connection. They either over-tightened the nut, used the wrong combination of nut and ferrule or did not set the tubing seating depth properly for the fitting. This can be avoided next time by making sure everyone involved has some basic training and awareness of the many fitting types and proper swaging techniques for both stainless steel and also plastic fittings (and of course hands-on training for practice).

"HPLC Tubing and Fittings; An introduction to Nuts, Ferrules and Tubing Choices"; https://hplctips.blogspot.com/2018/07/h ... ction.html

http://www.chiralizer.com/uploads/8/9/7 ... aphers.pdf

Hello,

I am happy this did get resolved. I have had this happen and was able to fix it myself with a left-handed drill bit and a drill press.

1. Cut off the tubing and , if necessary, pre-drill a pilot-hole with a regular drill or on a mill.

2. Now drill into it with a left-handed drill. The drill will make the nut turn left as it drills in, which will almost invariably loosen it quickly.