National Repository of Grey Literature 66 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Investigation of basic mechanical and fracture-mechanical properties of specimens cut from high pressure gas pipeline – locality L177/2 after a twentyone months exposition to moist and dry hydrogen at the pressure 3 MPa
Gajdoš, Lubomír ; Šperl, Martin ; Šorm, Filip ; Bejdl, Jan
Investigation of the effect of moist and dry hydrogen pressurized to 3 MPa on mechanical and fracture properties of gas pipeline steel ČSN 13126, tensile specimens, Charpy specimens and CT specimens were kept loaded during the exposition in moist hydrogen, after a 21th months exposition it was found that ductility of tensile specimens and fracture parameters Jin and J0,2 of CT specimens decreased whilst the parameter Jm was slightly increased.
The effect of the backfill on the integrity of a buried pipeline upon heavy-duty vehicle crossings
Gajdoš, Lubomír ; Šperl, Martin ; Slížková, Zuzana ; Drdlová, M.
The aim of this work was to determine stresses in the wall of a buried empty gas pipeline caused by the weight of backfill as well as by heavy-duty vehicles crossing the pipeline, and, on their basis to assess the applicability of protective sleeves. A buried pipeline with zero internal pressure of transported medium (empty pipeline) differs from an unburied pipeline by the vertical load due to the weight of the backfill which causes an ovalness of the circular cross section of the pipeline. This leads to the rise of through-wall bending stresses with the tensile stress at the outside surface at the 3 and 9 o´clock positions and compressive stress at the inside surface. At the 6 and 12 o´clock positions the stresses are tensile at the inside surface and compressive at the outside surface. The current depth of soil cover above gas pipelines is 0.5 m. For pipes DN500, t ~ 6.5 mm the through-wall bending stress is found to be σb ≈ ±10 MPa. In comparison with the yield stress of pipeline material, this stress is negligible. The situation is changed when heavy-duty vehicles cross the pipeline. For example, when a MAN truck with the mass load 3270 kg acting on a single wheel of the front axle crosses this pipeline, the pressure transmitted to the pipe will cause the through-wall bending stress σb ≈ ±76 MPa. This stress is superimposed to that of the backfill to give the total value ±86 MPa. When dead loads, imposed by backfill cover, together with live loads, caused by truck-wheel loads, are excessive a crushing of side walls of the pipeline and/or ring buckling of the pipe cross section can happen.
Investigation of basic mechanical and fracture-mechanical properties of specimens cut from high pressure gas pipeline – locality L177/2 after a fourteen months exposition to moist hydrogen at the pressure 3 MPa
Gajdoš, Lubomír ; Šperl, Martin ; Šorm, Filip ; Bejdl, Jan
Investigation of the effect of moist hydrogen pressurized to 3 MPa on mechanical and fracture properties of gas pipeline steel ČSN 13126, tensile specimens, Charpy specimens and CT specimens were kept loaded during the exposition in moist hydrogen, after a fourteen months exposition it was found that ductility of tensile specimens and fracture parameters Jin and J0,2 of CT specimens decreased whilst the parameter Jm was slightly increased.\n
Verification of the fatigue resistance of 40 kN pin load gauges from ČSN 17 029 material
Šperl, Martin ; Gajdoš, Lubomír ; Bejdl, Jan
Fatigue loading in three-point bending of two pin load gauges from ČSN 17 029 steel was carried out in the load range 5 – 35 kN for two million cycles to prove the required fatigue resistance of the pins.
Charpy tests of load measuring pins from ČSN 19 312 material
Šperl, Martin ; Gajdoš, Lubomír ; Bejdl, Jan
Charpy tests of load measuring pins from ČSN 19312 steel were carried out at the temperature 20 °C, 0 °C, -20 °C, and\n-40 °C with the aim to verify that Charpy notch toughness of the pins keeps its average magnitude even at -40 °C. The results showed that the steel did not exhibit a typical S-type transit curve in the temperature range 20 °C ÷ -40 °C due to which the Charpy notch toughness at -40 °C practically did not differ from that at higher temperatures.
Investigation of basic mechanical and fracture-mechanical properties of specimens cut from high pressure gas pipeline – locality L177/2 after a seven months exposition to moist hydrogen at the pressure 3 MPa
Gajdoš, Lubomír ; Šperl, Martin ; Šorm, Filip ; Bejdl, Jan
Investigation of the effect of moist hydrogen pressurized to 3 MPa on mechanical and fracture properties of gas pipeline steel ČSN 13126, tensile specimens, Charpy specimens and CT specimens were kept loaded during the exposition in moist hydrogen, after a seven months exposition it was found that ductility of tensile specimens and fracture parameters Jin and J0,2 of CT specimens decreased whilst the parameter Jm was slightly increased.
Material tests of pipe samples takes from high pressure gas pipeline Sviňomazy-Vřesová (locality L177 / 2), II. stage of part B1 (hydrogen exposure)
Gajdoš, Lubomír ; Šperl, Martin ; Šorm, Filip ; Bejdl, Jan
The main goal of this work is the evaluation of hydrogen effect to material properties of the pipeline steel and its possible transformations.
Evaluation of mechanical properties of the steel materials take from the electric transmission towers damaged by tornado
Šperl, Martin ; Gajdoš, Lubomír ; Bejdl, Jan
The report deals with the evaluation of mechanical properties of steels from high voltage masts destroyed by tornado.
The river dam Slapy - evaluation of material and mechanical properties of the steel quick-closing panels
Šperl, Martin ; Gajdoš, Lubomír ; Bejdl, Jan
An experimental research of the material and mechanical properties of two steel segments cut from quick-closing gate was carried out for suitability assessment to operation. The quick-closing gate is a technology part of the river dam Slapy.
Mechanical and fracture mechanical analysis of steel segments cut from Družba oil pipelines DN 500 and DN 700
Gajdoš, Lubomír ; Šperl, Martin ; Šorm, Filip ; Bejdl, Jan
Experimental research of mechanical and fracture mechanical properties of the pipe specimens taken from Družba oil pipeline. In addition to basic static tests and fracture toughness tests, the research also included the determination of the kinetic of fatigue crack growth, incl. analysis of critical crack size.

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