Forbes Marshall FMTD54M Manual

Forbes Marshall Thermodynamic Trap
FMTD54M
Installation and Maintenance Manual
Energy Conservation | Environment | Process Efficiency www.forbesmarshall.com

1. Preface ................................................................................1
2. Important Safety Notes .........................................................1
3. Brief Product Information .....................................................3
4. Product Working Principle ....................................................6
5. Installation Guidelines ..........................................................7
6. Start-up and Commissioning ...............................................8
7. Maintenance Guidelines .......................................................9
8. Troubleshooting ................................................................11
9. Available Spares .............................................................13
10. Warranty Period ...............................................................13
Table of Contents
PLEASE NOTE - Throughout this manual this cautionary symbol is used to
describe a potential damage or injury that might occur if the safety
considerations are overlooked. This symbol denotes CAUTION,
WARNING or DANGER.
Forbes Marshall Thermodynamic Trap

1
1. Preface:
This manual is intended for anyone using, commissioning, servicing, or disposing the below
mentioned products safely and efficiently.
Forbes Marshall Thermodynamic Trap [FMTD54M]
Size: DN 15 (½”) , DN 20 (¾”) and DN25 (1”)
PLEASE NOTE:
Throughout this manual the following cautionary symbol is used to describe a potential
damage or injury that might occur if the safety considerations are overlooked.
2. Important Safety Notes:
Read this section carefully before installing/operating/maintaining the product. The
precautions listed in this manual are provided for personnel and equipment safety.
Furthermore, Forbes Marshall accepts no responsibility for accidents or damage
occurring as a result of failure to observe these precautions. Note that the product is
designed to perform for non-contaminated fluids only. A contamination in the form of
chemical, foreign particle etc. can lead to problem with product performance and life
of the product.
If these products in compliance with the operating instructions are, properly installed,
commissioned, maintained and installed by qualified personnel (refer Section 2.7) the safety
operations of these products can be guaranteed. General instructions for proper use of tools
and safety of equipments, pipeline and plant construction must also be complied with.
2.1 Intended use:
Check if the product is suitable for intended use/ application by referring to the installation
and maintenance instructions, name plates and technical information sheets.
i) The product is suitable for use as defined in the technical information sheet. In case
the need arises to use the product on any other fluid please contact Forbes Marshall
for assistance.
ii) Check for the suitability in conformance to the limiting conditions specified in
technical information sheet of the product.
iii) The correct installation and direction of fluid flow has to be determined.
iv) Forbes Marshall products are not intended to resist external stresses, hence
necessary precautions to be taken to minimize the same.
2.2 Accessibility and Lighting:
Safe accessibility and working conditions are to be ensured prior to working on the
product.
FMTD54M

2
2.3 Hazardous environment and media:
The product has to be protected from hazardous environment and check to ensure that
no hazardous liquids or gases pass through the product.
2.4 Depressurizing of systems and normalizing of temperature:
Ensure isolation and safety venting of any pressure to the atmospheric pressure. Even if
the pressure gauge indicates zero, do not make an assumption that the system has been
depressurized. To avoid danger of burns allow temperature to normalize after isolation.
2.5 Tools and consumables:
Ensure you have appropriate tools and / or consumables available before starting the
work. Use of original Forbes Marshall replacement parts is recommended.
2.6 Protective clothing:
Consider for the requirement of any protective clothing for you/ or others in the vicinity for
protection against hazards of temperature (high or low), chemicals, radiation, dangers to
eyes and face, noise and falling objects.
2.7 Permits to work:
All work to be carried out under supervision of a competent person. Training should be
imparted to operating personnel on correct usage of product as per Installation and
Maintenance instruction. “Permit to work” to be complied with (wherever applicable), in
case of absence of this system a responsible person should have complete information
and knowledge on what work is going on and where required, arrange to have an
assistant with his primary goal and responsibility being safety. “Warning Notices” should
be posted wherever necessary.
2.8 Handling:
There is a risk of injury if heavy products are handled manually. Analyze the risk and use
appropriate handling method by taking into consideration the task, individual, the
working environment and the load.
2.9 Freezing:
Provision should be made to protect systems which are not self-draining, against frost
damage (in environment where they may be exposed to temperatures below freezing
point) to be made.
2.10 Product Disposal:
It is necessary to dispose this product only in accordance with local regulations at the
authorized, qualified collecting point specified for equipment’s and its parts—Please
refer the part details mentioned in the material table of this manual. Please follow all
waste disposal guidelines (Management & Handling) as published by local governing
authorities in India & abroad
2.11 Returning products:
Customers and Stockist are reminded that, when returning products to Forbes Marshall
they must provide information on any hazards and the precautions to be taken due to
contamination residues or mechanical damage which may present a health, safety or
environmental risk.
This information must be provided in writing including Health and Safety data sheets
relating to any substances identified as hazardous or potentially hazardous.
Forbes Marshall Thermodynamic Trap

3
3. Brief Product Information:
3.1 Description:
The Forbes Marshall Thermodynamic Trap FMTD54M, with inbuilt strainer and
Forged carbon steel construction, is best suited for header and mainline drains.
Replacable trap internals and built in strainer eases inline maintenance
3.2 Sizes and End Connections:
DN15, DN20 and DN25
Screwed BSPT/NPT/BSP and socket/butt weldable ends
Notes:
1. Available with end connections Class 150,300 and 600 (weld on flanges) on
request.
2. Available with IBR certificate on request.
3.3 Limiting Conditions:
Note: for lower operating temperatures consult Forbes Marshall.
PMOB : Maximum back pressure should not exceed 80% of the inlet pressure
under any conditions of operation otherwise the trap may not shut-off
3.4 Operating Range:
Body design conditions PN63
PMA Maximum allowable pressure 63 bar g @100°C
TMA Maximum allowable temperature 425°C @ 42 bar g
Minimum allowable temperature 0°C
PMO Maximum operating pressure 42 bar g
TMO Maximum operating temperature 425°C @ 42 bar g
Minimum operating temperature 0°C
Minimum operating differential pressure
for satisfactory operations 0.25 bar g
Designed for a maximum cold hydraulic 95 bar g
test pressure
The Product must not be used in this region.
The product should not be used in this region or beyond its
operating range as damage may occur to the internal.
0
Temperature C
400
300
200
100
0
0 20 40 42 63
Pressure bar g
425
FMTD54M
AA - #150
BB - #300
CB - #600
A
A
B
B
C
C

4Forbes Marshall Thermodynamic Trap
Figure 1: Forbes Marshall Thermodynamic Trap
4
11
2
3
9
8
6
10
7
5
1
Material
No Part Material
1. Body ASTM A105N
2. Outer Seat Gasket SS304+Graphite
3. Inner seat gasket SS304+Graphite
4. Disc Tool Steel AISI D2
5. Top Cover Gasket SS304+Graphite
6*. Screen SS304
7. Strainer Cap BS 3146 Part 2 ANC2
8. Stud ASTM A193 B7
9. Nut ASTM A194 2H
10. Seat Tool Steel D2
11. Top Cover ASTM A105N
12*. Nameplate SS304
13* Rivet SS304
14 Isotub SS304
* Marked not shown in fig.1.

5
3.5 Product Dimension and Drawing:
Dimensions (approx.) in mm:
3.6 Optional extras:
ISOTUB- An insulating cover which prevents the trap from being unduly influenced by
excessive heat loss such as when subjected to low outside temperature, wind, rain
etc.
3.7 Salient Features
1. Forged Carbon steel construction ensures better mechanical properties.
2. The disc and seat, hardened by induction hardening process to about 56 RC can
withstand continuous water hammering conditions.
3. Condensate entry below the disc concentric to disc/seat ensures clean and parallel
lift to disc with reference to seat, eliminating any localized wear and tear.
4. An inbuilt strainer screen of adequately large area ensures long and trouble free
operation.
3.8 Capacity Chart:
Figure 2: Dimensional Drawing of FMTD54M
Size A B C D E F Weight
DN 15
DN 20 42 78 50 44 57 150 0.8 kg
DN 25 49 92 50 44 62 160 1.5 kg
C
D
F
A
E
B
Weight mentioned is of bare FMTD64 Trap.
*
*
Size A B C D E F Weight in kg
DN 15 79 57 116 68 70 2.9
DN 20 79 57 116 68 70 2.9
DN 25 81 60 116 68 70 3.0
Note: * Weight mentioned is of bare FMTD54M Trap.
#150 #300 #600
217 227 239
227 237 249
233 245 259
15/20/25NB
800
700
600
500
400
300
200
100
0
Discharge capacity Kg/hr
16 11 16 21 26 31 36 41
Differential pressure bar g
FMTD54M
BA
D
C
±2.0
F
E
*#150 #300 #600
3.9 4.5 4.7
4.3 5.5 5.9
5.0 6.0 6.6

6Forbes Marshall Thermodynamic Trap
4. Product Working Principle:
The Forbes Marshall thermodynamic trap works on thermodynamic principle using the
dynamic effect of flash steam as hot condensate passes through the trap.
4.1. Operation of Forbes Marshall Thermodynamic Trap : [Refer figure 3]
1. The Forbes Marshall thermodynamic trap operates on thermodynamic principle
using the Bernoulli theorem i.e. the total pressure energy (static and dynamic) for a
moving fluid is same at all points.
2. Condensate enters the trap through post integral strainer screen (E) in the trap.
There is an increase in dynamic pressure of the steam and hot condensate flowing
under the disc (A) as the velocity of flow increases and consequential drop in static
pressure since the total pressure must remain constant, resulting in disc (A) being
drawn downward to the concentric seat rings (C).
3. As the disc (A) is drawn downwards, flash steam passes between the edge of the
disc (A) and the inner face of the cap (D) of the trap. The flash steam occupies the
space in the top surface of the disc (A).
4. The flash steam above the disc (A) exert pressure on the larger area on the top
surface area of disc (A) overcomes the inlet pressure acting on a smaller area at the
bottom of the disc (A). The disc (A) snaps shut against the concentric body seat
rings (C) and prevents further flow.
5. This position of the disc (A) continue until the flash steam above the disc (A) starts
condensing by radiating heat from the cap (D).Post the condensation of flash steam
the pressure acting on top of disc (A) is relief and the cycle mention in points 2,3,4
and 5 is repeated.
6. The Forbes Marshall Thermodynamic Trap has an intermittent discharge pattern.
The frequency of which is determinant by the condensate load and ambinent
temperature.
Figure 3 : Forbes Marshall Thermodynamic Trap
ACD
E

7
5. Installation Guidelines: [Refer figure 4]
Note:Before implementing any installations observe the 'Important Safety Notes' in
Section 2. Referring to the installation and maintenance instructions, name – plate
and technical information sheet check the product is suitable for the intended
installation.
1. As part of pre-installation all fluid handling equipment particularly piping should be
thoroughly cleaned of scale and the internal debris which accumulates during
construction. This is accomplished by blowing or flushing with air, steam, water and other
suitable medium.
2. Check materials, line pressure and temperature and their maximum values.
3. Before installation, flush the inlet drip leg to remove all dirt and oil. Ensure to remove all
protective seals from the trap.
4. The Forbes Marshall Thermodynamic Trap should be installed in a horizontal plane such
that disc movement happens only in vertically up and down directions.
5. The horizontal mainline should be provided with proper collecting pocket as provided by
equal Tee should end with a drip leg and at the end of the drip leg Forbes Marshall
Thermodynamic Trap should be fitted. Typically recommended drain pocket dimensions
relative to steam main pipe sizes are given below.
Note: Condensate should not be drained through a small pipe connection at the bottom
of mainline.
FMTD54M
Cold Condensate
to Outlet
Cold Condensate
Trapping
1. (Cold Start)
Condensate Condensate
2. Trapping
P2
P1Flash Steam
P2 P1
Condensate
3. Trap Closed
P2
P1
Flash Steam
P1 P2
Radiation loss
Condensate
Condensate
4. Trap Open
P2
P1
P2 P1
Figure 3 : Forbes Marshall Thermodynamic Trap

8Forbes Marshall Thermodynamic Trap
Figure 4 : Recommended installation of Forbes Marshall Thermodynamic Trap on
mainline
6. When a socket weld Forbes Marshall Thermodynamic Trap is being installed the welding
should be in accordance with an approved weld procedure to a recognized standard.
7. Isolation valves should be installed to allow for safe maintenance and trap replacement.
8. Always open isolation valve slowly until normal operation condition is achieved this will
avoid system shocks. Check for leaks and attend if any.
Note: 1.) If the trap is to discharge to atmosphere ensure it is to safe place, the discharging
fluid may be at a temperature of 100°C.
2.) For Socket weld / Butt weld end connections coat the weld ends with primer and
suitable high temperature paint immediately after welding before corrosion sets in.
6. Start-up and Commissioning:
6.1. Flushing of lines:
Follow these steps to carry out the flushing.
1. Close the upstream trap isolation valve and open the bypass isolation valve.
2. Let the condensate drain for 10-15 minute or until clear condensate starts coming
out, whichever is earlier.
3. Now slowly close the bypass isolation valve and open the upstream trap isolation
valve.
Note: For a detailed procedure on flushing of lines please visit Forbes Marshall website.
6.2. Commissioning:
After installation or maintenance ensure that the system is fully functioning by confirming
condensate is passing through it.
1. After flushing of lines is complete, ensure that bypass isolation valve is closed and
upstream trap isolation valve is opened.
2. Check for leaks and attend if any.
Mains
diameter-D
Pocket
diameter-d1
Pocket
depth-d2
Upto 100mm d = D
1Min d = 100mm 2
125-200mm d = 100mm
1Min d = 150mm 2
250 mm & above d > D/2
1Min d = D 2
D
d2
d1
Steam mainline
FMTD54M
Hot condensate
to return or drain
To drain

9
7. Maintenance Guidelines:
Note:Before undertaking any maintenance of the product it must be isolated from
both supply line and return line and ensure pressure is normalized to atmosphere.
The product should then be allowed to cool. When re-assembling ensure that all joint
faces are clean.
7.1. Routine and preventive maintenance:
Please refer to the maintenance schedule mentioned in the table below to undertake
routine maintenance of the Forbes Marshall Thermodynamic Trap.
7.2. Tool Kit:
To carry out maintenance of the Forbes Marshall thermodynamic trap [FMTD54M] refer
the tools mentioned in the table below.
7.3. Recommended tightening torques:
Table 1: Recommended tightening torque
Size Component Tool used and size
DN 15/20/25 Strainer Cap Open spanner 26 mm (A/F)
Stud Threaded Sleeve
Item Component Torque Range
2 Cap 180 - 200 Nm
5 Strainer Cap 170- 190 Nm
No. Parameters to be checked
Frequency for checking various parameters
Immediate Daily Weekly Monthly Quarterly Half
Yearly Annually
1Test High Pressure steam traps
(17.5 bar g and above) Y
2Test Medium Pressure steam traps
(3.5 bar g to 17.5 bar g) Y
3Test Low pressure steam traps
( below 3.5 bar g) Y
4Repair / Replace steam traps - when
testing shows leaks Y
5 Clean internals / strainer of FMTD54M Y
6 Visual Inspection for leakages Y
7 Arresting any other leaks Y
Nut Open spanner 17 mm (A/F)
Item No. Part Torque Range
7 Strainer Cap 26mm A/F 110 – 130 Nm
8 Stud M10 X 1.5 20 – 25 Nm
9 Nut 17mm A/F 45 – 50 Nm
FMTD54M

10 Forbes Marshall Thermodynamic Trap
7.4. Procedure to replace the disc and seat: [Refer figure 5]
Note: The top cover gasket (5) contains a thin stainless steel support ring
which may cause physical injury if not handled and disposed of carefully.
1. Spring off the insulating cover, unscrew the four nuts (9) and remove the top cover
(11).
2. Lift off the disc (26).
3. Remove the top cover gasket (5) and lift out the seat unit (10). Insert screw – driver
into the groove for easy removal.
4. Carefully remove the seat gaskets (2 and 3) from the body of the steam trap. Ensure
that no damage is caused to the steam trap body (1).
5. Ensure that the gasket contact surface in the body is clean and fit new seat gaskets
(2 and 3).
6. Fit new seat unit (10), new cover gasket (5) and new disc (4). Ensure that the disc is
fitted with the grooves facing the seat.
7. Replace the top cover (11) ensuring the cover gasket remains in place.
8. Replace the 4 nuts (9). Tighten the nuts diagonally in sequence to a suitable torque
of 45 – 40 Nm.
Note: The use of a thread lubricant is recommended.
9. After 24 hours check the torque on the top cover nuts (9).
10. Always open the isolation valves slowly and check for leaks.
7.5. Procedure to clean or replace the strainer screen: [Refer Figure 5]
1. Unscrew the strainer cap (7) using the spanner (26mm A / F).
2. Remove the strainer screen (6). Fit a new or cleaned strainer screen into the recess
in the strainer cap (7).
3. The strainer cap (7) screwed into the body and tightened to a suitable torque 142 –
158 Nm.
Note: The use of a thread lubricant is recommended.

7.6. Procedure to replace the cover studs: [Refer Figure 5]
1. After removing old cover studs (8), fit new cover studs.
Note: The use of a thread locking compound is recommended.
7.7. Steam traps testing:
Following methods can be used to determine the operating condition of a trap and
determine if its working properly:
1. Testing traps through visual inspection.
2. Testing traps using temperature gun / equipment
3. Testing traps using sound/ultrasound.
4. Testing traps through online monitoring.
11
FMTD54M
8. Troubleshooting:
If the expected performance is unachievable after installation of the Forbes Marshall
thermodynamic trap, check the following points for appropriate corrective measures.
Failure Mode Possible Cause Remedy
No
condensate is
discharged
(blocked).
Differential pressure is low.
Verify inlet and outlet pressure of the steam
trap. Minimum differential pressure required is
0.25 bar g
Air – Binding problem. Loosen Top Cover and tighten to suitable
torque.
Steam trap body is hot but no
condensate discharge.
To release flash steam locked (trapped) inside
the steam trap, pour water on top cover of the
steam trap to check it discharge condensate.
Steam
leakage.
Steam Leaking continuously.
Ensure bypass valve is fully closed.
Check installation i.e. Top Cover to be on top
and fluid flow direction same as arrow on the
steam trap body
Improper installation of the
product..
Check installation i.e. top cover should be on
top and fluid flow direction same as arrow on
the steam trap body.

Steam
leakage.
Disc stuck to the top cover.
Give a light tap on top of the top cover and
check step (inner surface of the top cover) is
worn out. If step is worn out replace with new
top cover.
Back pressure exceeds
allowable value.
Outlet pressure of the steam trap should not
exceed 80% of the inlet pressure.
12 Forbes Marshall Thermodynamic Trap
Foreign material or oil film
on disc or body seat.
Clean both disc and body seat, flatness on disc
and body seating faces can be improved by
lapping individually on flat surface or glass
plate. Note: The total amount of metal from
body seat face removed should not exceed
0.25mm (0.01”).
Note: Never attempt to modify the product. When replacing old parts with new parts, use the
spare parts listed in Section9.
Failure Mode Possible Cause Remedy
Motor-boating
(chattering) of
disc.
Scratch on disc or body seat.
Check if scratch depth is less than disc and
body seating faces flatness can be improved by
lapping individually on flat surface or glass
plate. If scratch depth is more replace with new
body seat. Note: The total amount of metal from
body seat face removed should not exceed
0.25mm (0.01”).
Disc or body seat is worn.
Replace with new disc. If body seat is slightly
worn it can be refaced by lapping on flat surface
or glass plate. If body seat is worn more replace
with new body seat. Note: The total amount of
metal from body seat face removed should not
exceed 0.25mm (0.01”).

13
FMTD54M
9. Available Spares: [Refer figure 5]
The parts available as spares are shown in heavy outline. Parts drawn in dotted line are not
available as spares.
No. Spares Part No. Spares Code
1FMTD54 Top Cover Stud and Nut Set 8,9 SPARE-152025CMTD42M/FMTD54M-HKIT
215NB FMTD54 Seat, Disc 10,4 SPARE-15CMTD42M/FMTD54M-SDKIT
320/25NB FMTD54 Seat, Disc 10,4 SPARE-1520CMTD42M/FMTD54M-SDKIT
4FMTD54 Strainer Screen 6 SPARE-152025CMTD42M/FMTD54M-SKIT
5FMTD54 Top Cover and Seat Gasket 5,2,3 SPARE-152025CMTD42M/FMTD54M-GKIT
10. Warranty Period:
As per ordering information and agreements in the contract.
How to Order :
Example: 1No. DN15 Forbes Marshall Thermodynamic Trap FMTD54M
How to Order Spares:
Always order spares by using the description given in the column headed “Available
Spare” and stating the size and type of trap.
Example: 1No. Strainer Screen for DN15 Forbes Marshall Thermodynamic Trap
FMTD54M
Figure 5: Exploded view of FMTD54M Thermodynamic Trap
1
2
3
4
5
6
7
9
8
10
11
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Forbes Marshall Pvt Ltd
Manufacturing: B-85, Phase II Chakan Indl Area, Sawardari, Chakan
Tal. Khed, Dist, Pune 410 501. Tel: [phone]
Sales: Opp 106th Milestone, Bombay Pune Road, Kasarwadi,
Pune 411034 Tel.: [phone]
CIN No: U28996PN1985PTC037806
Disclaimer:
This information is strictly proprietary and legally privileged. All contents herein shall be the property of Forbes
Marshall Pvt Ltd and having protection under the intellectual property rights. No part of this information or data may
be distributed or disclosed in any form to any third party. Any dissemination, use, review, distribution, printing or
copying is strictly prohibited, if you are not the intended recipient or user of this information.
Email : [email protected] www.forbesmarshall.com
Doc# FMSS/0417/UM-FMTD54M/R0