Advice on ATEX glanding.

Was the copper grease applied by the manufacturer / installer?

What is your thinking behind the need for a non-conductive grease?

You wouldn't be confusing this with the need for a non-setting grease to be used on Ex d enclosure flanges, where required?

- Ross

As you have mentioned that the piece of equipment is certified for gas subdivision IIC, is there any risk of acetylene being present?

- Ross

Hi Ross

Thanks for your reply.

Copper ease has been applied by the manufacturer.

A lubricant is used to stop galling to the threads between two stainless steel fittings.

I recall 60079 having information about grease being non conductive but I may be confused with non-setting. I'm on site and don't have access to all my standards and guidance at the moment.

No acetylene, the hazardous area is compressed hydrogen.

Latest Ed 6 of IEC 60079-14 Reg 8.7.3 "Protection of Flamepaths" indicates the following:

Of course the threaded entry for the cable entry device (Gland), is of course a threaded flamepath so 8.7.3 would apply if wishing to prevent corrosion. If the copper ease was applied by the manufacturer and not the installer, I would ask the manufacturer for written confirmation that the copper ease they applied is actually appropriate.

Cheers GTB 

PDFfor reference the datasheet for copperease is attached. Be aware that the 1100C temperature applies to the product once installed, and that the 'spray-on' version beloved of garages that do brakes has a propellant that is highly flammable (!) Lets hope they used the stuff that comes in a tub. It is certainly not a reliable insulator, but equally, according to the data, nor is it a reliable conductor, so I might be checking the continuity of the conduit afterwards ;-) In reality, I think the earthing will be unaffected.
But in non atex situations we use it to stop stainless parts from jamming, which otherwise they do depressingly easily, and it is very good at that and certainly has no effect on the passage of large RF current surges.
Mike.

IEC 60079-1 (the constructional standard for Ex d enclosures) gives effectively the same requriements for properties of grease for use on Ex d flanges and other flamepaths as those given in the extract by GTB from IEC 60079-14 with the addition of:

'. . . does not contain an evaporating solvent . . .'

There doesn't appear to be a explicit requirement in either standard relating to the conductivity or non-conductivity of grease, other than the requirement in the IEC 60079-14 extract that:

' . . . any earthing across the flamepath shall be maintained.'

However, I am slightly curious regarding the use of copper grease on equipment for gas subdivision IIC due to the potential for the formation of copper acetylide in contact with acetylene.

- Ross 

I didn't know what 'copper acetylide' was, or did, so I asked the web, which said

"It's a reddish-brown, explosive powder and is also known as cuprous acetylide or copper carbide."

I now see why it might be important... 

Yes - copper or silver in contact with acetylene have the potential to form explosive acetylides! 

On a related note, there are also restrictions on the use of aluminium, magnesium, titanium and zirconium in Ex equipment, but for a different reason - the risk of sparking as a result of impact or friction.

- Ross 

The manufacturer has employed Bureau Veritas to provide the certification. I need to do some more research before asking questions as I would imagine any answers will be slow to arrive.

Interesting new area I have not encountered before.

Thanks for your input