Heat tracing

Is there a question here?

?

that sounds like a project manager type of question.

I cant make sence from most of the questions they ask me either, and i am a heat trace guy.

If you are a heat trace guy perhaps you could help me? Do you have a simple non invasive means of indicating that heat trace is working properly? one that can be obvious to the naked eye and usable in Hazardous atmospheres.

Heat trace is used to prevent hydrates forming in impulse lines to instrumentation. If this heating fails it can represent a serious hazard by the impulse lines becoming blocked therefore trapping a measurement value, and blocking a true value. They are usualy buried inside insulation and difficult to monitor at low cost.

If technology that can perform this function is of interest to your company please let me know. The current range of this technology spans milliamp to Kiloamp levels regardless of the voltage rating AC or DC.

Here are 3 ways. (depending on you budget and what you want out of your system)

starting at the cheapest.

1. Install a pipe surface mounted tempurature gauge, the skin of the pipe will be about 1/2 to 1 Deg cooler than the product. depending on how thick your insulation is. Omega in the US make cheap ones $ $45 to 250 Us depending on the quaility you want.

2. You can install a low haz area tempurature switch that closes when the tempurature reaches the lowest piont that you want. this swich is then acticvates a haz area rated light. ( these switches can be bought from a local industrial electrical dist house)

3. Install a pipe mounted RTD and use a 1 piont EHT programable controller, these controlles have dislays that show the pipe temp, they allow you to set alarm pionts that you can wire to a light if you want but they do have loacal leds that blink alot when there is a larm condition.

They display all the electrical information, if the trace is on. Thermon and Tracer make scr type that are suitable for Class 1 zone 2 Hazardous areas cost about $1250 CDN. this can also be used to trigger an alarm on the main control system.

note if you want to have more than one sensor use a TRACER controller they have models that can take up to 4 pipe mounted RTD's.

Some EHt vendors will try and sell you a power and end kit with a light on it, and a pipe mounted tempurature switch. Warning on this, you will get alot of phone calls telling you that the EHT is not working right.

Here is why when the line is at operating tempurature the swich is open and there is no power on the trace, the EHT lights are off, the operators will think the EHT is not working right and they call the electricains telling them the EHt is off. this is a real Pain in the BUTT for the maint sup.

We only use mutiple 20+ point controllers due to the size of the systems we install on the plants here and all alarms go to a main EHT control panel.

DigiTrace 910

The 910 is a compact, full-featured microprocessor-based single-point heat-trace controller. The 910 provides control and monitoring of electrical heat-tracing circuits for both freeze protection and temperature maintenance, and can be set to monitor and alarm for high and low temperature, high and low current, ground fault level, and voltage. The DigiTrace 910 controller is available with two output types: an electromechanical relay (EMR) for use in ordinary, non hazardous areas and a solid-state relay (SSR) for use in ordinary or Class I Div 2/Zone 2 hazardous areas. Communications modules are available for remote control and configuration, complete with supervisor software capability.

please remember i work in oil and gas we only use CSA certified equipment. like the above,

Verb installation necessity

Yikes! And, the question is probably a good one, too! And, I very much appreciate the sense of humor that all have displayed in an attempt to get this question stated more clearly such that an answer can be found.

Let's see if I can do the 'verb installation necessity' justice and help move this discussion along. I, for one, supplied fiberglass insulation to heat trace applications but must admit I know NOTHING about the heat trace world. And, I had no idea that there were experts on this topic so there must be much more to this subject. Could we explore that here? Would you folks be interested in providing a primer on the subject?

As for the question that started this thread, I have a hunch the person wanted to know if heat trace lines are self-regulating (i.e have a thermistor control?) or if they are controlled by some sort of external input that can be adjusted by an operator. And, I also think the person wanted to know if these lines were run in series or parallel (but I'm not sure what the point of that question is; though it's probably very important and I just don't know any better).

From what I knew, heat trace was a big deal in power plants but maybe there's more to it than that. Can you folks help highlight opportunities, critical applications, requirements, etc.?

Thanks!

A breif basic explanation.

Heat trace is an insuance system used so that when a plant goes down in the winter, the plant wont feeze up and not be able to restart.

There are common three types of Heat trace. Steam, glycoll/hot oi, and electric trace. each one has advantages and disadvatages, I wont list them here unless some one asks.

There are three basic Electric heat trace types, Self regulating, mineral insualted, and Feromagnetic skin effect.

Before you even start to design a EHt system, you must find out the following minimum information. and the type of control you are going to use.

A, No controll ( trace always on) wastes lots of power. cheapest to install.

B, Ambient sensing ( snence the outside air temp and turn trace on when it is cold outside) still wastes power. mid range cost, but with the line lowing MI cable may be in violation of the area classification.

C, Line sensing a RTD monitors pipe tempurature and only turns the trace on when flow in the line stops, We all know that as long as fluid is flowing it wont freeze. This is the highest capital cost system to install cheapest to operate for 20 life span.

1. The tempurature that you are going to hold the line to. in our industy it varries between 10C and 225C. dpending on the product inside the pipe.

2. The mimimum ambient tempuature, we normally use -43C and 20km/h wind, but some of the locations we install EHT in are -65C.

3. The maximum exposure tempurature that the line will see. (this determins the type of trace to specify.) Each manufacturer's SL cable can take only so much exposure tempurature before it melts. read the cataloge data for the type you want to use.

3. Pipe line size, lenght, insualtion type and insualtion thickness.

4. Know the flow direction and how lines that jion the one you are tracing could effect your line. If you put your RTD on a hot spot the controller will think that the line is ok and it is for that small section only, the rest is frozen.

The above is only a scratch at the basics. hope it helps

I am talking about monitoring the current flow within the electric heat trace cable no matter if its self regulating or thermostat controlled. If there is a current flow then the cable is working and in the case of a thermostat controlled layout the thermostat could switch to half power by bringing a diode into circuit (Half wave) or/and arranging for two lengths of EHTcable to be connected in series during normal weather and parallel during cold conditions. Self regulating EHT varies the current within the cable by itself acording to the temperature prevailing. If my current detector is applied in-circuit or even through magnetic-coupling via a current transformer this process can generate a light signal and volt-free outputs to an alarm system.

Two possible senarios-

1. Invasive insertion of current detector in a single wire feeding EHT (line loss +or-0.35-1Volt max). This fractional volts loss is what powers my detector)

Range of detection 0.003 to10 Amperes regardless of line voltage feeding the EHT

Threshold adjustable from 3mA via an adjustable resistive shunt.

2. Magnetic coupling via a C.T. (only for AC powered EHT)

Threshold current 250 milliamps up to a maximum of 400 Amperes if required.

Does it interest your company to be able offer this product to your customers?

PS the dual light generated by this device can be routed through fibre optic pipe if required to make a local indicator at very very low cost.

The extent and importance of heat trace is relevent to the area in which the plant is located and the products inside the pipe.

We are located in canada and our major product is Heavy oil, from the Tar sands.

I think it is safe to say that without heat trace to a minimum 80 C hold T all of our lines would be solidified tar. The average new construction budget for EHT on these plants is 10 to 50 million for materials only depending on how many Barrels per day oil output of the plant.

If you are going to be purchasing Heat trace for industrial use I would recomend that you use products that are CSA ( Canadian standard Assosiation) certified. or tested to CSA standards ULC, CUL.

I belive CSA certification for EHT is the hardest one for a manufacturer to get.

There is good information on EHT design on the following manufacture's sites.

Thermon, Tracer, Nelson, and the one mentioned above. All of these manufactures allso have heat loss programs to calculate the pipe heat loss and size the EHT.

Plese note the the manufactures programs for added EHT at valves and pipe shoes ect. is set for 10C. you have to do a calculation for these items if the hold T is above that tempurature. Use IEEE 555, and 556 to walk you trough how to do that.