Tracer Applications 1 Typical Steam Tracing Piping Steam

Tracer Applications 1

Typical Steam Tracing Piping Steam distribution manifold Spares Steam supply Condensate return Outlet riser Condensate collecting manifold Traced pipe Tracer Spares

Convection Tracers Designed for use with medium-low to medium heat transfer requirements, the metallic tracer tube is either bare or covered with a thin, high temperature coating that provides a measure of personnel burn protection without sacrificing thermal performance. Process Temperatures: 101°F to 200°F

Conduction Tracers Designed for use when the heat requirements exceed the capabilities of isolated and convection tracers. Conduction tracers are aided by heat transfer compounds that provide excellent heat transfer at a fraction of the cost of a jacketed pipe system while eliminating the possibility of product contamination. A single tracer utilizing heat transfer compound will perform as well as 3 to 5 bare (convection) tracers. Process Temperatures: 151°F to 400°F

Tracer Materials The tracer is selected to fulfill thermal and installation requirements. The tracer metal should be close to the material of the process pipe to minimize galvanic corrosion. Copper tubing can be used if the saturated steam pressure or the item being traced does not exceed 400°F and there is no corrosion or other deterrent (copper oxide) for using copper. Stainless steel tubing can be used if the saturated steam pressure or the item being traced exceeds 400°F and there is no corrosion or other deterrent (chlorides) for using stainless steel. Carbon steel pipe should NEVER be used. During shutdown periods, air and moisture causes rapid rust and pitting.

AVTR is the accumulated vertical tracer rise i. e. the sum of all the elevation rises (see Figure 5. 1). The AVTR should be limited to 15% of the inlet steam pressure for any steam tracing circuit. For example, with an inlet steam pressure of 50 psig, the AVTR should not exceed 7. 5 feet. The AVTR is further reduced by losses due to bends, valves, and fittings in the tracer circuits (see Table 5. 2). The resultant losses must be deducted to determine the actual AVTR.

AVTR Example

AVTR Reduction Losses

Insulation Guidelines

Tracer Tubing Installation

Small Diameter Tube Tracing 1/2” or 3/8” tubing Steam Trap Valves Trap Pumps Instruments • Very light condensate loads; small diameter tubing ok • Condensate must flow downward by gravity to trap • Small diameter tube bends around objects easily • Each tracer circuit has separate trap

Process Pipe Tracing Methods • Hot product flowing in steel pipe loses heat through insulation • Products may solidify as they cool: – – Plastics solidify at low temperatures Asphalt solidifies at ambient temps Increased viscosity when cooled; won’t flow Sulfur solidifies above 350°F and below 250°F • Tracer internal with direct contact with product, potential product contamination • Tracer external to and in contact with product pipe under insulation Internal Tracing External Tracing

Process Pipe Tracing Horizontal No! Vertical Yes! Notes: • Low steam velocity to move condensate; must flow by gravity; don’t use wound tracer on horizontal runs • Vertical wound tracer on short runs only • Metal straps hold tracer • Insulating spacers used if product may char, burn or crystallize with intense heat Metal Strap Insulating spacer

Number of ½” Diameter Tracers Freeze Protection or Product solidification at 32°F - 75°F Product Solidification 75°F – 150°F Product solidification 150°F - 300° F 25 mm, 1" 1 1 1 40 mm, 1 -1/2" 1 1 2 50 mm, 2" 1 1 2 80 mm, 3" 1 1 3 100 mm, 4" 1 2 3 150 mm, 6" 2 2 3 200 mm, 8" 2 2 3 250 - 300 mm, 10" - 12" 2 3 3 350 - 300 mm, 14" - 16" 2 3 6 350 - 400 mm, 18" - 20" 2 3 8 450 - 500 mm, 2 3 10 Product line size

Multiple Tracer Spacing Vertical Horizontal Evenly spaced around pipe Space evenly at bottom of pipe

Tracer Lines! How Long? Condensing steam in small diameter tubing causes pressure drop. To insure enough pressure at the trap to remove condensate, tracer length should be limited. 3/8”, 8 mm 75 ft, 23 m 1/2”, 15 mm 125 ft, 38. 5 m 3/4”, 20 mm 150 ft, 46. 2 m

Multiple Tracing Traps No! • Multiple circuits - 1 trap Do not gang trap! Yes! • Multiple circuits multiple traps

Line Tracing Installation Expansion Loops Flange Loops Yes! No!

Steam Jacketed Pipe T 1 Insulation Steam Jacket Pipe Why? Rate of heat transfer = f((T 1 T 2), Cf) Product T 2 • Steam temperature close to product temperature • Product has low coefficient of heat transfer Steam Jacket Product Pipe

Steam Jacketed Installation Steam in • Steam flow counter to product flow • Pitch in direction of steam flow • Section <= 20 ft. 6 m • Moderate climates Ideal ! Steam in OK ! – Trap every 80 to 100 ft, 24 to 30 m • Severe climates – Trap every 40 ft, 12 m No ! Pitch Trap

Jacketed Line Sizing

Steam Tracing Condensate Q = L x A x U x (t 1 – t 2) x E/(H x N) • Q = Condensate load, lb/hr, kg/hr • L = Length of tracer, ft, m • U = Heat transfer coefficient pipe to air, btu/hr/deg f/sq ft, • t 1 = Product temperature, °F, • t 2 = Minimum air temperature °F, • E = 1 – insulation efficiency/100 • A = Area of pipe per ft length, sq ft/ft, • H = Latent heat of steam btu/lb, • N = Number of tracers Example: 20” pipe, 200 °F product, -20 °F air, 100 psig steam Q = 125 x 1. 93 x 12 x (200 -(-20)) x. 25/(880 x 4) = 45 lb/hr per tracer