XLPE problem

Good day to all!
Hi! I hope everyone is fine. I just want to ask for some opinions from the experts.

Well this is the situation:
We are producing our own XLPE.

For the last 2 weeks we are using XLPE produced from May-July plus new production in August. We are facing problems on May and June supply and some on July supply. There are too many blisters and that is why they need to bleed more.

As per our laboratory "The root cause of this defect is pre-curing of the XLPE due to humidity coming from the plastic lining (packaging) material which is not suitable for XLPE."

If EP can’t use suitable lining with aluminum coat, JCC must use incoming EP-XLPE ASAP (EP recommends 1 month)". Is this only about the packaging or there are anymore factors?

Thanks for the reply.

Hello again jprs_ie,

As we stated in your other message, stop using acronyms as typing short cuts. We may not understand what you mean. Here are some questions?

1) Who is "EP" and what is EP-XLPE? A Hyundai XLPE moisture cure compound? Is this compound like your Compound "A" below? (Pre-grafted with vinyl silane?)
2) Who is "JCC". Your company?
3) This seems to be a moisture cure process as follows. Please confirm:

Process "a" - The purchase or manufacture of a very clean LDPE or LLPE which has been compounded (pre-grafted) with vinyl silane. This first step is done in a mixing extruder and includes accurate mixing with a peroxide initiator and an antioxidant before pelletizing. We will call this Compound "A".

Process "b" - The purchase or manufacture of a catalyst masterbatch produced by the accurate mixing a very clean LDPE or LLPE compounded with an organo tin catalyst such as di-butyl tin laureate and then pelletizing. We will call this Compound "B".

Process "c" - The accurate mixing of compound "A" with the catalyst masterbatch (Compound "B") and a color masterbatch by gravimetrics at a regular PE extrusion line.

Process "d" - The wire or cable insulation is cross linked in a steam room, in boiling water or just by leaving it in a normal plant environment for some period of time.

4) Do you purchase or make your own Compound "A"? Is this where the moisture problem that your laboratory identified is?
5) Do you purchase or make your own Compound "B"?
6) Is your final pellet combining and mixing at the insulation or sheathing process done by accurate gravimetric machinery at the extruder hopper?
7) At sheathing, is the black color masterbatch also added at question 6) above? Is it first dried to a -40 C dew point?
Has anybody checked to see that gravimetric mixer at question 6) is calibrated and running properly?
9) Your sentence "If EP can’t use suitable lining with aluminum coat, JCC must use incoming EP-XLPE ASAP (EP recommends 1 month)" makes no sense to us. What do you mean?

Please, please take the time to compose your questions and descriptions carefully. We cannot see what you see!

Regards,
Peter Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com

Hello again jprs_ie,

As I recall, compound "A" generally has a shelf life of about one month. That would mean you have to stop manufacturing such large batches of this compound. Make sure the stored compound plastic bag is well heat sealed away from the atmosphere, out of the sunlight and in a cool, dry place. Practice good logistics to manage your perishable inventory.

Regards,
Peter Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com

Thanks for your reply Mr. Peter. Up to now our Plastic Plant is not responding to your questions. We will do what you have suggested. But I will also try to follow-up to our plastic plant for their answers.
Thanks.