engineering standard specification for steam tracing

8/12/2019 Engineering Standard Specification for Steam Tracing

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SHEET 1 OF 53STEAM TEACING

NO.

ENGINEERING STANDARD SPECIFICATION

FOR STEAM TRACING

Table of Contents


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1. Introduction

1.1 Purpose

1.2 Scope

1.3 Tracing Systems

1.4 Supporting Documents

2. References

2.1 Process Industry Practices

2.2 Industry Code and Standards

3. Definitions

4. Mechanical Criteria

4.1 Tracing System Temperature Control

4.2 Steam Supply Design/Layout

4.3 Steam Trap Selection

4.4 Steam Pressure Selection

4.5 Selection of Tracer Type

4.6 Size and Number of Tracers5. Materials

5.1 General

5.2 Preinsulated Leads

5.3 Tracer Material

5.4 Copper Tubing

5.5 Stainless Steel Tubing

5.6 Preinsulated Tracers

5.7 Tracer Tubing Fittings

5.8 Steam Traps

5.9 Insulation System

5.10 Selection and Application of HeatTransfer Compounds

6. Installation

6.1 Tracer Tube Cutting and Shaping

6.2 Tubing Unions

6.3 Steam Supply Layout

6.4 Trap and Condensate Return Systems

6.5. Tracer Location and Routing


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ST14 Typical Arrangement Detail

ST15 Maximum Accumulated Rise Data for Tracers

ST16 Steam Tracing Control Valve Stations

ST17 Typical Tracing of Flanged Valves

ST18 Typical Steam Jacketed Valve Tracing

ST19 Typical Single Tubing Steam Tracing

ST20 Arrangement Details for Installation of Vessel Tracing

ST21 Arrangement Details for Tracing on Pumps, Valves, & Cone Bottoms

ST22 Steam Tracing for Pressure Transmitter Liquid or Steam Service

ST23 Jacketed Level Glass Typical Arrangement Details for Installation of Instrument Tracing

ST24 Flanged D/P Level Transmitte Typical Arrangement Details for Installation of Instrument

Tracing

ST25 Jacketed Level Glass Typical Arrangement Details for Installation of Instrument Tracing

ST26 External Float Level Instrument Typical Arrangement Details for Installation of Instrument

Tracing

ST27 D/P Level Instrument on Vessel Typical Arrangement forInstallation of Instrument Tracing

ST28 Liquid Remote Pressure Gauge Typical Arrangement for Installation of Instrument Tracing

ST29 Remote Mounted D/P Instrument Typical Arrangement Details for Installation of Instrument

Tracing

ST30 Line Mounted D/P Instrument Typical Arrangement for Installation of Instrument Tracing

ST31 Pressure Transmitter Detail Typical Arrangement for Installation of Instrument Tracing

ST32 Pressure Switch or Pressure Gauge in Steam Traced Lines Typical Arrangement for

Installation of Instrument Tracing

1. Introduction

1.1 Purpose


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This Standard specification provides a guideline for the design and installation of steam tracing systems

with process fluids that require heating to prevent condensation, freezing, unacceptable viscosity,

crystallizing, separation, or temperature control.

1.2 Scope

This Standard specification covers minimum requirements for design, materials of construction,

installation, leak testing, and inspection of steam tracing systems on equipment, piping, and instruments

including steam supply piping, steam tracers, tracer traps, and condensate collection.

1.3 Tracing Systems

Systems requiring additional steam tracing specifications beyond this specification shall be covered by

the purchasers documentation.

1.4 Supporting Documents

Use of this Practice for contractual purposes requires the purchaser to make specific choices and

assemble additional supporting documents. Listing of or reference to supporting documents within this

Practice does not imply suitability for specific designs.

2. References

Applicable requirements in the latest edition (or the edition indicated) of the following Practices,

industry codes and standards, and detail drawings shall be considered an integral part of this Practice.

Short titles will be used herein when appropriate.

2.1 Industry Code and Standards

ASTM B68-99 - Standard Specification for Seamless Copper Tube, Bright

Annealed

ASTM B75-99 Standard Specification for Seamless Copper Tube

ASME B31.3 Process Piping

3. Definitions

For the purpose of this Standard specification, the following definitions apply:


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air convection tracing: Tracers attached to the pipe without the use of heat-transfer compounds.

Tubing can be bare or may have a polymer jacket. A tracer is attached to the pipe with high temperature

tape, tie-wires, or bands. Heat transfer is by means of air convection movement of heat in the annular

space between the thermal insulation and the heated pipe.

ambient temperature: The temperature of the air in the surrounding atmosphere condensate: Water that

is formed in the steam tracer tube when latent heat from the steam is given up to the heated pipe or

equipment.

conduction tracing: Tracer tube that is thermally bonded to the heated pipe or equipment by heat-

transfer compound when the primary heat transfer means is by conduction directly into the metal wall of

the pipe or equipment being heated.

contractor: Party that is responsible for furnishing and/or installing the insulation system .

dry steam: Steam containing no moisture; it may be either saturated or superheated.

heat loss: The rate at which heat flows from a hot surface such as a process pipe to a cooler atmosphere,

usually stated in Btu/h feet (kcal/m) of length of pipe. The heat loss is generally from the pipe through

the pipe insulation to the cooler atmosphere, but may also be from conduction through hangers and

supports.heatsink: A surface or mass such as a flange or valve that is at a lower temperature than the warm pipe.

heat tracing: The application of hot liquid, vapor, steam tracing tubes, electric heating cables, or tapes

to pipes, fittings, valves, pumps, tanks instruments, or instrument lines to offset the heat loss through

thermal insulation.

heat-transfer compound: A heat-conductive material with highly efficient thermal characteristics for use

on any steam or fluid tracer tube. The heat-transfer compound is used to establish a broad, heat-

conductive contact surface, for heat-transfer purposes, between the tracer tube and the surface to be

heated.

heated pipe: Any process, service, or utility pipe that is heat traced

heating media: Dry-saturated steam that flows from the point of supply on the steam main through to

the inlet of the tracing circuit steam trap.

heat-up: A steam tracing application in which process pipe or equipment requires the addition of heat to

raise its temperature from a lower to a higher level

high-pressure steam: Steam at a pressure of 250 psig to 600 psig (1,723 kPag to 4,136 kPag)

inline instruments: Instruments that are installed in the piping. These instruments are normally traced

with the same tracing circuit as the piping.


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instruments: Devices that are either used separately or in combination to measure, analyze, or monitor

the various aspects of a process.

instruments piping: All piping, tubing or tubing bundles, valves, and fittings used to connect

instruments to process piping and to other instruments and apparatus for measuring, analyzing, or

monitoring purposes.

isolated tracing: Tracing for sensitive piping and processes where the tracer tube is separated from the

pipe or equipment by a low conductive material. This tracing includes preinsulated tubing with a

polymer protective jacket. Heat transfer is primarily by air-convection movement of heat in the annular

space between the thermal insulation and the heated pipe.

low-pressure steam: Steam at a pressure of 15 psig to 50 psig (68 kPag to 344 kPag).

medium-pressure steam: Steam at a pressure of 50 psig to 250 psig (345 kPag to 1,722 kPag).

owner: Principal end user.

pockets: Bends, loops, or dips in a tracer tube circuit where condensate can collect and prevent the tracer

circuit from being self -draining.

process maintenance temperature: The temperature level that must be held on plant process pipes and

equipment to keep the contents from solidifying, condensing, crystallizing, separating, or becoming tooviscous to pump.

NOTE: The term is often used to refer to all traced utility, service, or process pipes.

process piping: Piping used to transport fluids between storage tanks and within process units per ASME

B31.3

purchaser: Owner or the owners authorized agent.

remote instruments: Instruments that are installed at a location that is remote from the piping.

These instruments are traced with a tracing circuit that is separate from the tracing circuit(s) used to

trace the piping.

saturated steam: Steam at the temperature at which vaporization takes place for that pressure and is free

of moisture.

service piping: Piping used to transport water, brine, steam, air, or other substances to process piping or

equipment to bring about the successful completion of the process.

steam supply manifolds: Modular prefabricated steam supply distribution manifolds designed

specifically for supplying steam to tracing circuits.

steam and condensate manifolds: Modular prefabricated steam supply and condensate collection units

designed specifically for steam tracing circuits


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steam and condensate return leads: Preinsulated tubing with a weather-protective jacket that is used to

interconnect headers to manifolds and manifolds to tracers for steam supply and condensate return

Referred to as leads, runs, lines, and takeoffs.

steam boiler: A closed vessel in which water is vaporized into steam to provide mechanical power and

process heat such as steam for tracing circuits .

steam header: The principal steam line supplying steam to all users in an area including tracer circuits

that is assumed to be supported on overhead pipe rack and may have several branches.

steam-out: A process for cleaning residue from piping by passing steam through the piping. It is

necessary to select a tracer material that can withstand exposure to the steam-out temperature.

Steam traced piping: All references to steam traced piping throughout this Practice is meant to imply all

steam traced piping, fittings, valves, pumps, tanks, vessels, instruments, instrument lines and any other

materials or equipment requiring steam tracers.

steam tracing: A tube or small pipe carrying steam, which is placed parallel and attached to the surface

of the pipe or equipment to be heated. The tube is referred to as the tracer, tracer tube, or simply

tracing.

steam tracing condensate subheader: A line that collects and returns condensate from one or moretracer circuits via a condensate collection manifold to the condensate header.

steam tracing subheader: A branch from the steam header to the steam distribution manifold for tracer

circuits.

steam trap: Automatic device used to hold steam in a steam tracing circuit until it has given up its latent

heat and allows condensate, air, and other gases to pass while preventing the passage of steam.

superheated steam: Steam at a temperature higher than that at which vaporization takes place for that

pressure.

temperature controllers: Automatic devices used to control steam pressure and/or flow to maintain pipe

temperature for freeze protection or process temperature control .

thermal insulation: For steam tracing purposes, it refers to materials used to retard the flow of heat from

piping and equipment to the surrounding atmosphere.

utilities piping: Piping that transports the primary plant commodities such as fuel gases, fuel oil, water,

air, steam, and condensate.

vessel: The term vessel in this specification refers to any large surface such as tanks, towers, drums,

reactors, or exchangers.

weather barrier: A protective material covering the outer surface of thermal insulation to repel rain,

snow, sleet, hose wash-down, or any other substance that might negatively affect the thermal insulation


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wet steam: Steam containing moisture.

winterization: Sometimes referred to as freeze protection or warming services, winterization is the

preparation of piping and equipment for operation in winter weather, including cold temperatures, high

winds, snow, and ice.

4. Mechanical Criteria

4.1 Tracing System Temperature Control

Proper temperature control based on an assessment of the actual system needs should be provided when

economically practical.

4.2 Steam Supply Design/Layout

4.2.1 Steam used to supply steam tracing must be from a constant source that can be maintained

independently of plant operations. The steam supply should be taken from a source that is continuously

available even during normal shutdown periods when possible. Steam should be distributed at the

highest pressure and reduced to the design requirements of the tracer system using a pressure-reducing

valve.

4.2.2 To help ensure the quality of the tracing steam, all steam supply manifolds and tracer circuits shall

have a separate steam trap station installed.

4.2.3 Tracing steam shall be dry saturated steam of a pressure that furnishes the tracing design heat input

requirements.

4.2.4 The tracing supply header shall be adequately sized to provide the maximum tracer design load

(steam pounds per hour) and trapped at its low points.

4.2.5 The number of tracer connections on a manifold should be held to a maximum of 12. A minimum

of two of these connections should be designated as spares.4.2.6 Vertical type manifolds should be utilized when possible.

4.3 Steam Trap Selection

4.3.1 Effective removal of condensate and air is essential to achieving uniform temperatures and

maximum heat-transfer rates from steam tracing circuits.

4.3.2 Consult trap manufacturers for information for the selection and sizing of the steam traps as well

as for sizing and proper installation techniques to provide trouble-free winter performance.

4.3.3 Preassembled steam trapping stations with universal connectors are preferred.

The type of traps selected shall meet the design and efficiency requirements of the tracing system.


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4.4 Steam Pressure Selection

The following criteria must be considered when selecting the steam pressure that can be utilized to meet

the steam tracing design requirements:

a. Desired maximum allowable number of tracers on a line

b. Desired maximum allowable length of the tracer tubing that is connected to the line

c. Elevation differences between the location of the steam manifold and traced piping

d. If process fluid or piping material is sensitive to conduction or localized heating

e. Plant site environmental design criteria (summer and winter design temperatures and mean wind

velocity)

f. Pressure differential between steam trap discharge and the condensate return header including

any static pressure head

g. Pressure of plant steam that is dedicated for steam tracing

h. Required maintenance temperatures (allowable minimum/maximum temperature

range for traced piping)

i. Safety factor for drops in steam pressure

j. Size and desired maximum length of all steam supply and condensate return leadsk. Traced piping size (outside diameter [OD]) and material of construction

l. Tracing size and type (air convection, conduction, or isolated tracing)

m. Type and thickness of the insulation system

4.5 Selection of Tracer Type

4.5.1 The selection of the steam tracer for each heated pipe and piece of equipment must be based on the

process sensitivity and the temperature to be maintained along with the heat load demand, tracer

capability, and the results of the design scenarios.

4.5.2 Isolated tracing should be considered for the following operating conditions :

a. When reduced thermal risk is important to aid in compliance with applicable safety standards.

b. When a controlled, predictable heat-transfer rate must be maintained to prevent corrosion or

other unacceptable temperature-related conditions.

c. When sensitive products such as caustics, acids, amines, resins, and aqueous fluids that require

low uniform heat for freeze protection.

4.5.3 Convection tracing should be utilized for the following operating conditions :

a. When only one convection tracer is needed to hold the required temperature.

b. When winterization is needed for lines carrying such material as air, water, gases, or other

noncorrosive aqueous solutions.


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c. When low heat density and flexibility is necessary for high-maintenance valves, pumps, and

other such equipment.

d. For process lines in which ambient temperature fluctuations or emergency shutdown and heat-

up requirements do not necessitate more heat than the convection tracer supplies.

NOTE: Multiple convection tracers usually cannot be economically justified when one tracer with

heat-transfer compound will suffice because of the additional steam supply connections and trap

assemblies required. However, a convection tracer may be doubled back when allowable pressure

drops are not exceeded.

The use of doubled-back tracers should be held to a minimum.

Spiraled convection tracers are not permitted, unless otherwise noted, because circumferential

expansion reduces the heat-transfer coefficient by increasing the air gap between the tracer and the

pipe and the increased number of pockets on horizontal runs requires more frequent trapping.

4.5.4 Tracers with heat-transfer compound may be utilized for the following operating conditions:

a. When more than one convection tracer is required.

b. When fast heat-up is essential after an emergenc y or a planned shutdown.

c. When a more even temperature distribution is required.d. When high heat density and flexibility is required at valves, pumps, and other such equipment.

e. When it is desirable to keep the required number of tracers to a minimum .

4.5.5 Preinsulated instrument tubing bundles and high-density polyurethane

instrument enclosures are recommended for the following situations:

a. When closely predicted thermal characteristics are required for pressure and differential

pressure transmitters, process analyzers, emissions analyzers, and other such applications .

b. When space is limited, pretraced and insulated bundles can be shaped to allow layout via the

shortest distance with simple supports in locations where field-fabricated lines are not practical.

c. When factory-applied polymer weather protection is preferred on critical lines.

4.5.6 Tracing with self-acting, off-on, or pressure-reducing control valves with sensors that respond to

the pipe wall or ambient temperature should be considered for:

a. Piping that operates intermittently.

b. When it is essential to prevent overheating of the product .

c. When constant viscosity is required for instrumentation.

d. When energy efficiency is a key requirement.

e. Piping that requires process heat-up.

f. Piping that requires freeze protection during shutdown periods .


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NOTE: When the process fluid is sensitive to over heating, self-acting off-on in steam tracers may not

be suitable.

4.6 Size and Number of Tracers

4.6.1 To facilitate designing a cost-effective tracing system, minimize the number of tracer circuits. To

establish the number and size of tracers required to supply the required heating, the following six factors

must be taken into consideration.

Three factors are given and three factors are variable. The variable factors must be balanced to establish

an appropriate design. Given factors:

a. Nominal pipe size

b. Desired pipe temperature

c. Lowest ambient temperature and highest wind speed

Variable factors:

a. Tracer type, size, and number

b. Steam inlet pressure and temperature

c. Insulation type and thickness

4.6.2 All flow diagrams shall be reviewed to determine the steam tracing requirements for each line.Isometric drawings identifying steam supply headers, tracer supply manifolds, tracer routing, tracer trap

stations, and condensate return lines will be provided to facilitate proper design and

installation of the tracing system.

4.6.3 The tracer size and number of tracer circuits required to supply the heating requirement on a line

or equipment item should be determined by calculation, manufacturers data, or the use of a computer

program developed for steam tracing design.

4.6.4 The maximum trapping length and the maximum vertical rise for each tracer circuit shall be

determined from calculation, manufacturers data, or the use of a computer program developed for

steam tracing design.

4.6.5 The maximum length of the tracing circuit shall not exceed the calculated maximum trapping

length for the tracer that must include the supply and return leads.

4.6.6 Maximum tracer length shall be applicable to the length of the tracer that is attached to the line.

The tracer length should be measured from the point where the tracer first contacts the line to be heated

to the point where it connects to the return lead that is routed to the trap station.

4.6.7 Pressure losses for preinsulated tubing that runs from the steam manifold to the tracer circuit, from

the tracer to the condensate manifold, and from the manifold to the condensate return header will be

calculated separately if the length of these runs exceeds 100-feet (30-m) total.


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5. Materials

5.1 General

5.1.1 All materials used to construct steam tracing components shall be new and in accordance with this

specification and its references. Refer to PIP piping and line class specifications as required for piping

details.

5.1.2 Steam supply, condensate return, and tracer tubing wall thickness shall be in accordance with

ASME B31.3.

5.1.3 Steam supply subheaders and tracing steam distribution manifolds shall be of the same materials

as the steam header.

5.1.4 Condensate return subheaders and tracing condensate collection manifolds shall be of the same

materials as the condensate return header.

5.2 Preinsulated Leads

105F (40C) or higher.

5.2.2 Sufficient insulation shall be furnished to provide a maximum surface temperature of 140F (60C)

during operation. The sensible temperature and wind speed for the location as well as the maximum

steam temperature and pressure expected for the particular application unless otherwise noted.

5.3 Tracer Material

5.3.1 The tracer in a steam tracing system must be as flexible as possible for the ease of installation and

conformance to the shape and layout of the pipes and equipment being heated and must act as a leak-

proof carrier of the heating media. Tubing should be used rather than pipe for tracing whenever

possible.

5.3.2 The tracer shall be selected to fulfill the thermal and installation requirements as determined by the

process pipe material, temperature of the process pipe and tracer, pressure of the heating media, and theenvironment. The tracer should be of metal close to the potential of the process pipe so as to minimize

galvanic corrosion.

5.4 Copper Tubing

5.4.1 Bare copper tubing tracers shall be soft-annealed grade 122 and meet or exceed ASTM Standard

B68 and ASTM Standard B75. Copper tubing shall be used if the saturated steam pressure or the item

being traced does not exceed 400F (204C) and there is no corrosion or other deterrent for using

copper.

5.4.2 Tubing thickness shall be:

a. 3/8-inch (9.52-mm) OD x 0.035-inch (.89-mm) wall

b. 1/2-inch (12.7-mm) OD x 0.035-inch (.89-mm) wall


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c. 3/4-inch (19-mm) OD x 0.049-inch (1.24-mm) wall

NOTE: 1/4-inch (6.35-mm) OD tracers should only be used when absolutely necessary for heating

relatively small tubes or similar application.

5.5 Stainless Steel Tubing

5.5.1 Bare stainless steel tubing shall be PIP PN50SD0L01 316/316L stainless steel tubing and shall be

used if the saturated steam pressure or the item being traced has a maximum temperature between 400F

(204C) and 800F (427C), and there is no corrosion or other deterrent for using stainless steel.

5.5.2 Tubing thickness shall be:

a. 3/8-inch (9.52-mm) OD x 0.035-inch (.89-mm) wall (minimum)

b. 1/2-inch (12.7-mm) OD x 0.035-inch (.89-mm) wall

5.6 Preinsulated Tracers

5.6.1 The material requirements for preinsulated tracer tubing shall be the same as specified herein for

bare tracers.

5.6.2 Preinsulated tracers shall be covered with a flexible insulation and a weathertight flexible jacket.

Flexibility of the jacket shall be adequate to allow for bending required to fit the preinsulated tracer to

typical installations.5.7 Tracer Tubing Fittings

The tracer tubing fittings shall be suitable for the pressure of the steam that they contain. Fittings shall

be compression type. The fittings shall be made of material that is compatible with the tracer

construction material.

5.8 Steam Traps

Steam traps shall be sized for the maximum calculated condensate load in the expected operating

pressure range and furnished with an integral strainer, air vent, and blow -off valve.

5.9 Insulation System

5.9.1 The next largest pipe-size rigid insulation (calcium silicate, expanded Perlite, cellular glass, etc.)

shall be selected; however, insulation of the actual pipe size may be used if board sections are cut to fit

the longitudinal joint to compensate for the steam tracer.

5.9.2 The insulation material to be used on steam traced piping and equipment shall be selected with

care and shall comply with related specifications.

Important aspects to be considered are:

a. Thermal insulating characteristics

b. Mechanical strength characteristics

c. Chemical stability characteristics under both normal and abnormal conditions


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a. Equipped with an isolation valve. These valves shall be located where they are accessible to the

plant operation personnel.

b. Routed from off the top of the tracer supply header at the highest point possible flowing

downward to the tracer steam supply distribution manifold subheader.

6.3.3 Preinsulated tubing with factory-applied insulation and a polymeric weatherprotective jacket may

be used for steam supply and condensate return leads.

6.3.4 Preinsulated leads shall be routed as follows:

a. From the distribution manifold block valve outlet to where the tracer that is attached to the

piping enters the insulation.

b. From the point of connection where the tracer piping exits the insulation to the inlet connection

of the steam trap station located on the condensate collection manifold.

c. All lines should be routed symmetrically and run together when possible to maintain a neat

appearance. Pockets shall be avoided when possible.

d. To ensure a cost-effective design, the length of the supply and return leads must be kept to a

minimum, preferably from 25 feet (7.6 m) to 70 feet (21 m) in length.

6.3.5 Steam supply manifolds shall be strategically located along the tracing route and shall beaccessible from grade, platform, or permanent ladder.

6.3.6 Steam supply manifolds shall be fitted with an isolation valve.

6.3.7 Supply manifolds shall be drained via a trap and discharged to the atmosphere directed to a safe

location when condensate is not returned.

6.4 Trap and Condensate Return Systems

6.4.1 Steam trap condensate manifold assemblies shall be provided with an internal siphon tube for

freeze protection of traps that are shut off and a freeze protection valve that senses condensate

temperature to drain the manifold if the condensate cools to a given set point.

6.4.2 Steam trap manifold assemblies shall be placed in an accessible location when possible to simplify

maintenance.

6.4.3 Manufactured steam trap, steam distribution, and condensate collection manifolds designed

specifically for steam tracing applications are preferred.

6.5. Tracer Location and Routing

6.5.1 Tracers serving the same or adjacent items shall be grouped and supplied from a common

manifold to facilitate maintenance. Condensate shall be returned to a common return manifold.


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6.5.2 The steam supply should start at the highest point of the lines to be traced, and the tracers shall be

arranged so that flow is generally downward avoiding pockets as much as possible. The accumulated

vertical tracer rise (pocket height) in feet should not exceed 15% of the steam supply pressure without

specific permission of the owner.

6.5.3 Each tracer shall be continuous from the supply manifold to the trap with no vents, drains, or dead-

end extensions at intermediate points. In general, branch connections shall be avoided. If branches are

required, each branch that is used shall have its own trap.

6.5.4 All tracers shall be installed parallel to and against the heated pipe or equipment and shall be

placed on the most accessible surface location in regard to supports, ease of installation, connection, and

thermal insulation. Multiple tracers shall be equally spaced around the circumference of the pipe.

6.5.5 Expansion of bare (convection) tracer tubes shall be absorbed at elbows and flanges when

possible. For long straight runs , a 12-inch (.305-m) diameter horizontal loop shall be provided at 60-feet

to 100-feet (18-m to 30-m) intervals, preferably midway between fittings. Tracer loops provided

specifically for expansion should not contain unions.

6.5.6 Tracer loops around flanges shall be horizontal so as to drain on shutdown, and unions shall be

provided so tracers can be disconnected at valves, pumps, tanks, or other flange -connected equipment.6.5.7 Tracing shall be included on dead legs and similar heatsinks along the traced line.

6.5.8 Each tracer circuit shall have a separate trap station installed at t he end of the tracer circuit.

6.5.9 Slots shall be provided in the thermal insulation to accommodate expansion of the tracer where it

joins and leaves the traced line. See detail drawing ST-17 for arrangement details.

6.5.10 Extra tracer lengths are not generally required at pipe hangers, piping tees, and ells.

6.5.11 Design shall include extra tracer length for valves or large pieces of equipment .

The engineer will indicate on critical service if pipe supports or flanges require additional tracer length.

Insulated pipe supports will be considered on critical temperature maintenance situations.

6.5.12 All tracers should be arranged to accommodate maintenance and removal of traced valves,

instruments, and other equipment.

6.6 Trap Station Installation

6.6.1 The steam trap shall be installed below the tracer circuit when possible and at a condensate

manifold located so as not to interfere with the operation and maintenance of equipment or obstruct

access ways.

6.6.2 Each tracer circuit shall be trapped individually at the tracer termination point determined from the

circuit design information. A new tracer shall be installed for continuing the tracing if the pipe-run

exceeds the specified maximum trapping length.


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6.6.3 Isolation valves shall be installed to accommodate servicing of the trap.

6.6.4 When condensate will be discharged to an overhead return line or against a lift, a swing check

valve shall be installed in the discharge line just beyond the trap at the bottom of the lift if the trap does

not have an integral check valve or is not otherwise designed to prevent back flow. The discharge line

from the trap shall feed into the top of the return main.

6.6.5 The pressure due to the lift shall be added to the pressure in the overhead return line to determine

the total back pressure against which the trap must discharge.

Use 0.5 psi per vertical foot of lift (11.31 kp/m) to calculate the pressure due to lift. The back pressure

shall not exceed the allowable limit of the selected trap.

6.6.6 A test tee should be installed just downstream of the trap to allow checking of the trap

performance.

6.7 Tracing Identification

6.7.1 Each tracer circuit shall be identified by two corrosion-resistant identification tags. One tag shall

be installed on the steam supply valve at the steam distribution manifold and the other tag shall be

installed on the isolation valve located on the steam trap assembly.

6.7.2 Steam tracer supply stations and condensate trap stations shall be given line numbers. Anisometric piping erection drawing will be made for each station.

These stations will be assigned numbers that are to be located on the plot plan and the model to indicate

unit number, station number, and whether they are supply or trap stations.

6.7.3 The identification tags shall be fabricated from 16-gauge corrosion-resistant material suitable for

the environment and attached to the supply valve and steam trap assembly valve with No. 16 gauge

corrosion-resistant wire.

6.7.4 Identification tags shall be stamped with 1/4-inch (6-mm) numbers and letters using the

identification system established for the project.

6.8 Tracers on Valves and Pumps

6.8.1 Tracing for valves and pumps shall be tubing in the form of hairpin loops so that the tracer makes

the least amount of complete circles. The number of feet of tracer to surface area of valve or pump shall

be sufficient to obtain the same ratio or higher of feet of tracer per unit of surface area as on the straight

pipe surface area.

6.8.2 Unless otherwise specified, hairpin tubing loops shall be attached to the valve or pump surface

with 1/2-inch x .020-inch (12-mm x .5-mm) stainless steel bands, high-temperature fiberglass tape or

No. 16 gauge stainless steel wire. (See detail drawings ST-20, ST-21, and ST-25 for arrangement

details.)


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6.9 Tracers on Vessels

6.9.1 External tracing for vessels should be prefabricated stainless steel heating panels formed to the

required radius or hairpin loop tubing panels, unless otherwise specified. (See detail drawings ST- 24

and ST-25 for arrangement details.)

6.9.2 Prefabricated stainless steel heating panels should have a layer of factoryapplied nonhardening

heat-transfer compound between the vessel surface and the back of the heating panel.

6.9.3 Small equipment with an outside radius of curvature less than 7 inches (178 mm) and vessel

bottoms with compound curved surfaces may be traced with tubing in the form of hairpin loops in lieu

of heating panels.

6.9.4 Hairpin circuits shall be embedded in heat-transfer compound, unless otherwise specified.

6.9.5 Each tracing panel shall have a separate steam trap station.

6.9.6 Tracing systems on equipment shall be systems that are separate from the tracing systems

dedicated for the piping.

6.10 Tracing on Instruments

6.10.1 Tracing for instruments and instrument impulse lines shall conform to information provided in

the attached details.6.10.2 Tracing shall be installed so that instruments can be removed for maintenance without

interruption or removing the tracing.

6.10.3 Tracing shall be applied only to the process-wetted parts of instruments, not to electronic or

pneumatic parts.

6.10.4 Tracer sizes shall be as follows:

a. 1/2-inch (12-mm) OD tubing shall be used for gauge glass and external displacer level

instruments.

b. 3/8-inch (10-mm) or 1/2-inch (12-mm) OD tubing shall be used for meter leads.

6.11 Heating Systems for Instruments Enclosures

6.11.1 Pressure gauge enclosures shall be heated with the heat from the process line by installing heat

conservation insulation up to the enclosure or by continuing the tracer at the gauge connection.

6.11.2 Differential pressure transmitters with partial enclosures shall be heated by a steam heater block

installed under the instrument. The heater shall have its own flexible thermal insulation cover and be

installed where it will not interfere with removal of the transmitter.

6.11.3 Preinsulated tubing bundles may be used in lieu of field-traced and insulated instrument lead

lines. Transmitters, controllers, recorders, etc., with complete polyurethane enclosures shall be heated

with a separate finned steam heater connected by tube fittings to the steam tracer.


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6.12 Process Piping Supports

Process piping supports shall be designed to allow for ease of installation of steam tracers and

insulation.

6.13 Preinsulated Lead Supports

6.13.1 The installation and support of preinsulated instrument tubing bundles and preinsulated steam

supply and condensate return lines shall be in accordance with the manufacturers specifications.

6.13.2 Routing and support is to be determined in the field. Lines shall be run together as much as

possible for common support. Preinsulated tubing shall be spaced and located in accordance with the

following considerations:

a. Ability to place a durable support at some desired location

b. Keep sag in the line within limits that will permit drainage

c. Avoid bends that exceed the minimum bend radius as recommended by the manufacturer

d. Allow for heat dissipation by keeping a 1/2-inch (12-mm) space (minimum) between the

preinsulated lines

6.14 Tracing Installation Sequence

After the process pipe has been installed with proper supports and hangers to allow for correctapplication of tracers and insulation, the following major steps are used for installations of the tracer

system:

Step 1: Ensure that all leak testing of the piping has been completed.

Step 2: Ensure that all the required coatings have been applied on the pipe.

Step 3: Perform surface preparation of process piping.

Step 4: Perform surface preparation of tracer.

Step 5: Perform installation of tracer and its securement.

Step 6: Perform pressure testing of tracer.

Step 7: Perform application of heat-transfer compound (when required).

Step 8: Ensure curing of heat-transfer compound (if required).

Step 9: Inspect the tracer system in accordance with the requirements specified

herein.

Step 10: Perform application of thermal insulation system in accordance with related specification.

Step 11: Perform inspection of insulation system in accordance its specification.

6.15 Surface Preparation of Piping

All tracer tubes and pipes or equipment to be traced shall be reasonably clean before installation of

steam tracers. For noncoated surfaces, dirt, rust, and scale can be removed with a wire brush. Oil and


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grease films on coated or noncoated surfaces may be removed with a rag and suitable solvent. For

coated surfaces, use clean compressed air, brushes, or rags to remove all loose dirt or dust. Preparation

for the application of heat-transfer compounds shall be done in accordance with the manufacturers

instructions.

6.16 Surface Preparation of Tracers

All tracers shall be free of dirt, grease, oil, loose scale, or any other nonspecified material before

installation on piping and equipment and before application of heattransfer compound when applicable.

6.17 Tracer Securement to Process Lines

6.17.1 Provide for expansion where required to prevent stress in the tracer tubing by properly securing

the tracer to the process pipe.

6.17.2 Tracers shall be fastened to piping and equipment with wire, bands, or hightemperature tapes.

6.17.3 Covering the tracer with galvanized or stainless steel channels before final attachment may be

required to protect the tracer from impacts.

6.17.4 Each method of tracing in this specification shall be installed in accordance with the attached

drawings.

6.17.5 Care shall be taken to use fastening materials that are galvanically compatible with the pipe andtracer materials. High-temperature tapes shall be free of chlorides or halides if used to secure stainless

steel pipe or tubing.

6.18 Pressure Testing and Cleaning

6.18.1 Steam supply headers and pipe or tubing runs to tracers shall be blown clean with steam or air

before connection to trap assemblies.

6.18.2 After all tracer connections to the supply header and trap have been completed, the circuit shall

be tested for leaks by subjecting it to a steam pressure equal to or greater than that to be used in the

system or by suitable hydrostatic tests.

6.18.3 All leaks shall be repaired and the system retested before the installation of heat-conducting

compound (when used) and insulation.

6.18.4 Performance of traps, gauges, pressure-relief valves, and pressure- and/or temperature-controlling

devices shall be periodically checked at prescribed intervals during start-up and during the first 48 hours

of normal operation.

6.19 Insulation Installation

Installation of the insulation system shall be in accordance with the requirements of related

specification.


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7. Inspection

7.1 Inspection Access

The purchasers inspector and the tracing or insulation manufacturers representative shall be given full

access to all stages of the work upon request.

7.2 Inspection Requirements

The inspectors shall ensure that all phases of the installation are in accordance with the materials and

application specifications. The inspector shall make certain that:

a. All materials used are as specified and in good condition.

b. All materials are stored in accordance with recommendations.

c. Surface preparations are as specified.

d. Tracer systems are installed in accordance with the design.

e. All tracing supply headers, preinsulated supply and condensate tubing runs, tracer

tubes, and manifolds are cleaned before they are connected to trap assemblies.

f. All tracer circuits and process pipe runs are pressure tested after all co nnections are completed.

g. Heat-transfer compounds are installed in accordance with these specifications.

h. Heat-transfer compounds are properly cured.

i. Water-soluble heat-transfer compounds are protected from rain and other moisture before

installing the thermal insulation and weather barrier.

j. High-temperature insulation is of proper thickness and installed in accordance with

specifications.

k. Insulation was dry when installed and protected from rain and moisture until weather barrier

was installed.

l. All insulation on vessels is properly supported.

m. Suitable insulation expansion joints are installed.

n. Weather protection is of type specified, installed in accordance with specifications and

recommendations, and dry thickness of mastic is of specified dimension.

o. All weather barriers are watertight, and projections and terminations are properly sealed.


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