Installation, Operation and Maintenance Manual for Pressure/Vacuum Relief Valves (Spring Loaded)
Models 1201B, 1202B 1203A, 1221B, 1222B, 1223A, 1261A, 1301A, 1361A, 2301A
IOM-1201B
Rev. D 12541
Ref. ID: 96337
© 2010 Groth Corporation
TABLE OF CONTENTS:
INTRODUCTION: |
3 |
DESIGN, FUNCTION & OPERATION |
4 |
GENERAL SAFETY INSTRUCTIONS |
5 |
SAFETY WARNINGS |
5 |
INSPECTION AND INSTALLATION |
6 |
TABLE 1: STUD SELECTION |
6 |
TABLE 2: BOLT TORQUE CHART |
6 |
PREVENTIVE MAINTENANCE |
7 |
RECOMMENDED SPARE PARTS |
7 |
TABLE 3: PART NUMBER FOR RECOMMENDED SOFT GOOD SPARE PARTS |
7 |
TABLE 4: VALVE DIAPHRAGM USAGE, BASED ON SETTING |
7 |
TABLE 5: REPLACEMENT CARBON STEEL SPRING PART NUMBERS |
8 |
TABLE 6: REPLACEMENT STAINLESS STEEL PART NUMBERS |
8 |
DISASSEMBLY |
9 |
TABLE 7: STEM LENGTH |
9 |
TABLE 8: RECOMMENDED PALLET ASSEMBLY TORQUE |
9 |
TESTING AND SETTING PROCEDURE |
13 |
TABLE 9 - NOMINAL PALLET ASSEMBLY WEIGHT PER UNIT OF PRESSURE |
13 |
MODEL INFORMATION |
19 |
PRODUCT LIMITED WARRANTY |
19 |
2
INTRODUCTION:
The Groth Spring-Loaded Pressure / Vacuum Relief Valves (PV) are designed to protect tanks from damage caused by overpressure or over vacuum conditions. By containing product vapors PV valves reduce costly product evaporation losses due to normal tank breathing. In addition, atmospheric contamination is reduced by containing product vapors until tank pressure reaches the set pressure of the PV valve.
All pallets include Groth's special "cushioned air" seating. Fluoropolymer seating diaphragms are standard; they minimize sticking caused by resinous vapors and atmospheric moisture. The valve has a self draining housing body and drip rings to protect seating surfaces from condensate and freezing. This design also avoids dangerous pressure or vacuum buildup due to binding or clogging of the vent. Diaphragms are available in Buna-N, FKM and other elastomers; metal-to-metal seat can be provided when required.
To insure the proper alignment of seating surfaces, there is both peripheral and stem pallet guidance. As with all Groth products, every spring loaded valve is factory inspected and tested.
Pressure and Vacuum Relief Valves are preset at the factory in accordance with the purchase order. These settings are printed on the stainless steel name tag.
All PV valves require regular inspection and maintenance, the frequency depending upon actual conditions. The gasket between the vent and the nozzle flange should also be regularly inspected.
The valve must be maintained by a knowledgeable valve technician. It should only be assembled under clean conditions - preferably in a shop environment. Carefully read and understand this Manual before installing or repairing this valve.
For information not contained in this manual, please contact:
Groth Corporation
13650 N. Promenade Blvd
Stafford, TX 77477 281-295-6800 (Phone) 281-295-6995 (Fax)
3
DESIGN, FUNCTION & OPERATION
Pressure Relief: As the pressure in the storage tank increases the vacuum pallet is held shut. When the set pressure is reached the pressure pallet lifts and relieves to a header (or to atmosphere if it is not a pipe away valve).
Vacuum Relief: As a vacuum is drawn on the storage tank (for example, when fluid is being pumped out), the pressure pallet is held shut by tank vacuum. When the vacuum setting is reached, the pallet lifts and air is drawn in from the atmosphere and flows into the tank.
NOTE 1: Minimum recommended clearance between vacuum inlet port and tank roof is nominal flange bore of valve.
Typical valve installation on a tank or vessel is illustrated in Fig.1 on the next page using a Model 1221A Pressure/Vacuum Relief Valve. Most tanks will have provision for an operating relief valve, an emergency relief valve, and a blanketing regulator that maintains a positive gas pressure in the tank.
The combination of these valves and regulator are designed to ensure that the tank is protected from both excess vacuum and pressure conditions.
Figure 1 - Typical Tank Installation
Tank protection equipment typically includes an operating valve which is designed to provide pressure/vacuum relief under normal pump in/out and thermal breathing conditions. An emergency relief valve can also provide both pressure and vacuum relief, normally sized to provide pressure relief if there is a fire in the immediate vicinity of the tank. It may also be sized by the tank designer to provide protection in the event of equipment failure (such as the rupture of a process steam line or an inert gas blanketing system failing “wide open”) or operator error.
A typical tank installation is shown in Fig. 1 which includes the following Groth products:
Model 1221B PV’ Valve
Model 3011 Blanket Gas Regulator
Model 2400 Emergency Relief Valve
4
GENERAL SAFETY INSTRUCTIONS
This section is an overview of safety guidelines that should be followed during the installation, operation and maintenance of Groth Pressure / Vacuum Relief Valves. To understand the context of these instructions and warnings, it is necessary to completely read and understand the contents of this manual.
The purpose of a pressure/vacuum relief valve is to prevent excessive pressure or vacuum in a tank or process system. The valve must be designed for the proper MAWP and flow requirements of the system. Consult API Standard 2000 for tank protection sizing procedures. An improperly specified or functioning relief valve may result in structural damage to the tank or system, and can cause severe personal injury or death.
SAFETY WARNINGS
PRESSURE/VACUUM CONSERVATION VALVES ARE DESIGNED TO PROVIDE FULL RATED CAPACITY AT 100% OVER-PRESSURE. IF THE VALVE IS TO BE OPERATED AT A REDUCED OVER-PRESSURE, CONSULT FACTORY FOR ACTUAL FLOW CAPACITY UNDER SPECIFIED CONDITIONS.
THE TANK PRESSURE REQUIRED TO DISCHARGE THE NORMAL OR EMERGENCY VENTING REQUIREMENTS OF THE TANK WILL BE INCREASED BY THE AMOUNT OF BACK PRESSURE IN THE DISCHARGE HEADER, ON A PIPE AWAY VALVE CONFIGURATION. MAXIMUM POSSIBLE DISCHARGE HEADER PRESSURE MUST BE CONSIDERED WHEN SIZING THE PRESSURE RELIEF VALVE.
DO NOT CHANGE PRESSURE RATING BY ADDING ADDITIONAL WEIGHTS TO PALLET ASSEMBLY OR ADJUSTING SPRING COMPRESSION WITHOUT CONSULTING FACTORY. ADDING WEIGHTS OR ADJUSTING SPRING COMPRESSION TO A VALVE MAY RESTRICT PALLET LIFT AND REDUCE FLOW CAPACITY. DO NOT CHANGE PRESSURE RATINGS BY ADDING ADDITIONAL WEIGHTS TO THE PALLET ASSEMBLY WITHOUT CONSULTING THE FACTORY OR YOUR LOCAL GROTH REPRESENTATIVE. ADDING WEIGHTS TO A VALVE MAY RESTRICT PALLET LIFT AND REDUCE THE VALVES’ RATED FLOW CAPACITY.
WHEN INSTALLING THE WEIGHT LOADED PALLET ASSEMBLY IN THE VALVE, MAKE SURE THAT THE STEM IS STRAIGHT AND FITS INTO THE GUIDE IN THE COVER. IF THE STEM IS COCKED, THE PALLET ASSEMBLY MAY NOT OPEN FULLY AND THE TANK CAN BE OVER-PRESSURED. UNDER THESE CONDITIONS, THE VALVE WILL NOT PROTECT THE TANK FROM RUPTURING DUE TO CHANGES IN INTERNAL PRESSURE. TANK FAILURE CAN CAUSE MATERIAL DAMAGE AND LOSS AND RESULT IN SEVERE PERSONAL INJURY OR DEATH.
DO NOT MIX WEIGHT LOADED PALLET ASSEMBLIES FROM DIFFERENT VALVES. FAILURES TO ENSURE THAT THE WEIGHT LOADED PALLET ASSEMBLIES ARE INSTALLED IN THE ORIGINAL AND CORRECT LOCATION CAN CHANGE THE PRESSURE OR VACUUM RELIEF SETTINGS. THIS CAN CAUSE A TANK FAILURE.
DO NOT LOOSEN HEX NUTS UNTIL ALL SPRING COMPRESSION HAS BEEN RELEASED. SPRING PRELOAD IS SUBSTANTIAL AND COULD CAUSE SEVERE PERSONAL INJURY IF FASTENERS WERE REMOVED WITH THE SPRING COMPRESSED.
DO NOT ATTEMPT TO REMOVE THE VALVE FROM THE TANK OR PROCESS VESSEL WITHOUT FIRST BLEEDING ALL PRESSURE FROM THE SYSTEM. ALTERNATIVE MEANS OF PRESSURE RELIEF MUST BE PROVIDED WHEN THE VALVE IS OUT OF SERVICE.
THE VALVE HAS BEEN EXPOSED TO PROCESS VAPORS WHILE IN SERVICE. OBSERVE ALL PLANT PROCEDURES AND MATERIAL SAFETY DATA SHEETS (MSDS) FOR THE PRODUCTS IN THE SYSTEM WHEN INSPECTING, ADJUSTING OR SERVICING THE VALVE. TAKE APPROPRIATE SAFETY PRECAUTIONS REGARDING EYE PROTECTION, RESPIRATION AND SKIN CONTACT.
DO NOT ADD ANY WEIGHT TO THE PALLET ASSEMBLY, CHANGE THE ADJUSTMENT SCREW (CHANGING SET PRESSURE OR VACUUM), OR CHANGE PALLET STEM WITHOUT FIRST CONSIDERING THE ALLOWABLE TANK PRESSURE OR WITHOUT MEASURING DESIGN LIFT TO ENSURE THE LIFT IS NOT RESTRICTED. RESTRICTING VALVE LIFT COULD “CHOKE” THE VALVE AND NOT ALLOW FOR FULL RATED CAPACITY. CHANGING THE WEIGHT OR ADJUSTMENT OF A SPRING COULD ALSO RESTRICT THE LIFT OF A VALVE AT A SPECIFIED OVERPRESSURE, REDUCING THE RATED CAPACITY OF THE VALVE. UNDER THESE CONDITIONS, THE VALVE WILL NOT PROTECT THE TANK FROM RUPTURING DUE TO CHANGES IN INTERNAL PRESSURE. TANK FAILURE CAN CAUSE MATERIAL DAMAGE AND LOSS AND RESULT IN SEVER PERSONAL INJURY OR DEATH.
5
INSPECTION AND INSTALLATION
The pressure/vacuum relief valve is carefully packaged to prevent damage or contamination during shipping. Inspect all equipment when it is received; report any damage to the carrier immediately. The valve should be protected during handling and storage. Keep all the ports plugged to prevent intrusion of foreign materials. Before installation, inspect the unit for indications of physical damage or internal contamination. If these are observed, the valve must be disassembled, cleaned and repaired before installation.
Groth's spring loaded PV Valves are designed to provide tank protection for set-pressures to 15 PSIG and vacuum to 12 PSIG. The valves provide full rated flow capacity at 100% over-pressure. Consult factory for performance under other conditions.
The valve should be installed in a vertical position as shown in Figure 1.
Follow the torque guidelines listed in Table 2 to avoid produce damage due to excessive fastener tightening. The valves are NOT rated for full flange pressure and do not require high bolting torque. Consult factory for special applications; torque values assume a maximum MAWP of 30 PSIG.
The following guidelines should be observed at installation:
1.Remove any flange protectors and discard all packing material.
2.Inspect the gasket seating surface of the tank nozzle flange. It must be clean, free of scratches, corrosion, tool marks, and flat.
3.Aluminum valves are furnished with flat face flanges; they should only be installed on a mating flat faced flange with a full faced gasket.
4.Inspect the gasket; make sure that the material is suitable for the application.
5.Lubricate all studs and nuts with an appropriate thread lubricant. If the valve will see high temperature service or stainless steel fasteners are used, select an anti-seize compound such as moly-disulfide.
6.Center the gasket within the bolt circle.
7.Set the valve carefully on the nozzle. Install the studs and tighten nuts hand tight. For stud selection for blind tapped holes see Table 1 below:
TABLE 1: STUD SELECTION |
|
|
Inlet Flange |
Thread |
Recommended |
|
Size |
Stud Length |
2" |
5/8" - 11 |
2.25" |
3" |
5/8" - 11 |
2.50" |
4" |
5/8" - 11 |
2.50" |
6" |
3/4" - 10 |
3.00" |
8" |
3/4" - 10 |
3.00" |
10" |
7/8" - 9 |
3.50" |
12" |
7/8" - 9 |
3.50" |
TABLE 2: BOLT TORQUE CHART, LB-IN [N-m]*
Inlet Flange |
Raised Face |
Flat Face |
Number |
|||
Bolts |
||||||
|
|
|
|
|
||
2" |
30 |
[3.4] |
60 |
[6.8] |
4 |
|
3" |
54 |
[6.1] |
108 |
[12.2] |
4 |
|
4" |
42 |
[4.7] |
78 |
[8.8] |
8 |
|
6" |
90 [10.2] |
150 |
[16.9] |
8 |
||
8" |
126 |
[14.2] |
228 |
[25.8] |
8 |
|
10" |
138 |
[15.6] |
246 |
[27.8] |
12 |
|
12" |
186 |
[21.0] |
348 |
[39.3] |
12 |
|
*Average values based on a nitrile binder synthetic gasket, 1/32" thick and lubricated threads.
8.Torque all fasteners to half the value listed in the table below in a staggered, alternating pattern.
9.Make sure that the flanges are not distorted and that the gasket is evenly compressed.
10.Make up the final torque and check that no further nut rotation occurs at the specified torque value, as specified in Table 2.
6
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