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Forbes Marshall FMPRV41, Installation And Maintenance Manual

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Forbes Marshall FMPRV41 Installation And Maintenance Manual Download Page 30

28

Forbes Marshall Pilot Operated Pressure Reducing Valve

8.

Troubleshooting:

Before undertaking the following fault finding procedure, ensure the valve has been isolated and 
that upstream & downstream pressures are zero. Possible fault checks are given in a logical order 
below.  A pressure reducing valve typically has the following failure modes:

1)

Downstream pressure zero or too low:

If downstream pressure of Forbes Marshall Pilot Operated Pressure Reducing Valve is zero, 
please  check  following  before  dismantling  the  Forbes  Marshall  Pilot  Operated  Pressure 
Reducing Valve.

1.

Downstream pressure gauge: - Please ensure that it should be in working condition.

2.

Upstream pressure: - It Should be as per the pressure reducing valve upstream design 

pressure.

3.

Isolation valve not fully Open - Ensure Upstream & Downstream Isolation valves are in 

full open condition 

4.

Upstream Strainer Clogged – Ensure upstream Strainer is in clean condition: Clean it if it 

is found as clogged.

Failure Mode

Possible Cause

Remedy

Downstream 
pressure zero 
or too low

Pressure adjustment bolt

Please ensure that pressure adjustment bolt is not in 
loose condition.  If so, rotate it clockwise slowly to set the 
desired downstream pressure.

Clogging in pressure 
reducing valve

Ensure Pilot valve strainer, Control pipe assembly &SS hex 
coupling fixed to bottom diaphragm chamberare clean. If 
found clogged clean it properly. Check the internal 
balancing line for blockage. 

Main Diaphragms

If main diaphragms are permanently deformed or 
punctured - replace the same.

Jamming of push rod

Please check if Push rod is jammed in liner bush at lower 
position. Open & clean it.

Main valve lift disturbed:

Check that pushrod lock nut is intact & it is in full 
tightens condition. If it is loose there is a chance that the 
main valve lift may be reduced. To re adjust the main 
valve lift, Please refer the main valve lift setting video clip.

Summary of Contents for FMPRV41

Page 1: ...Forbes Marshall Pilot Operated Pressure Reducing Valve FMPRV41 Installation and Maintenance Manual Energy Conservation Environment Process Efficiency www forbesmarshall com ...

Page 2: ...ance Guidelines 16 8 Troubleshooting 28 9 Available Spares 31 10 Warranty Period 33 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 Pilot Operated Pressure Reducing Valve ...

Page 3: ...oducts 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 inte...

Page 4: ...nstallation 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 ...

Page 5: ...ng Conditions 3 4 Pressure Sensing Pipe The FMPRV41 controls the pressure by sensing the downstream pressure through a pressure sending pipe taken to the union item L or through the internal sensing pipe item M Fitting of the external pressure sensing pipe is described in the user manual supplied with the valve Note Capacity is reduced and there is a possibility of hunting if an external pressure ...

Page 6: ...4 Forbes Marshall Pilot Operated Pressure Reducing Valve Figure 1 Forbes Marshall Pilot Oprated Presure Reducing valve FMPRV41 steam ...

Page 7: ...clip SS ASTM A240 Type 301 15 Pilot filter cap gasket SS BS 1449 304 S16 16 Pilot filter cap SS ASTM A743Gr CA 40 17 Pilot filter element Bronze 18 Internal strainer SS ASTM A240 Type 304 19 Body gasket SS forced exfoliated graphite 20 Main valve return spring Stainless Steel BS 2056 302 S26 21 Main valve Stainless Steel ASTM A276 Type 420 22 Main valve seat Stainless Steel ASTM A276 Type 420 23 B...

Page 8: ...0 DN20 160 181 410 130 DN25 180 203 430 144 DN40 212 251 450 149 DN50 232 251 480 174 FMPRV41 Steam FMPRV41 STEAM M FMPRV41 AIR Size Screwed A Flanged A1 B D E 15 160 181 360 130 DN15 LC 160 181 360 130 DN20 160 181 360 130 DN25 180 203 383 144 DN40 212 251 415 149 DN50 232 251 415 174 DN FMPRV41 Air Figure 2 Dimensional drawing of FMPRV41 STEAM Figure 3 Dimensional drawing of FMPRV41 Air ...

Page 9: ...pstream pressure line crosses the horizontal 4 bar g downstream pressure line A perpendicular dropped from this point gives the capacities of all FMPRV41 sizes under these conditions Superheated steam Because of the higher specific volume of superheated steam a correction factor must be applied to the figure obtained from the chart above For 55 C of superheat the factor is 0 95 and for 100 C of su...

Page 10: ...downstream pressure line A perpendicular dropped 3 from this point shows that a DN15 valve will pass approximately 120 dm s under these conditions and is the correct valve size to choose KV Values The Kv values are full capacities and should be used for safety valve sizing purpose only SIZE DN15 DN20 DN25 DN40 DN50 KV 2 8 5 5 8 1 17 28 For conversion Cv UK Kv x 0 963 Cv US Kv x 1 156 Compressed Ai...

Page 11: ...ure that the main valve 21 is also settled hence giving a stable downstream pressure When downstream pressure rises the pressure under the pilot diaphragm 8 becomes greater than the force created by the pressure adjustment spring 5 and this makes pilot diaphragm 8 to move upwards This closes the pilot valve seat 11 and will interrupt the transmission of steam pressure underneath the main diaphragm...

Page 12: ...ing loads or where stand by facility is required two or more valves may be used in parallel figure 6 For pressure turn down in excess of 10 to 1 consideration should be given to using the two valves in series To avoid turbulence between the two pressure reducing valves the distance must be equivalent to atleast 50 pipe diameters To ensure adequate drainage of the space between the two pressure red...

Page 13: ...41 in parallel This is a typical representation of Forbes Marshall Pilot Operated Pressure Reducing Valve Figure 8 Installation of Two FMPRV41 in series This is a typical representation of Forbes Marshall Pilot Operated Pressure Reducing Valve ...

Page 14: ...valve then a further drain point should be provided to keep the valve drained after shutdown 5 6 Preventing Dirt The valve should be protected from dirt foreign particles using pipeline strainer The strainer should be fitted on its side to prevent the accumulation of water 5 7 Pressure Control Pipe For applications that require closer control improved stability or maximum capacity condition the in...

Page 15: ...e station is recommended to allow for planned maintenance see fig 6 Alternatively a by pass line can be used see fig 7 It is important that the by pass should have a similar capacity to the Forbes Marshall Pilot Operated Pressure Reducing Valve which is achieved by choosing an appropriately sized valve or by using a reduced orifice in the line The hand wheel should be pad locked to prevent unautho...

Page 16: ... transmitted back causing unstable operation and premature wear or if this is impractical an intermediate vessel can provide a similar benefit Where a safety valve is required to protect the process system downstream of a FMPRV41 and where a temperature control valve is also being used downstream of the FMPRV41 it is recommended that the safety valve is fitted downstream of the temperature control...

Page 17: ...ation ensure that the upstream pipework has been cleared of all the loose dirt and hard particles and that the main strainer screen 4 is examined and cleaned if necessary 6 Slowly open the upstream stop valve 2 until it is fully open 7 Using a suitable sized spanner slowly turn adjustment screw of FMPRV41 5 in a clockwise direction until desired downstream pressure reading is obtained 8 Holding th...

Page 18: ...and disposed of correctly 7 1 Routine and Preventive Maintenance Please refer to the maintenance schedule mentioned in the table below to undertake routine maintenance of the FMPRV41 SR PARAMETERS TO BE CHECKED FREQUENCY FOR CHECKING VARIOUS PARAMETERS A Forbes Marshall Pilot Operated Pressure Reducing Valve Daily Weekly Monthly Quarterly Half Yearly Annually 1 Clean Main valve strainer Y 2 Clean ...

Page 19: ...17mm A F Split Pin Nose Plier M10 bolt for housing and spring assembly Box Spanner 17 mm A F 4 No control pipe Elbow fitting Open Spanner 13mm A F Lower drain Open Spanner 10mm A F Strainer cap Box Spanner 19 mm A F DN 40 Main valve assembly 31mm slot and OD 37mm Customer made tool has to be designed Veriner to measure depth and lift of the push rod main valve head and seat assembly 4 5 mm lift DN...

Page 20: ...g valve and completely depressurize the system in order to change the pressure adjustment spring 1 Release the adjustment lock nut 2 by turning in the anticlockwise direction 2 Turn the adjustment screw 1 anticlockwise Ensure there is no compression on the pressure adjustment spring 4 3 Undo the 4 off spring housing securing nuts and bolts 3 and remove the spring housing 4 Remove and replace the p...

Page 21: ...tions are being made to cable insulated PTFE The inhalation of these fumes is easily prevented by applying local exhaust ventilation to atmosphere as near to their source as possible Smoking should be prohibited in workshops where PTFE is handled because tobacco contaminated with PTFE will during burning give rise to polymer fumes It is therefore important to avoid contamination of clothing especi...

Page 22: ...2 Unscrew spring housing securing nuts and bolts 2 thereby releasing the spring housing spring 3 top spring plate 4 bottom spring plate 5 and pilot diaphragm 6 Figure 13 FMPRV41 air 3 Remove pilot valve housing 7 4 Ensure main return spring 8 is still in position 5 Unscrew and remove pilot valve assembly 9 22 mm A F 6 Screw new pilot valve into housing and tighten the nuts to the recommended torqu...

Page 23: ...to Figure 15 Isolate the reducing valve and zero the pressure 1 Unscrew the unions 1 and release the pipework 2 Unscrew the spring housing securing nuts and bolts 2 3 Remove the pilot valve housing 3 4 Remove the internal strainer screen 4 and clean or replace 5 Ensure the gasket 5 faces are clean 6 Check that the main valve return spring 6 is in position 7 Fit a new gasket 8 Replace the internal ...

Page 24: ...ate 5 and pilotdiaphragm 6 3 Ensure the bottom spring plate 5 and pilot valve assembly is clean 4 Replace the pilot valve diaphragms 6 5 Assemble the spring housing and tighten the nuts to the recommended torque as shown in Table 1 Bring the valve back into commission following as many steps as necessary in section 6 Figure 16 Replacing Maintaining Pilot valve diaphragm Spring Hsg securing nuts an...

Page 25: ... diaphragm chamber 3 on two bolts either side of the union connection 6 Bring the two new diaphragms together and slide into position If the diaphragms are not renewed but cleaned only care must be taken to replace the diaphragms in their original order 7 Push the lower chamber 3 and tighten the M12 nuts and bolts 2 Progressively and evenly tighten to a torque of 80 100 N m 8 Retighten the long un...

Page 26: ...igure 19 3 Remove the strainer screen 1 and gasket 2 and clean 4 Remove the main valve spring 3 and the main valve head 4 Clean to remove dirt or scaleas necessary 5 Remove the main valve seat 5 Clean and remove dirt and scale as necessary 6 Examine the faces of the main valve head 4 and seat 5 If they are only slightly wornthey may be lapped on a flat plate using a fine grinding paste If either i...

Page 27: ...od assembly 5 1 Undo the long nuts and pull away 2 Undo the M12 nuts and bolts 1 3 Drop away the lower diaphragm chamber 4 the two diaphragms 3 and diaphragm plate 2 and pushrod assembly 5 Figure 20 Resetting the main valve pushrod Table 2 TORQUE FOR MAIN VALVE SEAT FMPRV41 STEAM AIR Strainer screen 1 Gasket 2 Main valve spring 3 Main valve head 4 Main valve seat 5 M12 nuts and bolts 1 Push Rod as...

Page 28: ...gm plate 2 and pushrod assembly 1 and loosely fit the lower diaphragm chamber on two bolts 5 either side of the union connection to locate the spigot in the recess 9 Refit the diaphragms 3 in exactly the same way as when they were dismantled 10 Push the lower diaphragm chamber 4 home to locate in the recess and refit the M12 nuts and bolts Progressively and evenly tighten to a torque of 80 100 N m...

Page 29: ...the pilot valve housing complete with spring housing assembly and tighten the nuts to the recommended torques FMPRV41 AIR Assemble the pilot valve housing and tighten the nuts to the recommended torques 6 Refit the pipework and retighten the unions 4 to ensure a tight seal Bring the valve back into commission following as many Steps as necessary in Section 6 Unions 4 Unions 4 Internal Strainer Scr...

Page 30: ...pen condition 4 Upstream Strainer Clogged Ensure upstream Strainer is in clean condition Clean it if it is found as clogged Failure Mode Possible Cause Remedy Downstream pressure zero or too low Pressure adjustment bolt Please ensure that pressure adjustment bolt is not in loose condition If so rotate it clockwise slowly to set the desired downstream pressure Clogging in pressure reducing valve En...

Page 31: ...downstream pressure does not respond to the adjustment bolt rotation check the pilot valve or main valve leakage by following the next step A Close the upstream isolation valve B Loosen the pressure adjustment bolt and Make the downstream pressure zero C Remove the SS tubing from Pilot valve chamber center T Joints D Open the upstream isolation valve slowly check for steam leakage E If steam comin...

Page 32: ... should be in full closed condition and it should not be leaking 5 Upstream Strainer Clogged Ensure upstream Strainer is in clean condition Clean it if it is found as clogged 6 Bypass valve Check whether the bypass valve is leaking Replace if found so Failure Mode Possible Cause Remedy Hunting Sticking of push rod in the Main Valve Chamber Check that the Main valve pushrod is not sticking Open cle...

Page 33: ...9 Available Spares Figure 23 Parts Available as spares Heavy outline for FMPRV41 STEAM AIR Pilot valve assembly Pilot valve assembly D E F G AIR STEAM B A B C H I J K M O P Q S N R L T U A STEAM Push rod assembly ...

Page 34: ...in valve kit Assembly with Spring DN 50 S2055884 Main valve kit Assembly with Spring DN 15 AIR H I J K S2019705 Main valve kit Assembly with Spring DN 15 long neck S2055950 Main valve kit Assembly with Spring DN 15 low capacity S2055949 Main valve kit Assembly with Spring DN 20 S2019706 Main Valve kit Assembly with Spring DN 20 long neck S2055951 Main Valve kit Assembly with Spring DN 25 S2019707 ...

Page 35: ...ket Kit DN 15 20 25 STEAM AIR T S2019642 Gasket Kit DN 40 50 S019527 10 Pressure Adjustment Conical Spring STEAM AIR U S2038888 11 Main Valve Return Spring kit DN 15 20 STEAM AIR H S2019701 Main Valve Return Spring kit DN 25 S2019702 Main valve return spring kit DN 40 50 S2019703 12 Repair kit for DN 15 STEAM A B L S Q M R I O V S2055895 Repair kit for DN20 S2055896 Repair kit for DN25 S2055897 Re...

Page 36: ...his 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 inte...

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