This standard is applicable to ultrasonic flaw detection of high-pressure seamless steel pipes used in the manufacture of boilers, ships, aircraft, etc. and in the manufacture of petroleum, chemical industry, etc. It can also be used as a reference for ultrasonic flaw detection of seamless steel pipes for other purposes. GB 5777-1986 Ultrasonic flaw detection method for seamless steel pipes GB5777-1986 standard download decompression password: www.bzxz.net

1 Introduction
GB5777-86 Ultrasonic flaw detection method for seamless steel pipes 1.1 This standard is applicable to ultrasonic flaw detection of high-pressure seamless steel pipes for the manufacture of boilers, ships, aircraft, etc. and for the petroleum, chemical and other industries. It can also be used as a reference for ultrasonic flaw detection of seamless steel pipes for other purposes. 1.2 This standard is applicable to seamless steel pipes with an outer diameter of 12-480mm and a wall thickness of 2-30mm (or stainless steel pipes with an outer diameter of 12-160mm and a wall thickness of 2-10mm). The flaw detection of other special specifications of steel pipes shall be negotiated by the supply and demand parties. 1.3 The flaw detection method described in this standard is mainly to detect longitudinal or transverse defects of steel pipes, but cannot effectively detect delamination defects.
2 Flaw detection method
2.1 Using the transverse wave pulse reflection method, when the probe is rotated circumferentially and moved axially relative to the steel pipe, the liquid immersion method or contact method is selected according to the steel pipe specifications. 2.2 When detecting longitudinal defects, whether the ultrasonic wave is transmitted from the center line of the steel pipe cross section to the center line of the steel pipe cross section is determined by the ultrasonic wave pulse reflection method. The ultrasonic beam is incident obliquely from the side and propagates in a zigzag shape along the circumferential direction in the pipe wall (as shown in Figure 1). When detecting transverse defects, the ultrasonic beam is incident obliquely along the axial direction and propagates in a zigzag shape (as shown in Figure 2).
2.3 Both the immersion method and the contact method should use a coupling medium with good coupling effect and no damage to the surface of the steel pipe. 2.4 The determination of the inspection result is based on the comparison of the amplitude of the defect echo of the inspected steel pipe and the artificial defect echo of the comparison sample, which is an equivalent method.
3 Preparation and requirements of comparison samples
3.1 Materials
Comparison samples should be prepared from steel pipes with the same specifications, materials, heat treatment processes and surface shapes as the inspected steel pipes. The comparison samples shall not have natural defects that affect the normal indication of artificial defects. 3.2 Length
The length of the comparison sample shall meet the requirements of the flaw detection method and flaw detection equipment. 3.3 Artificial defects
3.3.1 Shape
When detecting longitudinal defects, The artificial defect is a longitudinal groove, and its cross-sectional shape is U-shaped, V-shaped or rectangular (as shown in Figure 3). When detecting transverse defects, the artificial defect is a transverse groove, and its cross-sectional shape is arched, rectangular or V-shaped (as shown in Figure 4). When quality disputes occur between the supply and demand parties, the longitudinal and transverse artificial defects shall be based on U-shaped and rectangular respectively.
3.3.2 Position
The longitudinal groove shall be processed on the inner and outer surfaces of the specimen respectively, but the steel pipe with an inner diameter less than 25mm can be processed only on the outer surface. The transverse groove is generally only processed on the outer surface, but the steel pipe with an outer diameter of not less than 80mm and a wall thickness of not less than 10mm shall be processed on the inner surface at the same time. There should be enough spacing between the inner and outer surface artificial defects of the same specimen along the axial direction of the steel pipe to make it easy to distinguish during dynamic debugging
3.3.3 Size
3.3.3.1 For steel pipes with a wall thickness/outer diameter less than 0.200, the depth of the artificial defect shall be determined by the supply and demand parties according to the type and purpose of the steel pipe. Table 1 specifies. For steel pipes with a wall thickness/outer diameter of 0.200-0.250, the depth of artificial defects on the outer surface is the same as the above provisions, and the depth of artificial defects on the inner surface is in accordance with the provisions of Table 2. 3.3.3.2 The allowable deviation of the depth of artificial defects is ±15% (the minimum value is ±0.05mm). 3.3.3.3 The width is not more than twice the depth, but the widest is not more than 1.50mm. 3.3.3.4 The effective length is 20-80mm
3.3.3.5 The angle of the V-shaped groove is 60°
3.3.4 Production and measurement
The longitudinal U-shaped groove is processed by electro-etching. The longitudinal V-shaped groove, rectangular groove and transverse groove are all processed by mechanical methods. The groove depth is measured by optical methods or other methods with an accuracy of 0.01mm or more. 4 Flaw detection equipment and its debugging
4.1 Flaw detection equipment
The flaw detection equipment consists of an ultrasonic flaw detector, a probe, a mechanical transmission device and other necessary auxiliary devices. 4.1.1 The flaw detector shall be a pulse reflection multi-channel or single-channel instrument. Its attenuator, vertical linear error, dynamic range and horizontal linear error shall comply with the provisions of Article 3.2 of ZBY230-84 "General Technical Requirements for Type A Pulse Reflection Ultrasonic Flaw Detectors"
4.1.2 For flaw detectors with alarm devices, the alarm sensitivity shall be continuously adjustable within 20%-100% of the full range. The alarm gate drift and alarm sensitivity fluctuation shall not exceed 2Ⅱs and ±5% respectively when the instrument works continuously for 4 hours. 4.1.3 Liquid immersion flaw detection uses line focusing probe The contact method of flaw detection uses an oblique probe that fits the steel pipe surface well. The length or diameter of the piezoelectric chip of a single probe shall not exceed 25 mm. 4.1.4 In addition to meeting the requirements of Articles 2.1 and 2.2 of this standard, the mechanical transmission device shall ensure that the relative rotation and linear motion speed between the probe and the steel pipe is stable within ±10% of the value calculated according to the requirements of Article 5.1.3 of this standard. The length of the steel pipe end that cannot be effectively detected due to the equipment itself shall not exceed 200 mm. 4.1.5 The comprehensive sensitivity of the flaw detection equipment composed of the flaw detector, probe and mechanical transmission device shall be able to Reliably detect the artificial defects specified in Article 3.3 of this standard 4.2 Equipment debugging
4.2.1 Each time the flaw detection equipment is reused or the inspection specifications are changed, the double comparison test specimens specified in this standard shall be used for static and dynamic debugging.
4.2.2 Static debugging shall obtain clear artificial defect echoes, and the echo used for alarm shall be adjusted to a certain amplitude between 50%-100% of the full amplitude as the reference amplitude. When an alarm gate is used for internal and external surface defects, the difference in the reference amplitude of the artificial defect echoes on the internal and external surfaces after debugging shall not be greater than 2dB, and the difference shall be between 2dB and 100%. The lower the amplitude, the higher the alarm sensitivity. The inner and outer surface defects of thick-walled pipes should be alarmed by two alarm circuits as far as possible. 4.2.3 Dynamic debugging is carried out under production inspection conditions. After debugging, the sensitivity fluctuation in the circumferential direction should not exceed ±2dB to ensure good repeatability of artificial defect detection. 5 Flaw detection conditions and steps
5.1 Flaw detection conditions
5.1.1 The steel pipe is inspected in the effective state, and its inner and outer surfaces must be clean. When mechanized flaw detection is carried out, the steel pipe should have good straightness to pass through the flaw detection device smoothly. 5.1.2 The detection frequency is 2.5-10Mhz
5.1.3 The pitch of the probe relative to the spiral feed of the steel pipe should ensure that the ultrasonic beam scans 100% of the steel pipe surface and has a coverage rate of not less than 10%
5.2 Flaw detection steps
5.2.1 After the flaw detection equipment is debugged according to the provisions of 4.2.2 and 4.2.3 of this standard, it can be used for flaw detection. Generally, only longitudinal defects are detected, and the detection of transverse defects is negotiated by the supply and demand parties. 5.2.2 During continuous use, the equipment needs to be tested every 2-4 hours and before each shutdown. If the equipment does not meet the requirements of 4.2.3 of this standard, the equipment should be re-debugged. After debugging, the steel pipes that were inspected last time should be re-inspected.
6 Result evaluation
6.1 After the inspection, if there is no defect echo or the defect echo amplitude is less than the reference amplitude of the artificial defect echo of the comparison sample, it is judged as qualified.
6.2 After the inspection, if the defect echo amplitude is equal to or greater than the reference amplitude of the artificial defect echo of the comparison sample, it is judged as unqualified. The supplier is allowed to reprocess the unqualified products. If they meet the requirements after processing The standard stipulates that ultrasonic testing can be re-performed. After testing, if it meets the requirements of Article 6.1 of this standard, it can be judged as qualified. 7. Testing report
When the purchaser requires, the supplier shall provide a testing report issued by a technical qualification personnel of ultrasonic level II or above recognized by the relevant department. The testing report shall include the following contents: a. Furnace batch number, steel grade, specification, number of roots; b. Flaw detector model, probe type and specification, testing method; c. Flaw detection standard, including the shape of artificial defects of the comparison sample and the depth code of artificial defects in Table 1 of this standard; d. Flaw detection results:
e. Inspection date, operator name, name of the signer and their technical qualification level. Additional notes:
This standard was proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard was drafted by Shouzhe Iron and Steel Company Special Steel Company. The main drafter of this standard is Yang Xuezhi. www.bzxz.net
From the date of implementation of this standard, the former Ministry of Metallurgical Industry standard YB943-78 "Ultrasonic Inspection Method for High-Pressure Seamless Steel Tubes for Boilers" will be invalidated.
This standard refers to the American Society for Testing and Materials standard ASTME213-83 "Ultrasonic Inspection Standard for Metal Pipes"
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