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A-3270 11-26-84

NUVLEAR SAFETY lWRAfY

SCOPING TEST ON CONTAINMENT

PURGE AND VENT VALVE SEAL MATERIAL i

B.E. MILLER

. % .,; ;.. '~

DATE PUBLISHED - DECEMBER 1984

ENGINEERING ANALYSIS AND HUMAN FACTORS GROUP

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SCOPING TEST ON CONTAINMENT

PURGE AND VENT VALVE SEAL MATERIAL

Bruce E. Miller

Date Completed - May 1984

Date Published - December 1984

Prepared by

Engineering Analysis and Human Factors Group

Department of Nuclear Energy

Brookhaven National Laboratory

Upton, Long Island, New York 11973

Prepared for

U.S. Nuclear Regulatory Commission

Electrical Engineering Branch

Office of Nuclear Regulatory Research

Contract No. DE-AC02-76CH00016

Washington, DC 20555

FIN A-3270
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TABLE I

Introduction/Purpose . . . . . . . .

Summary of Test Results . . . . . .

Conclusion . . . . . . .

Severe Accident Testing Procedure for

Containment Purge and Vent Valves

Results of Test Sequence 1 . . . . .

Results of Test Sequence 2 . . . . .

Results of Test Sequence 3 . . . . .

Figures 1 - 13 . . . . . . . . . . .

OF CONTENTS

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2

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Introduction/Purpose

Severe accidents-in nuclear. power.plants result ir.'containment environments that'may accelerate th' degradation of seal material used in containment

spurge and vent 'butterfly valves. This- degradation may initiate valve seal

leakage,.thus breeching containme'nt. "A scoping'test was performed to gather

information on the behavior'of the seal material ethylene propylene,.whe'n-exposed to severe accident conditions, (i.e., steam at 3500F 120 psig and 400'F

sand'232 'psig). Three separate'test-sequences were performed during which the

test assembly was monitored for leakage. The-results.of these'tests revealed

no6.seal leakage, however, seal degradation was'evident.

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Summary of Test Results

The valve seals were tested in accordance with the enclosed procedure.

For test sequences 2 and 3,,the procedure was revised to include modified

temperature profiles and seal testing sequence. Figures 2 and 3 show the test

fixture. Figure 1 illustrates a typical purge and vent butterfly valve.

In test sequence 1, the specimen was subjected to a steam environment at

3500F and 120 psig for 11 hours in each valve direction. A minor leak was detected and monitored during the initial test run. Valve seal integrity was

maintained throughout the elevated temperature portion of the procedure for

both test runs. Upon cooling down from each test run, the valve seal was

bubble tested. The valve seal was found to be bubble tight to at least 182

psig on the ring side of the disc and 200 psig on the shaft side.

The bubble test performed following the first test run revealed that the

minor leak previously mentioned was at the disc/pin connection (Figure 8).

The leak was caused by a manufacturing error in squeezing the pin and the disc

together, Figures 6 and 7. The resultant leak, very minor in magnitude, had

no effect on the seating or seal integrity of the valve. (Note: the manufacturer of the valve states that the valve had not been processed through final

quality inspection as would be the case for all valves shipped and is not a

significant concern.)

Removal and inspection of the valve seat following this test sequence

revealed minor remolding of the seat material at the disc/body interface with

no deformities noted. Approximately one week later, cracks had developed in

the seat. The cracks were located in an area that would be compressed by the

retaining ring and in no instance effected the sealing integrity of the

valve. Figure 9 shows these cracks.

In test sequence 2, the test environment was revised to be steam at 4000 F

and 250 psig for 11 hours in each valve direction. The specimen again

maintained its seating integrity throughout the elevated portion of the test

in both directions. After the initial cool-down, the seat was found to be

.bubble tight to at least 75 psig with the pressure applied to the ring side of

the disc. When the pressure was applied to the shaft side of the disc after

the cool-down period, following the second test run, the seat was found to be

bubble tight to at least 200 psig.

Removal and inspection of the valve seat revealed some remolding of the

seat and a minor crack in the compressed retaining portion of the seat. Approximately one week after removal, the crack had propagated to about 4 inches

in length and one-half the thickness of the seat. As in test sequence 1, the

seat was retained in the valve and the compressive force of the seat ring

minimized the growth of the crack. Figure 10 shows the crack that developed

as a result of this test sequence

2
In test sequence 3, the temperature pressure profile was stepped with a

maximum temperature of 4000F and a pressure of 232 psig. The test sequence

was reversed to apply the pressure to the shaft side of the disc for the first

11 hours and to the ring side for the second 11 hours.

Upon completion of the initial 11 hours of testing and cooling, the valve

was found to be bubble tight to at least 200 psig. Prior to performing this

test, the pin/disc connection was repressed, resulting in no leakage.

Initial bubble testing of the valve prior to the second run or retaining

ring side test, there was general seal leakage starting at 1 psig. The seat

was readjusted to maintain 140 psig. There was no leakage observed or recorded during the second test run and was bubble tight to at least 83 psig

upon cooling. The valve was again re-oriented such that pressure would be applied to the shafts at the disc. This resulted in a bubble tight condition to

at least 200 psig.

Inspection of-the seat upon removal,'revealed minor circumvential cracks

at the edge of'the retaining ring (Figure 11). The seat profile had been re0molded to conform to the mating surface.

Conclusion

The results of this scoping test revealed no seal leakage. 'The seal de-'

gradation,-cracking, was visuallyevident in -the compressed retaining portion

of the seat. -However the result'should not.'be 'construed as representing Ithei

entire ethylene propylene family. Ethylene propylene'-is-anelastomer'prepared t

Ef'romiethylene andj'propylene mionomers. --Varying.the relationship of these monoimers',"effects'the characteristics a'nd-their- ability to withstand-.ehvironmental

conditions. It should also be noted that-all mechanisms by which rubber

deteriorates with time are attributable to environmental conditions. The-,

,Parker-Seal Company states that it is environment',-not age that is-significant

to seal life, both in storage'a'nd.'actual service. d

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SEVERE ACCIDENT TESTING PROCEDURE FOR

CONTAINMENT PURGE AND VENT VALVES
SEVERE ACCIDENT TESTING PROCEDURE

FOR

CONTAINMENT PURGE AND VENT VALVES

1.0 Purpose

The purpose of this test procedure is to describe the procedure used

to test a valve assembly, hereinafter called the specimen, for the

Department of Energy, Brookhaven National Laboratory.

2.0 Specimen Description

One series 1200 nuclear butterfly valve to be furnished by, and remain the property of, the Henry Pratt Company.

3.0 Specimen Testing

3.1 Mounting

The specimen will be mounted to the Henry Pratt static seismic loading platform and bolted between a set of approximately sized test

fixtures.

3.1.1 Specimen Orientation

The specimen shall be oriented such that the specimen mounting

flanges will be in the horizontal plane (see Figure 12).

3.2 Method of Test

3.2.1 General Description

High temperature steam will be supplied against a closed valve disc

in accordance with the given profile (see Figure 13).

3.2.2 Testing Schedule

3.2.2.1 Mount the specimen in the test figure in accordance with Figure 12

such that the pressure in the lower chamber is applied to the retaining ring side of the specimen disc when the disc is in the fully

closed position.

3.2.2.2 Close the disc.

3.2.2.3 Apply saturated steam in accordance with the attached temperature

profile.

3.2.2.4 Continuously monitor the test chamber temperature and pressure.

NOTE: The upper chamber is vented to atmosphere.

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3.2.2.5 Read and record the lower chamber pressure and temperature and the

valve leakage rate in the upper chamber once very hour.

3.2.2.6 Upon completion of the test duration, allow the specimen to cool below 1250F, remove the upper chamber and physically inspect the

specimen.

3.2.2.7 Reorient the specimen such that the pressure in the lower chamber

will be applied to the shaft side of the specimen disc when the disc

is in the fully closed position.

3.2.2.8 Repeat steps 3.2.2.2 through 3.2.2.6.

3.3 Instrumentation

3.3.1 Temperature potentiometer using Type "J" thermocouple with the thermocouple extending into the lower pressure chamber.

3.2.2 Pressure gages for monitoring the pressure in the lower chamber.

3.3.3 Rotometer connected to the upper chamber to monitor the specimen

leakage.

3.3.4 Auxiliary thermocouples connected to a strip chart recorder (if the

recorder is available).

3.4 Data Collection -a,,* . .- ,., 1,, ' ., t

All data sheets will contain the Henry Pratt Company name, job number, date, customer name, and signatures of those personnel reading

and recording data.

The data collection portion of the data sheets will have a minimum of

the following headings starting from left to right:

a) Data entry number - b) Time

c) Lower chamber pressure (psig)

d) Lower chamber temperature (0F)

e) Rotometer reading and scale

f) Leakage rate

g) Initials (of person taking specific data line).

4.0 Acceptance Criteria

This test is being performed for the purpose of determining the

amount of specimen leakage under the given criteria and for informational purposes only.

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R E S UL T S T E S T S E Q U E N C E 1.2.3.
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RESULTS OF TEST SEQUENCE 1

TEST SEQUENCE 1

PROCEDURE. The procedure used was that given in the previous section of

this report.

OBSERVATION. During the initial period of the test, it was observed that

the rotometer ball would occassionally spike while otherwise remaining at

zero.

In order to determine what was happening, a tube was connected to the rotometer input. The other side of the tube was placed in an inverted graduate and the graduate partially submerged in a beaker of water.

It was noted that the water positvely displaced a maximum of 10 mL which

occurred in a six minute time interval. Further observation noted positive changes up to 16 mL above the zero mark and negative changes of 8 mL below the

zero mark. Since the leakage appeared to be very small and not consistent,

the test was completed. An investigation would be initiated at the end of the

test run to determine this source of the leak. Ignoring the spikes of the rotometer, there was no seal leakage observed or recorded during the initial 11

hours of testing at 350'F.

Upon completion of the initial 11 hours, the valve was allowed to cool to

below 1250F and leak tested with the pressure applied to the ring side of the

disc. The seat was found to be bubble tight to at least 182 psig.

The bubble test performed following the first 11 hours of testing revealed a minor leak at the pin/disc connection. This leakage was caused by a

manufacturing error in squeezing the pin. Since the valve had not bee processed through final quality inspection as would be the case for all valves

shipped to customers, it is not a significant concern.

The fluxuation on the rotometer was caused by minute amounts of steam

seeping past the pin, condensing in the cooler upper chamber, and then dropping onto the heated disc. The droplets would then flash causing an increase

in.pressure and a decrease in pressure as .they cooled.

Since this minute leakage did not affect the sealing integrity of the

valve seat, it was agreed to note the phenomenon, ignore the spikes, and continue with sequence 1 of the test.

The specimen was reoriented in accordance with paragraph 3.2.2.7 of the

procedure, leak tested, and found to be bubble tight to at least 200 psig.

There was also no seat leakage observed or recorded during the second

portion of the test.

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e

On completion of the second 11 hours at 2500F, the specimen was allowed

to cool below 1250F and the seat was found to be bubble tight to at least 200

psig .

INSPECTION

'Removal . and inspection of the valve seat following this test sequence revealed minor remolding of the seat material at the disc/body interface with no

other deformities noted.

After a period of one

(Figure 9). These cracks,

pressed by the retaining ri

of the valve.

week following the test, the seat developed cracks

however, were located such that they would be comng and in no instance effect the sealing integrity

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RESULTS OF TEST SEQUENCE 2

TEST SEQUENCE 2

PROCEDURE.

Due to the

1, the top

valve seat

The procedure was revised to include the use of test profile 2.

occasional spiking of the rotometer as explained in test sequence

head was raised to allow for continuous visual inspection of the

throughout test sequence 2.

OBSERVATIONS. During the second test sequence, the top chamber was raised to

visually monitor seat leakage, of which there was none, and to observe the

pin. An occasional droplet of water would dance around the pin which substantiated the previous hypothesis regarding pin/shaft leakage.

Upon completion of the initial 11 hours of testing, the specimen was allowed to cool below 1250F and the leak tested. With the pressure applied to

the retaining ring side, the specimen seat was found to be bubble tight to at

least 75 psig.

Reorientating the specimen in accordance with paragraph 3.2.2.7 of the

procedure and then leak testing the sane with the pressure appl ied to the

shaft side of the valve resulted in a bubble tight valve seat to at least 200

psig.

There was no seat leakage observed during the second portion of the 4100F

test.

On completion of the second portion of the test, the valve was leak

tested and the seat was found to be bubble tight to at least 200 psig.

INSPECTION

Removal and inspection of the valve seat following the testing sequence

revealed some remolding of the valve seat and a minor crack in the caipressed

retaining portion of the seat.

After about one week of dornancy, the crack had propagated to about 4

inches in length and one-half the thickness of the seat (Figure 10). It

should be noted that the means by which the seat is retained in the valve, the

compressive force of the seat ring would minimize this condition. Hbwever, in

either instance, Figure 9 or 10, location of the cracked area would not

interfere with the seating integrity of the specimen.

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RESULTS OF TEST SEQUENCE 3

TEST SEQUENCE 3

PROCEDURE. The procedure was revised as follows:

a. Paragraph 3.2.2.1 - mount the specimen in the test fixture in accordance with Figure 1 such that the pressure in the lower chamber is

applied to the shaft side of the specimen disc when the disc is in

the fully closed position.

b. Paragraph 3.2.2.7 - reorient the specimen such that the pressure in

the lower chamber will be applied to the retaining ring side of the

specimen when the disc is in the fully closed position.

c. Test profile 2 will be followed during the first 11 hours and test

profile 3 will be followed after reorientating the specimen during

the second 11 hours.

Note: There was sufficient time between test sequence 2 and 3 penmitting

the specimen to be sent to the manufacturing facility and the pin re-

- squeezed into the disk. The following leak test revealed no pin leakage.

OBSERVATION. There was no leakage observed or recorded during the first

11 hours at the elevated temperature of 400'F.

Upon completion of the initial 11 hours of testing, the specimen was allowed to cool below 1250F and leak tested.

With the pressure applied to the shaft side of the disc, the valve was

found to be bubble tight to at least 200 psig. The specimen was reoriented in

accordance with the revised paragraph 3.2.2.7 and leak tested.

With the pressure applied to the retaining ring side of the valve there

was general seat leakage starting at 1 psig. This was due to the "set" that

-the seal had taken from the first test run. The seat was then adjusted to

maintain 140 psig and the second portion of the testing sequence was perfonned

using test profile 3. There was no leakage observed or recorded during the

elevated portion of the testing sequence using test profile 3.

When the specimen had cooled below the 1250F, it was again leak tested.

With the specimen pressurized fran the retaining ring side, the specimen was

found to be bubble tight to at least 83 psig.

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The valve was again reoriented such that the pressure was applied against the shaft side of the disc resulting in a bubble tight condition to at least 200 psig.

INSPECTION

Inspection, upon removal of the se

cracks at the edge of the retaining rin

to conform to the mating surface.

These discrepancies do not effect

normal containment isolation purposes.

Mat, revealed minor circumferential

g. The seat profile had been remolded

the seat integrity of the valve for

14
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150

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T I E Hours
F I GU R E S
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Figure 1. Typical purge and vent butterfly valve manufactured by Pratt.

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Figure 2. Testing assembly with monitoring instrumentation in foreground.

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Figure 3. Testing assembly with insulation with monitoring

instrumentation in foreground.

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e 4.Viw of haftside f dic andvalv- s

Figure 41. View of shaft side of disc and valve seal - valve open. -

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Figure 5. View of retaining ring side of disc - valve open.

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Figure 6. Valve closed - area indicated by arrow shows where pin/shaft leak defaced valve body. -.Leak was passed pin then down the

cavity between the shaft and disc.

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Figure 7. Valve closed - area indicated by arrow shows where pin/shaft

leak defaced valve body. Leak was passed pin then down the

cavity between the shaft and disc.

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,-~~~--

;->-;~~~~~~~~~~~~~~- -- M

-

Figure 8. Arrows indicate bubbles forming, when leak test was performed, verifying pin/shaft leakage path.

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Figure 9. Degradation as a result of :test sequence 1.

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Figure 10. Degradation as a result of. test sequence 2.

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Figure 11. Degradation as a result of test sequence 3.

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To Rotometer

r ACTUATOR

r%3 Pressure &'Temperature Taps Do

STEAM

GENERATOR To Atmosphere

Figure 12
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400

300. -

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~psig*~vi timnetemp vs time

300 F

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200

150

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TIME ( hours) .

.. .-. . ..... ..... Figure 13. Test Profile.