plate freezers and flexible line replacment...

[mattmechanic]

Hi all i believe it is that time when i need to replace all the hoses feeding the plate stack

i am told it should be done every 2 years by one organization and 5 years by another...
dose any one here know if there is legislation in place that states a time frame they must be replaced by ( in Australia ) ?
as the actual hoses on this system are dated 1997 and are made of a steel braid outer

i have called a few local hose manufactures and they have no idea on what type of material to use or how often they should be replaced and i do not know exactly what type of material they need to use other then it is stainless steel braided outer.

looking for some advice on this one
cheers

[RANGER1]

Latest hoses are of stainless steel bellows design, previously Teflon lined.
No shortcuts or cheap hoses or expect disaster.
Believe bellows best like anaconda.
Milmech or Gordon Bros, ask them about any legislation or recommendations.
I'm thinking if Teflon lined, replace now, bellows when they leak.

http://www.hoseflex.com/product/metallic-hose-high-pressure/

[mattmechanic]

Hi, i was told the current hoses are just a rubber hose with stainless braid but one of the maintenance workers at the plant but who really knows unless you cut them open,
however they are very flexible like rubber so that might be true
thanks for your input!

[RANGER1]

I would suggest that get them through manufacturer of plate freezer & also follow their recommended maintenance procedure.
That way at least you are covered in case of accident etc.

I know that one manufacturer uses the bellows hoses, which are very good.
Previous to that it was Teflon lined.

Consider how how much ammonia in plant, possibly 20 to 30 tonnes.

[Tycho]

What Ranger1 said...

Get replacements from the manufacturer, to make sure you get parts that are under warrantay.

Small point here that I can't get behind is the "lifeline" of the hose, with the new hoses, teflon inner and steel braided outer, they have a lifeline og 50 years during normal operations. (could be 200 years, but whatever)

Depending on your operation, I would make sure to have 2-5 hoses in stock, ready for the maintenance personnel to replace as they go (with the braided steel outside none will have a catastrophic failure), but can have a big leak during defristing

[AMP]

What Ranger1 said...

Get replacements from the manufacturer, to make sure you get parts that are under warrantay.

Small point here that I can't get behind is the "lifeline" of the hose, with the new hoses, teflon inner and steel braided outer, they have a lifeline og 50 years during normal operations. (could be 200 years, but whatever)

Depending on your operation, I would make sure to have 2-5 hoses in stock, ready for the maintenance personnel to replace as they go (with the braided steel outside none will have a catastrophic failure), but can have a big leak during defristing

Tycho, completely agree with you.

There are mainly two ways to have a leak on the actual hoses: hitting them; or with a wrong defrost. Taking care with both issues, the life of the hoses is very, very long. Of course, assuming they are made of antistatic PTFE and stainless steel braid.

[RANGER1]

Hose length also very important as well.
Have since found out teflon lined seem to last longer, but may also need coil up middle to stop vacuum in hose, collapsing teflon.

[kiwi]

Matt. Im pretty sure you do not need to renew the hoses on a time basis. I have not seen any AS/NZS standard that would support that.
Most plate freezer hoses we are using are teflon lined with stainless steel braid cover. There is also an option for convoluted hose which have much better bending radius. Some systems are also subject to static discharge. The ammonia (or other refrigerant) moving through the line can create static charge which discharges along the hose. I not too long ago saw a hose that had tiny burn marks all along it. This was identified as static discharge. We were able to get our hose supplier to source an anti static hose for this application.
Do you still have the contact details for Milmeq? They should be able to help you out here.

[mattmechanic]

thanks for all the input
i am going to send 6 random hoses off for testing and if they are all ok we will just leave them i think
thanks!

[RANGER1]

thanks for all the input
i am going to send 6 random hoses off for testing and if they are all ok we will just leave them i think
thanks!

Matt,
Good plan as it's being proactive.
We had a job that pumped 20 tonne of ammonia in plate freezer complex, expensive cleanup.
Room was below -35 C, so ocean of ammonia.

[mattmechanic]

yeh its a scary thing to happen i have just installed a 4 NH3 sensors along the room in the middle of each stack and connected it to the PLC so if there is a leak it will shut down the liquid supply solenoid to the header just as a safety first precaution to minimize some risk...