GB/T 40073-2021External pressure strength test procedure for metal pressure hull of submersibles (English PDF)

3.1 Submersible

The general term for various underwater operating appliances.

Note: Submersibles include manned submersibles and unmanned submersibles. Manned submersibles are submersibles that carry occupants. They usually include operational manned submersibles and deep dive rescuers.

Lifeboats, underwater excursion boats, diving bells, life-saving bells, single atmospheric diving suits and dual-function submersibles, etc.; unmanned submersibles are submersibles that do not carry occupants.

Often include remotely operated submersibles, autonomous submersibles, underwater gliders and towed submersibles.

3.2 Metal pressure shell

The metal shell on the submersible can withstand the external sea water or fresh water pressure, providing a normal pressure and sealing for the occupants or instruments and equipment. space.

3.3 Pressure hull accessory

The structural parts or equipment installed at the openings of the metal pressure shell.

Note: Such as electrical penetrations, hatch covers, observation windows, etc.

3.4 External pressure strength test

A test conducted by applying external pressure to a metal pressure-resistant shell (including accessories of the pressure-resistant shell) to determine its bearing capacity without damage.

3.5 Out of tolerance

The actual measured value exceeds the design allowable value.

3.6 Maximum working depth

The maximum operating or sailing depth at which a submersible can be safely used.

Note: The unit is meter (m).

3.7 Maximum working pressure

Relative to the water pressure at the maximum working depth.

Note: The unit is megapascals (MPa).

5.1 Requirements for metal pressure shells (including pressure shell accessories)

5.1.1 The metal pressure shell (including the accessories of the pressure shell) shall be inspected according to relevant quality after welding, heat treatment (if any) and assembly are completed.

It is required that the external pressure strength test can only be carried out after the acceptance is passed.

5.1.2 The pressure that the pressure shell accessories can withstand should not be lower than the maximum working pressure of the submersible, and it should be able to ensure that the metal pressure shell opening seal.

5.1.3 When necessary, the following quality certification documents shall be provided.

a) The material certification documents and re-verification records of the metal pressure shell (including the accessories of the pressure shell);

b) Shape inspection records and wall thickness inspection records of metal pressure shells (including pressure shell accessories);

c) Non-destructive inspection and repair records of welds of metal pressure-resistant shells (including pressure-resistant shell accessories);

d) Out-of-tolerance measurement records and out-of-tolerance enhancement processing records of metal pressure shells (including pressure shell accessories);

e) The pressure test qualification certificate of the pressure shell accessories.

5.2 Material

When necessary, the material mechanical properties data and curves of the metal pressure shell (including the pressure shell accessories) should be provided, such as the elastic modulus E, Poisson's ratio µ, The tensile strength Rm, the yield strength Rp0.2 and the tensile/compression curve of the material, etc.

5.3 Documentation

Before the test, the test client should prepare a test program, which should include the parameters of the metal pressure shell (including the accessories of the pressure shell), test requirements, and test program.

Test content, test procedures, test results processing methods and test report content requirements, etc.

5.4 Test equipment and instrumentation

5.4.1 The test equipment (such as pressure environment simulation device, loading system and test system, etc.) should meet the test requirements and be in good working condition. It has the conditions to provide external pressure strength test for metal pressure shell (including pressure shell accessories).

5.4.2 The measuring instruments and meters used in the test should be qualified by metrological verification and within the validity period. Instruments and meters should be calibrated before and after the test Test, and maintain a normal state during the test period.

5.4.3 The measuring instruments and meters used in the test should be installed in a suitable position according to the requirements of the test item and related operating procedures, and pay attention to Moisture-proof, to prevent the external environment and other factors from affecting the test results during the test.

5.4.4 When measuring the test pressure, two pressure gauges with the same range and accuracy should be used, or a pressure sensor can be used to replace one of the pressures. table. The range and accuracy of the pressure gauge should meet the requirements specified in 11.2 of GB/T 150.4-2011. Pressure sensor range and pressure gauge The range requirements are the same, and the accuracy should not be lower than that of the pressure gauge.

5.4.5 When measuring displacement and deformation, an electric displacement sensor or dial indicator can be used, and the range of the displacement sensor should not be less than the measurement range. 2 times, the accuracy should not be less than 0.01mm within 30mm.

5.4.6 During the test, the supply voltage and voltage deviation should meet the voltage input requirements for the normal operation of the test equipment and instruments.

5.5 Test medium

The test medium is water.

5.6 Test environment

The test environment requirements are as follows.

a) The temperature of the test medium is room temperature, that is, 10°C~30°C; for metal pressure-resistant shells with plexiglass observation windows, the test description The quality temperature should be the same as the design temperature of the plexiglass observation window. The requirements of 5.4.1.3 of the Rules for Classification and Construction of Water Apparatus;

b) Atmospheric pressure. 84kPa~106kPa;

c) Relative humidity requirement. 30%~95%.

5.7 Test pressure

The test pressure is established according to the following principles.

a) For submersibles with a maximum working depth not greater than 6000m, the test pressure of the metal pressure shell (including pressure shell accessories) is 1.25 times The maximum working pressure of the submersible.

b) For submersibles with a maximum working depth greater than 6000m, the test pressure of the metal pressure shell (including pressure shell accessories) is 1.1 times~ 1.25 times the maximum working pressure of the submersible. When designing metal pressure shells (including pressure shell accessories), such as the safety factor and the allowable material The stress used is selected in accordance with the "Code for Classification and Construction of Diving Systems and Submersibles", and the test pressure should be 1.25 times the maximum of the submersible Working pressure, if the safety factor and allowable stress of materials are not selected in accordance with the "Code for Classification and Construction of Diving Systems and Submersibles" The selected material is not within the scope of the "Code for Classification and Construction of Diving Systems and Submersibles", and its test pressure can be determined by itself, but It should not be lower than 1.1 times the maximum working pressure of the submersible.

The maximum working pressure of the submersible shall be calculated according to Appendix A.

6.1 Preparation before the test

6.1.1 Before the test, the integrity of the metal pressure shell (including the accessories of the pressure shell) should be checked. The inspection content includes the metal pressure shell and its reinforced structure, Electrical penetrations and auxiliary tooling equipment or components, etc. The metal pressure hull used for the manned cabin should also be checked for the hatch cover and the hatch cover opening and closing mechanism and Observation window and other contents. The fasteners of each connection part should be fully assembled and fastened properly. Temporary pressure element assembled for external pressure test It is necessary to take appropriate measures to ensure its safety.

6.1.2 Before the test, the appearance inspection of the metal pressure shell (including the accessories of the pressure shell) shall be carried out, and the appearance shall be intact, and the surface shall not affect the bearing capacity Scratches, pits and other defects. If there are defects, it should be reassessed whether the external pressure strength test can be carried out.

6.1.3 If conditions permit, a sensor with a water leakage alarm function can be installed at a location where water is easy to store after the metal pressure shell leaks before the test.

6.1.4 The requirements for the sealing test before the test are as follows.

a) Before the test, the metal pressure shell (including the pressure shell accessories) should be tested for tightness, and the metal pressure shell (including the pressure shell accessories) should not be sent.

Leakage can be detected by hydrostatic external pressure tightness test or air tightness test. After the sealing test is qualified, the outside can be carried out. Compressive strength test.

b) In the hydrostatic external pressure sealing test, the detection pressure should not be less than 0.3MPa. It is advisable to mark the area prone to leakage, such as smearing white Powder, etc., in order to determine the specific leakage location. Visually observe the metal pressure shell (including pressure shell accessories) or check the number of water leakage alarms It is judged whether the metal pressure shell (including the pressure shell accessories) leaks.

c) Air tightness test detection, the test medium is air, and the test pressure is the design pressure. If the inside of the metal pressure shell is normal pressure, the test The pressure should be no more than 0.1MPa, and the pressure holding time should be no less than 0.5h, which should be enough to leak all welded joints and connections Check whether there is leakage through foaming agents such as soapy water or soaking in water. Use foaming agent to detect, there should be no bubbles on the surface Health; immersion test, there should be no air bubbles on the water surface.

d) If the metal pressure shell (including the accessories of the pressure shell) cannot be tested for the overall tightness, the auxiliary test tool can be used to test the metal pressure shell.

The tightness of the opening position is tested, and the test medium is water. During the test, the auxiliary test tool is used in the local area of the opening position Establish a closed cavity that can withstand internal pressure, and inject water and pressurize the closed cavity. The test pressure should not be less than 0.3 MPa.

The time is not less than 15min, and there should be no leakage at the opening position.

e) If leakage occurs, re-test the leak tightness after repair until it is qualified.

6.2 External pressure strength test

6.2.1 General requirements

At least two loading and unloading tests shall be carried out for the external pressure strength test. During the test, if required by the test client, strain measurement and displacement or Deformation measurement. If strain measurement and deformation or displacement measurement are not required, the loading and unloading steps of the test shall be in accordance with the test steps of the strain measurement test. carried out.

During the test, the metal pressure shell (including pressure shell accessories) shall not produce permanent deformation such as creep during the pressure holding process.

6.2.2 Requirements for loading and unloading

The loading speed of the test should not be less than the designed diving speed of the submersible, and the unloading speed should not be less than the designed floating speed of the submersible. Installed The unloading speed of the metal pressure-resistant shell of the machine glass observation window should not be greater than 4.5 MPa/min.

During the test, according to Table B.1 in Appendix B, record the pressure value and time at the beginning and end of each stage of the loading and unloading of the test.

6.2.3 Strain measurement

6.2.3.1 General requirements

According to the purpose of the test, determine the strain measurement location, uniformly number the corresponding strain, and compile the strain of the metal pressure shell (including the pressure shell accessories) Layout plan of measurement points.

6.2.3.2 Strain measurement location

The strain measurement location of the metal pressure shell (including the attachment of the pressure shell) shall be determined by the test client according to the design results, and the following parts should be included.

a) Typical parts, that is, the shell plate and reinforced ribs on the typical section of the shell;

b) The connection part between the opening reinforced area and the shell;

c) The location of local structural stress concentration, such as the opening position of the electrical penetration, can be determined according to the finite element calculation results;

d) The location where the construction process factors affect the strength, such as the position of the weld;

e) Process defects, such as out-of-tolerance in shape, out-of-tolerance in wall thickness, forced assembly, multiple repair welding, etc.;

f) Welded on the shell and used to connect and fix the components;

g) Other parts considered by the test client to be measured.

6.2.3.3 Strain gauge pasting requirements

When the strain gauge is pasted, follow the requirements below.

a) The patch part of the strain gauge should be polished, and the surface of the structure directly under water pressure, the polished area of each measuring point is generally not less than 50mm× 50mm (same requirements for compensating strain gauges), the surface of the structure that is not subject to water pressure, the grinding area of the measuring point is not less than 30mm×30mm (compensation Strain gauge requirements are the same), the surface roughness Ra should not be greater than 3.2µm after polishing, and the strain gauge should be pasted with patch glue. Should Check the quality of the paste after at least 24h after the variants are pasted.

1) There is no obvious deviation between the sticking position of the strain gauge and the marking direction, the strain gauge has no warpage, no degumming, and there is no gap between the strain gauge and the shell surface. bubble;

2) The resistance value of the strain gauge is within ±0.5ohm of the factory nominal value, and the measured value is recorded in Table C.1 of Appendix C;

3) The insulation resistance value of the strain gauge should not be lower than 100Mohm, and the measured value should be recorded in Table C.1.

b) After the quality of the strain gauges meets the requirements, weld them with the connecting wires according to their respective numbers, check the resistance value and insulation resistance value, and measure the number The value is entered in Table C.1, and the qualified conditions are in 2) and 3) in a), in which the resistance value should be added with the resistance value of the wire. Connection of all strain gauges The connecting wires should be of the same specification.

c) Use vulcanized silicone rubber or other sealant to cover the strain gauges and the welding points of the strain gauges and the wires layer by layer.

The coverage area of the measuring points on the surface receiving water pressure is not less than 30mm×30mm, and the coverage area of the measuring points on the surface that is not directly subjected to water pressure Not less than 20mm×20mm, avoid bubbles in the glue layer, and the coating should be evenly transferred to the surface of the shell. Check after the sealant is cured.

Check the total resistance value and total insulation resistance value of the strain gauge and connecting wire, and record the measured value in Table C.1, and the total insulation resistance value is qualified The conditions are 3) in a).

6.2.3.4 The first loading and unloading (i.e. pre-compression test)

The first loading and unloading is carried out in accordance with the following requirements.

a) The pre-pressure test pressure should not be greater than the maximum working pressure of the submersible, and may be 80% of the maximum working pressure.

b) In order to ensure the smooth progress of the test, a step-by-step loading and unloading procedure is adopted. Load slowly to the maximum working pressure during the test After confirming that there is no leakage, press 10% of the maximum working pressure or the test client's requirements to load to the maximum 50% of the maximum working pressure, if there is no abnormal phenomenon, continue to load step by step until the pre-pressure test pressure, after the pressure is maintained for 10 minutes, slow down Unload slowly to zero or the initial pressure value. Collect and record the strain value under the loading and unloading pressure of each stage.

c) There is no abnormality in the pre-pressure test before the next stage of external pressure test can be carried out.

6.2.3.5 The second loading and unloading

The second loading and unloading is carried out in accordance with the following requirements.

a) In order to ensure the smooth progress of the test, a step-by-step loading and unloading procedure is adopted.

b) During the test, load slowly to 10% of the maximum working pressure, hold the pressure for 5 minutes, and press 10% of the maximum working pressure after confirming that there is no leakage Or the test client requires to load to 50% of the maximum working pressure step by step, and after confirming that there is no abnormal phenomenon, add step by step according to the above requirements.

Pressure, load to the pressure of each stage, after the pressure is stable (holding time should not be less than 1min), collect and record the strain value. carry on After loading to the test pressure, stop pressurizing, maintain the pressure for at least 30 minutes, after the pressure is maintained, every 5 minutes or according to the time specified by the test client Collect and record the strain value.