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Basic requirements for hydrostatic test of oil pipe

2020-12-15 10:00:50   COMMENT:0 HITS:
  The hydraulic test of oil pipe is an indispensable link in the steel pipe manufacturing process. Its function is to test the anti leakage performance of the steel pipe under the standard test pressure and pressure stabilizing time. It is an important means to inspect the overall quality of petroleum steel pipe, just like X-ray, ultrasonic, etc. The simple explanation is to fill the pipe with water and test its ability to maintain the specified pressure without leakage or rupture under pressure. Its operation includes three steps: flushing, pressure test and water control.

  一、 Technical operation points of workers

  1. Parameter setting: set the test pressure value and pressure stabilizing time according to the specification size, steel grade and thread type of the oil pipe to be tested;

  2. Carry out full length hydrostatic test for each oil pipe. The actual test pressure and minimum pressure stabilizing time shall meet the requirements of the process card.

  3. In the process of pressure test, it is necessary to check whether the sealing parts are in good condition, whether there is leakage or not, and there is no trace of water leakage.

  4. The test pressure control range of oil pipe is: ≥ standard hydrostatic test pressure.

  5. Fill in the hydrostatic test record carefully.

  二、 Calculation formula of hydrostatic pressure of petroleum steel pipe

  The standard hydraulic test pressure is calculated according to the following formula, and the calculated value should be rounded to the nearest 0.5MPa, and the maximum value is 69.0mpa


  P - hydrostatic test pressure, MPa;

  The f-coefficient is 0.6 for J55 and K55 steel grades with specification > 95 / 8 ", and 0.8 for other steel grades and specifications;

  Ysmin specified minimum yield strength of oil pipe body, MPa;

  T - specified wall thickness, mm;

  D - specified outer diameter, mm;

  Example: 140 * 7.72 P110 steel grade




  340 * 10.92 J55 steel grade



  =14.6-14.5 should be rounded to the nearest 0.5MPa.

  193.68 * 12.70 P110 steel grade



  =5, but the maximum value is 69.0mpa, so the hydrostatic pressure level is 69.0mpa

  三、 Relevant provisions of api-5ct standard for hydraulic test

  1. The hydrostatic test pressure of oil pipe is the minimum value of hydrostatic test pressure of oil pipe, maximum hydrostatic test pressure of coupling and internal pressure leakage resistance, but the standard maximum pressure is 69mpa, and the calculated pressure value is generally rounded to the nearest 0.5MPa.

  2. According to API requirements, the hydrostatic test pressure measuring device should be calibrated within 4 months before each use.

  3. If the demander has special requirements, higher hydrostatic test pressure can be selected.

  4. Hydrostatic test leakage is the basis for rejection.

  5. Unless otherwise agreed by the buyer and the manufacturer, hydrostatic test is not required for coupling blank, coupling material, nearby material or q125 steel grade nipple.

  6. If the actual hydrostatic test pressure cannot reach the standard pressure due to equipment reasons, the technical department shall be informed in time to make corresponding process adjustment.

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