Document QQRKpOK2BEYKq8M4KKnyxNp4
To: M. L. Ashby
Interoffice Communication
From:
Date:
Subject:
J. B. Chorn - Alliance Engineering February 11, 1987
VISTPressure Control Loop for VCM Loading Lines -
Final Issue - Design No. 240-400-287-JBC
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 recirculation line 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 ccs RAC-PEM-GEH-SRA-MLA(4)-JRH(4)-WPS-MGH-ERT-BED-SCR
DKH-HEK-RDH-SVC
CUH 000001887
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 monitoring.
tag on the valve for future
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 000001S88
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 4"-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.
CUH 000001889
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.
CUH 000001890
BYd&.Okffrj?.. DAT
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DATE___________
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SHEET NO____,,,,.3<rr. ,,os.3^_
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Item No. PCV-701
PIC-701
Instrument List
No. Reauired
1
1
Description
Durco G-4 Valve, Cast Steel, 4"-300#, with actuator
Foxboro 43 HP Controller, 0-200 psig
CUH O000lS93
(COflOCOJ
Citv. Oklahoma
PROJECT NO------------------------------------------------------------
GENERAL
DESIGN DETAILS
*
pi ant
(/
1 ITEM NO.
2 SERVICE
3 4 MANUFACTURER
5 MOOEL NO. 6 | INSTRUMENT FUNCTION
7 | INSTRUMENT MOUNTING
8 | ELECTRICAL CLASSIFICATION
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 AND TYPE
19 CHART RANGE
20 | CHART NUMBER
21 | CHART FACTOR 22 | CHART DRIVE
Indicators. Recorders. Controllers fReceiver instruments)
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23 24 |
CONTROLLER
25 CONTROL MOOE (SEE LINE 44) 26 CONTROLLER ACTION 27 SCALE RANGE 28 SET POINT ADJ.: MAN.--REMOTE 29 AUTO --MAN. SWITCH ANO ADJ. 30 OUTPUT SIGNAL 31
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32 33 ALARM FUNCTION 34 QUANTITY ANO FORM
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ACCESSORIES ALARMS
35 CONTACT RATING
36
37
38
39
40
41
42
43 |
44 CONTROL MODES: P - PROPORTIONAL (GAIN). 1 - INTEGRAL (RESET). 0 - DERIVATIVE (RATE), BIAS, GAP. RATIO. BATCH
45 RECORDER INK SUPPLY: CAPILLARY WITH 6 MONTHS MIN. SUPPLY.
46 Ciw-trvl}fv~ /tc-tt'nto
J hr
47 abfti/-* Tbs
48
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NOTES
49
50
51 52
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4-439-S
Q Conoco Inc. Engineering Center Ponca City, Oklahoma
SPECIFICATION SHEET PROJECT NO.______________ __
A.F.E NO.
--
Pressure Instruments
REO. NO..---- ---- --------------------------
PATP
APPHRY
uin*v .) Fi thorn
GENERAL
1 TAG NO. 2 SERVICE 3 4 INSTRUMENT TYPE 5 LOCATION 6 7 TYPE 6 9 LOCATION
pcir-'id! Vc M
Vmutrt. c.ovrtr$ VC M Lead "Rack
* fi'
>
i'*.
ELEMENT
10 TEMPERATURE. *F 11 PRESSURE
. fc.. i
12 MATERIAL 13 TRANSMITTER: PNEU OR ELECT. 14 RANGE. PSIG
i
15
16 TYPE
17 LOCATION
18 MATERIAL:
BOOY
19 SIZE:
BODY
TRIM PORT
Durco (t--'4UCN Hrrirr, Live. Cs,rt C*yt ytft J
7 " -Wfc
20 NUMBER OF PORTS
ui 21 PLUG FORM
3 22 AP:
MIN.
NORM
<
> 23 CALC CV --NORMAL FLOW
24 VALVE CV -- FULL OPEN
25 FAILURE POSITION
26 MAX SHUT OFF AP
27 DESIGN PRESSURE
( MAX MAX. FLOW
Bqu#/ Percsn'ta
up 1 no \ o// 1 9
)7
1
TT0
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i
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28
29 FLUID <NOTE: UQ./VAP.)
30 TEMP. -F:
NORM
31 PRESSURE, PSIG
32 API (MW)
33 SPGRATSTD.COND.
34 SP GR AT TAP
Li Quid MAX atmbi-PM^ trP
no-i fo
ip Ah. - D#t ' -
0-r2- -
1
; - v -
< ;
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- iaats '- " .
35 VAPOR PRESSURE AT T.PSI4
3$ WEIGHT % VAPOR, W-OUT
37 viscosrrr at tap
38 % ua,
IN
39 RATE: NORMAL
40 RATE:
MAX
41
-
OUT
MIN
-
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NOTES
42 i/*\v< hbwM br r'Luiptfrrf.
43 Dp+rttor
'a P-V2-
44 'rteriKKfj nr f Lwiw/M,
45
46 Vph/
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47 Or(7*b///T\ 'to
48 W
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50
51 CWH OOOOOlfl^s
VALVE SERVICE CONDITIONS
(X) WDICATES MANUFACTURER TO GIVE INFORMATION IN HIS QUOTATION.
SPEC NO.. SHEET___
REV., OF__