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GB/T 9444-2019 PDF in English

GB/T 9444-2019 (GB/T9444-2019, GBT 9444-2019, GBT9444-2019)
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GB/T 9444-2019: PDF in English (GBT 9444-2019)

GB/T 9444-2019
ICS 77.040.20
J 31
Replacing GB/T 9444-2007
Steel and iron castings - Magnetic particle inspection
(ISO 4986:2010, Steel castings - Magnetic particle inspection, MOD)
Issued by: State Administration for Market Regulation.
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 6
4 General requirements ... 6
5 Acceptance criteria ... 9
6 Indication ratings and evaluations ... 12
7 Reinspection ... 13
8 Inspection records and reports ... 13
Appendix A (Informative) Comparison of Article numbers and technical differences
with the original standards when adopting international standards and their reasons 16
Appendix B (Informative) Recommended surface roughness for magnetic particle
inspection ... 19
Appendix C (Informative) Quality grade reference diagram (single) for non-linear
indication (SM) ... 20
Appendix D (Informative) Quality grade reference diagram for line indication (LM)
and aligned indication (AM) ... 25
Appendix E (Informative) Magnetic particle inspection report format ... 40
References ... 42
Steel and iron castings - Magnetic particle inspection
1 Scope
This standard specifies the general requirements, acceptance criteria, indicated grading
and evaluation, re-inspection, inspection records and reports, etc., for magnetic particle
inspection of steel and iron castings.
This standard is applicable to magnetic particle inspection of surface and near-surface
defects in ferromagnetic iron and steel castings.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
GB/T 5097 Non-destructive inspection - Penetrant inspection and magnetic particle
inspection - Viewing conditions (GB/T 5097-2005, ISO 3059:2001, IDT)
GB/T 9445 Non-destructive inspection - Qualification and certification of NDT
personnel (GB/T 9445-2015, ISO 9712:2012, IDT)
GB/T 12604.5 Non-destructive inspection - Terminology - Terms used in magnetic
particle inspection
GB/T 15822.1 Non-destructive inspection - Magnetic particle inspection - Part 1:
General principles (GB/T 15822.1-2005, ISO 9934-1:2001, IDT)
GB/T 15822.2 Non-destructive inspection - Magnetic particle inspection - Part 2:
Inspection media (GB/T 15822.2-2005, ISO 9934-2:2002, IDT)
GB/T 15822.3 Non-destructive inspection - Magnetic particle inspection - Part 3:
Equipment (GB/T 15822.3-2005, ISO 9934-3:2002, IDT)
GB/T 23906 Non-destructive inspection - Rings for magnetic particle inspection
GB/T 23907 Non-destructive inspection - Shims for magnetic particle inspection
of defects and sensitivity requirements that need to be detected. The inspection
sensitivities of different inspection methods are different, which shall be determined
based on the surface roughness, batch size, inspection conditions, ordering information
of the inspected parts.
4.3.2 The timing of inspection is usually based on delivery status or contract stipulations.
4.3.3 Inspection technology shall include: surface cleaning methods, surface roughness,
inspection methods, indication observation, recording and evaluation, as well as
demagnetization and cleaning requirements after inspection.
4.3.4 Before inspection, it shall be verified whether the surface magnetic field intensity
of iron and steel castings meets the requirements. When the magnetic field intensity on
the surface of the iron and steel casting is 2.4 kA/m, if the magnetic induction intensity
is greater than 1 T, it can be determined that the iron and steel casting is ferromagnetic.
4.3.5 During inspection, magnetization shall be carried out in two mutually
perpendicular directions. When mutually perpendicular magnetization is not possible,
the supplier and the buyer shall reach an agreement on the magnetization direction.
Magnetization may be performed in one direction, unless otherwise specified or when
the direction of stress is known and only the most dangerous defects are to be inspected.
4.3.6 Magnetization and media application shall comply with standard requirements.
For example, in the continuous method, the inspection medium shall be continuously
applied just before magnetization and during the magnetization process; magnetization
shall continue for a certain period of time after stopping the application of the inspection
medium, so that there is enough time to form magnetic traces.
4.3.7 Castings shall be cleaned when required after inspection. In the final delivery state,
when the residual magnetism of the casting is higher than the specified maximum
residual magnetic induction value, it shall be demagnetized.
4.4 Personnel qualifications
Inspection personnel shall meet the requirements stipulated in GB/T 9445 or other
relevant standards; hold qualification certificates issued by the corresponding
assessment institutions. The qualifications of inspection personnel shall be
unanimously recognized by both the supplier and the buyer.
4.5 Surface requirements
4.5.1 The surface of the workpiece shall be inspected before inspection. The surface to
be inspected shall be clean, dry, free of oil, grease, sand, rust, or other contaminants and
coatings that would interfere with the implementation of the test and the evaluation of
the test results.
4.5.2 Surface contaminants and coatings can be treated by one or several methods (the
applicability and impact on the parts being inspected must be considered). Surface
treatment methods can include cleaning, water washing, solvent (solution) cleaning,
steam degreasing, pickling, alkali washing, ultrasonic cleaning, mechanical cleaning,
4.5.3 The surface to be inspected can be sandblasted, shot peened, polished or machined;
however, the impact of sandblasting and shot peening on defect inspection shall be
4.5.4 Based on the need to evaluate the minimum size of magnetic trace indication,
please refer to Appendix B for the recommended surface roughness for magnetic
particle inspection.
4.5.5 Thin (not larger than 0.05 mm) non-conductive coating generally will not interfere
with the formation of magnetic traces; however, the coating at the conductive contact
point shall be removed.
4.6 Observation conditions
Observation conditions shall comply with the provisions of GB/T 5097. It shall be
observed visually or with a 3X maximum magnification.
5 Acceptance criteria
5.1 Types of defects
According to the shape and size of the defective magnetic trace indication, measure the
length L and width b of the indication; determine the defect indication type according
to the aspect ratio. Indication types are divided into three categories: non-linear
indication (SM), linear indication (LM), aligned indication (AM).
5.2 Quality grade
5.2.1 General requirements
The quality grade is determined in advance. Different quality grade acceptance can be
selected, for the shape and size indication of different types of defects. The rectangular
evaluation area is 105 mm × 148 mm.
5.2.2 Non-linear indication Table 1 specifies the quality grades of non-linear indications. The minimum length of the indication that needs to be evaluated is L1.
Indications that are shorter than this length do not need to be evaluated. The maximum length allowed to be indicated is L2.
5.2.5 Quality grade expression method The method of expressing quality grades in contracts and test reports shall
comply with this standard. Examples of correct expression methods are as follows:
- Non-linear indication level 2: SM2;
- Linear indication level 5, wall thickness interval category a: LM5a.
6 Indication ratings and evaluations
6.1 Overview
6.1.1 The nature of defects (such as cracks, shrinkage holes, etc.) does not need to be
considered when grading and evaluating according to indication types, unless otherwise
specified in the agreement. When there is a dispute about the nature of a defect, other
inspection methods may be used for confirmation.
Note: Indications are not necessarily all defects. For example, false defects or other factors may
also produce magnetic trace indication.
6.1.2 The assessment result of quality grade is only the quality of the current surface
condition of the workpiece. When the force or surface condition changes in the future
(such as processing, etc.), the quality grade needs to be re-confirmed according to this
6.1.3 There are slight differences between the values in Table 2 and the corresponding
quality grade reference diagram. The quality grades in Table 2 are the same as the
quality grades of the corresponding reference diagram. If there is a dispute, the data in
the Table will be the final basis for judgment.
6.2 Indication rating
6.2.1 General requirements During rating and evaluation, the 105 mm × 148 mm rectangular evaluation area
shall be in the most serious position. When the inspection area is less than 105 mm × 148 mm, the allowed indication
quantity, indication length and cumulative length should be converted according to the
area ratio; however, in principle it shall not be increased by one quality grade. The inspection area for weld repairs of castings is the repair welding area and
25 mm outside the boundary.
6.2.2 Non-linear indication For indications whose length is evaluated to be greater than or equal to L1 and
less than or equal to L2 (see Table 1), the maximum size of the indication shall be the
length of the indication. The quality grade of non-linear indication shall be evaluated according to Table
6.2.3 Linear indication and aligned indication According to the wall thickness of the inspection area, measure the length
indicated greater than or equal to L1 and less than or equal to L2. Calculate the
cumulative length indicated in the assessment area. The cumulative results shall be
compared with the "accumulation" in Table 2. The linear and aligned indications shall
be evaluated according to Table 2. The aligned indication length is the total length of indication and spacing.
6.3 Evaluation of test results
When the defect indication level is better than or equal to the quality grade specified in
the contract, it can be judged to be in compliance with this standard. When non-linear
indications, linear indications, or aligned indications appear simultaneously in the same
area of the casting, rate them according to Table 1 and Table 2, respectively.
7 Reinspection
Re-inspection is required when the following situations occur:
- The operation method is wrong during the inspection process.
- Verify that the inspection sensitivity does not meet the requirements at the end of
the test.
- There is doubt on inspection results.
- The parties to the contract have disputes or deem it necessary.
8 Inspection records and reports
8.1 Inspection records
8.1.1 Record relevant inspection information (see 4.2).
8.1.2 If there are no special provisions in the agreement, it shall record at least all
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.