Consolidated* 2700 Series Safety Valve

Transcription

1 GE Oil & Gas Consolidated* 2700 Series Safety Valve Maintenance Manual (Rev. C) GE Data Classification : Public

2 ii GE Oil & Gas

3 THESE INSTRUCTIONS PROVIDE THE CUSTOMER/OPERATOR WITH IMPORTANT PROJECT-SPECIFIC REFERENCE INFORMATION IN ADDITION TO THE CUSTOMER/OPERATOR S NORMAL OPERATION AND MAINTENANCE PROCEDURES. SINCE OPERATION AND MAINTENANCE PHILOSOPHIES VARY, GE (GENERAL ELECTRIC COMPANY AND ITS SUBSIDIARIES AND AFFILIATES) DOES NOT ATTEMPT TO DICTATE SPECIFIC PROCEDURES, BUT TO PROVIDE BASIC LIMITATIONS AND REQUIREMENTS CREATED BY THE TYPE OF EQUIPw xment PROVIDED. THESE INSTRUCTIONS ASSUME THAT OPERATORS ALREADY HAVE A GENERAL UNDERSTANDING OF THE REQUIREMENTS FOR SAFE OPERATION OF MECHANICAL AND ELECTRICAL EQUIPMENT IN POTENTIALLY HAZARDOUS ENVIRONMENTS. THEREFORE, THESE INSTRUCTIONS SHOULD BE INTERPRETED AND APPLIED IN CONJUNCTION WITH THE SAFETY RULES AND REGULATIONS APPLICABLE AT THE SITE AND THE PARTICULAR REQUIREMENTS FOR OPERATION OF OTHER EQUIPMENT AT THE SITE. THESE INSTRUCTIONS DO NOT PURPORT TO COVER ALL DETAILS OR VARIATIONS IN EQUIPMENT NOR TO PROVIDE FOR EVERY POSSIBLE CONTINGENCY TO BE MET IN CONNECTION WITH INSTALLATION, OPERATION OR MAINTENANCE. SHOULD FURTHER INFORMATION BE DESIRED OR SHOULD PARTICULAR PROBLEMS ARISE WHICH ARE NOT COVERED SUFFICIENTLY FOR THE CUSTOMER/OPERATOR'S PURPOSES THE MATTER SHOULD BE REFERRED TO GE. THE RIGHTS, OBLIGATIONS AND LIABILITIES OF GE AND THE CUSTOMER/OPERATOR ARE STRICTLY LIMITED TO THOSE EXPRESSLY PROVIDED IN THE CONTRACT RELATING TO THE SUPPLY OF THE EQUIPMENT. NO ADDITIONAL REPRESENTATIONS OR WARRANTIES BY GE REGARDING THE EQUIPMENT OR ITS USE ARE GIVEN OR IMPLIED BY THE ISSUE OF THESE INSTRUCTIONS. THESE INSTRUCTIONS ARE FURNISHED TO THE CUSTOMER/OPERATOR SOLELY TO ASSIST IN THE INSTALLATION, TESTING, OPERATION, AND/OR MAINTENANCE OF THE EQUIPMENT DESCRIBED. THIS DOCUMENT SHALL NOT BE REPRODUCED IN WHOLE OR IN PART WITHOUT THE WRITTEN APPROVAL OF GE. Consolidated 2700 Series Safety Valve Maintenance Manual iii

4 Conversion Table All the United States Customary System (USCS) values are converted to metric values using the following conversion factors: USCS Unit Conversion Factor Metric Unit in mm lb kg in cm 2 ft 3 /min m 3 /min gal/min L/min lb/hr kg/hr psig barg ft lb Nm F 5/9 ( F-32) C Note: Multiply USCS value with conversion factor to get metric value. iv GE Oil & Gas

5 Table of Contents I. Warranty Information... 1 II. Safety Notice... 2 III. Product Safety Sign and Label System... 3 IV. Safety Alerts... 4 V. Handling and Storage... 6 VI. Pre-installation and Mounting... 6 VII. General Planning for Maintenance... 7 VIII. Terminology for Pressure Relief Valves... 8 IX. Consolidated 2700 Series Safety Valve... 9 A. Flanged Inlet... 9 B. Buttweld Inlet... 9 X. Operating Principles...11 XI. Recommended Installation Practices A. General Requirements...12 B. Outdoor Safety Valve Installation...16 C. Indoor Safety Valve Installation...16 XII. Disassembly Instructions A. General Information B. Specific Steps XIII. Inspection and Part Replacement A. General...19 B. Specific Components...19 XIV. Re-Assembly Instructions A. General Information B. Specific Steps XV. Setting and Testing A. General Information...27 B. Application of Test Gags...27 C. Presetting Adjusting Rings...28 D. Steam Testing Instruction...29 E. Consolidated Hydroset* Test Device/Electronic Valve Tester (EVT*) Software F. Hydrostatic Test Plug Removal F.1 General Information...32 F.2 Hydrostatic Test Plugs...34 XVI. Troubleshooting the Consolidated 2700 Series Safety Valve...36 XVII. Maintenance Tools and Supplies...37 XVIII. Replacement Parts Planning A. Basic Guidelines B. Identification and Ordering Essentials XIX. Consolidated Genuine Parts Consolidated 2700 Series Safety Valve Maintenance Manual v

6 XX. Manufacturer s Repair and Training Program A. Factory Setting vs. Field Setting...41 B. Field Service...41 C. Factory Repair Facilities...41 D. Safety Valve Maintenance Training...41 vi GE Oil & Gas

7 I. Warranty Information Warranty Statement Warranty Statement 1 - GE warrants that its products and services will meet all applicable specifications and other specific product and service requirements (including those of performance), if any, and will be free from defects in material and workmanship. CAUTION: Defective and nonconforming items must be held for GE s inspection and returned to the original F.O.B point upon request. Defective and nonconforming items must be inspected by GE S E A L E D Incorrect Selection or Misapplication of Products - GE cannot be responsible for customer s incorrect selection or misapplication of our products. Unauthorized Repair Work - GE has not authorized any non-ge affiliated repair companies, contractors or individuals to perform warranty repair service on new products or field repaired products of its manufacture. Therefore customers contracting such repair services from unauthorized sources must do at their own risk. Unauthorized Removal of Seals - All new valves and valves repaired in the field by GE Field Service are sealed to assure the customer of our guarantee against defective workmanship. Unauthorized removal and/or breakage of this seal will negate our warranty. Note 1: Refer to GE s Standard Terms of Sale for complete details on warranty and limitation of remedy and liability. Removal or breakage of seal will negate our warranty. Consolidated 2700 Series Safety Valve Maintenance Manual 1

8 II. Safety Notice Proper installation and start-up is essential to the safe and reliable operation of all valve products. The relevant procedures recommended by GE, and described in these instructions, are effective methods of performing the required tasks. It is important to note that these instructions contain various safety messages which should be carefully read in order to minimize the risk of personal injury, and/or the possibility that improper procedures will be followed which may damage the involved Consolidated product, or render it unsafe. It is also important to understand that these safety messages are not exhaustive. GE can not possibly know, evaluate, and advise any customer of all of the conceivable ways in which tasks might be performed, or of the possible hazardous consequences of each way. Consequently, GE has not undertaken any such broad evaluation and, thus, anyone who uses a procedure and/or tool, which is not recommended by GE, or deviates from GE recommendations, must be thoroughly satisfied that neither personal safety, nor valve safety, will be jeopardized by the procedure and/or tools selected. If not so satisfied, contact your local Green Tag Center if there are any questions relative to procedures and/or tools. Wear necessary protective equipment to prevent possible injury. The installation and start-up of valves and valve products may involve proximity to fluids at extremely high pressure and/or temperature. Consequently, every precaution should be taken to prevent injury to personnel during the performance of any procedure. These precautions should consist of, but are not limited to, ear drum protection, eye protection, and the use of protective clothing, (i.e., gloves, etc.) when personnel are in, or around, a valve work area. It is the responsibility of the purchaser or user of GE s Consolidated products to adequately train all personnel who will be working with the involved product. For more information on training schedules, call +1 (281) Further, prior to working with the involved product, personnel who are to perform such work should become thoroughly familiar with the contents of these instructions. 2 GE Oil & Gas

9 III. Product Safety Sign and Label System If and when required, appropriate safety labels have been included in the rectangular margin blocks throughout this manual. Safety labels are vertically oriented rectangles as shown in the representative examples (below), consisting of three panels encircled by a narrow border. The panels can contain four messages which communicate: The level of potential harm from the hazard The nature of the hazard The consequence of human and/or product interaction with the hazard. The instructions, if necessary, on how to avoid the hazard. The top panel of the format contains a signal word (DANGER, WARNING, CAUTION or ATTENTION) which communicates the level of potential harm from the hazard. The center panel contains a pictorial which communicates the nature of the hazard, and the possible consequence of human and/or product interaction with the hazard. In some instances of risk to human health and safety the pictorial may, instead, depict what preventive measures to take, such as wearing wearing the appropriate personal protective equipment (PPE). The bottom panel may contain instructions on how to avoid the hazard. If there is a risk to human health and safety this message may also contain a more precise definition of the hazard, and the consequences of human and/or product interaction with the hazard, than can be communicated solely by the pictorial. 1 DANGER Immediate hazards which WILL LIKELY result in severe personal injury or death. 2 WARNING Hazards or unsafe practices which COULD result in severe personal injury or death. 3 CAUTION Hazards or unsafe practices which COULD result in minor personal injury. 4 ATTENTION Hazards or unsafe practices which COULD result in product or property damage Do not remove bolts if pressure is in the line, as this will likely result in severe personal injury or death. Know all valve exhaust/leakage points to avoid possible severe personal injury or death. Wear necessary protective equipment to prevent possible injury Do not drop or strike. Consolidated 2700 Series Safety Valve Maintenance Manual 3

10 IV. Safety Alerts Read Understand Practice 1. DANGER: High temperature/pressure can cause injury. Be sure all system pressure is absent before repairing or removing valves. 2. DANGER: Don t stand in front of valve outlet when discharging. STAND CLEAR OF VALVE to prevent exposure to potentiality trapped, corrosive media. 3. DANGER: When inspecting a pressure relief valve for leakage. BE VERY CAREFUL! Be sure all system pressure is absent before repairing or removing valves. Stand clear of valve when outlet is discharging. 1. WARNING: Allow the system to cool to room temperature before cleaning, servicing or repairing the system. Hot components or fluids can cause severe personal injury or death. 2. WARNING: Always read and comply with safety labels on all containers. Do not remove or deface the container. Do not remove or deface the container labels. Improper handling or misuse could result in severe personal injury or death. 3. WARNING: Never use pressurized fluids/gas/air to clean clothing or body parts. Never use body parts to check for leakage and/or discharge rates of valve areas. Pressurized fluids/gas/air injected into or near the body can cause severe personal injury or death. 4. WARNING: It is the responsibility of the owner to specify and provide guarding to protect persons from pressurized or heated parts. Contact with pressurized or heated parts can result in severe personal injury or death. 5. WARNING: Do not allow anyone under the influence of intoxicants or narcotics to work on or around pressurized systems. Workers under the influence of intoxicants or narcotics are a hazard both to themselves and other employees and can cause severe personal injury or death to themselves and/or others. 6. WARNING: Incorrect service/repair could result in product/property damage and/or severe personal injury or death. Improper use or repair of a pressurized device may result in severe personal injury or death. Provide and use guarding to prevent contact with heated and/or pressurized parts. Heed all container label warnings. XXX Do not work with valves while under the influence of intoxicants or narcotics. 4 GE Oil & Gas

11 IV. Safety Alerts (Contd.) 7. WARNING: The misuse of a tool or the use of an improper tool could result in personal injury and/or product/property damage. All potential hazards may not be covered in this manual. Improper tools or improper use of right tools could result in personal injury or product damage. 1. CAUTION: Heed all service manual warnings. Read installation instructions before installing valve(s). 2. CAUTION: Wear the appropriate hearing protection when testing or operating valves. 3. CAUTION: Wear the appropriate eye and clothing protection. 4. CAUTION: Wear the appropriate self-contained breathing apparatus (SCBA) to protect against toxic media. Know nuclear "health physics" procedures, if applicable, to avoid possible severe personal injury or death. Heed all service manual warnings. Read installation instructions before installing valve(s). Wear necessary protective equipment to prevent possible injury Always use appropriate restoration procedures. Consolidated 2700 Series Safety Valve Maintenance Manual 5

12 V. Handling and Storage Pressure relief valves should be stored in a dry environment and protected from the weather. They should not be removed from the skids or crates until immediately prior to installation. Flange protectors and sealing plugs should remain installed until just prior to installation. Pressure relief valves, either crated or uncrated, should never be subjected to sharp impact. This would be most likely to occur by bumping or dropping during loading or unloading from a truck or while moving with a power conveyor, such as a fork lift truck. The valve, either crated or uncrated, should always be kept with the inlet down (i.e., never laid on its side), to prevent misalignment and damage to internal components. Even crated valves should always be lifted with the inlet down. Uncrated valves should be moved or hoisted by wrapping a chain or sling around the discharge neck, then around the upper yoke structure, in such manner as will ensure the valve is in a vertical position during lift. Never lift the full weight of the valve by the pilot assembly, tubing, lifting lever or other external device. Always keep valve in an upright position. VI. Pre-installation and Mounting When a valve is uncrated and the flange protectors removed, prior to installation, meticulous care should be exercised to prevent dirt from entering the outlet port. While hoisting a valve to the installation area, care should be exercised to prevent bumping the valve against steel structures and other objects Pressure relief valves should be mounted in a vertical, upright position. Installing a valve in any other position will adversely affect its operating in varying degrees as a result of induced misalignment of parts. Flanges and gasket surfaces must be free from dirt and debris when valves are installed. Flange bolts should be tightened evenly to prevent distortion of the valve body and inlet nozzle. Before start-up be sure all threaded points are tight and secure. Do not subject valves to impact. Prevent dirt from entering the outlet or inlet port. 6 GE Oil & Gas

13 VII. General Planning for Maintenance A 12-month maintenance interval is recommended for general service conditions. For severe service applications, a 3 to 6 month inspection and testing interim may be more appropriate. The specific plant s operating and service history will better determine this frequency. GE encourages preventive maintenance. Occasionally, remachining may be necessary to extend the service life of a valve. Keep all parts for each valve separated to ensure replacement in the same valve. DANGER: Insure there is no pressure in the inlet of the valve before attempting to remove it from the piping system. Note: For maintenance questions not covered in this manual, please contact your local Green Tag Center. Always use appropriate restoration procedures. Decontaminate or clean if necessary before pretesting or disassembly. Safety and environmental precautions must be taken for the decontamination or cleaning method used. Do not interchange parts from one valve to another. Consolidated 2700 Series Safety Valve Maintenance Manual 7

14 VIII. Terminology for Pressure Relief Valves A. Accumulation: The pressure increase over the maximum allowable working pressure of the vessel during discharge through the valve, expressed as a percentage of that pressure or in actual pressure units. B. Backpressure: The static pressure existing on the discharge side of a pressure relief valve: 1. Built-up Backpressure: Pressure that develops at the valve outlet as a result of flow, after the valve has opened. 2. Superimposed Backpressure: Pressure in the discharge header before the valve opens. 3. Constant Backpressure: Superimposed backpressure that is constant with time. 4. Variable Backpressure: Superimposed backpressure that will vary with time. C. Blowdown: The difference between set pressure and reseat pressure of a valve, expressed as a percentage of the set pressure or in actual pressure units. D. Cold Differential Set Pressure: The pressure at which the valve is adjusted to open on a test stand. This pressure corrects for backpressure when a pop action pilot s vent is piped to the main valve outlet. E. Differential Between Operating and Set Pressures: Valves in process service will generally give best results if the operating pressure does not exceed 90% of the set pressure. However, on pump and compressor discharge lines, the differential required between the operating and set pressures may be greater because of pressure pulsations coming from a reciprocating piston. The valve should be set as far above the operating pressure as possible. F. Lift: The actual travel of the disc away from the closed position when a valve is relieving. G. Maximum Allowable Working Pressure: The maximum gauge pressure permissible in a vessel at a designated temperature. A vessel may not be operated above this pressure or its equivalent at any metal temperature other than that used in its design. Consequently, for that metal temperature, it is the highest pressure at which the primary pressure relief valve is set to open. H. Operating Pressure: The gauge pressure to which the vessel is normally subjected in service. A suitable margin is provided between operating pressure and maximum allowable working pressure. The suitable margin depends on the type of pressure relief valve in service. I. Overpressure: A pressure increase over the set pressure of the primary relieving device. Overpressure is similar to accumulation when the relieving device is set at the maximum allowable working pressure of the vessel. Normally, overpressure is expressed as a percentage of set pressure. J. Rated Capacity: The percentage of measured flow at an authorized percent overpressure permitted by the applicable code. Rated capacity is generally expressed in pounds per hour (lb/hr) or kg/hr for vapors, standard cubic feet per minute (SCFM) or m³ /min for gases, and in gallons per minute (GPM) or Liter/min (L/min) for liquids. K. Set Pressure: The inlet static pressure at which a pressure relief valve begins to operate under service conditions. In liquid service, the inlet pressure at which a valve starts to discharge determines the set pressure. In gas or vapor service, the inlet pressure at which the valve pops or starts to leak, determines the set pressure. L. Simmer: The audible passage of a gas or vapor across the seating surfaces just before a pop. The difference between this start-to-open pressure and the set pressure is called simmer. Simmer is generally expressed as a percentage of set pressure. 8 GE Oil & Gas

15 IX. Consolidated 2700 Series Safety Valve A. Flanged Inlet 20 Part No. Nomenclature THRU 2777Q VENT 90 OUT OF POSITION DO NOT PLUG 2737 THRU 2777Q Disc Holder 2 Guide 3 Base 4 Yoke 5 Upper Adjusting Ring 6 Upper Adjusting Ring Pin 7 Lower Adjusting Ring 8 Lower Adjusting Ring Pin 9 Spring 10 Top Spring Washer 11 Bottom Spring Washer 12 Seat Bushing 13 Disc 14 Disc Collar 15 Lift Stop 16 Spindle 17 Compression Screw 18 Compression Screw Adaptor (4 to 7_Q Orifices Only) 19 Thrust Bearing 20 Lever and Cap Assembly 21 Studs (Studded Inlet) 22 Nuts 23 Compression Screw Locknut 24 Cotter Pins (Not Shown) Figure 1: 2700 Series Safety Valve Construction - Flanged Inlet Consolidated 2700 Series Safety Valve Maintenance Manual 9

16 IX. Consolidated 2700 Series Safety Valve (Contd.) B. Buttweld Inlet 20 Part No. Nomenclature W THRU 2775QW VENT 90 OUT OF POSITION DO NOT PLUG 2735W THRU 2775QW Disc Holder 2 Guide 3 Base 4 Yoke 5 Upper Adjusting Ring 6 Upper Adjusting Ring Pin 7 Lower Adjusting Ring 8 Lower Adjusting Ring Pin 9 Spring 10 Top Spring Washer 11 Bottom Spring Washer 12 Seat Bushing 13 Disc 14 Disc Collar 15 Lift Stop 16 Spindle 17 Compression Screw 18 Compression Screw Adaptor (4 to 7_Q Orifices Only) 19 Thrust Bearing 20 Lifting Gear 21 Studs (Studded Inlet) 22 Nuts 23 Compression Screw Locknut 24 Cotter Pins (Not Shown) Figure 2: 2700 Series Safety Valve Construction - Buttweld Inlet 10 GE Oil & Gas

17 X. Operating Principles The Consolidated 2700 Series Safety Valve operates on the principle that when steam pressure at the valve inlet, acting over the area of the disc seat (C) and bushing seat (A), generates a force that approaches that produced by the spring, the valve opens. Minimal leakage into the volume generated by the lower adjusting ring (B) causes additional force over a larger area acting on the disc holder (E), causing the valve to pop open. Proper adjustment of the upper adjusting ring allows the disc to go into full lift at overpressure. When full lift is attained, lift stop (H) rests against the yoke to prevent hunting, thus adding stability. When the inlet pressure drops to the desired closing pressure, the disc (C) moves downward, causing the valve to close. The arrangement of the disc and its complement of parts, that is disc holder (E), spindle (G), disc collar (F), and lift stop (H), allow the disc to seek its natural position for tight closure. GE s Thermoflex* Disc design, by allowing for the rapid equalization of temperature around the valve seat, provides a degree of tightness designed to exceed that offered by competitive valves. H G F E C D B A Figure 3: Valve Operation Consolidated 2700 Series Safety Valve Maintenance Manual 11

18 XI. Recommended Installation Practices A. General Requirements ANCHOR DISCHARGE PIPING SOLIDLY TO BLDG. STRUCTURE RADIAL CLEARANCE REQUIRED WHEN VALVE IS OPERATING BORE EQUAL TO MINIMUM VALVE OUTLET DIAMETER VENT (SEE FIGURE 5) VERTICAL CLEARANCE REQUIRED WHEN VALVE IS OPERATING DRAIN X BODY DRAIN FLANGED INLET SHOWN WELDED INLET SIMILAR BORE EQUAL TO MINIMUM OF VALVE INLET DIAMETTER Figure 4: 2700 Series Safety Valve Installation Table 1: Maximum Dimension Inlet Size X max Class in. mm in. mm The valve should be installed to meet all the requirements of Figure 4. The safety valve shall be connected to the header independent of any other connection, and attached as close as possible to the header, without any unnecessary intervening pipe or fitting. Necessary intervening pipe or fittings shall not be longer than the face-to-face dimension of the corresponding tee fitting of the same diameter and pressure, per ANSI/ASME Standards. No valve of any description should be placed between the safety valve and the header, nor on the discharge pipe between the safety valve and the atmosphere. In no case may the inlet piping to the valve have a flow area less than the area of the valve inlet. Excessive pressure loss at the inlet of the safety valve will cause extremely rapid opening and closing of the valve, that is known as chattering. Chattering may result in lowered capacity as well as damage to the seating surface of the valve. Severe chattering can cause damage to other parts of the valve. The following recommendations will assist in eliminating the factors that produce chatter: 1. The downstream corner of the header nozzle must be rounded to a radius of not less than.250 (6.35 mm) of the opening diameter. (See Figure 5.) 2. Pressure drop due to friction flow to the inlet of the valve should not be greater than 50 percent of the expected blowdown of the safety valve. To decrease the effects of a phenomenon known as sonic vibrations, or flow induced vibrations, the following recommendations are made: 1. Safety valves should be installed at least eight to ten pipe diameters downstream from any bend in a steam line. This distance should be increased when 12 GE Oil & Gas

19 XI. Recommended Installation Practices ( Contd. ) the valve is installed on the horizontal section of a header that is preceded by an upward section. 2. Safety valves should not be installed closer than eight to ten pipe diameters either upstream or downstream from a diverging, or a converging, Y. 3. In cases where a piping configuration renders the above two recommendations impractical, or impossible, the downstream corner of the header nozzle inlet should be rounded to a greater extent than the upstream corner. The header nozzle entrance should be rounded so the radius at the downstream corner will be equal to a minimum of one-fourth of the nozzle diameter. The radius should be reduced gradually, leaving only a small portion of the upstream corner with a smaller radius. (See Figure 5.) 4. Safety valves should never be installed, in a steam line, in a position directly opposite to a branch line. Excessive line vibrations are known to produce shifts in safety valve set pressures. Vibrations may possibly introduce chatter, causing damage to the valve and reducing its capacity. Vibration also contributes to increased incidents of seat leakage. Considerations should be given to eliminating this problem prior to installing the valve on the unit. Orifice Designation Table 2: 2700 Yoke Vent Sizes Steam flowing vertically out of a discharge elbow produces a downward reaction on the elbow. Effects of reaction force, vibration, and seismic loads, on all valve components and discharge piping, should be considered when designing the valve system. Refer to ANSI B.31.1, Non-Mandatory Appendix II, GE Product Information Sheet SV/PI-15, and GE Bulletin SV-5 for further information. For optimum performance, safety valves must be serviced regularly and otherwise maintained. So that servicing can be properly performed, valves should be located in a manner that allows for easy access. in. Yoke Vent Size (NPT) mm Q Note 1: #5 is a smaller orifice than #4 ANCHOR DISCHARGE PIPING SOLIDLY TO BUILDING STRUCTURE FABRICATED DRIP PAN SHOWN A A YOKE VENT SCHEDULE 40 PIPE DRAIN UNION SECTION A-A AS CLOSE POSSIBLE Figure 5: Valve Installation Consolidated 2700 Series Safety Valve Maintenance Manual 13

20 XI. Recommended Installation Practices ( Contd. ) Sufficient working space should be provided around and above the valve to permit access to adjusting rings. If two or more valves are located close together, the outlets should be parallel so as to offer as much protection as possible to personnel repairing, or working close to, the safety valve. Because foreign material passing into and through, a safety valve is damaging, the system on which the valve is installed must also be inspected and cleaned. New systems are prone to contain welding beads, pipe scale, and other foreign materials that are inadvertently trapped during construction, and they can destroy the valve seating surfaces the first few times the valve opens. With regard to weld-end inlet valves, completely assembled valves may be installed without disassembly being necessary at the time of welding. During welding, the valve neck should be insulated to reduce thermal stresses. When stress relieving, insulation should also be utilized to reduce thermal stresses. In service, the valve neck should be insulated at least to the point of the inlet neck/valve body-bowl juncture. Safety valves should be installed in a vertical position. Nominal tolerance on vertical installation is plus or minus 1 degree. The discharge area of the outlet piping from a safety valve should not be less than the area of the outlet connection. Where more than one safety valve is connected to a common outlet pipe, the area of the pipe should not be less than the combined area of the outlet connections to the safety valves. All safety valve discharges should be piped so that the effluent is discharged clear from walkways or platforms. Ample provision for gravity drain should be made in the discharge pipe at, or near, each safety valve where water or condensation, may collect. Each valve has an open gravity drain through the body, below the level of the valve seat, and this drain should be piped to a safe discharge area. If a silencer is used on a safety valve, it should have sufficient outlet area to prevent back pressure from interfering with the proper operation and discharge capacity of the valve. The silencer or other piping components should be constructed so as to avoid the possibility of creating corrosion deposit restrictions in the steam passages. Exhausts, drains, and vents must be installed so that they will not impose undue stresses on the safety valve. Any such stresses can produce body distortion and leakage. Therefore, the following recommendations are provided: 1. Discharge piping should not be supported by the valve. The maximum weight on the outlet of the valve should not exceed the weight of a flange and short radius elbow, plus a 12-inch (304.8 mm) straight length of standard weight thickness pipe (with drip pan). 2. Clearance between the valve exhaust piping and the discharge stack should be sufficient to prevent contact when considering thermal expansion of the header, valve, and discharge stack. Movements due to vibration, temperature changes, and valve reaction forces should also be considered, to ensure adequate clearance between the exhaust piping and the discharge stack. 3. Flexible metal hoses are not generally recommended, but if used to connect valve outlets to discharge stacks, they must be of sufficient length, and be configured/installed in such a manner, that they will not become solid in any one position. Better results are obtained if the hoses are installed so that they will permit movement by bending, rather than by stretching and compressing along their length. The yoke can be vented to the atmosphere as in Figure 4 and 5. Precautions should be taken to vent the yoke in such a manner that it will exhaust into a safe area to prevent injury to personnel near the valve. The yoke vent piping must not be connected to the body drain piping. Do not plug the yoke vent hole or reduce the vent hole pipe size, (Reference Table 2), as this could lead to valve malfunction and damage. Precautions should be taken to prevent accumulations of foreign material or water in the vent pipe. This vent is a critical part of the valve system for controlling valve blowdown and lift. All face surfaces that require gaskets, to seal pressure, should be inspected for cleanliness, or any defects that can cause leakage. Burrs, mashed serrations, uneven surfaces, etc., are all possible leakage-producing defects. Proper gasket sizes and pressure ratings should be checked prior to starting valve installation. 14 GE Oil & Gas

21 XI. Recommended Installation Practices ( Contd. ) It is of utmost importance that the gaskets used be dimensionally correct for the specific flange, and that they fully clear the valve inlet and outlet openings. Gaskets, flange facings, and bolting should meet the service requirements for the pressure and temperature involved. Other valve installation considerations include: 1. Install the inlet gasket, if required, on the header mounting flange. Check for cleanliness, surface alignment condition, gasket condition, etc. When possible, inlet studs on the mounting flange should be used to guide the valve on the header mounting flange. Inlet studs should be lubricated with the appropriate lubricant. 2. When installing flanged valves, the flange bolts must be pulled down evenly to prevent body distortion, misalignment, and leakage. 3. With valve in position, screw on the stud nuts until all nuts are finger tight. An initial torque shall be placed, in turn, on each stud nut. Increase the torque progressively until the final torque is applied. Upon completion, recheck each stud nut s torque. Required torque will vary with bolting material and gaskets used. See your company engineering or specification department for details on torquing sequence and torque values. As an extra precaution, the gap between the two mating flanges should be checked during the torquing process to ensure that the flanges are being pulled together evenly. A final inspection and review should be made to ensure that all of the requirements for bolting the valve inlet have been implemented. 4. The outlet piping may now be installed. A complete inspection of components and their cleanliness is to be made prior to further work. Studs are to be lubricated with an appropriate lubricant. 5. Install the outlet gasket, studs and nuts. Stud nuts are to be pulled down finger tight. An initial value of torque is to be applied. The additional procedures outlined, in Step 3 should also be followed. Prior to completing the installation, a visual check should be made to ensure that the valve lifting lever has room and is free to operate. At the time of installation, an inspection of the valve should be made to confirm that all adjustment components (i.e., ring pins, cap, etc.) are properly locked and sealed, as required by the ASME Code. For operational hydrostatic tests at the valve inlet, that do not exceed valve set pressure, the valve should be gagged. Refer to the final Field Testing portion of this manual for proper techniques. Ensure that the gag is removed upon completion of the inlet hydrostatic test. Prior to startup of the unit on steam, the sections of this manual that specify requirements for set pressure testing should be reviewed. For conditions where the valve is subjected to high steam pressures (i.e., those exceeding normal operating conditions), preparations should be made to gag the valves. These preparations should then be cleared with the boiler manufacturer and GE. Refer to Section XIV. B.3 of this manual for the proper gagging techniques. The safety valve should be tested with full steam pressure to ensure that the safety valve installation has been properly accomplished. In some cases this is not practical, thus the use of Consolidated Hydroset Test Device or EVT* software, should be considered. For valves being tested for set pressure by using a Consolidated Hydroset Test Device or EVT* software, only the set pressure is being verified. Other factors such as blowdown, lift, reaction force, proper discharge stack sizes and effects of thermal expansion cannot be determined, using these setting devices. Full flow steam testing is recommended at initial start-up to adjust blowdown and verify proper installation. Proper adjusting ring position can then be recorded and maintained when valves are serviced. Vent and drain piping should have a union connection to facilitate valve removal or servicing in place. (See Figure 4) After being assured that the valve is properly installed, the drainage piping from the valve body-bowl is to be connected. This line also must be flexible, so it will not create stress on the valve under operating conditions. Consolidated 2700 Series Safety Valve Maintenance Manual 15

22 XI. Recommended Installation Practices ( Contd. ) B. Outdoor Safety Valve Installation Safety valves operating under the best possible conditions (i.e., favorable operating gap, relatively stable ambient temperatures, the absence of dirt and in relatively still air) will provide the maximum degree of safety, tightness and dependability. When a safety valve is installed in an outdoor location, it may be exposed to wind, rain, snow, ice, dirt and varying temperatures. Therefore, the following recommendations are made for proper protection and to ensure that operational dependability can be restored to a level near that of the valve installed under ideal conditions: Know all valve exhaust/ leakage points to avoid possible severe personal injury or death. The inlet neck of the safety valve and safety valve body, up to the top of the base, should be insulated. The exterior surface of any such insulation should be made weather-proof by any suitable means. In addition to maintaining a more even temperature within the valve body, especially during widely fluctuating ambient temperatures, this insulation will effectively reduce thermal stresses due to high temperature gradients through the walls of the safety valve nozzle. Spring covers should be used to stabilize, as nearly as possible, the temperature of the spring to prevent the accumulation of snow and ice between the coils of the spring and to prevent dirt and fly ash from accumulating between the coils of the spring. Lifting gear covers should be installed to prevent ice, dirt and fly ash from accumulating in areas inside the safety valve cap. C. Indoor Safety Valve Installation Indoor valve installations should have inlet necks insulated only up to the underside of the valve body. Considerations should be given to ambient temperature changes greater than 100 F (37.8 C), because of possible set point changes that may occur. 16 GE Oil & Gas

23 XII. Disassembly A. General Information The Consolidated 2700 Series Safety Valve can be easily disassembled for inspection, reconditioning seats or replacing internal parts. The initial spring load can be established after reassembly. (Refer to Figure 1 and 2 for parts nomenclature). NOTES: Before starting to disassemble the valve, be sure that there is no steam pressure in the drum or header. Parts from one valve should not be interchanged with parts from another valve. B. Specific Steps 1. Remove the top lever pin and top lever. 2. Loosen the cap set screw and remove the lever and cap assembly. 3. Remove the cotter pin that retains the release nut, and then remove the release nut. Do not disassemble the valve with pressure in the drum or header, as this will result in severe personal injury or death. 4. Refer to Figure 6, and measure and record Dimension A, as this information will be required to correctly re-assemble the valve. 5. Loosen the compression screw locknut and the compression screw, to remove tension from the spring. 6. Loosen and remove the yoke stud nuts. DISC DEPTH MICROMETER DISC COLLAR DISC HOLDER YOKE A SPINDLE COMPRESSION SCREW COMPRESSION SCREW LOCKNUT LIFT STOP SOFT METAL VISE Figure 6: Yoke Disassembly Figure 7: Spindle Disassembly Consolidated 2700 Series Safety Valve Maintenance Manual 17

24 XII. Disassembly (Contd.) 7. Carefully lift the yoke and spring assembly over the spindle, and away from the valve. 8. Remove the thrust bearing assembly and the spring washer assembly. Mark the spring to indicate the top of the spring, as this formation will be used in reassembly. 9. Remove the spindle, disc and disc holder assembly from the valve by lifting the spindle. Take care to ensure that the disc seating surface is not damaged from improper handling. 10. To remove the disc and disc holder from the spindle, first insert the spindle into a vise (see Figure 7), being careful not to damage the threaded end of the spindle. Then, lift up on the disc holder and turn the disc/disc holder counterclockwise to engage the drop-thru threads. Once the threads are engaged, release the disc holder and continue to unthread and remove the disc. After the disc is removed, lift the disc holder from the spindle. Note: Removal of the lift stop and/or the disc collar from the spindle is usually unnecessary, unless the spindle is to be replaced. 11. Measure from the top of the guide to the bushing seat (Dimension B, Figure 8) with a depth micrometer or other suitable measuring device. Record Dimension B. 12. Place a scale or other thin flat metal surface against the lower face of the upper adjusting ring and measure from the top of the guide to the face of the upper adjusting ring (Dimension C, Figure 8). Record Dimension C. 13. Remove the upper adjusting ring pin from the valve base. 14. Remove the guide and upper adjusting ring. 15. Loosen the lower adjusting pin until the pin is slightly clear of the notches in the lower adjusting ring. Being careful not to move the lower adjusting ring, place a ring lap on top of the bushing seat. (See Figure 9.) Then, using the ring pin as a pointer, or reference point, rotate the lower adjusting ring counterclockwise and count the number of notches that pass in front of the pointer until contact is made with the ring lap. Record this information, as it will be required to correctly reassemble the valve. 16. Remove both the lower adjusting ring pin and the lower adjusting ring from the valve base. 17. The valve is now ready to be cleaned and the parts inspected for proper size and condition. UPPER ADJ. RING PIN RING LAP B SEAT C LOWER ADJUSTING RING SCALE SEAT BUSHING LOWER ADJ. RING PIN Figure 8: Bushing Seat Figure 9: Placing a Ring Lap on Top of the Seat Bushing 18 GE Oil & Gas

25 XIII. Inspection and Part Replacement A. General Once the valve is disassembled, appropriate parts can be inspected for damage to determine their suitability for reuse. B. Specific Components 1. Lever and Cap Assembly Visually inspect the lever and cap assembly for damage from improper handling or severe corrosion. Components should be replaced if damage interferes with proper function or manual lifting of the valve. 2. Compression Screw and Locknut The compression screw must be replaced if the threads are damaged to the point that spring adjustment is affected. The wrench flats should not be worn, rounded or distorted due to the improper use of an adjusting wrench on either the compression screw or locknut. The spring washer bearing surface or compression screw adapter surface (5 through Q orifice only), should not be pitted or torn and should have a 32 RMS finish. 3. Thrust Bearing The aligning washer must match evenly to the lower thrust bearing spherical surface, such that full face contact is achieved between the parts. Therefore, grind together, or replace the entire thrust bearing, as necessary. 4. Top and Bottom Spring Washers 6. Spindle It is important that the spindle be kept very straight in order to transmit the spring force to the disc without lateral binding. Overgagging is one of the common causes of bent spindles. A method to check the essential working surfaces of the spindle is illustrated in Figure 10. This may be performed either with or without the disc collar and lift stop on the spindle. a. Using Figure 10 as a reference, clamp a V block (A) made of wood, fiber or other suitable material onto the platform railing. Imbed the ball end of the spindle in a piece of soft wood (B) and place the top of the spindle below the threads, in the V block (A). Clamp a dial indicator onto the railing and locate at point (C). The total indicator reading should not exceed.007 (0.18 mm) when the spindle is rotated. If it does, the spindle must be straightened prior to reuse. b. To straighten the spindle, place the unthreaded portion of the small and large end in padded V blocks, with the point of maximum indicator readout upward, and then apply a downward A X X A The lower spring washer bearing surface must be ground to the spindle. To grind the lower spring washer, a 320-grit (Clover 1A) lapping compound is used for roughing in, and then finish the lap with 1000-grit Kwik- Ak-Shun lapping compound until a satisfactory bearing band is obtained. The bearing width should be (3.20 mm) minimum to (4.80 mm) maximum. Clean the lower spring washer and spindle when complete. C 45 0 Section X-X 5. Spring Visually inspect for pitting and corrosion of coils that will reduce the coil diameter. When this condition is found, replace the spring. Inspect for end parallelism in the free height and any obvious unevenness in coils, collapse of coils or general distortion. B Figure 10: Spindle Consolidated 2700 Series Safety Valve Maintenance Manual 19

26 XIII. Inspection and Part Replacement (Contd.) SPINDLE DISC SPINDLE NOSE BEARING BAND WIDTH R SEAT STEP FLAT DIAMETER Figure 12: Disc to Spindle Lapping DISC FLAT SURFACE RING LAP Figure 11: Spindle Tip and Disc Pocket Figure 13 force with a padded press or jack as required, until the spindle is within the specifications. c. Other parts of the spindle not used as working surfaces may run out considerably more than.007 (0.18 mm), but this should not be regarded as unacceptable. Although the upper thread end is not a working surface, excessive bending in this area could affect the accuracy of the Consolidated Hydroset Test Device or EVT* software, if either of these devices is used to verify valve set pressure. d. Apply a small amount of lapping compound (1A) on the tip of the spindle. Install the disc without the disc holder - onto the spindle tip, turning it clockwise until the disc threads drop out. Place a ring lap on a table, or similar flat surface, and wipe the exposed surface of the lap clean. Insert the disc nose into a ring lap, so that the seat contacts the lap surface. Oscillate the spindle using 360-degree oscillations for approximately 15 seconds, then check the spindle tip and disc pocket to determine progress. (See Figure 11.) e. The spindle nose should be ground into the disc pocket until the bearing is clearly marked. The band position is shown in Figure 12. f. Place the disc holder on the spindle, allowing it to rest on the face of the disc collar as previously shown in Figure 7 on Section XI.B. Then assemble the disc holder and new disc. The disc should be free enough to rock on the spindle tip. If there is no freedom, lower the disc collar until the disc is free to rock slightly initially, approximately.001 to.002 (0.25 to.05 mm) rock. The disc collar must then be lowered two additional notches from this initial position and secured with a stainless steel cotter pin. (See Figure 13.) 20 GE Oil & Gas

27 XIII. Inspection and Part Replacement (Contd.) Orifice Table 3: Disc to Spindle Lapping Information , 5, 4, Q Nose Radius Flat Diameter Bearing Band Width in. mm in. mm in. mm Table 4: Allowable Guide / Disc Holder Clearance Orifice #1 #2 #3 #5 #4 #6 #Q Temp. Class Maximum Clearance in. mm B D B D B D B D B D B D B D Note: Failure to provide the recommended disc rock at assembly will result in a leaking valve. g. The desired band width for Consolidated Series 2700 Safety Valves is shown in Table 3. In addition, the finished machined size of the spindle nose radius, and the flat diameter for each orifice size, are also shown in this Table. If the required bearing band cannot be obtained by hand grinding, then this radius should be checked and remachined if necessary. h. If the band extends too high on the radius it will be difficult to rock the disc, and the disc may lock up under pressure. If the band is too narrow, the spindle may indent the disc and again the rock will be lost. i. When the bearing area is re-established, clean both surfaces. Then apply lubricant to the spherical surface of the spindle tip, and work it into the surfaces by rotating the disc on the spindle. 7. Guide Inspect the guide inside diameter for egging, and ensure the inside surface is smooth. The threads on the outside must be in good condition to ensure the upper ring will adjust, even when the valve is hot. If serious galling is present, the guide should be replaced. a. Clearance The maximum clearance between the disc holder and guide should be in accordance with Table Disc Holder The surface on the end of the disc holder closest to the disc must be free from steam erosion. The two small holes must be open to ensure the passage of steam to the chamber above the disc. Make sure the outside diameter is not egg shaped and the surface is smooth. If any small indication of galling is present, polish the high spots with an emery cloth. If serious or large-scale galling is present, the disc holder should be replaced. 9. Disc Inspect the disc seat for steam cuts, nicks, or other damage. If the seat step measures less than dimensions specified in Table 5, this indicates that the thermal lip has been lapped to the minimum thickness. Do not machine any Thermodisc*; however, a disc that is not below minimum relief can be lapped to remove minor damage. a. To Lap Disc Seat (i) The above lapping method is also used on the disc seat. When lapping the disc seat, the disc should be held stationary, but not rigidly, and the lap moved as above. Use care not to strike the cone of the disc, as this would cause the seat to be high on the inside. (ii) The Thermodisc cannot be machined. If, after lapping, Dimension M, in Figure 14, does not meet the minimum specified in Table 5, the disc should be replaced. Consolidated 2700 Series Safety Valve Maintenance Manual 21

28 XIII. Inspection and Part Replacement (Contd.) SURFACE L M min. BEARING SURFACE X (iv) To recondition a ring lap, wipe all compound from the lapping plate and ring lap, then move the ring lap in a figure-eight motion on a lapping plate. If the lap is not flat, a shadow will be apparent. To remove the shadow, coat the lapping plate with 1000-grit compound and lap the ring with figure-eight motions covering the lapping plate. 10. Seat Bushing Orifice Figure 14: Disc Table 5: Minimum Seat Relief in. M min. mm # # # # # # #Q (iii) It may not be necessary to use all the laps at any one time, but having a sufficient supply on hand will save reconditioning time. The laps should be reconditioned on a flat lapping plate. A lap should not be used on more than one valve without being reconditioned. Laps must be checked for flatness prior to use, and at frequent intervals during use. A lap that is flat within one-half light band is considered satisfactory. Information on the Monochromatic Light and optical flat is available, upon request, from GE Consolidated Field Service Department. a. A GE reseating machine should be used to recondition badly worn and out of tolerance bushing seats. This machine can be provided by GE s Service Department, and eliminates the need to remove a valve from the unit. The machine is mounted in place of the yoke and cuts the top face, inside diameter, and outside of the bushing, to establish the correct height, angles, and diameters. b. The use of a reseating machine is suggested for reconditioning badly worn seats, or for re-establishing Dimension E per Figure 15. Dimension E should be re-established when it is less than.010 (0.25 mm) for orifices 1, 2, 3, 5 and 4; and less than.030 (0.76 mm) for orifices 6 and Q. c. To lap the bushing seat. Note: If the bushing seat surface requires extensive lapping or reconditioning, a reseating machine should be used prior to lapping. E (i) Cover the seat lap face with a light coating of 1-A Clover Compound and gently place the lap on the valve bushing seat. D Figure GE Oil & Gas