Glossary of Heat Traced Tubing Bundle Terms

Short definitions of the terms used for heat traced, steam traced and pre-insulated tubing bundles: product codes, heating cable types, temperatures, materials and hazardous-area words. Each entry links to the page that covers it in more detail.

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Bundle types

Tubing bundle: One or more process tubes, a tracer (or none), insulation and an outer jacket, assembled in a factory into a single cable-like unit and laid on site. Bundle vs field tracing
Heat traced tubing: Tubing kept at a set temperature by a heat source running beside it: an electric heating cable or a steam tracer tube. Buyer guide
EHTL — electrical heat traced tubing: A bundle heated by an electric heating cable (self-regulating, constant-wattage or power-limiting), used where power is available and a controlled temperature is needed. EHTL
SHTL — steam heat traced tubing: A bundle heated by a copper or stainless-steel steam tracer tube. Techwin SHTL bundles take saturated steam up to 17 bar (204 °C / 399 °F). SHTL
PIT — pre-insulated tubing: Tubing insulated and jacketed in the factory with no tracer. It limits heat loss on small steam, condensate, liquid and gas lines, and replaces field insulation and weatherproofing. PIT
Coated tube: Tubing with an extruded plastic jacket that protects it against atmospheric, galvanic and marine corrosion, abrasion and moisture. Coated tubes
Traceline: Techwin International’s registered brand for its tubing bundles.

Heating and temperatures

Self-regulating cable (SRC; SRLT / SRMT / SRHT): Heating cable whose output falls as the tube warms and rises as it cools. It can be cut to any length. Techwin bundles use low, medium and high ranges of about 40 °C (104 °F), 110 °C (230 °F) and 120–150 °C (248–302 °F).
Constant-wattage cable (CWC): Heating cable with a fixed output per metre, cut to zone length. In Techwin bundles it maintains up to 200 °C (392 °F), with exposure up to 260 °C (500 °F), on circuits of about 150 m (490 ft).
Power-limiting cable (PLC): Heating cable for longer circuits and higher temperatures. In Techwin bundles it allows circuits up to 450 m (1,475 ft).
Maintain temperature: The temperature the tracing must hold the process fluid at, for example above its dew point or freezing point.
Exposure temperature: The highest temperature a heating cable or bundle can withstand, for example during a steam-out, without damage. It is not the same as the maintain temperature.
Circuit length: The longest run one heating cable can heat from a single power connection. It depends on cable type and output.
Heavy steam tracing: Steam tracing with the tracer in direct contact with the process tube, for high heat transfer and high-temperature maintenance. Light vs heavy
Light steam tracing: Steam tracing with the tracer separated from the process tube, for gentle heat: freeze protection and fluids that must not be overheated. Light vs heavy
Personnel protection: Keeping the outer surface cool enough to touch. Techwin bundles keep the outer jacket below 60 °C (140 °F).

Materials

FR-PVC jacket: Flame-retardant, UV-resistant PVC outer jacket, rated −40 °C to 105 °C (−40 °F to 221 °F).
TPU jacket: Extruded thermoplastic polyurethane outer jacket, offered as an alternative to FR-PVC. Other jacket materials are made to order.
Fibre glass insulation: Standard non-hygroscopic insulation layer in Techwin bundles.
Aerogel insulation: Insulation option for high process temperatures above 400 °C (752 °F). It withstands exposure over 649 °C (1,200 °F).
SilcoTek® coating: Inert chemical vapour deposition coatings (such as SilcoNert®, Silcolloy® and Dursan®) that stop reactive compounds, such as sulfur species, sticking to tubing and fittings. Techwin is the authorised SilcoTek distributor for the Middle East and India. SilcoTek coatings
Electropolished tubing: 316L stainless steel tubing with an electrochemically smoothed bore, for high-purity and analyser service. Electropolished tubing

Applications and hazardous areas

Analyser sample line: A heated or insulated line that carries a gas or liquid sample from the process to an analyser (CEMS, process analyser, gas chromatograph) without changing its composition. Analyzer sample lines
Impulse line: A small tube that carries process pressure to a transmitter. It often does not flow, so it is prone to freezing. Freeze protection
Lag time: The time a sample takes to travel from the take-off point to the analyser. It depends on line volume, flow and pressure. Lag time calculator
IECEx / ATEX: Certification schemes for equipment used in explosive atmospheres: international (IECEx) and European Union (ATEX). In Techwin bundles the heating cables carry IECEx, ATEX and IEC certification, issued to the cable manufacturer. Hazardous areas
T-class (temperature class): A rating (T1 to T6) for the highest surface temperature equipment may reach in a hazardous area. It must stay below the ignition temperature of the gas present. T-class table

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