Defectoscope for Polyethylene Pipelines
The Ultrasonic Device for Detection of Defects in Butt-Welded Connections of Polyethylene Gas Pipelines
Tech Area / Field
- INS-MEA/Measuring Instruments/Instrumentation
3 Approved without Funding
National Academy of Sciences of the Republic of Belarus / Institute of Applied Physics, Belarus, Minsk
- Michigan State University / College of Engineering, USA, MI, East Lansing\nBundesanstalt für Materialforschung und prüfung, Germany, Berlin\nTriSolver Consulting, Germany, Hannover\nSaM Service GmbH, Germany, Gilching
The project goal is a development of a compact ultrasonic device for non-destructive testing of butt-welded connections in polyethylene pipelines.
Task definition. Replacement of metal pipes with plastic pipes is the general trend within the pipeline transport industry. Successful construction pipelines requires surveillance of the quality and reliability of connections. It is necessary to note that polyethylene is a material with the strong factor of thermal expansion. Therefore, seasonal thermal changes and natural ageing sometimes cause the development of defects in welded connections. Today inspection of welded connections of polyethylene pipelines uses visual testing and selective tensile strength tests.
Various technological methods of welded seam quality testing can used to increase reliability of pipeline welds. However, these methods allow testing joints only during the welding process, but not during operation. From experience it is clear that testing of the welding process alone cannot guarantee the absence of defects in a welded joint.
Attempts to apply methods of x-ray and ultrasonic non-destructive testing have been made to estimate welded joint quality [Munns I.J. and Georgiou G.A. TWI, Abington UK: “Ultrasonic and radiographic NDT of butt fusion welded polyethylene pipes”, NDTnet-April 1996, Vol.1 No.04]. But, available ultrasonic methods and devices cannot find defects such as those associate with "tight contact of surfaces without mutual diffusion of materials".
It is considered that these defects occur because of inappropriate surface temperature during welding. In other words, the compression of pipes butts begins when crystallization process has already begun on their surface. The “kissing bonds” type defects are the most dangerous, because they continue to develop. It is necessary to note, that all the methods of the ultrasonic research which are used now require highly skilled experts and are labor intensive. Moreover, scanning of all pipe perimeters requires great time expenses.
It is well known that X-ray methods allow finding not only volumetric defects with the sizes that are not less that 1-2% from the thickness of testing products. However, they are expensive and ecologically dangerous. Moreover, x-ray equipment is bulky and demands creation of special conditions for the personnel and it is insufficiently mobile. The technique and the equipment that permit to reveal defects with the sensitivities 0.67% were developed in TWI (The Welding Institute, UK). However, in any case, defects that are revealed with the help of X-ray or radiographic equipment have typically reached full development. Accordingly, these defects are not defects of “kissing bonds” type.
It is proposed to develop a special small-sized device will allow carrying out the operative testing of butt-welded connections in field conditions directly at installation of gas pipelines and during operation. The development of this devise is important not only from the point of view of gas pipelines testing, but also for other objects used for storage and transportation of dangerous substances. It will be useful for maintenance of social security and preservation of the environment.
Project participants. The highly skilled experts from IAP NASB, which have a great experience in development of electronic and ultrasonic equipment for non-destructive testing, will be involved in performance of the project. Among 15 basic developers 5 have a scientific degree of candidates and doctors of sciences, 11 experts have wide experience in the field of aviation and rocket technologies.
Influence of the proposed project on progress in the field of development. The expected results will be useful for development of means of the adhesion testing and quality of plastic in general. For example, it will be useful from the point of view of reception of data about a process of polymerization of both thermoplastic and thermosetting materials. During the realization if the project a quality monitoring based on time and phase measurements will be developed. It is a new qualitative step in development of ultrasonic flaw detection means.
Expected results: At the decision of five tasks of the project the following results will be obtained:
1. the technology of “kissing bonds” defects modeling for connections of polymers will be developed and samples of defective welded connections will be made;
2. transducers for the testing will be developed; their sensitivity to the ”kissing bonds” and volumetric defects will be investigated; general requirements to an electro-acoustic path of the device will be set up; a technological process of testing procedure and technical projects of the hardware of the device and of its software will be developed;
3. engineering specifications for the device hardware will be developed;
4. software of the device will be developed;
5. the pre-production model of the device will be made, the technical and operational documentation including description and the maintenance instructions will be developed; tests program will be prepared; tests in laboratory and field conditions will be carried out.
Practical results: a new device and technology for realization of the operative testing of butt-welded polyethylene pipes connections; technical and operational documentation, which allows producing devices and carrying their delivery to consumers.
Advantages of the device: unique ability to test “kissing bonds” defects in polyethylene pipes; high efficiency (test of one joint lasts not more than 5 minutes); an opportunity of tending by unskilled personnel; ecological safety; documenting results of the tests; simple operation.
Scientific results: results of research of interaction of the elastic wave’s field with particularly fixed interface of environments; ways of excitation of non-uniform elastic waves in the welded joint area in materials with low speed of sound; ways of the analysis and processing of the measurements results. These results are interesting not only from the point of view of testing of polyethylene pipelines welded connections, but also, for example, to quality testing of adhesion in general, quality of welding by explosion, friction welding, electromagnetic and electrostatic percussive welding.
There will be patenting of the intellectual property created during the project.
As a result of the project realization:
- ecological safety will be raised during the exploiting of gas pipelines due to maintenance of their testing;
- expenses for construction and operation of gas pipelines will be decreased.
Usage of new methods of ultrasonic testing the polyethylene pipes welded connections (for example, ultrasonic testing by transducers with a magnetic contact fluid) will allow to assess quality of welded connections with greater quality and at less time, will allow to receive the evident and objective documentation of testing results. Technical decisions received during the realization of the project later on will be used to develop specialized testing equipment.
The developed methods, means and algorithms will be find an usage at development of other ultrasonic instruments.
Application of the project results: The devices developed during the proposed project are intended for the organizations engaged in construction and operation of polyethylene gas pipelines, boards of supervision of technical and ecological safety of pipeline transport means, manufacturers of responsible products from plastic (petrol tanks, various capacities). Besides the received results will be used for development of the series of small-sized flaw detections and measuring instruments of a sound speed for quality surveillance of products at the machine-building enterprises. Received at development and manufacturing of the given device constructive decisions, technological processes will be used in the subsequent work at creation of the automated and mobile quality systems.
Meeting ISTC’s goals. The project meets to following purposes of ISTC:
- gives to the “weapon-making” scientists and experts, participants of the project, an opportunity for reorientation of their abilities on peace activity by development of the device for civil purpose, teamwork with experts of a civil specialties;
- encourages integration of the project participants connected to the weapon in world scientific community due to participation in conferences, information interchange, teamwork with collaborators;
- supports fundamental and applied researches in the field of acoustics and measurements methods and means;
- supports transition to market economy as the created device will be realized to consumers on a competitive basis, and incomes will be used for the further researches in civil appendices. It will provide employment of the personnel.
Work volume. All amounts of works are estimated for two years. It is required 265 man*mths of work for its realization. From them an expense of weapon scientists is 201 man*mths. The technology of the testing, the equipment for its realization will be developed, preconditions for the subsequent manufacture and realization of devices will be created. All works will be carried out in IAP NASB. Five tasks of the project assume their consecutive solution for achievement of an overall aim. Tasks include: theoretical and experimental researches of testing methods and of samples manufacturing; development of the hardware and of the software; manufacturing experimental and pre-production models of the device, test, updating of the engineering specifications and completion of the device.
To foreign collaborators within the framework of the tendered project the following forms of participation are proposed:
- information interchange during the project realization;
- provide of comments to technical reports under the project;
- assistance to the project performers in participation in the international conferences, seminars;
- realization of joint seminars and working meetings;
- tests and an estimation of the equipment and technology developed during the project performance;
- participation in technical check of activity under the project;
- participation and assistance in certification of the device according to the international standards in the future.
Participants of the project expect for long-term cooperation with collaborators.
The technical approaches and methodology. Approaches and methodology of decision of a task of development of the ultrasonic device for non-destructive testing of polyethylene pipelines butt-welded connections are based on the experience, which has been accumulated by experts from IAP NASB at the decision of problems of reliability of arms systems and nuclear stations. Participants of the project are the authors of more than thirty patents connected to non-destructive testing and acoustic measurements.
In a basis of theoretical methods of researches the original results earlier received by participants of the project lay:
a)for interaction of the elastic wave’s field with particularly fixed interface of environments;
b)for conditions of distribution of non-uniform waves in materials with structural heterogeneities and small speeds of a sound;
c)for methods of control of ultrasound sources directional characteristics.
At experimental researches the methods developed earlier by authors will be used, in particular:
a) ways of formation of special magneto-fluid sound ducts for input of acoustic waves into the testing objects;
b) method of modeling of welded connections samples with “kissing bonds” defects;
c)methods of measurement of time and phase characteristics of acoustic signals.
In a basis of the technical approach to development of the hardware, the experience accumulated by the authors during the development of automated monitoring and measurements systems will be used. Original technical solutions concern the execution of device structure and ways of measurement of acoustic signals parameters. The software will be constructed using the authors experience at designing the equipment for acoustic measurements.
The International Science and Technology Center (ISTC) is an intergovernmental organization connecting scientists from Kazakhstan, Armenia, Tajikistan, Kyrgyzstan, and Georgia with their peers and research organizations in the EU, Japan, Republic of Korea, Norway and the United States.
ISTC facilitates international science projects and assists the global scientific and business community to source and engage with CIS and Georgian institutes that develop or possess an excellence of scientific know-how.