Tests and checks at Mannesmann Line Pipe are not restricted to those prescribed by the various standards. We carry out a large number of additional internal in-process checks and tests in order to ensure that the finished products more than meet the customers' specifications.
Both our locations are fully equipped with state-of-the-art measuring and testing facilities. During each process step, we check whether the pipe meets all the relevant requirements and specifications. This includes measuring the pipe length, diameter and wall thickness, checking its weight, testing the mechanical and technological properties, leak-tightness, coating layer thickness, etc.
Regular evaluation of the results obtained serves as the basis for preventive measures to ensure that the high quality of our processes and products is maintained all along the line.
In very complex diagnosis cases, we have the full backing of our Group's own research center, Salzgitter Mannesmann Forschung, with its specialists in every sphere of pipe science and technology.
Tests we carry out (a selection)
In addition and besides our materials research work, we carry out a wide range of tests, including – but not limited to – drop-weight tear tests, residual stress measurements, welding tests, fatigue tests, fracture mechanical texts, and simulations.
Notched-bar impact bending tests
The notched-bar impact bending test to DIN EN ISO 148-1 und ASTM E-370 serves to determine a material's resistance to fracture (i.e. toughness) under the effect of a dynamic impact load. During the test, a notched specimen whose ends rest on thrust bearings is broken with the aid of a pendulum impact testing machine or pulled through the thrust bearings. The impact energy absorbed before fracture occurs is measured. Optical evaluation of the fracture surface allows information to be derived regarding the ductile and brittle fracture portions. The notched-bar impact bending test is used, for example, for monitoring heat treatment and for verifying a material's susceptibility to brittle fracture.
Steel heat analysis
Our ultramodern equipment in conjunction with well-established technologies and strict process monitoring ensure maximum reliability and very close tolerances of the analytical values. Steel produced from such heats is extremely homogeneous and offers the best preconditions as a starting material for pipe production to the customer's specifications.
Peel resistance of plastic coatings
A plastic coating must, above all, protect the pipe body against corrosion and therefore has to reliably resist external influences (pressure, impact, etc.). Peel resistance is an important quality feature of 3-layer polyolefin coatings, and indicates whether or not the 3-layer coating system consisting of a primer, an adhesive, and a polyolefin top layer has been applied correctly. The test is described in DIN 30670, DIN 30678 and ISO 21809-1. In addition, all our coatings have been approved for their respective application by external laboratories.
The lining of a pipe is subject to numerous loads in the course of its service life, such as erosion, temperature fluctuations, pressure or vibrations. The resistance of the lining material to these loads is regularly tested by determining its pressure resistance and tensile bending strength in accordance with DIN 1164. In addition, the lining components are tested and approved by external laboratories for their suitability for drinking water applications.
HIC test (hydrogen-induced cracking)
The HIC test serves to determine a material's resistance to hydrogen-induced cracking. It provides information about the material's suitability for use with sour gas media. The tests are performed under standardized conditions to NACE TM0284, or under modified conditions adapted to the actual service environment as described in EFC 16 (EFC = European Federation of Corrosion). For the tests, modern, well-equipped laboratories accredited to ISO 17025 are available.
SSC-4-point bending test (sulfide stress cracking)
The SSC 4-point bending test is used to determine a steel's resistance to hydrogen-induced stress cracking. It provides information about a material's suitability for use with media containing sour gas and is described in ASTM G39. The tests can be carried out under standardized or modified conditions adapted to the application environment. The respective test conditions are described in NACE TM0177 and/or in EFC 16. For the tests, modern, well-equipped laboratories accredited to ISO 17025 are available.
CD tests (cathodic disbondment)
The cathodic disbondment test (CD test) is carried out in the area of a coating holiday to determine the coating's susceptibility to disbondment due to cathodic corrosion protection. In addition, the test provides information about the quality of the tested coating, since the surface preparation before coating and the actual coating process itself have an effect on the coating's behavior regarding cathodic tunneling. The applicable standards are ISO 21809-1 for 3-layer polyolefin coatings and ISO 21809-2 for FBE coatings.
Internal pressure tests
Component tests under internal pressure are carried out on line pipe and pressure vessel tubes. In the context of final inspection, these products are subjected to a pressure equal to 1.5 times the design operating pressure, to ensure that they can resist the service loads involved in the intended application. In addition, burst tests are carried out to determine their maximum loadability and failure mechanisms.
Offshore service in deep-sea regions involves enormous external pressures on the pipe used. Resistance to these pressures is tested in collapse tests. These tests determine a pipe's collapse resistance under real service conditions. When the external pressure is raised to the point of collapse, the test results provide information about the maximum loadability and failure behavior of the tested pipe.
The strain-based design properties of onshore pipe and the reeling properties of offshore pipe are determined in full-scale bending tests. On the LiSA (limit state analyzer) test stand, pipe can be subjected to 4-point bending tests until failure occurs, e.g. by buckling or cracking. This test can be carried out with and without internal pressure. By means of alternating bending cycles, the reeling process simulates the loads acting on offshore pipelines under real service conditions.
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