GB/T 20801.5-2020 PDF English
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Pressure piping code - Industrial piping - Part 5: Inspection and testing
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GB/T 20801.5-2020: PDF in English (GBT 20801.5-2020) GB/T 20801.5-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 23.040
J 74
Replacing GB/T 20801.5-2006
Pressure piping code - Industrial piping - Part 5:
Inspection and testing
ISSUED ON: NOVEMBER 19, 2020
IMPLEMENTED ON: JUNE 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 6
4 Examination requirements ... 7
5 Examination methods ... 8
6 Examination scope and acceptance criteria ... 10
7 Examination process ... 19
8 Examination certificate and records ... 19
9 Testing ... 19
10 Record ... 29
Pressure piping code - Industrial piping - Part 5:
Inspection and testing
1 Scope
This Part of GB/T 20801 specifies the basic safety requirements for pressure
piping inspection, examination and testing.
This Part applies to the inspection, examination and testing of pressure piping
which is defined by the scope of GB/T 20801.1.
2 Normative references
The following referenced documents are indispensable for the application of
this document. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any
amendments) applies.
GB/T 20801.1-2020, Pressure piping code - Industrial piping - Part 1:
General
GB/T 20801.2-2020, Pressure piping code - Industrial piping - Part 2:
Materials
GB/T 20801.3-2020, Pressure piping code - Industrial piping - Part 3: Design
and calculation
GB/T 20801.4-2020, Pressure piping code - Industrial piping - Part 4:
Fabrication and assembly
GB/T 20801.6-2020, Pressure piping code - Industrial piping - Part 6:
Safeguarding
NB/T 47013.1, Nondestructive testing of pressure equipments - Part 1:
General requirements
NB/T 47013.2, Nondestructive testing of pressure equipments - Part 2:
Radiographic testing
NB/T 47013.3, Nondestructive testing of pressure equipments - Part 3:
Ultrasonic testing
NB/T 47013.4, Nondestructive testing of pressure equipments - Part 4:
Magnetic particle testing
Examination personnel
The full-time personnel engaged in the examination work in the manufacturing
plant, fabrication, construction, and erection units, which shall be held by
personnel independent of the manufacturing, fabrication and erection
departments.
4 Examination requirements
4.1 General provisions
4.1.1 This Chapter stipulates the piping installation, including requirements for
the examination of each component and its fabrication and processing
technology, additional examinations and acceptance standards required by any
engineering design. The examination of the chromium-molybdenum alloy steel
piping in Table A.1 of GB/T 20801.2-2020 shall be carried out after the end of
all heat treatment; the welding of branch piping and the repair of pressure-
bearing welded joints shall be completed before the welding of reinforcement
rings or saddle-shaped reinforcement parts.
4.1.2 The examination and testing of the piping components (or their elements)
which are processed by the factory shall meet the requirements of relevant
product standards and design documents.
4.2 Acceptance criteria
The examination and testing requirements, which are given in this Part, are
basic safety requirements. When there are special examination and testing
requirements in the design document, the examination, testing and acceptance
shall be carried out in accordance with the requirements of the design document.
4.3 Processing of out-of-gauge defects
The inspected parts, which are found to have defects that exceed the
acceptance criteria of this Part, shall be repaired or replaced. The new part shall
be inspected in the same way with the same acceptance criteria in the same
scope according to the requirements of the original.
4.4 Progressive examination
When out-of-gauge defects are found in partial or sampling examination, they
shall be dealt with according to the following requirements:
a) Take another two identical parts (if they are welded joints, they shall be
welded joints in the same batch and welded by the same welder) for the
same examination;
b) If the two inspected parts required by a) pass the examination, the batch
represented by the additional examination shall be deemed qualified, but
the defective parts shall be repaired or replaced for re-examination;
c) If any one of the two inspected parts required by a) is found to have an
out-of-gauge defect, two identical parts shall be added for each defect
item for examination;
d) If the two inspected parts required by c) pass the examination, the batch
represented by the additional examination shall be deemed qualified, but
the defective parts shall be repaired or replaced for re-examination;
e) If any one of the two inspected parts required by c) is found to have out-
of-gauge defects, all the batch shall be examined, and the unqualified
shall be repaired or replaced for re-examination;
f) If the defective part, after repair or re-examination after being replaced, is
found to have an out-of-gauge defect again, for the defect found in the
repair, it is not necessary to continue the progressive examination
according to a), c), and e); however, the out-of-gauge defective part shall
be repaired or replaced for re-examination, until it meets the acceptance
criteria of this Part. If possible, other un-examined welded joints can also
be examined partially or randomly.
4.5 Examination personnel
Field fabrication and welding examination and testing, if there is no special
indication, shall be carried out by the construction unit. The examination
personnel shall meet the definition in 3.4.
5 Examination methods
5.1 General provisions
5.1.1 This Chapter specifies the main examination methods that confirm to this
Part, the engineering design or the inspector’s requirements. If methods other
than those specified in this Chapter are used, the acceptance criteria shall be
specified in the engineering design.
5.1.2 The examination ratio includes 100% examination, sampling examination
and partial examination, which are defined as follows:
a) It is called 100% examination when, in a designated batch of piping, a
certain specific item is completely examined;
b) It is called sampling examination when, in a designated batch of piping, a
certain percent of a certain specific item is completely examined;
5.4 Hardness examination
Welded joints, hot bending and hot formed components shall be subjected to
the hardness examination, to check the reliability of the heat treatment process.
The number and requirements of the hardness examination shall comply with
the relevant regulations of GB/T 20801.4-2020.
6 Examination scope and acceptance criteria
6.1 Examination grade
6.1.1 Pressure piping is divided into five examination grades I, II, III, IV, V
according to piping grade, material category and nominal pressure. When
pressure piping is divided into different examination grades according to 6.1.2
~ 6.1.6, the examination grade shall be determined according to the higher
examination grade. Special requirements in relevant design documents, if any,
shall also be met.
6.1.2 The examination grade of the pressure piping that meets one of the
following conditions is grade I:
a) Piping, of which the design document indicates severe cyclic conditions;
b) Grade GC1 piping;
c) Piping used for elevated temperature fluid service (as shown in 3.2 of GB/T
20801.3-2020);
d) Titanium and titanium alloys, nickel and nickel-based alloys, high-
chromium-nickel-molybdenum austenitic stainless steel, zirconium and
zirconium-based alloy piping;
e) Piping whose nominal pressure is greater than PN160;
f) The inner pipe of the jacketed pipe;
g) Piping that can be exempted from pressure test according to 9.1.7;
h) Piping that is required for 100% non-destructive testing of welded joints
by the design.
6.1.3 The examination grade of the pressure piping that meets one of the
following conditions is grade II:
a) Carbon steel piping whose nominal pressure is greater than PN50 (impact
test required in this Part);
b) Austenitic stainless steel piping whose nominal pressure is greater than
PN110;
c) Low-temperature nickel-containing steel, chromium-molybdenum alloy
steel, duplex stainless steel, aluminum and aluminum alloy piping;
d) Piping that is required for 20% non-destructive testing of welded joints by
the design.
6.1.4 The examination grade of the pressure piping that meets one of the
following conditions is grade III:
a) Grade GC2 piping whose toxic degree is toxicity;
B) Carbon steel piping, except for grade GC3 piping, whose nominal
pressure is not greater than PN50 (impact test is required in this Part);
c) Austenitic stainless steel piping, except for grade GC3 piping, whose
nominal pressure is not greater than PN110;
d) Piping that is required for 10% non-destructive testing of welded joints by
the design.
6.1.5 The examination grade of the pressure piping that meets one of the
following conditions is grade IV:
a) Grade GC2 piping other than 6.1.4a);
B) Carbon steel piping, except for grade GC3 piping, whose nominal
pressure is not greater than PN50 (there is no impact test requirement in
this Part);
c) Piping that is required for 5% non-destructive testing of welded joints by
the design.
6.1.6 The examination grade of grade GC3 pressure piping is grade V.
6.2 Visual examination
6.2.1 The contents of the visual examination shall meet the following
requirements:
a) For grades GC2 and GC3 piping, it shall meet the requirements of 5.2.
The items for visual examination are:
1) Randomly select a sufficient number of materials and piping
components, so that the examination personnel is satisfied that they all
meet the technical requirements and are free of defects;
6.3.1 Non-destructive testing methods
The non-destructive testing methods shall meet the following requirements:
a) The non-destructive testing of welded joints of pressure piping shall adopt
the methods specified in NB/T 47013.2, NB/T 47013.3, NB/T 47013.4,
NB/T 47013.5, NB/T 47013.10, and NB/T 47013.11. When the non-
recordable pulse reflection method is used for ultrasonic testing,
radiographic testing or ultrasonic time of flight diffraction technique shall
be used as additional local or sampling testing.
b) For butt joints, of which the nominal thickness of the piping is less than or
equal to 30 mm, radiographic testing shall be preferred. The use of
ultrasonic testing instead of radiographic testing shall be agreed by the
designer and owner; butt joints, of which the nominal thickness is greater
than 30 mm, can be subjected to ultrasonic testing instead of radiographic
testing.
c) Butt joints of non-ferrous metal pressure piping shall be subjected to X-ray
inspection preferentially.
d) Surface cracks of welded joints shall be subjected to surface non-
destructive testing preferentially.
e) The surface inspection of the welded joints of pressure piping made of
ferromagnetic materials shall be subjected to magnetic particle testing
preferentially.
6.3.2 Radiographic and ultrasonic testing of welded joints
6.3.2.1 Unless otherwise specified in the design documents, the butt joints and
branch joints of piping and piping components which are welded on site shall
be subjected to radiographic or ultrasonic testing. The examination quantity
shall meet the following regulations:
a) When the nominal diameter of the piping is less than 500 mm, the
sampling inspection can be carried out in accordance with the examination
ratio in Table 1 according to number of circular butt joints; there shall be
no less than 1 circular butt joint. All the circular butt joints to be tested shall
include the entire circumference. The sampling inspection ratio of fixed
welded circular butt joints shall not be less than 40% of the testing quantity;
b) When the nominal diameter of the piping is greater than or equal to 500
mm, each circular butt joint shall be partially inspected according to the
examination ratio in Table 1, and the examination length shall not be less
than 150 mm;
c) Longitudinal butt joints shall be tested according to the examination ratio
in Table 3; the length of partial examination shall not be less than 150 mm;
d) The welded joints of chromium-molybdenum alloy steel pipes and fittings
used for elevated temperature fluid service shall be subjected to 100%
radiographic testing or ultrasonic testing;
e) When selecting welded joints to be inspected, the welded joints welded by
each welder or welding operator participating in the welding of the product
shall be included, and the intersection with the longitudinal welded joint
shall be included to the maximum extent. When the circular welded joint
and the longitudinal welded joint intersect, the adjacent longitudinal
welded joint of an examination length of not less than 38 mm shall be
included.
6.3.2.2 Radiographic testing shall be carried out in accordance with the
provisions of NB/T 47013.2 and NB/T 47013.11. The quality requirements and
qualification grades are as follows:
a) For welded joints subjected to all non-destructive testing, the radiographic
testing technology grade is not lower than grade AB, and the qualification
grade is not lower than grade II;
b) For partial or sampling welded joints, the radiographic testing technology
grade is not lower than grade AB, and the qualification grade is not lower
than grade III.
6.3.2.3 Ultrasonic testing shall be carried out in accordance with the provisions
of NB/T 47013.3 and NB/T 47013.10; the quality requirements and qualification
grades are as follows:
a) For welded joints subjected to all non-destructive testing, the pulse
reflection method ultrasonic testing technology grade is not lower than
grade B, and the qualification grade is grade I;
b) For partial or sampling welded joints, the pulse reflection method
ultrasonic testing technology grade is not lower than grade B, and the
qualification grade is not lower than grade II;
c) For welded joints subjected to ultrasonic time of flight diffraction technique,
the testing technology grade, in principle, is not lower than grade B, and
the qualification grade is not lower than grade II;
6.3.2.4 When radiographic, ultrasonic and other methods are used for
combined non-destructive testing, the quality requirements and qualification
grades shall be determined in accordance with the respective implemented
standards, and all shall be qualified.
9.1.1.1 Replacement of the pressure test
The replacement of the pressure test shall meet the following requirements:
a) For grade GC3 piping, with the consent of the owner or designer, the initial
operating pressure testing specified in 9.1.6 can be used instead of the
hydraulic test.
b) When the owner or designer thinks that the hydraulic test is impractical,
the air pressure testing specified in 9.1.4 can be used instead; if the
danger of the air pressure testing is taken into account, the hydraulic-air
pressure testing specified in 9.1.5 can also be used instead.
c) When the owner or designer believes that both the hydraulic test and the
air pressure testing are impractical, if both of the following conditions exist,
the exemption (or alternative) method specified in 9.1.7 can be adopted:
1) The hydraulic test will damage the lining or internal insulation, or pollute
the production process (the process will become dangerous, corrosive
or inoperable due to moisture), or cause the pipe-supporting structure
overloaded due to the test load, or have a risk of brittle fracture due to
low temperature in the test;
2) The air pressure testing has a greater risk than the hydraulic test, or
may have the risk of brittle fracture due to low temperature in the test.
d) The piping that is used to discharge and are connected to the atmosphere,
such as the vent piping or the sewage piping after the last shut-off valve,
do not need to be subjected to pressure test unless there are special
regulations in the design.
9.1.1.2 Pressure limitation
The limitation of test pressure shall meet the following requirements:
a) If the piping circumferential stress or axial stress generated by the test
pressure exceeds the yield strength at the test temperature, the test
pressure can be reduced to the maximum pressure that does not exceed
the yield strength at that temperature;
b) If the test pressure needs to be maintained for a period of time, and the
test fluid in the piping system is subject to thermal expansion, care shall
be taken to avoid overpressure;
c) Before the hydraulic test, use air with a pressure not greater than 170 kPa
to find the leakage point.
9.1.1.3 Other test requirements
Other test requirements shall meet the following requirements:
a) The holding time of the pressure test is not less than 10 minutes; the
pressure can be reduced to the design pressure after holding the pressure;
all joints and connections shall be checked for leakage and other
abnormalities;
b) The pressure test shall be carried out after all heat treatment is completed;
c) When the pressure test is carried out at a temperature close to the ductility-
brittle transition temperature of the metal, the possibility of brittle failure
shall be considered.
9.1.1.4 Special provisions for pressure test
The special (exempt) provisions for the pressure test are as follows:
a) The piping components or piping prefabricated parts can be tested
individually or assembled on the piping and tested together with the piping;
b) The flanged joints that have been tested before the assembly of the piping
system and the flange joints that are inserted into the blind plate to isolate
the vessel or other piping during the pressure test do not need to be
subjected to the pressure test again;
c) If the last welded joint connecting the piping system or component has
been inspected during the production process according to the provisions
of 6.4, and has passed 100% radiographic testing or 100% ultrasonic
testing, and the piping system or component has passed the pressure test
in accordance with this chapter, this welded joint does not need to be
subjected to the pressure test again;
d) The instrument joints (threads and/or other pipe joints) after the pressure
test of the piping system do not need to be tested for pressure again.
9.1.1.5 Vacuum or external pressure piping
The pressure test of vacuum or external pressure piping shall meet the following
requirements:
a) Vacuum or external pressure piping shall be subjected to the internal
pressure test at 1.5 times the internal and external pressure difference,
which, however, shall not be less than 105 kPa;
b) With the consent of the owner or designer, for the vacuum piping, a
vacuum test can be used to replace the internal pressure test listed in a),
but corresponding test procedures shall be developed.
c) For grade GC3 piping, with the consent of the owner or designer, during
the hydraulic test or initial operating pressure test, the joint can be covered
with a thermal insulation layer or a covering layer, but the pressure holding
time shall be extended to observe whether there are leaks and other
abnormalities.
9.1.2.2 Temporary supports
If necessary, the piping for conveying steam or gas shall be equipped with
temporary supports to support the weight of the test fluid.
9.1.2.3 Expansion joint
During the pressure test, the expansion joint shall meet the following
requirements:
a) For metal corrugated expansion joints, if the test pressure determined in
accordance with the requirements of this chapter is greater than the test
pressure of the manufacturer (in accordance with the requirements of
Appendix F of GB/T 20801.3-2020), the test pressure of the manufacturer
shall be used;
b) Except for the case of a), the unconstrained expansion joints that rely on
the external main fixing frame to restrain the end pressure load shall be
tested on the piping system at 1.5 times the design pressure of the
expansion joint without temporary restraint. If the test pressure required
by the system is greater than 1.5 times the design pressure of the
expansion joint, and the main fixing frame cannot withstand this pressure
test load, then, the expansion joint shall be removed from the piping
system, or temporary restraints shall be adopted to withstand the pressure
test load;
c) Except for the case of a), self-constrained metal corrugated expansion
joints (i.e., duplex, hinged and pressure balanced, etc.) with restraining
components to withstand pressure loads and their piping systems shall be
subjected to pressure test in accordance with the requirements of this
chapter. If the pressure test has been carried out by the manufacturer, the
pressure test can be isolated from the system (but does not include the
sensitivity leakage test). The restraint components of all types of
expansion joints shall be designed to ensure that they can withstand the
load under the test pressure.
9.1.2.4 Partition of piping pressure test
The vessel that is not to be tested shall be separated from the piping during the
pressure test of the piping system, or be separated from the piping by blind
...... Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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