Milestone-Proposal:Self-regulating Trace Heater

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Docket #:2017-10

This Proposal has been approved, and is now a Milestone

To the proposer’s knowledge, is this achievement subject to litigation? No

Is the achievement you are proposing more than 25 years old? Yes

Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes

Did the achievement provide a meaningful benefit for humanity? Yes

Was it of at least regional importance? Yes

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes

Has an IEEE Organizational Unit agreed to arrange the dedication ceremony? Yes

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes

Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes

Year or range of years in which the achievement occurred:

1972 to Present

Title of the proposed milestone:

Conductive Polymer Self-Regulating Heat-Tracing Cable, 1972

Plaque citation summarizing the achievement and its significance:

In 1972, Raychem Corporation patented and began producing the first commercially successful electric self-regulating heat-tracing cable. The conductive polymer in this cable revolutionized the temperature maintenance of process piping, which has had major applications in refineries and chemical plants, and made freeze protection of water pipes simple and energy efficient. By 2008, the firm had manufactured and sold one billion feet of this cable.

200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.

IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.

In what IEEE section(s) does it reside?

Santa Clara Valley Section

IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

Unit: Santa Clara Valley Section
Senior Officer Name: Joseph Wei, chair

IEEE Organizational Unit(s) arranging the dedication ceremony:

Unit: Santa Clara Valley Section
Senior Officer Name: Joseph Wei, chair

IEEE section(s) monitoring the plaque(s):

IEEE Section: Santa Clara Valley Section
IEEE Section Chair name: Joseph Wei

Milestone proposer(s):

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):

2555 Bay Road, Redwood City California

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. Pentair, a surviving entity of Raychem, is still producing the product at the named in the historical site.No other historical markers.

Are the original buildings extant?


Details of the plaque mounting:

To Be determined, multiple plaques probable.

How is the site protected/secured, and in what ways is it accessible to the public?

Who is the present owner of the site(s)?


What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include justification here. (see section 6 of Milestone Guidelines)

Electrical heating has many aspects including less energy use and tighter temperature control that make it the choice for heating process pipes and freeze protection. Two notable deficiencies are corrected by the parallel circuit self-regulating heaters invented by Raychem in 1972. The heaters are cut to length in the field and won’t easily burn out unlike constant wattage heaters. Historically electrical trace heaters were constant wattage series circuit and the resistance had to be factory determined and fabricated. The key electrical achievement is making a parallel circuit heater by putting a nano carbon black matrix in a polymer between bus wires making a distributed semiconducting positive temperature coefficient resistor. Specific carbon blacks and polymers create a resistance path between the bus wires and the polymer matrix expands through the polymer’s crystalline melt temperature, separating the carbon paths. Thus the resistance goes up. At each section the temperature of the polymer controls the expansion and one has essentially an infinite number of “thermostats” controlling that segment of the circuit. A key for repeatability is radiation crosslinking the polymer so when the matrix cools back below the crystalline melt temperature, the resistance goes back down to original resistance allowing more current to flow and the I^2R (current squared times resistance) heating. The picture below shows an illustration of the process.

Self- rEgulation Heater.jpeg

The idea of conductive polymers was in its infancy and researchers at Raychem looked at silicones and polyolefins as a possible matrix with carbon black infused into the matrix for conductivity. Radiation chemistry was critical to the repeatability of the heating cooling system as shown in the IEEE paper in this package. The circuit was elegant, parallel wires with a positive temperature coefficient matrix between the wires. What you had was basically a distributed temperature sensor controlling each section of the heater independently. The product was also cut to length in the field. The solution in 1971 for heating pipes was MI Cable which was manufactured to a specific length in a factory. As one would expect, the field as built piping was never quite the drawing estimates and returns for a different length were common. Today the vast majority of electrical trace heating is now done by self-regulating heaters with over 10 manufacturers all over the world making this type of heating cable. By 2007, over a billion feet of the self-regulating heater was manufactured in the building proposed for the installation of the IEEE Milestone Plaque.

What obstacles (technical, political, geographic) needed to be overcome?

Conductive polymer PTC (Positive Temperature Coefficient) tests were made by loading polymers with conductive elements, usually metal powders or carbon black. The resistance change was one way, the resistance went up and never came back. This was solved by radiation crosslinking the polymer which "pulled" the polymer back to the original shape when the temperature decreased. Radiation crosslinking was the secrete.

What features set this work apart from similar achievements?

No conductive polymer had ever been able to cycle to different temperatures and return to its original resistance.

Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.

IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. IA-9, NO. 4, JULY/AUGUST 1973 Some Aspects of a Self-Limiting Resistive Electric Heating Element JOSEPH A. OAKES AND CHET L. SANDBERG

US 3861029 AutoTrace Patent

IEEE 515 Standard for the Testing, Design, Installation, and Maintenance of Electrical Resistance Heat Tracing for Industrial Applications 1997

TYCO THERMAL CONTROLS CELEBRATES AN INDUSTRY FIRST - One Billion Feet of Raychem Self-Regulating Heat-Tracing Cable Manufactured and Sold March 14, 2008

1972 AutoTrace brochure 72

Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to Please see the Milestone Program Guidelines for more information.

One of first self-regulating patents

Presentation showing IEEE 515 and 844 standards. These are industry created standards supporting a critical technology for Process Plants, Snow Melting, Freeze protection of piping. All the self-regulating technologies help save many Megawatt hours of energy use every year.

IEEE Transactions Paper, Lardear

Market forecast showing Self-regulating is the most used electrical heat tracing

IEEE 1972 Self-Regulating Paper by Oakes and Sandberg describing Technology

Press Release for 1 Billion Feet


Please email a jpeg or PDF a letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property, and a letter (or forwarded email) from the appropriate Section Chair supporting the Milestone application to with the subject line "Attention: Milestone Administrator." Note that there are multiple texts of the letter depending on whether an IEEE organizational unit other than the section will be paying for the plaque(s).

Please recommend reviewers by emailing their names and email addresses to Please include the docket number and brief title of your proposal in the subject line of all emails.