The present invention relates to a stress-strain testing system for a large-diameter steel pipe pile of an offshore wind turbine and a construction method, comprising a steel pipe pile, wherein copper belt type sensor cables are correspondingly welded on both sides of the steel pipe pile along an axis direction; each sensor cable is sequentially covered with an epoxy adhesive, gold foil paper and an angle steel welded on the steel pipe pile centering on the copper belt type sensor cable; a fiber core of each copper belt type sensor cable is transferred into a high-strength armored optical cable by a special fixture and then is led out; and the high-strength armored optical cable is connected with a Brillouin optical fiber demodulator. The present invention is applicable to the field of foundation engineering testing and detection technology.

A method of offset load testing a tubular composite specimen with two pairs of aligned holes and having at least one defect, the method comprising: providing a testing apparatus having a pair of arms including a fixed arm and a mobile arm; securing the pair of arms using a fastener assembly in each of the two pairs of aligned holes; and moving the mobile arm to impart an offset load force to the tubular specimen. One aspect includes a method of offset load testing comprising: providing a testing apparatus having a pair of arms including a fixed arm and a mobile arm; providing a tubular composite specimen with a top portion and a bottom portion; securing the pair of arms to the top and bottom portions of the tubular composite specimen; and moving the mobile arm to impart an offset load force to the tubular composite specimen.

A test system includes subsystems for application to a test sample of a range of conditions that might be encountered in an actual application. Conditions may include the presence of particular fluid environments, temperatures, pressures, and mechanical loads including tensile and bending loads. The system is particularly suited for elongated samples such as tubular products used in oil and gas applications, though a range of samples may be tested.

The present invention discloses a thermal fatigue crack generator for a large pipe. According to the present invention, the thermal fatigue crack generator for a large pipe precisely manages and controls the heating and cooling conditions for the large size test pipes having a diameter of 250 to 610 mm to significantly improve the reliability of the accuracy and a reproducibility of the thermal fatigue cycle so that a useful advantage is expected to ensure the reliability and the effectiveness of the skill verification of the non-destructive testing.

For improving the signal quality while simultaneously improving the function of test objects, a load measuring arrangement includes a test object and a load measuring device for measuring a load applied between a first and a second region of the test object. The test object has a transmission region receiving a major part of the load between the first and the second region. A secondary transmission element is connected to the first and second regions of the test object so as to receive a smaller portion of the load between the first and second regions in parallel with the transmission region. The load measuring device includes a magnetic field generating device for generating a magnetic field at the secondary transmission element, and a magnetic field detection device for detecting a magnetic field parameter changing due to the load at the secondary transmission element.

A pipeline has a fitting with a wedge-shaped plug pressed into a wedge-shaped fitting recess by a retaining ring to block flow through the fitting for pressure testing. The plug has an extractor plate fastened to the plug through a center of the retaining ring so the retaining ring can rotate relative to the plug and extractor plate. But the extractor plate is a predetermined maximum distance from the plug and is larger than the center opening of the retaining ring to captivate the retaining ring between the plug and extractor plate. That limits the retaining ring motion along the port's axis. Threading engagement between the retaining ring and port allow the retaining ring to push the plug into the fitting in a first rotation direction while rotation in the opposite direction allows the retaining ring to push the extractor plate and the connected plug out of the fitting.

A method of determining a minimum wall thickness for a pipe joint for use in a subsea pipeline comprises the steps of: i) determining an internal diameter of the pipe joint; ii) determining a minimum allowable hydrostatic pressure at the depth at which the pipe joint is to be used; iii) determining a target wall thickness for the pipe joint, the target wall thickness corresponding to the internal diameter and the minimum allowable hydrostatic pressure; iv) manufacturing a plurality of preliminary pipe joints having the internal diameter and the target wall thickness; v) carrying out external pressure collapse tests resulting in data representative of the hydrostatic collapse pressures at which the plurality of preliminary pipe joints collapse; vi) determining a probability distribution corresponding to the data based on a statistical tail model derived from Extreme Value Theory; vii) determining from the probability distribution a hydrostatic collapse pressure occurring with a probability of 10.sup.−5 or lower; and, viii) determining a wall thickness of the pipe joint corresponding to the internal diameter and the hydrostatic collapse pressure.

A steel pipe collapse strength prediction model generation method, a steel pipe collapse strength prediction method, a steel pipe manufacturing characteristics determination method, and a steel pipe manufacturing method capable of highly accurately predicting the collapse strength of a steel pipe after forming or a coated steel pipe in consideration of the pipe-making strain during forming. Into a steel pipe collapse strength prediction model generated by the prediction model generation method, steel pipe manufacturing characteristics including the shape of a steel pipe to be predicted after forming, strength characteristics, and the pipe-making strain are input to predict the collapse strength after forming. Into a steel pipe collapse strength prediction model, steel pipe manufacturing characteristics including the shape of a coated steel pipe to be predicted after forming, strength characteristics, the pipe-making strain, and coating conditions are input to predict the collapse strength of the coated steel pipe.

Apparatus and methods related to low cycle fatigue testing are described. For example, some embodiments may contain a control box, two fitting connections, a pressure gauge, a plurality of clamps, a plurality of hydraulic cylinders, a plurality of control cables, and a strain gauge, for testing the low cycle fatigue properties of a testing specimen, for example, a steel tube umbilical.

A method of inspecting a pipe joint for use in a subsea pipeline and a method of manufacturing a pipe joint for use in a subsea pipeline employing said inspection method are disclosed, the inspection method comprising the steps of: receiving a pipe joint; measuring the ovality of the pipe joint to obtain ovality data; determining that the ovality data does not exceed a predetermined maximum pipe joint ovality value; and carrying out external pressure collapse tests on a ring cut from one end of the received pipe joint, resulting in data representative of the hydrostatic collapse pressure of said pipe joint for use in confirming that the pipe joint is suitable for its intended use.