P.1 

OAR Box 1107 

Prepped by Ollie Stewart 

Document Number: 

54) IV-B-4 

Docket Number: 

A-81-21 

Printed 4/11/2008 3:03:4 7 PM Sheet 54 of 90 
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•4 i 

MEMORANDUM 

£-'8~l - 2 

IV-B-4 

DATE: June 20, 1985 

TO: Les Evans 

Chemicals and Petroleum Branch 

FROM: Karen Fidler 

Radian Corporation 

SUBJECT: Large Relief Valve Discharges at PVC and EDC/VC Plants 

Purpose 

This memorandum presents information pertaining to large relief valve 

discharges of vinyl chloride (VC) from PVC and EDC/VC plants. Information 

was obtained from 10-day compliance reports submitted by 23 PVC plants and 

13 EDC/VC plants during the 6-year period from 1978 through 1983 (Refs. 1, 

2, 3) . This information has been summarized for the purpose of evaluating 

options for regulating large relief valve discharges under the VC standard. 

Characterization of Large Relief Valve Discharges 

For the purpose of this memorandum, large relief valve discharges are 

considered to be those in which the estimated amount of VC discharged 

exceeds 6,000 pounds. For the 609 relief valve discharges incidents between 

1978 and 1983 for which compliance information is available, Figure 1 shows 

the distribution of discharges by size. As shown in Figure 1, 61 discharges 

(or 10 percent) were estimated by plants to exceed 6,000 pounds of VC. A 

total of 51 large discharges were reported by PVC plants and 10 large 

discharges were reported by EDC/VC plants. 

In PVC plants, 46 of the 51 large discharges occurred from polymerization reactors. The five large nonreactor discharges at PVC plants occurred 

from equipment associated with the polymerization process such as blowdown 

vessels, strippers and seed tanks. The large relief valve discharges 

reported by EDC/VC plants occurred from equipment involved in the VC 

production and purification processes, particularly VC purification columns 

and VC storage vessels. 

The analysis for selecting numerical relief valve discharge limits for 

the VC standard was based on discharge performance data during the 2-year 

period between August 1981 and July 1983. The majority of large relief 

valve discharge incidents at PVC plants occurred prior to this 2-year 

period. Specifically, 47 of the 51 large discharges (or 92 percent) 

occurred prior to August 1981. At EDC/VC plants, 6 large discharges were 

reported during the 2-year period from August 1981 to July 1983, and 4 large 

discharges were reported before August 1981. Table 1 summarizes the annual 

frequency of large discharge incidents between 1978 to 1983. 

Progress Center/3200 E. Chapel Hill Rd./Nelson Hwy./P.O. Box 13000/Research Triangle Park, N.C. 27709/(919)541-9100 
P.3 

This memorandum provides information on all large discharges between 

1978 and 1983 for which compliance information is available. Those large 

discharges occuring during the 2-year period corresponding to the analysis 

for selecting the numerical limits have been identified separately. 

Causes of Large Relief Valve Discharges 

Reported causes of large relief valve discharges vary. Tables 2 and 3 

include a summary of the reported causes of the large discharges at PVC and 

EDC/VC plants, respectively, for which compliance information is available. 

In general, the large discharge incidents investigated occurred for the same 

types of reasons as smaller discharge incidents. Examples of the types of 

reported causes of large discharges include: 

Operator error - when operators fail to follow established 

standard operating procedures (SOP); 

Premature release - when a pressure relief device relieves at a 

pressure lower than the minimum rated pressure; 

Instrument malfunction - most commonly involving pressure and 

temperature controls and level indicators; 

Equipment failure - examples include failure of reactor cooling 

and agitation equipment; and 

Power loss - resulting from external and internal power or 

electrical failure 

Preventability of Large Relief Valve Discharges 

No attempt was made to assess the preventability of each of the large 

relief valve discharge incidents investigated. However, a review of the 

reported causes of the large discharges indicates that many of the discharges 

are representative of the types of discharges that have been considered in 

previous analyses to be preventable by taking reasonable measures 

(Reference 4) . In the previous analyses, discharges caused by operator 

error, due to operator negligance, or failure to follow SOP were considered 

clearly preventable. Also, operator errors resulting from insufficient 

training or lack of established SOP were considered preventable. Other 

examples of types of discharges considered clearly preventable are premature 

releases and repetitive discharges caused by the same set of preventable 

circumstances as previous discharges. Not all of the large discharges fall 

into the previously identified categories of preventable discharge types. 

Although some of these discharges may also be preventable, this judgment can 

not be made in all cases based on the information contained in the 10-day 

compliance reports. Thus, it can not be assumed that all of the large 

relief valve discharges are preventable. 
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Factors Affecting Size of Discharges 

Available compliance information on large relief valve discharges was 

reviewed to determine how the amount of VC discharged during a relief valve 

discharge incident is affected by actions taken after the discharge begins. 

For some of the large discharges investigated, Tables 2 and 3 include a 

description of factors reported by plants that apparently contributed to the 

size of the large discharge. Examples of factors reported to influence 

discharge size include: 

Operator error in failing to identify and implement appropriate 

actions to stop discharge; 

Polymerization shortstop system inoperable due to operator error 

or lack of maintenance; 

Plant had insufficient or no backup power available for agitation 

and/or cooling during power outages; or backup power generation 

capability was impaired; 

Plant had no DC power source for instrumentation during power 

outage; 

Use of double rupture disc assemblies instead of rupture 

disc/relief valve assemblies, where the latter are feasible; and 

Failure of pressure relief valves to reseat properly. 
P.5 

REFERENCES 

1. Memorandum from Fidler, K. K., Radian Corporation, to file. August 21, 

1984. Relief valve discharge compliance reports from Region VI. 

(Docket Item II-B-44). 

2. Letter and attachments from Varner, B., EPA Region V, to Howie, R., 

Radian Corporation. January 12, 1984. Response to request for relief 

valve discharge compliance information for PVC plants. (Docket Item 

II-D-47). 

3. Memorandum from Fidler, K. K., Radian, to file. August 10, 1984. 

Relief valve discharge compliance reports from Region II. (Docket 

Item II-B-30). 

4. Memorandum from Howie, R. H. and Fidler, K. K., Radian Corporation, to 

file. April 16, 1984. Numerical limits for relief valve discharges. 

(Docket Item II-B-26). 
>a 

o 

e 

at 

0 

c 

u 

400-| 

390 

100 

90 

80 

70 

80 

60 

40 

30 

20-

10 

393 

Frequency of discharges 

Cumulative frequency by percent 

100 

88 88 9 0 91 93 *± 

98 

81 

75 

86 86 

37 

30 

10 10 9 11 

26 

0-1.000 1,000- 2.000- 3.000- 4,000- 6,000- 8,000- 7,000- 8,000- 9,000- k4An m 

2,000 3.000 4,000 6,000 6.000 7,000 8,000 9.000 10,000

 >1 ° ' o w 

Pounds VC Emitted per Discharge 

Figure 1 Distribution of relie f valve discharges by size 
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TABLE 1. FREQUENCY OF LARGE RELIEF VALVE DISCHARGE 

INCIDENTS BETWEEN 1978 and 1983 

Year No. of Large Discharges3 

PVC EDC/VC 

1978 20 2 

1979 12 2 

1980 12 0 

1981 5 1 

1982 2 5 

1983 0 0 

aRelief valve discharges during which the estimated amount of VC discharged 

exceeded 6,000 pounds. 
TABLE 2. SUMMARY OF LARGE RELIEF VALVE DISCHARGE INCIDENTS AT PVC PLANTS BETWEEN 1978 AND 1983 

Plant Discharge 

Code Amount (Pounds) Date Source Cause of Discharge Factors Affecting Size of Discharge 

R-l 

R-2 

R-3 

50.000 

30,000 

33,000 

38,000 

10,000 

10,249 

6,500 

17,926 

8/13/78 

11/26/78 

3/23/80 

6/21/78 

5/5/80 

9/9/80 

Suspension reactor 

Suspension reactor 

7/27/79 Suspension reactor 

10/20/79 Suspension reactor 

12,090* 5/22/82 

Suspension reactor 

Suspension reactor 

Suspension reactor 

Suspension reactor 

Suspension reactor 

Premature failure of 2 rupture discs 

on double RD assembly 

Power failure 

Operator error in setting reactor 

temperature controller 

Premature failure of 2 rupture discs on 

double RD assembly during power failure 

Operator error during reactor charging 

operations caused hydroful 

Premature rupture disc failure during 

charging; SRV lifted during heat up 

Electrical short on reactor temperature 

controller 

Reactor cooling control loop instrumentation failed 

Improper control of reaction when analog 

temperature and pressure control 

instrumentation drifted out of calibration 

Because double RD assembly was used instead 

of SRV/RD, no method was available for 

stopping discharge. 

Shortstop could not be successfully added 

because operator failed to close Inert vent 

valve. 

Reason for unsuccessful shortstop was not 

immediately identified. 

Operator left control room; unqualified 

operator did not react properly to high 

temperature and pressure alarm. 

Decision to kill reaction was not made 

until after several power dips. 

Because double RD assembly burst, no method 

was available for stopping discharge. 

Cause of overpressure not Immediately 

Identified. 

Operator error causing hydroful Interfered 

with regular method of adding shortstop. 

SOP was to continue batch even after RD 

failure. 

Operators attempted to equalize pressure with 

another reactor but valve did not operate. 

Steam valve was leaking; shortstop 

injection tubing was blocked. 

Plant nitrogen pressure was too low to inject 

shortstop. 

•Discharge occurred during 2-year period between August 1981 and July 1983. Performance during this 2-year period was the basis for proposed 

numerical relief valve discharge limits in the VC standard (see 40 FR 1182). 
TABLE 2. (Continued) 

Plant Discharge 

Code Amount (Pounds) Date Source Cause of Discharge Factors Affecting Size of Discharge 

R-6 6,000 

6,750 

7,720* 

12,825* 

3/24/78 

10,000 1/5/79 

12,000 11/17/79 

8,560* 8/15/82 

4/18/78 

12,600 7/3/78 

7,500 9/30/78 

8/21/81 

10/10/81 

Suspension reactor 

Suspension reactor 

Suspension reactor 

Suspension reactor 

R-8 

R-10 

R-ll 

8,710 

41,866 

7,356 

8,000 

9/28/78 

6/NA/81 

2/10/80 

3/29/78 

Dispersion reactor 

Dispersion reactor 

Suspension reactor 

Blowdown tank 

Blowdown tank 

Suspension reactor 

Blowdown tank 

Suspension reactor 

Power failure required plant to shutdown; 

manual venting was necessary to avoid 

relief valve discharges from 4 reactors 

Malfunction in reactor charge pump caused 

reactor to be overfilled with water 

Power failure when main high voltage 

feeder to plant was knocked out; 

manual venting of 2 reactors was required 

Water continued to enter reactor after 

charge because of failure of automatic 

control valve 

Premature rupture disc failure 

Power failure caused six reactors to 

overpressure and discharge 

Circuit breaker failure caused power 

loss to cooling tower pumps 

Water contamination In containment 

system relay caused wrong reactor to 

be dropped 

Low instrument air prevented containment 

system from operating and wrong reactor 

was dropped 

Wrong rupture disc installed 

Manual valve on containment system 

controller line was closed 

Operator error when reactor temperature 

controller was in manual mode 

Suspension reactor Plant-wide power failure 

Emergency power used for reactor agitation 

and cooling, but 4 reactors required 

controlled manual venting to prevent 

overpressure. 

Relief valve failed to reseat and 

eventually had to be reseated manually. 

Emergency power was also lost because 

voltage surge blew fuses. 

Flow meter that would Indicate water flow 

into reactor malfunctioned. 

No information provided. 

Backup generator malfunctioned; plant was 

evacuated before shortstop could be added 

to all reactors. 

No 10-day report. 

No 10-day report. 

No 10-day report. 

No 10-day report. 

No 10-day report. 

No 10-day report. 

Emergency breaker for agitation 

malfunctioned. 

•Discharge occurred during 2-year period between August 1981 and July 1983. Performance during this 2-year period was the basis for proposed 

numerical relief valve discharge limits in the VC standard (see 40 FR 1182). 
Plant Discharge 

Code Amount (Pounds) 

R-13 11,300 

10,300 

9,540 

13,200 

9,900 

8,383 

9,450 

9,817 

9,500 

8,600 

8,200 

10,092 

41,866 

R-19 8,390 

9,551 

11,130 

6,240 

9,850 

Date 

1/1/78 

3/11/78 

3/24/78 

4/15/78 

6/9/78 

7/22/78 

8/21/78 

6/5/79 

11/19/79 

2/9/80 

2/24/80 

6/15/80 

3/6/80 

3/10/78 

5/2/78 

11/7/78 

11/13/78 

1/2/79 

TABLE 

Source 

Suspension reactor 

Suspension reactor 

Suspension reactor 

Suspension reactor 

Suspension reactor 

Blowdown tank and 

stripper column 

Suspension reactor 

Dispersion reactor 

Suspension reactor 

Dispersion reactor 

Dispersion reactor 

Seed tank 

Reactor 

Suspension reactor 

Suspension reactor 

Suspension reactor 

Suspension reactor 

Dispersion reactor 

2. (Continued) 

Cause of Discharge 

Reactor overcharge 

Temperature controller incorrectly 

placed in manual mode 

Reactor overcharge 

Reactor overcharge 

Operator error-wrong reactor was washed 

Failure to close bottom valve on reactor 

before charge 

Pressure transmitter failure 

Reactor overcharge and failure of relief 

valve to containment system 

Premature rupture disc failure 

Hydroful. Relief valve to containment 

system plugged 

Hydroful. Relief valve to containment 

system plugged 

Use of water and nitrogen to dislodge a 

plug in seed tank caused overpressure 

( 

Power failure and subsequent cooling 

water loss caused 6 reactor and 

6 blowdown tanks to discharge 

Cooling water lost to all reactors; 

emergency vent valve opened on 2 reactors 

Overcharge of VCM 

Abnormally fast reaction; premature 

rupture disc failure during shortstop 

Reactor temperature transmitter damaged 

by maintenance personnel 

Pressure transmitter froze; reactor was 

manually vented to relieve apparent 

overpressure 

Factors Affecting Size of Discharge 

No 10-day report. 

No 10-day report. 

No 10-day report. i' .S?., ;• ' 

No 10-day report. 

No 10-day report. 

No 10-day report. 

No 10-day report. 

No 10-day report. 

No 10-day report. 

No 10-day report. 

No 10-day report. 

Due to storm, discharge went unnoticed for 

75 minutes. 

Backup feeder down for maintenance. Newly 

Installed automatic shortstop system was 

not operable because of leaks; manual 

shortstop was used instead. 

None given. 

None given. 

None given. 

Cause for oyerheated reaction not 

immediately Identified. 

None given. 

» •. 
TABLE 2. (Continued) 

Plant " Discharge 

Code Amount (Pounds) Date Source Cause of Discharge Factors Affecting Size of Discharge 

R-19 

(cont.) 

R-20 

R-22 

9,540 

10,870 

8,300 

13,200 

6,300 

6,000 

8,000 

6,000 

4/12/79 

4/12/80 

4/20/80 

9/17/80 

5/20/81 

6/11/78 

6/14/81 

5/4/78 

Suspension reactor 

Reactor 

Reactor 

Reactor 

Dispersion reactor 

Bulk reactor (po-po) 

Bulk reactor (po-po) 

Bulk reactor (po-po) 

R-23 

Premature rupture disc failure 

Premature rupture disc failure 

Operator error 

Power failure 

Malfunction in cooling water control 

Overpressure 

Pressure transmitter out of calibration 

and flex line to pressure transmitter 

plugged 

13,000 2/14/79 Bulk reactor (po-po) Excess initiator in experimental batch 

7,000 3/14/79 Bulk reactor (po-po) Overpressure during experimental batch 

8,000 6/24/79 Bulk reactor (po-po) Overpressure; cause unknown 

to alternate RD. 

7,838 8/6/79 Solution reactor Premature rupture disc failure 

Shortstop addition was delayed because of 

Insufficient Injection pressure and 

plugged Injection line. 

No 10-day report. 

No 10-day report. 

No 10-day report. 

None given. 

No 10-day report. 

No 10-day report. 

Rupture disc only; venting was stopped by 

switching to alternate RD. 

After switching to backup rupture disc, It 

burst, and venting had to be stopped by 

manually closing block valve below RD. 

Rupture disc only; discharge was stopped 

by switching to alternate RD. 

Rupture disc only; discharge was stopped 

None given. 
TABLE 3. SUMMARY OF LARGE RELIEF VALVE DISCHARGE INCIDENTS AT EDC/VC PLANTS BETWEEN 1978 AND 1983 

Plant Discharge 

Code Amount (Pounds) Date Source Cause of Discharge Factors Affecting Size of Discharge 

V-2 

V-6 

8.500* 

11,000* 

11/2/82 

2/9/82 

VC furnace 

VC column 

Power failure caused overpressure in 

vinyl furnace 

Vinyl column overpressured during 

startup because cooling water valves 

were left In incorrect position after 

maintenance 

Pressure control valves failed close due to 

electrical and air failure; no DC back-up 

power source. . :-,,'-'.•:'.> 

Relief valve did not reseat because of 

error in valve assembly. 

Reason for overpressure not readily detected. 

V-7 9,600* 10/30/82 Light ends column 

V-9 

V-10 

V-ll 

13,878* 

7.500 

3/25/82 

4/30/78 

VC storage tank 

VC column 

7,500 

7,000 

12,000 

6,000 

6/1/79 

9/8/79 

5/23/78 

8/31/78 

VC rundown sphere 

Quench column, HCI 

column 

Storage tank 

Compressors 

Light ends column overpressured because 

of failed pressure transmitter 

6,000 7/28/79 NA 

Product storage vessel overpressured 

when a valve In the tank's Incinerator 

vent header was closed for maintenance 

Power failure caused overpressure in VC 

column 

VC rundown sphere was overfilled 

HCI column and 2 quench colums 

overpressured when VC unit was shutdown 

to repair failed thrust bearing In 

refrigeration system 

Operator error filling storage tank 

Process compressor emergency valve 

discharged when a relay protecting the 

compressor motor operated. 

Misconmunlcation occurred when trying 

to deal with a failed valve 

Overpressure condition not detected because 

backup pressure transmitter indicated column 

pressure was normal. 

Operator closed safety valve because he 

believed it was leaking; this caused 

safety rupture disc to burst. 

Approximately 20 minutes were required to 

stop discharge by equalizing pressure 

with another tank. 

No backup power available for reflux pumps. 

Higher-than normal HCI in VC column because 

of prior HCI column upset. 

Sphere's level Indication equipment was 

reading 20 percent low and high pressure 

alarm failed. 

No 10-day report. 

No 10-day report. 

No 10-day report. 

•Discharge occurred during 2-year period between August 1981 and July 1983. Performance during this 2-year period was the basis for proposed 

numerical relief valve discharge limits in the VC standard (see 40 FR 1182). 
TABLE 3. (Continued) 

Plant Discharge 

Code Amount (Pounds) Date Source Cause of Discharge Factors Affecting Size of Discharge 

V-13 46,556* 12/22/81 VC column, VC vent 

header 

43,209* 6/2/82 VC column, VC 

reboiler, VC 

reflux drum 

Power failure caused 2 VC columns and 

dry VC vent collection header to 

overpressure 

Power failure caused 3 VC columns, 

1 reboiler and 1 reflux drum to 

overpressure 

No backup power or cooling. 

No backup power or cooling. 

•Discharge occurred during 2-year period between August 1981 and July 1983. Performance during this 2-year period was the basis for proposed 

numerical relief valve discharge limits in the VC standard (see 40 FR 1182).