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Instruction Manual
D104734X012
Fisher™ ATST Desuperheater
ATST Desuperheater
July 2022
Contents
Introduction 1.................................
Scope of Manual 1.............................
Description 1.................................
Educational Services 2.........................
Installation 3..................................
Maintenance 5.................................
Servicing 6...................................
Parts Ordering 8................................
Parts List 8....................................
Introduction
Scope of Manual
Figure 1. Fisher ATST Desuperheater
X1892
This instruction manual includes installation, maintenance, and operation information for the Fisher ATST
desuperheater.
Do not install, operate, or maintain an ATST desuperheater without being fully trained and qualified in
valve, actuator, and accessory installation, operation, and maintenance. To avoid personal injury or
property damage, it is important to carefully read, understand, and follow all the contents of this manual,
including all safety cautions and warnings. If you have any questions about these instructions, contact your
Emerson sales office
before proceeding.
Description
Water atomization and vaporization are key elements in any steam conditioning application. The ATST design
incorporates a manifold of patented nozzles to inject atomizing steam and spraywater into process steam. These
specialized nozzles produce an optimized spray pattern over a wide operating range. These nozzles are strategically
placed to achieve optimal mixing and quick vaporization at all flowing conditions. Years of experience with other
steam atomized desuperheater designs went into the development of this construction. Extensive use of
computational analysis, in addition to field performance feedback, was used to validate spray system performance.
www.Fisher.com
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ATST Desuperheater
July 2022
Table 1. Specifications
Instruction Manual
D104734X012
Connections
(1)(3)
Steam Line: NPS 8 through NPS 60
(DN 200 through 1500)
Spraywater: NPS 1 through 4 (DN 25 through 100)
Atomizing Steam: NPS 1 (DN 25)
Construction Materials
Desuperheater Body and Liner (if applicable):
J Carbon Steel, J 2-1/4 Cr-1 Mo J 9 Cr-1 Mo-V
J 9 Cr-2 W-V
Spray Nozzles:
Gaskets:
Bolting:
J R31233 Cobalt-Chrome Alloy
J N06600/Graphite
J SA193 Grade B7, J SA193 Grade B16,
(5)
J N07718
Connection Types
Steam Line (all sizes): JButtweld , JRaised Face
Flanges,
JRing Type Joint Flanges
Spraywater:
Face Flanges (all sizes),
JSocket Weld
sizes),
Atomizing Steam (all sizes):
JRing Type Joint Flanges
(1)(3)
JASME Buttweld (all sizes), JRaised
JRing Type Joint Flanges (all
JRaised Face Flanges,
Maximum Inlet Pressures
(1)
Consistent with applicable pressure-temperature
ratings per ASME B16.34
Maximum Unit Cv (for Spraywater Flow)
Contact your Emerson sales office
Spraywater Pressure Required
(2)
3.5 to 35 bar (50 to 500 psi) greater than steam line
pressure
(4)
(1)(3)
Atomizing Steam Pressure Required
Atomizing steam source pressure typically should be
at least 2 times the pressure of the steam to be
desuperheated
Pressure Class
Steam Line: According to the customer design
pressure and temperature
Spraywater and Atomizing Steam: ASME CL150 to
CL2500
1. Do not exceed the pressure or temperature limits in this manual, nor any applicable code or standard limitations.
2. A function of required turndown and equipment selection.
3. Offerings meet ASME standards. Consult your Emerson sales office for additional options.
4. Intermediate rating above CL2500 available upon request. PN ratings also available per pressure requirements of EN1092-1. Consult your Emerson sales office for additional information.
5. EN material options available upon request, consult your Emerson sales office for additional information.
Educational Services
Emerson Automation Solutions
Educational Services - Registration
Phone: 1-800-338-8158
E-mail: education@emerson.com
emerson.com/mytraining
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Instruction Manual
D104734X012
Figure 2. Typical Fisher ATST Installation
USPL
KEY:
DSPL = DOWNSTREAM STRAIGHT PIPE LENGTH
PI = PROPORTIONAL INTEGRAL CONTROLLER
PSL = PRESSURE SENSOR LENGTH
PT = PRESSURE TRANSMITTER
TE = TEMPERATURE SENSOR ELEMENT
TSL = TEMPERATURE SENSOR LENGTH
X0355A-1
USPL = UPSTREAM STRAIGHT PIPE LENGTH
ATST Desuperheater
July 2022
PI PT
TSL
PSL
DSPL
TE
Installation
WARNING
Always wear protective gloves, clothing, and eyewear when performing any installation operations to avoid personal
injury.
Personal injury or equipment damage caused by sudden release of pressure may result if the ATST desuperheater is
installed where service conditions could exceed the limits of the pressure rating noted on the nameplate. To avoid such
injury or damage, provide a relief valve for over pressure protection as required by government or accepted industry codes
and good engineering practices.
Check with your process or safety engineer for any additional measures that must be taken to protect against process
media.
If installing into an existing application, also refer to the WARNING at the beginning of the Maintenance section in this
instruction manual.
WARNING
When ordered, the desuperheater configuration and construction materials were selected to meet particular pressure,
temperature, pressure drop, and fluid conditions. Do not apply any other conditions to the desuperheater without first
contacting your Emerson sales office
1. Before installation, all piping upstream of the desuperheater must be cleaned so that no loose materials such as
welding slag, dirt or other foreign matter are left in the pipe. Use care to keep foreign matter out of the line
openings while preparing the desuperheater installation.
.
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ATST Desuperheater
July 2022
Instruction Manual
D104734X012
WARNING
Do not lift the desuperheater by its cooler manifold piping. Personal injury or damage to equipment could occur if the
desuperheater is improperly lifted into place.
All lifting and rigging must be completed in accordance with federal/national/provincial, state and local regulations
and applicable lifting and rigging equipment standards. Only personnel trained in proper lifting and rigging practices
shall perform desuperheater assembly lifting, rigging and installation. Because each lift will be unique, the method of
lifting thedesuperheater assembly, the correct location for attaching and lifting the desuperheater assembly, and what
the desuperheater assembly will do when lifted shall be considered for each lift.
Lifting and rigging equipment used to lift, install or remove a desuperheater assembly or component must be
properly selected and sized for the weight and configuration of the desuperheater assembly or component being
lifted. The weight of the complete desuperheater assembly, including attached accessories, must be taken in
consideration for this purpose. The lifting and rigging equipment must be properly maintained and inspected for
damage before each use.
Lifting lugs or other lifting equipment attached to the desuperheater must never be used to lift or support the weight
of attached piping.
If the ATST is equipped with buttweld ends, the desuperheater body must be supported using a lifting sling or other
method that does not place a load or force onto the finished surface of the buttweld ends. The ATST does not have a stable
resting condition. The desuperheater inlet and outlet must be fully supported until fully welded (buttweld end
connections) or bolted (flanged end connections) into the piping.
2. Arrange lifting slings, or other lifting and rigging equipment appropriate for the desuperheater weight and
configuration
, around the main steam pipe to safely lift the ATST to the pipe opening.
WARNING
Do not expose the ATST to undue stresses by installing it in bent pipes or flanges. Personal injury and equipment damage
could result from flange sealing failure due to improper installation.
3. Flanged Connections—Lubricate the flange connection bolts with a high temperature thread lubricant. Install flange
gaskets and connection bolts per accepted practices and tighten securely.
4. Welded Connections—Welding procedures should be in accordance with the applicable codes and the base
materials. For preheat, welding electrodes, and postweld heat treatment, refer to the applicable codes and
practices applicable for the specific facility. Materials are specified on the customer specification sheet.
NOTICE
Depending on desuperheater body materials used, post weld heat treating may be required. If so, damage to internal parts
is possible. In general, if post weld heat treating is to be performed, all nozzles should be removed. Contact your Emerson
sales office for additional information.
5. Remove the spraywater control valve and flush the cooling water line until all debris is removed from the line prior
to connecting it to the ATST desuperheater. Use only clean sources of cooling water to reduce the possibility of
nozzle clogging. A strainer should be installed in the water line as close to the ATST desuperheater as possible. To
determine appropriate mesh size, refer to desuperheater sizing and specification document, or contact your
Emerson sales office. Review strainer manufacturer's pressure drop curves to determine appropriate strainer body
size. You may need to use a strainer that is larger than the water line size.
6. Remove the atomizing steam valve and flush the steam line until all debris is removed from the line prior to
connecting it to the ATST desuperheater.
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ATST Desuperheater
July 2022
WARNING
Failure to use a strainer could result in nozzle clogging and subsequent property damage or loss. Uncontrolled
temperatures resulting from clogged nozzles may result in equipment or process temperature limits being exceeded.
Exceeding system temperature limits could result in property damage or personal injury.
7. A length of straight pipe is required downstream of the ATST desuperheater to ensure complete vaporization of
cooling water. An example of a typical installation appears in figure 2. Consult the ATST cooler sizing sheet for the
required distance of straight pipe. This is unique for each application and is supplied by Emerson.
8. Typically, a temperature sensor will be mounted downstream of the ATST desuperheater. This distance will vary
depending on a number of factors including steam velocity and percentage of spraywater. Consult the ATST cooler
sizing sheet provided with the unit for this temperature sensor distance. The steam line should not have any branch
lines dividing the steam flow between the ATST desuperheater and the temperature sensor. If you have any
questions, contact your Emerson sales office
9. A typical installation is illustrated in figure 2. A temperature sensor (TE) measures changes in temperature and a
temperature transmitter (TT) transmits the signal to the temperature control device. The output signal from the
controller is sent to the positioner on the cooling water (spraywater) control valve (SWCV). The positioner's output
signal strokes the SWCV open, increasing water pressure on the nozzles. Increasing water pressure upstream of the
nozzles increases water flow through the nozzles.
.
The atomizing steam valve operates either as on/off or control depending on application, and the type of operation
will be listed in the ATST sizing. In on/off operation, the atomizing steam valve is normally controlled so it fully
opens just prior to the spraywater control valve opening. In control operation, the valve signal is modulated based
on a downstream pressure target, as noted in the ATST sizing.
Maintenance
WARNING
Avoid personal injury or property damage from sudden release of process pressure or bursting of parts. Before performing
any maintenance operations:
D Always wear protective gloves, clothing, and eyewear when performing any maintenance operations to avoid personal
injury.
D Use bypass valves or completely shut off the process to isolate the desuperheater from process pressure. Relieve
process pressure and drain process media from the desuperheater.
D Use lock‐out procedures to be sure that the above measures stay in effect while you work on the equipment.
D Check with your process or safety engineer for any additional measures that must be taken to protect against process
media.
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ATST Desuperheater
July 2022
Instruction Manual
Servicing
Table 2. Inspection Summary
Key Part Description Inspection Tips and Diagnostics Repair Replacement
1
2
3 Nozzle Alignment Pin Refer to Nozzle Maintenance Section As needed
7 Nozzle Body Flange
10 Nozzle Refer to Nozzle Maintenance Section
12
Steam Pipe
(not replacement part)
Nozzle Body
(not replacement part)
Steam Pipe Liner
(not replacement part)
Inspect for erosion, thermal fatigue,
and other damage
Inspect for erosion, thermal fatigue,
and other damage
Inspect gasket surfaces for damage
that could indicate gasket leakage when
spray nozzles are replaced
Inspect for erosion, thermal fatigue,
and other damage
Consult your local Emerson Service Center or
Emerson Accredited Service Provider for a recommendation
on necessary weld repair or replacement
Consult your local Emerson Service Center or
Emerson Accredited Service Provider for a recommendation
on necessary weld repair or replacement
Replacement Only As needed
Replacement every 30-42 months
for optimal performance
Consult your local Emerson Service Center or
Emerson Accredited Service Provider for a recommendation
on necessary weld repair or replacement
Nozzle Maintenance and Replacement
D104734X012
When subjected to normal operating conditions, it is possible that wear, blockage, and/or fatigue will occur to the
nozzle assembly. During regularly scheduled maintenance, visually inspect the nozzles for wear and blockage. Your
local Emerson Service Center or Emerson Accredited Service Provider can help to determine the extent of fatigue and
the correct course of action. Poor performing nozzles or nozzle failure is typically caused by wear, corrosion, erosion,
and/or blockage. The following instructions will help to determine if any of these problems are present and provide a
recommended course of action for each.
Note
For optimal performance, nozzles should be inspected every 18-24 months and replaced every 30-42 months.
1. Loosen and remove the nozzle body flange stud nuts (key 6) and washers (key 4). Then, remove the nozzle body
flange assembly (key 7). Inspect the nozzle body flange gasket surfaces for damage. If damage is present,
replacement is necessary.
Figure 3. Fisher ATST Nozzle
X1886
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Instruction Manual
D104734X012
ATST Desuperheater
July 2022
2. Remove the nozzle (key 10), nozzle gaskets (key 9), and nozzle body flange gasket (key 8).
3. Inspect the water and atomizing steam injection orifices for excessive wear, erosion/corrosion, or blockage due to
particulate. Wear is defined as any cuts, gouges, or widening of the openings at the point of water and steam
injection. Erosion/corrosion is defined as any form of rust or erosion of the nozzle. Blockages are defined as small
particulate becoming trapped within the flow channels of the nozzle, impeding flow. Replacement of the nozzle is
recommended if any of the preceding problems are present.
4. Rinse the nozzle (key 10) to remove any loose particulate that may be present.
Figure 4. Spray Nozzle Alignment Pin Location
PIN
GH01927
5. Reassemble in the following order: nozzle gasket (key 9), nozzle body flange gasket (key 8), spray nozzle (key 10),
second nozzle gasket (key 9), nozzle alignment pin (key 3), nozzle body flange assembly (key 7), washers (key 4),
and stud nuts (key 6). Ensure the nozzle is installed such that the flow arrow is aligned with the direction of process
steam flow. It is recommended that any used gaskets be discarded and replaced with new ones.
6. Torque nozzle body flange nuts as indicated in table 3.
Table 3. Recommended Nozzle Body Flange Bolting Torque with Nickel Anti-Seize Lubricant
BOLT SIZE, INCH THREADS PER INCH LUBRICATION
5/8 11
3/4 10 258 190
7/8 9 373 275
1
1‐1/8 712 525
1‐1/4 942 695
1‐3/8 1268 935
1‐1/2 1654 1220
1. For other lubricants, contact your Emerson sales office for recommended bolt torque.
2. Torques for lubricated studs with heavy hex nuts.
8
Nickel Anti-Seize
RECOMMENDED BOLT TORQUE
NSm LbfSft
163 120
522 385
(1)
(2)
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ATST Desuperheater
July 2022
Instruction Manual
D104734X012
Parts Ordering
Each ATST desuperheater is assigned a serial number. Refer to the serial number when contacting your Emerson sales
office for technical assistance. When ordering replacement parts, refer to the serial number and key numbers for each
part required. The key numbers in the Parts List and the assembly drawing in figure 5 can be used to help in part
identification.
WARNING
Use only genuine Fisher replacement parts. Components that are not supplied by Emerson should not, under any
circumstances, be used in any Fisher desuperheater, because they may void your warranty, might adversely affect the
performance of the desuperheater, and could cause personal injury and property damage.
Parts List
Key Description
Note
Contact your Emerson sales office
Key Description
1 Steam Pipe
2 Nozzle Body
3 Nozzle Alignment Pin
4 Nozzle Body Flange Washer
5 Nozzle Body Flange Stud
6 Nozzle Body Flange Stud Nut
7 Nozzle Body Flange Assembly
for Part Ordering information.
8* Nozzle Body Flange Gasket
9* Nozzle Gasket
10* Spray Nozzle
11 Steam Pipe Liner Guide Ring
12 Steam Pipe Liner
13 Steam Pipe Liner Retention Pin
14 Nameplate (not shown)
8
*Recommended spare parts
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Instruction Manual
D104734X012
Figure 5. Fisher ATST Desuperheater
ATST Desuperheater
July 2022
FLOW
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ATST Desuperheater
July 2022
Figure 6. Fisher ATST Desuperheater Alternate View
Instruction Manual
D104734X012
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ATST Desuperheater
July 2022
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ATST Desuperheater
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Instruction Manual
D104734X012
Neither Emerson, Emerson Automation Solutions, nor any of their affiliated entities assumes responsibility for the selection, use or maintenance
of any product. Responsibility for proper selection, use, and maintenance of any product remains solely with the purchaser and end user.
Fisher is a mark owned by one of the companies in the Emerson Automation Solutions business unit of Emerson Electric Co. Emerson Automation Solutions,
Emerson, and the Emerson logo are trademarks and service marks of Emerson Electric Co. All other marks are the property of their respective owners.
The contents of this publication are presented for informational purposes only, and while every effort has been made to ensure their accuracy, they are not
to be construed as warranties or guarantees, express or implied, regarding the products or services described herein or their use or applicability. All sales are
governed by our terms and conditions, which are available upon request. We reserve the right to modify or improve the designs or specifications of such
products at any time without notice.
Emerson Automation Solutions
Marshalltown, Iowa 50158 USA
Sorocaba, 18087 Brazil
Cernay 68700 France
Dubai, United Arab Emirates
Singapore 128461 Singapore
www.Fisher.com
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E 2022 Fisher Controls International LLC. All rights reserved.
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