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Valve Selection Guide

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LEADER VALVES LIMITED & LEADER EXPORTS (JALANDHAR)

 
Ref No.
CE/TECH/01

DESIGN & DEVELOPMENT

Issue Date
01.05.2010
   

INSTALLATION, OPERATION & MAINTENANCE MANUAL

Rev no.
00
Rev Date.
New
 
THE TROUBLE - FREE PERFORMANCE OF A VALVE LARGELY DEPENDS ON THE SELECTION OF A RIGHT VALVE FOR THE JOB FOLLOWED BY PROPER STORAGE, NEAT INSTALLATION GENTLE OPERATION AND TIMELY MAINTENANCE. PLEASE FOLLOW THERE GIVEN STEPS FOR THE VALVE TO FUNCTION WELL TO YOUR SATISFACTION.
 
 

GENERAL :

On receipt, inspect the valve for any shipping damage. as per the packing - slip placed inside the box, verify the goods received. Items packed loose within the box are separately identified in the packing - slip check for short supply. Do not take - off the end protectors until the installation.

PRE-INSTALLATION CARE :

  1. Before installation, have a general check on the valve condition, grease or rust preventive media be removed from unpainted portion. Grease may be applied at grease point and graphite powder on stem threads for smooth operation. It is suggested to get the valves hydraulically tested to check the condition of the gaskets, Rubber sleeves, diaphragms or other electrometric components, which become hard during long storage. It may be necessary to replace these parts.
  2. The pipe-line should be thoroughly cleaned of all traces of dirt, scale, rust and welding splashes etc.
GATE/GLOBE VALVES : The actuating stem will project out while opening and hence provide enough head room. Take off end-protectors just prior to the installation. Clean the seating surfaces.

CHECK VALVES : Remove additional packing stuff placed inside the valve bore.

BALL VALVES : Ball valve may required more side room while operated due to lever length.

INSTALLATION OF VALVES IN PIPE –LINE :

  1. It is necessary at the design stage to consider where and how the valve will be located in the pipe-line. Valves should be provided adequate support where necessary.
  2. The valves should not carry the weight of the pipe line, otherwise it will create distortion which result in inefficient operation, Jamming and the necessity of early maintenance. If the valve is of flanged construction, it will be difficult to tighten the flanges properly.
  3. Valve should be accessible for adjustment, maintenance and repair.
  4. Consideration should be given to the possibility of removing single valve for overhauling, rather than shut down of whole system.
  5. Easy removal and replacement of important valves should be ensured by provision of slip joints etc. and isolating valves at appropriate locations.
  6. it is essential that the flow indication Arrow on the valve body should be observed.
NOTE : Do not use the gate valve and ball valve for throttling, left partly open or cracked open, the wedge would erode rapidly and may cause a severe damage to the seat faces, valve chattering and also gland leakage. Some more greasing maybe done at the stem threads, if required. Direction of hand wheel rotation facing the hand wheel, clockwise rotation to close the valve and anti-clockwise rotation to open the valve.
 
Selection
In order to obtain satisfactory flange joints the following points should be observed: -
  1. Check the mating flange facing if a condition is found which might cause leakage i.e., deep radial grove cut by retracing cutting tool, do not attempt to assemble untill the condition has been corrected.
  2. Check the bolting for proper size, length and material. A carbon steel bolt on a high temperature flange can revert in early joint failure.
  3. Full face gaskets on flat flanges provide desirable protection against flange breakage (in case the flanges used, are of Cast Iron) by over tightening of flange Nuts. A flat face flange should not be installed against a raised face flange.
  4. Flanged joint are made by bolting the flange of the valve together with gasket between their machined faces to obtain a tight seal. With flanges secured in position, slip in half the bolts at the bottom. They will hold the gasket in place. Gaskets should be coated with little graphite or other recommended lubricant before they are inserted. Lubricated gaskets are easier to remove when the joints is opened for maintenance. Also lubricate studs and nuts to minimize friction during tightening.
  5. All bolts should be pulled down gradually to a uniform tightness. Make all bolts finger tight first, then take three or four turns with a wrench on Bolt then tighten the opposite bolt ten or twelve times as required ,then return to the former , repeat the process ,until the joint is tight. Uniform stress across the entire cross section of the flange eliminates a leaky gasket.
 

STEM UP :

Stem up is always best, horizontal position is also satisfactory, but still with a compromise. Installing a valve in inverted position with stem in down position is not recommended.
WATER HAMMERING :
  1. Adequate air chambers or other cushioning devices should be installed ahead of quick opening valves.
  2. While installing rising stem valves, be sure to allow sufficient clearance for operation and for removal of the stem and bonnet, if necessary.
 

PROPER OPERATION AND MAINTENANCE OF VALVES :


MAINTENANCE :
The valve hardly needs any maintenance. Regular greasing at the stem threads and periodic cleaning of the seat faces would keep the valve smooth and efficient in its function. The moment any trouble is noticed with the valve, examine and take corrective action. If attended initially itself, problem would be simpler and easier to solve. Do not attempt any modifications repairs.

The valve should be operated by the movement of the hand wheel or other manual operator in the direction of the arrow marked on it. It is opened normally by turning the hand wheel in counter clockwise and shut by turning in the clockwise direction when viewed by facing the hand wheel.
  1. When valves are provided with built in by passes, by-pass valve should be opened gradually before opening the main valve. This will enable the pipe line to up and the pressures on either side of main valve will equalize.
  2. When valves are not provided with by-pass, they must be slowly opened in sequence, so that the valves and the pipe lines get warmed up on steam lines.
  3. All the work connected with the assembly of valves should be carried out by fully qualified technicians who are well conversant with valves and pipe lines assembly work.
  4. It is recommended that all important valves be thoroughly inspected after trial operation. This should be to ensure that there is no damage cause to the valve components during trial run.
  5. If a valves leaks slightly when shut-off, open it a little to flush particles that may be hindering seats. Trying to force it shut with a crow bar is likely to ruin the seats.
  6. The valves must be closed tightly otherwise premature failure of the valve seat discs can occur due to wire drawing.
  7. The surfaces of the valves are finished to extremely fine finished and special care should be taken to ensure that these surfaces are protected from even the slightest damage. Slight damaged may result in serious leakage.
  8. Prolonged storage may spoil gland packing, so before operating the valve for the first time packing should be checked and if the need be, stuffing box should be filled afresh with packing.
  9. It is important the stuffing box be inspected before and during operation. The gland must be tightened before and during operation, because the packing generally tends to settle down in the early stages of use.
  10. Another means of correcting the leaking is to inject sealant into the stuffing box through lantern ring. This method has been used successfully in many critical areas.
  11. To change gland packing while valve is under pressure: The valve should be fully opened with its backseat in position so that there is no danger of the fluid leaking through the stuffing box while the operator is doing the refilling operation of the gland box. Literatures should be checked whether the valves are back seated type, before changing the gland packing.
  12. Whenever the operating conditions of a system are altered, check the valves to ensure that they are suitable for the new working conditions.
  13. Safety and relief valves of all types ought to be periodically tested by easing lever to maintain freedom from sticking.
  14. Isolation and emergency valves only work occasionally but when they are needed, they are needed urgently so they should be tested regularly.
  15. When screwed bonnets are hard to remove, use a short wrench and tap it a few times with a hammer. This is more effective than a sustained pull and reduces the risk of distortion.
  16. Regular checks should be made on air-release valves on water mains ensure that the ball are free. Any sign of leakage from an air release valve, should be watched immediately and if it occurs it should be dealt with utmost priority. A leaking valve will attract vegetation which could grow rapidly to such an extent that the valve may fail to function.
  17. Severe damage can occur to stems, gates, nuts and faces of gate valves by the use larger had wheel, tee-keys etc. than those originally supplied.
  18. When faulty gaskets are the cause of leakage, care should be taken to ensure that replacements are of the correct material.
  19. When it is necessary to keep a valve closed in cold weather, precaution should be taken to prevent if from “Freezing-Up”.
  20. Valves those are not operated frequently and which may remain open or close for long periods, should be worked even partially, about once a month.
  21. It is recommended to inspect all valves in the system during overhauling whenever the pipeline is put out of operation every valve should be inspected at least twice a year. This must be done for all the valves irrespective of the actual period for which the individual valve has been in operation.
  22. The valves should be dismantled for inspection and the components thoroughly cleaned and inspected to ensure :
    • i. That there is no indication of corrosion or cavitations under the seat or anywhere else.
    • i. That there is no pitting or any indication of seizing noticed on the surfaces of moving components.
  23. After every dismantling, the seating surfaces should be ground or lapped with suitable grinding or lapping paste, if necessary.
  24. After re-assembly, the valves should be tested for their proper functioning.
  25. Careful repairs of minor defects can be carried out by trained technicians themselves. If however the defects are of serious nature, the repairs of which can not be undertaken by the users themselves, they should be referred to the manufacture.
  26. Users should report to the manufacture even for such defects, which can be rectified by them, for their future so that manufacturer may avoid similar defects in future.
 

GENERAL INSTRUCTIONS FOR THE OPERATION OF THE VALVE

  1. Do not use the valve pressure & temperature higher than pressure temperature rating as given bellow .
  2. Provide suitable draining and venting in pipe line if condition demands.
  3. If over pressure is expected. Install pressure relief valve in the pipe line.
  4. If system demands valve position, use locking arrangement to avoid risk of misuse.
ESSENTIAL SAFETY REQUIREMENTS - WHICH ARE NOT CONSIDERED
  1. Traffic. Wind. Earthquake loading
  2. Protection against exceeding the allowable limits of pressure equipment
  3. Decomposition of unstable fluids
ESSENTIAL SAFETY REQUIREMENTS - WHICH ARE NOT APPLICABLE
  1. Dangerous Discharge Of Pressure Relief Blow-Off
  2. Devices to prevent physical access whilst pressure or a vacuum exists
  3. Safety accessories
  4. Pressure limiting devices temperature monitoring devices
  5. External fire
  6. Fired or otherwise heated pressure equipment with a risk of over heating
 
 

TROUBLE SHOOTING

 
1 NATURE OF TROUBLE (AS APPLICABLE) POSSIBLE CAUSES & REMEDY (KEY NO.)*
2 Seat leakage 1. 2. 3. 4. 5. 6
3 Back seat leakage 7. 8. 9
4 Stem OD gets deep scoring along the length b 10. 11
5 Leakage through packing 12. 13. 14
6 Leakage through body - to - bonnet / cover joint 15. 16, 17
7 Leakage across the pressure seal ring 18. 19. 20
8 Seat faces get damaged in short duration 21
9 Gear actuator hand wheel is struck and cannot be rotated 22
10 Gear actuator hand wheel rotates but stem does Not move up and down 23
11 Gear actuator' s operation is noisy and not smooth 24
12 Pneumatically operated (piston type) valve does Not take either full seating or full back seating 25
13 Lever operation is very hard 26
 
  • GATE, GLOBE .BALL AND CHECK VALVE
  • GATE AND GLOBE VALVE
  • GATE , GLOBE AND BALL
  • GATE GLOBE AND CHECK BALL
  • BALLVALVE
 
     
KEY NO.* POSSIBLE CAUSES REMEDY
01 Pipe-Lines Are Not Properly Flushed Prior To Installation Flush Thoroughly
02 Sealing Faces Of Seat Ring And Wedge Disc Are Damaged Remove The Damage By Machining (If Required) And Lapping
03 Soft Seal Ring (If Provided) Is Damaged Replace The Soft Seal Ring
04 Body - To - Seat Ring Threaded Joint Is Leaking Because Of Damage On Body Face Or Seat Ring's Back Face Remove The Damage By Machining (If Required) And Lapping
05 Body - To - Seat Ring Seal-Weld Joint Leaking Weld The Leaking Spot
06 Operating Torque Is Insufficient, In Case Of Motor Operated Or Piston Actuated Gate Globe Valves In Case Of Motor Operated, Torque Setting Can Be Regulated From 40% To 100% And Incase Of Piston Actuator, Air Supply Pressure Can Be Increased
07 Back Seat Sealing Faces Of Stem Collar And Bonnet Are Damaged Remove The Damage By Machining (If Required) And Lapping
08 Bonnet- To- Bonnet Bush Press Fitted Joint Is Leaking Remove The Damage, If Any And Lap The Bonnet Face And 5° Back-Face Of Bonnet Bush
09 Back Seat Bore Is Not Concentric To Stem C/L Maintain Concentricity
10 Packing Contain Foreign Matter Of Hard Particles Replace With Clean Packings
11 Compression Load On Packing Is Insufficient Tighten The Gland Flange Nut Further
12 Packing Have Worn Out Operate The Valve To Full-Open To Take Back-Seating And Install Additional Packings Or Replace All The Packings
13 Scoring On Stem Od Along Sealing Length Avoid Scoring (Refer 9 And 10 Above)
14 Gasket Sealing Faces Of Body And Bonnet I Cover Are Damaged Remove The Damage Marks
15 Gasket Is Damaged Replace
16 Body Bolting Are Not Properly Tightened Bolting To Be Tightened Uniformly And In A Criss - Cross Pattern
17 Insufficient Pre - Load Tighten Bonnet-To-Yoke Nut
18 Pressure Seal Ring Is Damaged Replace
19 Sealing Faces In Contact Are Damaged Remove Damage
20 Hardness Is Low For The Service Conditions Provide Increased Hardness For The Seat Faces (Eg. Stellite)
21 Gear Teeth Broken Replace
22 Mating Gear Teeth Have Insufficient Engagement Replace
23 Grease Inside The Gear Case Is Insufficient Or Has Contamination Of Foreign Matter Fill Extra Grease
24 Gap Between Stem Ends At The Coupling Is Set Less Or More Respectively Reset The Gap Appropriately
25 Travel Length Is To Be Adjusted Adjust Accordingly
26 Check The Stem, Stem May Be Bend Due To Mishandling Replace stem
     
 
 
 
 
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