En-Gauge

The cathodic protection industry is a rugged one, and cables used in CP applications need to be able to withstand extreme soil, water and gaseous environments: brackish water, corrosive liquids, harsh underground conditions.

CP Cables can have several layers of coating on them.  In addition to the HMWPE layer (which can be used alone for CPC), one of the most important layers is fluoropolymer insulation, which is often then covered with an HMWPE jacket.  At Kris Tech, we use two different types of fluoropolymers: ECTFE and PVDF.

ECTFE

Stands for: polyethylenechlorotrifluoroethylene (say what?)
aka: Halar (Solvay Solexis brand)
Description: Semi-crystalline melt-processable copolymer of ethylene and chlorotrifluoroethylene.
Attributes:

• Excellent abrasion resistance
• Mechanical properties over a wide range of temperatures
• Chemical resistance to a variety of acids, bases and organic solvents
• Rated for continuous use from cryogenic temperatures up to 150°C and higher
• Good electrical properties
• Fire and Smoke performance
• Excellent weatherability
• Thermal stress-cracking resistance

PVDF

Stands for: polyvinylidene fluoride (that one’s a little easier)
aka: Kynar (Arkema brand), Hylar and Solef (both Solvay Solexis brands)
Description: Semi-crystalline melt-processable vinylidene fluoride based homopolymers and copolymers
Attributes:

• Excellent fatigue, creep and cut-through resistance
• Readily cross-linkable with ionizing radiation after compounding with co-agents
• Chemical resistance to a variety of acids, bases and organic solvents
• Low melting point of 177°C (easier melt process)
• Fire and Smoke performance
• Good electrical properties
• Excellent weatherability
• Low density
• Low cost

We cover both of our products with HMWPE, and suggest Halar as the fluoropolymer of choice.  Both of these insulation types significantly increase the level of durability of the CPC, making them much more reliable once installed in a cathodic protection system.

Are you looking for our CPC product? Visit our Cathodic Protection page for more information and to request a quote.

The insulating materials commonly used to cover copper wire (and other) electrical conductors fall into two broad classes: Thermoplastic and Thermoset.

What’s the difference?

If we take a look at our Fundamentals of Rome Wire and Cable Manual (yes, it’s from a long time ago but yes, it’s still entirely applicable), we have the following descriptions:

Thermoplastic: This material is one that will soften and even melt when exposed to a sufficiently high temperature.  In other words, when the material is originally compounded, it becomes relatively hard yet pliable, much like most plastics we encounter in our daily lives.  However, if it is exposed to high temperature at some future time, it softens and melts. The major reason for selecting a thermoplastic material is because it is the most economical type of insulation.

Some of the commonly used thermoplastic insulations used nowadays:

PVC (Polyvinyl Chloride)

PE (Polyethylene)

ECTFE

PVDF

Nylon

Thermoset: This material, on the other hand, does not soften when exposed to high temperatures.  Once it’s compounded and cured, it becomes “rubbery” and retains its properties even when exposed to high temperatures….Thermoset insulations are usually used where the wire or cable will be exposed to high temperatures.

Some thermoset insulations often used are:

• XLPE
• CPE
• EPR

[UPDATE: We've added a few more pieces of useful information on this topic here]

Photo credit: John