Pressure vessel inspection program
1, in the contents with the pressure vessel inspection program should include all of the following article:
① basis of regulations, norms, rules, standards, technical requirements on the drawing.
② pressure vessel technology parameters.
③ classification test: Tests on Completion, commissioned reinspection, periodic inspection, non-periodic inspection.
④ detection site, testing methods and technical standards.
⑤ testing procedures
Parking - cut off all the equipment related to power - Turn off all equipment associated with the valve - Replacement Cleaning - disintegration (remove trim) - inner and outer surface treatment (removal of insulation, sand, rust, etc.) - internal and external macroscopic examination, thickness measurement, nondestructive testing, metallurgical testing, etc. - to eliminate defects - intermediate detection - hydraulic test - the ultimate test.
⑥ safety testing requirements.
2. Factors used in pressure vessel inspection program
In particular when formulated with the pressure vessel detection scheme, due to the influence of the detected operating conditions of the pressure vessel, the container structure, mounting position, and the characteristics of common detection method, and the program will be specifically different. During program development, must take full account of the particularity of these contradictions and face, otherwise, it could lead to failure. Here to talk about their views on these aspects.
Features and adapt the scope of the impact of common detection method ①
In Site "Five Common NDT methods Feature Comparison Table", the list of five common methods of use of non-destructive testing, the detection sensitivity and the main advantages and disadvantages and so on. In the specific formulation testing program, it is necessary according to the characteristics of the seized vessel characteristics and various testing methods for supporting the selection.
For example, the choice of internal defect detection ray testing, ultrasonic testing;
Detection of surface defects chosen magnetic particle testing, penetration testing and eddy current testing;
Detect porosity, slag volume of a class-like defects can be the first choice of radiographic inspection;
Detection of internal cracks of a class of linear defects, mainly first choice ultrasonic flaw. Because ultrasonic testing, the upper surface of the blind under the influence, the container wall thickness of 10 mm below the detection PMB difficult, so for thin-walled containers and in the detection of low-pressure pipeline to the main X-ray detection; only in container pieces can not be withdrawn, they can not patch from the inner wall, only the choice of ultrasonic testing, conduct informative test.
To detect ferromagnetic material surface and near surface defects, in order to use magnetic particle testing is better, because the magnetic detection sensitivity is relatively high penetration testing, and faster detection speed; non-ferromagnetic material for detection of surface defects, use penetration testing is right ; for large containers of small localized surface inspection, and the sensitivity of the general requirements, or may choose penetrant inspection.
In addition to the selection of the above features, but also using a variety of testing methods comprehensive testing to supplement each other to achieve more comprehensive testing purposes.
② vessel operating parameters influence, pressure, temperature, structure detection program
Vessel operating parameters: temperature, pressure, media and materials, these factors will affect the generation and expansion of defects in the development of testing protocols for specific analysis should be treated separately.
Various pressure vessels, low, medium, high pressure, high pressure, dangerous and potentially different probability of defects, should be treated separately;
Different temperatures containers, container at room temperature, cryogenic vessels, high temperature vessels, may produce different defects, cryogenic vessels should pay attention to discover whether the cold brittle cracks will have to pay attention to whether the vessel temperature creep, decarbonization and ball defects; different container media, explosive media, toxic and corrosive media, in addition to pay attention to the density of checks, paying particular attention to corrosion defects, especially the generation of stress corrosion cracking;
Containers of different materials, carbon steel, stainless steel, ordinary low-alloy steel, high strength steel, cold steel, heat-resistant steel, container and non-container steel and other steel, they have different properties, temperatures, pressure, media also different working conditions combined analysis of defects that may arise, targeted checks.
③ shape on the container and the structure, the mounting position of the container
Different structural forms of container, required the use of different detection methods, the analysis should be targeted, effective approaches.
Welding container region mainly to check welded joints defects;
Forging container housing the main check forging forging internal cracks, surface cracks and folding;
Single-layer and multi-layer container vessel, the composite layer container, the liner vessel;
There are pieces of container and non-container trim;
Spherical and cylindrical container vessels;
Flanged container and fixed tube plate connection impossible demolition container;
Some holes can enter the internal testing, and can only be detected in the container, and so from the outside.
All of these in the development of testing protocols should be taken into account, so practical, accurate and effective.
Ben "on a regular basis with petrochemical equipment monitoring program," try to make some investigate conditions on the relevant factors, the test methods and test site for the development of reference when detection scheme.
Formulating detection scheme, the installation site should also be considered a container which spatial location, such as distance from buildings, structures the distance between the devices off, would not affect the implementation of the detection means. As another example, the tall container, to internal and external weld and the vessel wall is detected, you will need to do in advance and setting up a shelf or slides, hanging frames, etc.