GB/T 23711.7-2019 PDF in English
GB/T 23711.7-2019 (GB/T23711.7-2019, GBT 23711.7-2019, GBT23711.7-2019)
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivered in | Name of Chinese Standard | Status |
| GB/T 23711.7-2019 | English | 235 |
Add to Cart
|
0-9 seconds. Auto-delivery.
|
Test method for pressure vessels lined with plastics -- Part 7: Leakage testing
| Valid |
Standards related to (historical): GB/T 23711.7-2019
PDF Preview
GB/T 23711.7-2019: PDF in English (GBT 23711.7-2019) GB/T 23711.7-2019
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 71.120;83.140
G 94
Test method for pressure vessels lined with plastics -
Part 7: Leakage testing
ISSUED ON: DECEMBER 10, 2019
IMPLEMENTED ON: NOVEMBER 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Principle ... 4
4 Test equipment ... 4
5 Sample ... 5
6 Test method ... 5
7 Test result judgment ... 15
8 Test report ... 15
Appendix A (Informative) Leakage test report ... 17
Foreword
GB/T 23711, Test method for pressure vessels lined with plastics, is divided into
8 parts:
-- Part 1: Spark testing;
-- Part 2: Low-temperature testing;
-- Part 3: High-temperature inspection;
-- Part 4: Negative pressure inspection;
-- Part 5: Cold-hot cycling inspection;
-- Part 6: Anti pressure testing;
-- Part 7: Leakage testing;
-- Part 8: High-resistance testing.
This Part is Part 7 of GB/T 23711.
This Part was drafted in accordance with the rules given in GB/T 1.1-2009.
This Part was proposed by China Petroleum and Chemical Industry Federation.
This Part shall be under the jurisdiction of National Technical Committee 162
on Non-metallic Chemical Equipment of Standardization Administration of
China (SAC/TC 162).
The drafting organizations of this Part: Ningbo Special Equipment Inspection
and Research Institute, Wenzhou Institute of Calibration and Testing for Quality
and Technical Supervision, Guangzhou Special Pressure Equipment Inspection
and Research Institute, Tianhua Institute of Chemical Machinery & Automation
Co., Ltd., Xi’an Sauron Welding Equipment Co., Ltd., Wenzhou Zhaoflon Co.,
Ltd., Tianjin Special Equipment Supervision and Inspection Technology
Research Institute, Wenzhou Jiahe Standardization Information Technology
Office, Henan Province Boiler Pressure Vessel Safety Inspection & Testing
Institute.
The drafters of this Part: Lv Sheng, Ying Ren’ai, Dang Lihua, Li Maodong, Hang
Yuhong, Zhao Feng, Chen Guolong, Jin Aidie, Sun Zhongren.
Test method for pressure vessels lined with plastics -
Part 7: Leakage testing
1 Scope
This Part of GB/T 23711 specifies the principle, test equipment, sample, test
method, test result judgment and test report of the leakage testing of steel
pressure vessels lined with plastics.
This Part applies to the leakage testing method of steel pressure vessels lined
with plastics such as rigid polyvinyl chloride (PVC-U), chlorinated polyvinyl
chloride (PVC-C), polyethylene (PE), ethylene-tetrafluoroethylene copolymer
(ETFE), fluorinated ethylene propylene (FEP), perfluoroalkoxy alkanes (PFA),
polytetrafluoroethylene (PTFE), and polyvinylidene difluoride (PVDF), whose
container shell material is steel.
2 Normative references
The following documents are indispensable for the application of this document.
For dated references, only the dated version applies to this document. For
undated references, the latest edition (including all amendments) applies to this
document.
GB/T 13979, Mass spectrometer leak detector
GB/T 35974.5, Plastics and plastic lining pressure vessels - Part 5:
Fabrication, inspection and testing for pressure vessels with plastic lining
3 Principle
When there is a leakage in the steel pressure vessels lined with plastics, the
helium mass spectrometer leak detector detects the leaked gas and sends out
a warning signal or displays a leakage reading. Through calculation and
comparison with the standard leakage rate, it can be determined whether the
vessel has a leakage.
4 Test equipment
4.1 It shall use a helium mass spectrometer leak detector that meets the
requirements of GB/T 13979. For a helium mass spectrometer leak detector
that uses the conventional leak detection method, at full pumping speed, the
minimum detectable leakage rate of the helium mass spectrometer leak
detector shall not be greater than 2 × 10-11 Pa · m3 · s-1 (to air); for a helium
mass spectrometer leak detector that uses the counter-diffusion leak detection
method, the minimum detectable leakage rate of the helium mass spectrometer
leak detector shall not be greater than 2 × 10-10 Pa · m3 · s-1 (to air).
4.2 The pressure testing device shall be equipped with two pressure gauges of
the same range. The accuracy level of the pressure gauge shall not be less
than level-1.6; the range limit of the pressure gauge is 1.5 times ~ 3 times the
maximum test pressure. The diameter of the dial of the pressure gauge shall
not be less than 100 mm. The installation position of the pressure gauge shall
be easy to observe.
4.3 Select the appropriate equipment and sealing device according to the test
pressure range, so as to ensure that the pressure can be smoothly increased
and maintained during the test.
4.4 The anti-pressure testing site of the test shall have reliable safety protection
facilities; besides, the test shall be inspected and approved by the technical
responsible person of the unit and the safety department.
5 Sample
The samples of the leakage testing are steel pressure vessels lined with plastics,
which do not need to be specially made.
6 Test method
6.1 Preparation
6.1.1 The samples are manufactured according to the design drawings and
related standards; a closed space is formed for testing.
6.1.2 Check the sample: before the test, conduct a comprehensive inspection
on the sample assembly and the test preparation; handle the clean observation
surface; keep it dry.
6.2 Air tightness test
6.2.1 The medium of the air tightness test shall be dry air, helium or other inert
gas.
6.2.2 The test pressure of the air tightness test shall meet the requirements of
GB/T 35974.5.
6.2.3 During the test, the observation surface shall be kept clean and dry.
6.2.4 The pressure of the air tightness test shall be increased according to the
following requirements:
a) During the test, increase the pressure slowly. When the pressure is
increased to 30% ~ 50% of the test pressure, stop the pressure increase
for preliminary inspection;
b) When the pressure is increased to the working pressure, stop increasing
and check for abnormal conditions;
c) Increase the pressure to the test pressure if there is no abnormality; the
pressure holding time shall not be less than 30 min.
6.2.5 During the test, observe the pressure gauge at any time; it’s not allowed
to maintain the test pressure through continuous pressure increase.
6.2.6 During the pressure-holding process, observe the pressure gauge at any
time; pay attention to possible leakage, especially the connection and seal.
6.3 Helium leakage test
6.3.1 General
When a helium mass spectrometer leak detector is used to perform a leakage
testing on the steel pressure vessels lined with plastics, connect the scale-
indicating pressure gauge directly to the sample, or connect it to the test piece
from a long distance, so as to make it easy for the tester to observe the pressure
gauge/ vacuum gauge throughout the process. For large vessels or tested
systems that require the use of one or more pressure gauges/ vacuum gauges,
it should use a recordable pressure gauge/ vacuum gauge instead of one of
two or more indicator pressure gauges/ vacuum gauges, or use a helium leak
test in accordance with the design drawings.
The use of helium leak test methods shall not cause plastic lining failure,
otherwise, it shall not be used.
Standard leaks of helium mass spectrometer leak detector can be divided into
two categories:
a) permeable standard leak: permeable standard leak is a permeable leak of
fused and calibrated glass or quartz, which has the helium leak rate of 1
× 10-11 Pa · m3 · s-1 ~ 1 × 10-7 Pa · m3 s-1, and shall be calibrated to meet
requirements;
b) channel-type standard leak: channel-type standard leak test is a channel-
type leak that allows the tracer gas to pass through a tube that uses the
helium gas standard. It has a leakage rate not greater than the product of
the required test sensitivity and the actual mass fraction of the tracer gas,
and shall be calibrated to meet the requirements.
6.3.2 Sniffer technology
6.3.2.1 Overview
Helium mass spectrometer leak detector leakage testing - sniffer technology:
use tracer gas or a mixed gas that contains a certain proportion of tracer gas to
pressurize the test piece; then, use a sniffer to scan.
6.3.2.2 Scope
Helium mass spectrometer leak detector leakage testing - sniffer technology
test method is a locating and qualitative method to test the leak and determine
its location, which shall not be used as a quantitative analysis method.
6.3.2.3 Calibration
6.3.2.3.1 Instrument calibration
6.3.2.3.1.1 Preheating
Before using standard leaks for calibration, power on to preheat the instrument;
the minimum time of preheating shall meet the requirements of the instrument
manufacturer.
6.3.2.3.1.2 Calibration
For the instrument, use a permeable standard leak to calibrate in accordance
with the instrument manufacturer's operation and maintenance manual, so as
to make the device at the best or most appropriate sensitivity. For a helium
mass spectrometer leak detector that uses the conventional leak detection
method, at full pumping speed, the minimum sensitivity of the instrument to
helium is 1 × 10-11 Pa · m3 · s-1; for a helium mass spectrometer leak detector
that uses the counter-diffusion leak detection method, the minimum sensitivity
of the instrument to helium is 1 × 10-10 Pa · m3 · s-1.
6.3.2.3.2 System calibration
6.3.2.3.2.1 Leakage standard leak size
For a capillary standard leak that is used for system calibration and contains
100% of helium concentration, the maximum leakage rate Q is calculated
according to Formula (1):
Where:
Q -- maximum leakage rate of the capillary standard leak, in pascals cubic
meter per second (Pa · m3 · s-1);
Qs -- the required sensitivity of the tested system, in pascals cubic meter per
second (Pa · m3 · s-1);
C -- the actual helium concentration in the tested system, %.
6.3.2.3.2.2 Scanning rate
When calibrating the instrument, use the sniffer nozzle to scan over the
standard leak. During the scan, keep the distance between the sniffer nozzle
and the standard leak within 3 mm. The scanning rate does not exceed the rate
at which the standard leak rate can be detected at Q.
6.3.2.3.2.3 Response time
During system calibration, the response time shall be no greater than 3 s, so as
to reduce the time that is required to determine the location of the leak.
Note: The response time is the time that is required to observe the appearance
of an indication signal and to stabilize the output of the instrument.
6.3.2.3.2.4 Calibration frequency and sensitivity
Unless otherwise specified, the sensitivity of the test system shall be
determined once before the test, after the test, and at an interval that does not
exceed 4 h during the test. In any one determination, the instrument deflection,
audible alarm or indicator light, if any, indicates that the system cannot detect
the leakage; the test system shall be recalibrated, and all test parts after the
last qualified standard shall be retested.
6.3.2.4 Test
6.3.2.4.1 Test site
The tested work piece, if possible, needs to be in a place that is protected from
ventilation, or where the required sensitivity will not be reduced due to
ventilation.
6.3.2.4.2 Tracer gas concentration
Unless otherwise specified in the design code, the volume fraction of the helium
tracer gas at the test pressure shall not be less than 10%; the test pressure is
determined by design.
6.3.2.4.3 Pressure holding time
Before the test, the test pressure shall be maintained for at least 30 minutes. If
the helium gas will diffuse immediately under the following conditions, the
minimum pressure holding time can also be shorter than the above
requirements:
a) open samples that use special temporary devices (such as extraction
hoods) to test the short circuit;
b) samples that have been partially evacuated before the first pressurization
of helium.
6.3.2.4.4 Scanning distance
After the required pressure holding time is over, the sniffer nozzle shall sweep
across the entire tested surface; the distance between the sniffer nozzle and
the tested surface during the scanning shall be kept within 3 mm. If a smaller
distance is used for system calibration, the distance during the test scan shall
not exceed this distance.
6.3.2.4.5 Scanning rate
The maximum scanning rate shall be determined in accordance with 6.3.2.3.2.2.
6.3.2.4.6 Scanning direction
The scanning shall start at the lowest part of the test piece, and gradually
upward.
6.3.2.4.7 Leakage display
Leakage display or inspection shall be implemented in accordance with the way
that the instrument displays.
6.3.3 Tracer probe technology
6.3.3.1 Overview
Helium mass spectrometer leak detector leakage testing - tracer probe
technology: evacuate the test piece; connect it to the helium mass spectrometer
leak detector; then, spray helium on the tested area to test.
6.3.3.2 Scope
Helium mass spectrometer leak detector leakage testing - tracer probe
technology test method is a locating and qualitative method to test the leakage
and determine its location, which shall not be used as a quantitative analysis
method.
6.3.3.3 Calibration
6.3.3.3.1 Instrument calibration
6.3.3.3.1.1 Preheating
Before using standard leaks for calibration, power on to preheat firstly; the
minimum time of preheating shall meet the requirements of the instrument
manufacturer.
6.3.3.3.1.2 Calibration
For the instrument, use a permeable standard leak to calibrate in accordance
with the instrument manufacturer's operation and maintenance manual, so as
to make the device at the best or most appropriate sensitivity. For a helium
mass spectrometer leak detector that uses the conventional leak detection
method, at full pumping speed, the minimum sensitivity of the instrument to
helium is 1 × 10-11 Pa · m3 · s-1; for a helium mass spectrometer leak detector
that uses the counter-diffusion leak detection method, the minimum sensitivity
of the instrument to helium is 1 × 10-10 Pa · m3 · s-1.
6.3.3.3.2 System calibration
6.3.3.3.2.1 Standard leak
Connect the calibrated standard leak to the workpiece; place it away from the
connection between the helium mass spectrometer leak detector and the
workpiece as far as possible. When calibrating the test system, the calibrated
standard leak shall remain open.
6.3.3.3.2.2 Scanning rate
When the vacuumed workpiece reaches a sufficient degree of vacuum, connect
the helium mass spectrometer leak detector to the system. Use the tracer
prober to scan the standard leak to calibrate the system; the probe shall be
within 6 mm from the leak standard hole. For a known flow rate of a 100%
helium tracer probe, the scanning rate shall not exceed the rate at which a
standard leak can be detected.
6.3.3.3.2.3 Response time
During system calibration, the response time shall be no greater than 3 s, so as
to reduce the time that is required to determine the location of the leak.
Note: The response time is the time that is required to observe the appearance
of an indication signal and to stabilize the output of the instrument.
6.3.3.3.2.4 Calibration frequency and sensitivity
Unless otherwise specified, the sensitivity of the test system shall be
determined once before the test, after the test, and at an interval that does not
exceed 4 h during the test. In any one determination, the instrument deflection,
audible alarm or indicator light, if any, indicates that the system cannot detect
the leakage; then, the test system shall be recalibrated, and all test parts after
the last qualified standard shall be retested.
6.3.3.4 Test
6.3.3.4.1 Scanning rate
The maximum scanning rate shall be determined in accordance with 6.3.3.3.2.2.
6.3.3.4.2 Scanning direction
The test scanning shall start from the uppermost part of the test piece, and
gradually downward.
6.3.3.4.3 Scanning distance
The tracer probe shall sweep over the tested surface; the distance between the
probe and the tested surface during scanning shall be kept within 6 mm. If a
shorter distance is used for system calibration, it shall not exceed this distance
during the test scanning.
6.3.3.4.4 Leakage display
Leakage display and detection shall be determined according to the signal
instructions of the instrument.
6.3.4 Shield technology
6.3.4.1 Overview
Helium mass spectrometer leak detector leakage detection - shield technology:
evacuate the test piece; connect it to the helium mass spectrometer leak
detector; then, place the test piece in a helium-filled shield for testing.
6.3.4.2 Scope
The helium mass spectrometer leak detector - shield technology test method is
a quantitative measurement method to determine the location of leakage and
measure the amount of leakage.
6.3.4.3 Calibration
6.3.4.3.1 Instrument calibration
6.3.4.3.1.1 Preheating
Before using standard leaks for calibration, power on to preheat the instrument
firstly; the minimum time of preheating shall meet the requirements of the
instrument manufacturer.
6.3.4.3.1.2 Calibration
For the instrument, use a permeable standard leak to calibrate in accordance
with the instrument manufacturer's operation and maintenance manual, so as
to make the device at the best or most appropriate sensitivity. For a helium
mass spectrometer leak detector that uses the conventional leak detection
method, at full pumping speed, the minimum sensitivity of the instrument to
helium is 1 × 10-11 Pa · m3 · s-1; for a helium mass spectrometer leak detector
that uses the counter-diffusion leak detection method, the minimum sensitivity
of the instrument to helium is 1 × 10-10 Pa · m3 · s-1.
6.3.4.3.2 System calibration
6.3.4.3.2.1 Calibration leak
Connect the calibrated standard leak with 100% of helium to the workpiece;
place it away from where the leak detector is connected to the workpiece as far
as possible.
6.3.4.3.2.2 Response time
Evacuate the workpiece to an absolute pressure that is sufficient to allow the
helium mass spectrometer leak detector to connect to the system; connect the
standard leak to the system.
The standard leak shall remain open until the instrument signal is stable.
The time for the calibrated standard leak to open to the workpiece and the time
for the output signal to increase to stable shall be recorded. The time difference
between the two readings is the response time; the response time shall not be
greater than 3 s; the reading after the instrument is stable is recorded as M1.
6.3.4.3.2.3 Background reading
The background reading M2 is determined after the response time M1 is
measured. Close the standard leak and the detection system. When the reading
of the instrument is stable, record the reading of the instrument as M2.
6.3.4.3.2.4 Initial calibration
The initial system sensitivity S1 shall be calculated according to Formula (2):
Where:
S1 -- the initial system sensitivity, in pascals cubic meter per square second
(Pa · m3 · s-2);
Q -- leakage rate of the standard leak, in pascals cubic meter per second
(Pa · m3 · s-1);
M1 -- response time, in seconds (s);
M2 -- background reading, in seconds (s).
When the arrangement of the leak detection device is changed (that is, when
using the auxiliary pump to change the distribution of the helium gas flow
between the bypass and the auxiliary pump) or the calibrated leak is changed,
the calibration shall be re-performed. After completing the initial sensitivity
calibration of the system, the verified leak standard leak shall be disconnected
from the system.
6.3.4.3.2.5 Final calibration
After the system test is completed, and the workpiece is still in the shield, in the
case that the verified standard leak is closed, measure the time reading M3 of
the instrument output. Then, open the calibrated standard leak to the tested
system again; increase the instrument output to the time reading M4.
The final system sensitivity S2 shall be calculated according to Formula (3):
Where:
S2 -- the final system sensitivity, in pascals cubic meter per square second
(Pa · m3 · s-2);
Q -- leakage rate of the standard leak, in pascals cubic meter per second
(Pa · m3 · s-1);
M4 -- the reading of the calibration leak that is opened to the tested system
again after the detection;
M3 -- the background reading after the detection.
If the final system sensitivity S2 is less than 35% of the initial system sensitivity
S1, the instrument shall be tested again after cleaning or repairing and
recalibration.
6.3.4.4 Detection
6.3.4.4.1 Shield
For single-walled workpieces or parts, the shield (bagging) container can be
made of plastic and other materials.
6.3.4.4.2 Fill the shield with tracer gas
After the initial calibration is completed, between the workpiece surface and the
shield, fill with helium after the workpiece is evacuated.
6.3.4.4.3 Estimate or determine the tracer gas concentration in the shield
Determine or estimate the tracer gas concentration in the shield.
6.3.4.4.4 Detection duration
Fill the shield with helium. After the response time that is determined by
6.3.4.3.2.2, record the output reading M5 of the instrument; or if the output signal
is unstable, maintain the test duration until the output signal is stable.
6.3.4.4.5 Leakage rate that is measured by the system
After the final calibration of the workpiece is performed in accordance with
6.3.4.3.2.5, the system leakage rate shall be determined as follows:
a) For the case where the output signal does not change (namely M2 = M5),
the system leakage rate shall be recorded as "below the detectable range
of the system" and the test is qualified;
b) For the case where the output signal M5 changes (but the output signal is
still in the detectable range), the measured leakage rate Qs shall be
calculated according to Formula (4):
Where:
Qs -- measured leakage rate, in pascals cubic meter per second
(Pa · m3 · s-1);
S2 -- the final system sensitivity, in pascals cubic meter per square second
(Pa · m3 · s-2);
M5 -- detection duration, in seconds (s);
M2 -- background reading, in seconds (s);
C -- the actual helium concentration in the tested system, %.
c) For the case where the output signal M5 exceeds the detectable range of
the system, the system leakage rate shall be recorded as "greater than
the detectable range of the system" and the test is judged to be unqualified.
7 Test result judgment
7.1 Air tightness test
7.1.1 During the test, if there is no leakage, no visible deformation, and no
abnormal sound, the sample is judged to be qualified.
7.1.2 If there is leakage during the test, the test shall be repeated after repair.
7.1.3 Other requirements of the air tightness test shall be in accordance with
relevant standards.
7.2 Helium leakage test
7.2.1 Leakage
Unless otherwise provided in relevant codes, standards and/ or contracts, if the
detected leakage rate does not exceed the allowable leakage rate of 1 × 10-6
(Pa · m3 · s-1), the tested area shall be regarded as acceptable.
7.2.2 Repair and retest
When a leakage that does not meet the requirements occurs in the test, the
location of the leakage shall be marked; the test pressure shall be reduced; the
leakage shall be repaired. All reworked parts shall be retested in accordance
with 6.3.
8 Test report
8.1 The test report includes but is not limited to the following:
a) the name of the manufacturer;
b) product name, product number, model specifications;
c) plastic lining material name, plastic lining thickness;
d) test standard and test type;
e) pressure gauge accuracy, pressure gauge range, pressure gauge number,
pressure gauge verification effective date;
f) test medium, test ambient temperature;
g) helium mass spectrometer leak detector model, manufacturer, measured
leakage rate;
h) design-required pressure test curve diagram, actual pressure test curve
diagram;
i) test result.
8.2 For the format of the test report, see Appendix A.
Appendix A
(Informative)
Leakage test report
The format of the leakage test report is shown in Table A.1.
Table A.1 -- Leakage test report
Report number: Name of the manufacturer:
Product name Product number
Model
specifications
Plastic lining
material name
Plastic lining
thickness
mm
Standard code
and name on
which the test
is based
Test type
Air tightness: □
Helium leak
detection: □
Pressure
gauge
accuracy
Pressure gauge range
Pressure gauge
number
Pressure
gauge
verification
effective date
Test medium
Ambient
temperature
during the test
°C
Helium mass
spectrometer
leak detector
model
Helium mass
spectrometer
leak detector
manufacturer
Measured leakage
rate
Pa · m3 · s-1
Design-
required
pressure test
curve diagram
Actual
pressure test
curve diagram
Test result:
Inspectors:
Date:
Person in charge of inspection and test:
Date:
Inspection unit (stamp):
Date:
__________ END __________
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
|