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.

This month’s (or two month’s) edition of Wiring Harness News had a good article written by Anixter on “Thermoplastic vs Thermoset Wire and Cable Materials.”  Since we highlighted this subject last month, we thought we’d give you some more information.

Firstly, Anixter created a nice reference graph listing general characteristics of the two material types and their implications to users:

“The variety of materials available to modern wire and cable manufacturers is immense.  This results in a wide range of properties within each material type.  The table is a generalized summary that does not apply to every material.  It is important to understand how the properties impact the performance of the product in the intended application.  Generally speaking, within a given material type, the old adage, “You get what you paid for,” still applies.”

Aside from describing the main characteristics of the two materials, which we did in our original post, they offer some thoughts in response to the question of how do I choose a material for my application?

“Knowing that the key difference between a thermoplastic and thermoset is in the way they respond to elevated temperatures can be an important aspect of which material to choose.  For example, thermoset materials are often chosen for circuits that may experience and overload.  This is because thermoset materials have a reduced likelihood of failure if momentarily operated at the higher temperatures that often accompany an overloaded conductor.  Comparatively, thermoplastics are often easier to strip, which makes them easier to process on automated equipment for large volume applications.”

Some great additions, thanks to Anixter.  You can find their full article here (.pdf format)

If you work anything like we do around here, you’ve probably gotten into the habit of using all the wire acronyms in the book, but may not have spent a ton of time reflecting on what they mean in a while.

Well, we opened up our old manuals again to refresh our memories, and thought we’d remind everyone else while we were at it.

Wire Insulation Abbreviations

Let’s test it out:

RHW: Rubber insulated, moisture resistant, good up to 75°C

USE-2: Underground Service Entrance wire that can stand wet environments up to 90°C

XHHW: Cross-linked polyethylene insulation, moisture resistant and good up to 90°C in dry environments

Photo credit: Tom Magliery

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