Non-Destructive Testing of Railway Tankers

The main role of NDT is to ensure product quality and prevent parts or materials from failing to meet the designed functional requirements during use. The extent to which NDT guarantees product quality depends on the reliability of NDT. One of the many factors that affect the reliability of NDT is the NDT processability of the product.

NDT

The role and content of the NDT process review 

NDT processability is the ability of the product's components to adapt to the NDT process, i.e. the possibility or ease of obtaining a qualified product in accordance with the process methods specified in the NDT standard.

When the product drawings containing NDT requirements are initially completed, they should generally be reviewed by NDT engineers for NDT processability. 

The NDT process review has three main aspects.

① Whether the testing parts, testing methods and testing ratios comply with the relevant product regulations and standards.

② Whether the non-destructive testing standards, testing technology levels and qualification levels used for the product are correct.

③ Product structure, materials, etc. can be non-destructive testing in accordance with the method specified in the drawings.

NDT process reviewers should understand the regulations and standard systems implemented for products and be familiar with the range of capabilities and limitations of NDT standards and various NDT methods. Therefore, each unit generally has NDT level 3 personnel to implement the NDT processability review.

Problems found in the process review and improvement measures 

① Ultrasonic inspection of butt welds in the bottom frame

In addition to bearing the gravity of the tank, the bottom frame of the tank also transmits the traction force of the train and is a stressed steel structure.

With reference to the previous drawings, the designers specified the technical requirements for non-destructive testing as "24 hours after the completion of butt welding of the centre beam, ultrasonic testing of the welded joint will be carried out according to Grade B as specified in GB/T 11345, with Grade 1 passing."

②Nondestructive testing of outer tank head butt welds

The material of the outer tank end head of the railway tank car is 16MnDR, which is cold-pressed from two plates after splicing, and the design requires 100% radiographic inspection of this splice weld.

Non-destructive testing

The NDT processability reviewer consulted the relevant General Administration of Quality Supervision, Inspection and Quarantine safety technical code (TSG R0005-2011 "Safety Technical Supervision Regulations for Mobile Pressure Vessels"), which stipulated that the butt joint should also be subject to magnetic particle testing. After communication with the designer, the design drawings added the requirement for 100% magnetic particle testing of the head splice joint.

 ③ Ultrasonic testing of the ring seam at the outer tank end

According to the General Administration of Quality Supervision, Inspection and Quarantine safety specifications, the outer tank body butt welds of the LNG railway tank car should be subject to radiographic or ultrasonic testing, and as the end ring seams B11 and B17 of the outer tank body cylinder and head joint were already assembled when the inner tank was welded, radiographic testing could not be carried out and ultrasonic testing could only be considered.

The difficulties of ultrasonic inspection of the welded joint include: the length of the straight edge of the end ring seam head is only 40mm, and when the large-angle probe is used for the thin plate, the probe movement range is insufficient; when detecting from the barrel side, ultrasonic waves will enter the pad and barrel fillet weld, and there is a partial detection blind zone; the ring seam and pad are partially fused, and there may be reflections in the uncombined parts, which affects the determination of defects; when ultrasonic waves enter the fused pad through the ring weld The secondary wave detection cannot be used. As there are blind spots in the ultrasonic inspection, in addition to the specific ultrasonic inspection process, magnetic particle inspection is also recommended as a supplement.

HS PA20-Ex Ultrasonic Flaw Detector can be adapted to 2 groups of TOFD inspection channels and can scan welds covering 100mm thickness at one time.

Wuhan Zhongke Innovation Technology Co., Ltd. has passed GB/T1 9001-2000/IS09001: 2000 and GB/T1 9001-2008/IS09001:2008 international quality management system certifications respectively in 2002 and in 2008. The product design and manufacturing are implemented in strict accordance with the international quality standard to guarantee advanced product technology and excellent quality. 

All products of the company adopt optimal materials and are supplemented by first-class manufacturing process to fully comply with the requirements of the latest China's relevant product quality standard, and meet the world's strictest EU standard about ultrasonic nondestructive testing (EN12668-1:2010). If you want to know more about the Ultrasonic flaw detector price, please contact us.

The information is provided by the ultrasonic flaw detector supplier.