SAMSUNG ENGINEERING CO., LTD SAMSUNG SEI TOWER, 467-14 Dogok – 2 Dong, Kangnam-Ku, Seoul, KOREA 135-280
DESIGN MANUAL SEM-9513E PROCESS DESIGN MANUAL
Preparation of Datasheet for Safety Valve REV. DATE
:0 : 2006.8.23
SAMSUNG ENGINEERING CO., LTD.
DATE : 2006. 8. 23
DESIGN MANUAL
SEM – 9513E
Preparation of Datasheet
REV. : 0
for Safety Valve
PAGE i OF i
CONTENTS Page 1
GENERAL................................................................................................1
2
INFORMATION.........................................................................................1
3
2.1 2.2 2.3 2.4 2.5
TAG NUMBER...................................................................................1 QUANTITY........................................................................................1 SERVICE..........................................................................................1 LINE CLASS.....................................................................................1 FLUID NAME..................................................................................2
2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 2.20 2.21 2.22 2.23 2.24 2.25
RELIEVING STATE.............................................................................2 OPERATING PRESSURE / OPERATING TEMPERATURE.........................2 SIZING BASIS...................................................................................2 RELIEVING RATE..............................................................................2 SET PRESSURE................................................................................3 BACK PRESSURE (CONSTANT)..........................................................3 BACK PRESSURE (FROM - TO)..........................................................3 OVERPRESSURE %..........................................................................4 RELIEVING TEMPERATURE................................................................4 SPECIFIC GRAVITY...........................................................................4 VISCOSITY, CP.................................................................................5 MOLECULAR WEIGHT.......................................................................5 CP/CV.............................................................................................5 Z, COMPRESSIBILITY FACTOR...........................................................5 SUPERHEAT OF STEAM 。C..............................................................6 EQUIPMENT DESIGN PRESSURE KG/㎠.G..........................................6 MAWP KG/㎠.G...............................................................................6 BUBBLE TIGHT @ 90% SET PRESSURE............................................6 P&ID NO.........................................................................................7 REMARK..........................................................................................7
REVISION HISTORY................................................................................9
DESIGN MANUAL
SEM – 9513E
Preparation of Datasheet
REV. : 0
for Safety Valve
PAGE 1 OF 9
DATE : 2006. 8. 23
1
GENERAL In case that Project specification is supplied, apply this specification first. This guide is used to fill-up properly in the data sheet of safety valves. The API codes and regulations as follows can be referred for the more details of the technique. - API RP 520, 521 - API Std.526, 527 - ASME section I, VIII - Regulation for high pressure vessel and so on
2
INFORMATION 2.1
Tag Number The tag number of every safety valve is marked as "PSV-000"
2.2
Quantity The quantity of valves is marked with Arabic numerals.
2.3
Service Describe the equipment number or the location which safety valve is installed on. ex) D-1100, P-1234 discharge, C-1104 OVHD , etc
2.4
Line Class Fill up the line class or line specification of safety valve according to P&ID. This is helpful to decide the material of PSV. If the line class is not shown on P&ID at early engineering stage, base material is filled up as follows. ex) carbon steel : C.S
DESIGN MANUAL
SEM – 9513E
Preparation of Datasheet
REV. : 0
for Safety Valve
PAGE 2 OF 9
DATE : 2006. 8. 23
stainless steel : S.S or 304 S.S, 316 S.S, monel etc 2.5
Fluid Name Fill up the fluid name which flows through safety valve. If it is toxic, fill up "toxic service" in remark.
2.6
Relieving State The fluid status at relieving condition is described as follows. ex)
2.7
Gas : G or GAS Vapor : V or VAPOR Liquid : L or LIQUID Steam : S or STEAM
Operating Pressure / Operating Temperature Fill up the normal operating condition of the equipment or line which the safety valve is installed on. It is based on PFD (Process Flow Diagram). In case of multiple operating conditions as like Regeneration, Describe these conditions in remark for the selection of gasket's material and so on.
2.8
Sizing Basis The basis for deciding relieving flow rate, pressure, temperature and relieving properties is described with one letter A~H with referring note 1. The basis is described directly in case that this basis is not included in note 1.
2.9
Relieving Rate At the sizing basis of the safety valve, fill up the required relieving flow rate through safety valve to reduce the pressure
DESIGN MANUAL
SEM – 9513E
Preparation of Datasheet
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for Safety Valve
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DATE : 2006. 8. 23
from overpressure to normal operating pressure.. Relieving rate is described with unit "kg/hr". This value must be calculated at the relieving condition (pressure/temperature). 2.10
Set Pressure It is the pressure which safety valve is set to open. Generally, the set pressure of safety valve is equal to the design pressure of the equipment or line which safety valve protects. In case of multiple installations, the set pressures are different according to the code applied. For example, API RP520 is as follows,
Percent of set pressure Max. accumulation percent (Fire) (Non-fire) PSV first valve 100 % 121 % 110 % additional valve(s) 105 % 121 % 116 % supplemental valve 110 % 121 % 121 % the tolerance of set pressure : 3% 2.11
Back Pressure (Constant) This is superimposed back pressure in API RP. It is equal to the static pressure that exists at the outlet of a pressure relief device at the time the device is required to operate.
2.12
Back Pressure (from - to) This is summation of superimposed back pressure and built-up back pressure (variable back pressure). The built-up back pressure is equal to the increase in pressure at the outlet of a pressure relief device that develops as a result of flow after the pressure relief device opens. When safety valve opens alone, "from" is always equal to "to". But, "to" is higher than "from" when safety valves open together.
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DATE : 2006. 8. 23
2.13
Overpressure % It is the pressure increase over the set pressure of the relieving device allowed to achieve rated flow. Overpressure is expressed in pressure units or as a percentage of set pressure. It is the same as accumulations only when the relieving device is set to open at the maximum allowable working pressure of the vessel. According to code & standard applied, the following values are filled up. .Three percent for steam generators (example: boiler) under ASME section Ⅰ .Ten percent for steam, gas, vapor and liquid under ASME section Ⅷ or API .Twenty percent for vapor resulting from fire only ASME section Ⅷ .Twenty one percent for vapor resulting from fire only under API .Twenty five percent for liquid discharge under ANSI piping code The above are for only single installation. In case of multi installation, the applied code must be reviewed.
2.14
Relieving Temperature In block outlet case, the relieving temperature is almost same as the operating condition of the process. In other cases, It is the expected temperature for the upset condition which is higher than operating temperature. If the process condition is saturation condition (vapor/liquid equilibrium), the relieving temperature is the temperature at relieving pressure (set pressure + overpressure).
2.15
Specific Gravity
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It is filled up for only liquid case. It is the specific gravity at relieving condition. 2.16
Viscosity, cP This is the viscosity at the relieving condition.
2.17
Molecular Weight This is filled up for only gas or vapor case and it can be obtained from PFD or others. In case of multi component, the average molecular weight or molecular weight of light component which can be vaporized can be filled up. In case of water, air and nitrogen, Filling up molecular weight is not necessary.
2.18
Cp/Cv This is specific heat ratio. Cv is difficult to obtain from the reference. In case of low pressure, Cv can be calculated with this equation "Cv = Cp - R (R : gas constant)" assuming as an ideal gas. (Cp : heat capacity at constant pressure, Cv : heat capacity at constant volume) This values is at relieving condition. In case of steam, air and nitrogen, Fill up is not necessary.
2.19
Z, Compressibility Factor If this value is unknown, this value can be filled up with 1.0. This value is based on relieving condition. In case of steam, air and nitrogen, Fill up is not necessary.
DESIGN MANUAL
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DATE : 2006. 8. 23
2.20
Superheat of Steam 。C In case of steam, the superheated degree above saturation temperature is described. In case of saturation steam, Fill up is not necessary.
2.21
Equipment Design Pressure kg/㎠.G It is the design pressure of the equipment which safety valve protects and is equal to set pressure in general. If the equipment thickness is decided without considering any margin, in other words, corrosion allowance or load. Without considering load, It is equal to MAWP. It is just for reference and is not required to fill up.
2.22
MAWP kg/㎠.G Maximum Allowable Working Pressure is the maximum gauge pressure permissible at the top of a completed vessel in its normal position at the designated coincident temperature specified that pressure. The maximum allowable working pressure is the basis for the pressure setting of the pressure relief devices that protect the vessel. The MAWP is normally greater than the design pressure but must be equal to the design pressure when the design rules are used only to calculated the minimum thickness for each element and calculations are not made to determine the value of the MAWP. It is just for reference and is not mandatory to fill up.
2.23
Bubble Tight @ 90% Set Pressure When the vendor is required to guarantee that leakage through valve seat is lower than the specific value, "yes" is filled up. In general, the leakage test report shall be supplied by vendor
DATE : 2006. 8. 23
DESIGN MANUAL
SEM – 9513E
Preparation of Datasheet
REV. : 0
for Safety Valve
PAGE 7 OF 9
according to PSV requisition made by piping department. It is not necessary to fill up in process data sheet. If the operating pressure is very close to safety valve set pressure or leakage is not allowed, Leakage test at least 90% of set pressure is required based on API Std.527. If Leakage is not allowed, soft seat shall be used instead of metal seat. But soft seal can not be used at high temperature. 2.24
P&ID No. Fill up the drawing number of P&ID.
2.25
Remark The following items can be added in remark. ex 1) Lifting lever to be required 2) Toxic Service 3) If Relieving pressure is very high pressure considering back pressure and light hydrocarbon is released, the discharge of safety valve is cooled down and needs material selection for low temperature. For this case, the calculated temperature or the material required for discharge line of safety valve is filled up in remark. Line class must be changed according to this requirement. 4) If estimated PSV size is filled up, write inlet nozzle size orifice letter - Outlet nozzle size in order. ex) inlet 1½ inch, orifice F, outlet 2 inch : 1½F2 But, it is just for reference and is confirmed by vendor.
DATE : 2006. 8. 23
DESIGN MANUAL
SEM – 9513E
Preparation of Datasheet
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5) Fill up the calculated required orifice area and selected orifice area Required orifice area : 1.88 (vendor to confirm) Selected orifice area : 1.98 (vendor to confirm) 6) Valve Type Fill up "Conventional type" or "Balanced type". Basically, conventional type is applied for constant back pressure and balanced type is applied for variable back pressure. In general, conventional type is used for back pressure which is lower than 10% of safety valve set pressure (based on gauge pressure) and balanced type is used for high back pressure. 7) The case rupture disc (RD) is installed with safety valve is as follows, (scope of supply for rupture disc and pressure gauge must be shown) . Process fluid is very corrosive . Plugging is possible at the inlet of safety valve . Leakage must be minimized because fluid is too expensive or very toxic Check point for the installation of rupture disc . Burst pressure is equal to set pressure in general. . The vent between PSV and RD shall be installed and free vent is possible for even pressure gauge. When fluid is toxic or flammable, vent must be closed system.
DESIGN MANUAL
SEM – 9513E
Preparation of Datasheet
REV. : 0
for Safety Valve
PAGE 9 OF 9
DATE : 2006. 8. 23
3
REVISION HISTORY Rev
Date
Page
0
06.08.23
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Revision Status - Team : Process Eng'g Team - Made by : F.S. Choi - Checked by : J.C. Ro, E.D. Lee, Henry Sung, B.S. Son - Approved by : C.S. Jung
