Broken tap in expensive unit!

[Fowlers FuryParticipant @fowlersfury]

"……..the possibility that Hydrochloric Acid will react with Iron in the tap to make Iron (III) Chloride. Now that chemical is well known for dissolving copper to make printed circuits. "

Not quite, the reaction between HCl and Fe will produce ferrous (III) chloride irrespective of the acid concentration.

It is the ferric (II) chloride of course which is the etchant. However ferrous chloride does attack Cu to a lesser extent though with the problem described any effect would surely be insignificant.

If Andrew T does decide to use either alum or dilute HCl, it's important to keep agitating the solution with a piece of thin wire in order to displace the hydrogen bubbles which will form on the tap's surface and prevent the reaction. Also keep the reaction warm for a faster dissolution of the steel.

Forgot to add > if a thread lubricant was used before breakage then this will inhibit acid contact with the tap, so degrease as much as possible first with some solvent.

Edited By Fowlers Fury on 14/09/2017 16:21:24

[SillyOldDufferModerator @sillyoldduffer]

Posted by Fowlers Fury on 14/09/2017 16:18:29:

"……..the possibility that Hydrochloric Acid will react with Iron in the tap to make Iron (III) Chloride. Now that chemical is well known for dissolving copper to make printed circuits. "

Not quite, the reaction between HCl and Fe will produce ferrous (III) chloride irrespective of the acid concentration.

It is the ferric (II) chloride of course which is the etchant.

…

Edited By Fowlers Fury on 14/09/2017 16:21:24

Ah yes, thanks for the clarification. I'd like to blame my aged brain for the mistake. Unfortunately I remember all too well being chastised at school for not paying attention. Many times. Many, many times…

Dave

[Thor 🇳🇴Participant @thor]

Isn't the iron (III) chloride the ferric and iron (II) chloride the ferrous?

Thor

[mark smith 20Participant @marksmith20]

Thor ,speaking as an ex chemist ,you are correct.

[Fowlers FuryParticipant @fowlersfury]

Apologies, yes of course, ferrous is divalent form.

Age is taking its toll; a moments thought about ferrous chloride being FeCl2 would have avoided the silly error.

[Message to self: do not rely on failing memory, check first]

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