Document MMDkxo1pw4dxzZKvNggnbknwM
To: M. L. Ashby
Interoffice Communication
From: Dote:
Subject:
J. B. Chorn - Alliance Engineering February 11, 1987
Pressure Control Loop for VCM Loading Lines Final Issue - Design No. 240-400-287-JBC
vist*
A VCM release occurred on 2/28/86 when the line to the shiploading dock overpressured and caused the relief valve on S-402 to relieve momentarily. The attached control loop design will enable the dock loading line pressure to be maintained above the normal loading pressure but below the relieving pressure (200. psig) of the Bauxite Dryer, S-402.. The excess pressure will be relieved into the VCM recirculationline and recovered in the sphere being loaded from. An operating procedure is attached as a part of the design.
By copy of this design to J. R. Holcomb, a definitive
estimate is requested.
If you have any questions,
please call me at 5075. Since the comments from the
review issue were few and minor, they were addressed in
the final issue and no review meeting was held.
J. B. Chorn Alliance Engineering
br cc: RAC-PEM-GEH-SRA-MLA(4)-JRH{4)-WPS-MGH-ERT-BED-SCR
DKH-HEK-RDH-SVC
CWH 000005528
Work List
Reference: VCM shiploading Line Pressure Control Loop Drawings 1 and 2
This project should be done when the dock loading line can be out of service for a week.
Preparatory Work
1) Mount the local controller, PIC-701, at a convenient spot.
2) Run instrument air supply, signal and output lines to and from PIC-701.
3) Run instrument air supply and signal lines to approximate PCV-701 location.
Project Execution
1) Close valves 2, 3, 4, 5, 6, and 7.
2) Depressure and clear Line C for removal per normal VCM line clearing procedures.
3) Remove line to a safe location for welding.
4) Install 2 4"-300# flanges at a convenient spot on Line C and install the Durco valve with actuator.
5) Put a numbered VCM VHAP tag on the valve for future monitoring.
6) Reinstall Line C with the new valve in the original position.
7) Hook up supply and signal lines to the actuator and controller.
8) Using the controller, open and close the new valve to verify operability.
9) Re-commission Line C to VCM service per normal commissioning procedures.
10) Open valve 2 and seal it open.
11)
Install a red plastic sign with white letters near Valve which reads:
"Open Only For Dock Loading Operations"
3
12)
Install a red plastic sign with white letters near Valve which reads:
"Close Only for Dock Loading Operations"
1
CUH 000005529
Design Basis and Discussion
A pressure control loop will be added which will prevent the pressure on the VCM line to the shiploading dock from reaching the relieving pressure (200 psig) of the Bauxite Dryer, S-402. The loop will consist of (1) an existing pressure recorder-indicator, (2) a locally mounted pneumatic indicator-controller, and (3) a 4M-300# Durco G-4 valve with an actuator and positioner. An operator can set the controller at 175 psig. Should the dock line pressure reach that point, an alarm will sound in the control room and the pressure control valve will relieve the excess pressure to the existing VCM recirculation line. When the dock line is not in use, the pressure control valve or an alternate valve should be opened to allow the pressure to relieve to the recirculation line. Valve 2 (see P&ID) must be sealed open.
Operation When a vessel is to be loaded at the dock, valve 1 must be closed, valve 3 must be open (see P&ID), and the pressure controller set at 175 psig. If the line pressure reaches 175, the pressure control valve (PCV-702) will open and an alarm will sound in the control room. When dock loading is complete, valve 3 should be closed to prevent accidentally refilling the dock line and valve 1 should be opened to allow the dock line and recirculation line pressures to equalize. The pressure controller setting can remain at 175 psig.
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Energy Impact Statement
This project will have no effect on plant energy consumption.
A
Process Design Energy Checklist has been completed and is on file.
Environmental Impact Statement
The possibility of emergency releases of vinyl chloride to the atmosphere due to overpressurization of the dock loading line at the loading rack will be eliminated. The environmental checklist has been completed and is on file.
Safety & Health Impact Statement
The likelihood of exposure to VCM in the loading rack area will be
reduced since overpressurization of the dock loading line will be
relieved into the closed recirculation system.
The
safety
checklist has been completed and is on file.
CUM 000005531
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Item No. PCV-701
PIC-701
Instrument List
No. Required
1
1
Description
Durco G-4 Valve, Cast Steel, 4"-300#, with actuator
Foxboro 43 HP Controller, 0-200 psig
Ct/H 0000
4-439-S
(conoco)
Engineering Center Ponca City, Oklahoma
Indicators, Recorders, Controllers
(Receiver Instruments)
SPECIFICATION DATA SHEET
PROJECT NO________________________
A.F.E. NO____________________________
REQ. NO.
__________________
DATE U VV^APP'p BY____
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GENERAL
DESIGN DETAILS
INDICATOR-RECORDER
CONTROLLER
1 ITEM NO. 2 SERVICE 3
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4 MANUFACTURER 5 MOOEL NO. 6 INSTRUMENT FUNCTION 7 INSTRUMENT MOUNTING 8 ELECTRICAL CLASSIFICATION
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9 POWER SUPPLY
10 INPUT SIGNAL 11 ACCURACY
12 REPEATABILITY
13
14
15
16 NO. OF PENS OR POINTERS 17 SCALE RANGE 18 CHART SIZE ANO TYPE 19 CHART RANGE 20 CHART NUMBER 21 CHART FACTOR 22 CHART DRIVE
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24
25 CONTROL MODE (SEE LINE 44) 26 CONTROLLER ACTION 27 SCALE RANGE 28 SET POINT ADJ.: MAN. -- REMOTE
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29 AUTO--MAN. SWITCH AND ADJ.
30 OUTPUT SIGNAL 31
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32
33 ALARM FUNCTION 34 QUANTITY AND FORM
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35 CONTACT RATING
36
37
38
39
40
41
42
43
144 CONTROL MODES: P - PROPORTIONAL (GAIN). - INTEGRAL (RESET). D - DERIVATIVE (RATE). BIAS. GAP. RATIO. BATCH
45 RECORDER INK SUPPLY: CAPILLARY WITH 6 MONTHS MIN. SUPPLY.
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NOTES
QUOTATION WILL NOT BE CONSIDERED IF MANUFACTURER DOES NOT COMPLETE FORM BY FURNISHING INFORMATION FOR BLANK SPACES.
7-82
SPEC NO. SHEET___
REV, OF _
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(conoco)
Conoco inc. Engineering Center Ponca City, Oklahoma
Pressure Instruments
SPECIFICATION SHEET
PROJECT NO___________
A.F.E. NO_______________
REQ. NO,.
_______
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7 TYPE
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9 LOCATION
ELEMENT
10 TEMPERATURE. T
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11 PRESSURE
12 MATERIAL
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13 TRANSMITTER: PNEU OR ELECT.
14 RANGE, PSIG 15
16 TYPE
17 LOCATION
16 MATERIAL:
BODY
TRIM
19 SIZE:
BOOY
PORT
20 NUMBER OF PORTS
21 PLUG FORM
22 &P: MIN. | NORM
MAX
23 CALC CV -- NORMAL FLOW
MAX FLOW
24 VALVE CV -- FULL OPEN
25 FAILURE POSITION
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26 MAX SHUT OFF AP 27 DESIGN PRESSURE
28
29 FLUID (NOTE: UO^VAP.)
30 TEMP. T:
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31 PRESSURE. PSIG
32 'API (MW)
33 SPGRAT STD. COND.
34 SP Gfl AT TAP
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36 WEIGHT % VAPOR, IN-OUT
H 37 VISCOSITY AT TAP
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38 % LX).. IN J OUT
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39 RATE: NORMAL
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TO INDICATES MANUFACTURER TO GIVE INFORMATION IN HIS QUOTATION.
2-81
SPEC NO. SHEET___
REV.___
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