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GB/T 20801.5-2020 English PDF (GBT20801.5-2020)

GB/T 20801.5-2020 English PDF (GBT20801.5-2020)

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GB/T 20801.5-2020: Pressure piping code - Industrial piping - Part 5: Inspection and testing

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.
GB/T 20801.5-2020
GB
NATIONAL STANDARD OF THE
PEOPLE 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 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 b...

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