“There is a lot of knowledge about the design and manufacture of pressure vessels, covering a wide range of aspects. Let's share the relevant issues together with Xinyuan Chemical Machinery.”
There is a lot of knowledge about the design and manufacture of pressure vessels, covering a wide range of aspects. Let's share the relevant issues together with Xinyuan Chemical Machinery.
What is working pressure in the design and manufacture of pressure vessels? What is calculated pressure? What is design pressure?
Working pressure refers to the maximum pressure that the top of the container should be able to achieve under normal working conditions. Calculated pressure refers to the pressure (including the static pressure of the liquid column) used to determine the thickness of the component at a certain design temperature. When the static pressure of the liquid column borne by the component is less than 5% of the design pressure, it can be ignored. Design pressure refers to the maximum pressure set at the top of the container, which, together with the corresponding design temperature, serves as the design load condition. Its value should not be lower than the working pressure. In the design and manufacture of pressure vessels, it is called calculated pressure. What are the differences between design pressure and calculated pressure in the design and manufacture of pressure vessels, and how are they determined?
The design pressure in the design and manufacture of pressure vessels mainly targets each cavity of the vessel. It serves as a crucial basis for vessel inspection requirements, determination of test pressure, selection of materials, classification, and manufacturing proposals. It is also the primary basis for calculating the pressure of each pressure-bearing component of the vessel. The design pressure of each chamber of the liquefied gas tanker is determined based on the bursting pressure or working pressure of its rupture disc, the opening pressure of the safety valve, etc. The design pressure must not be lower than the working pressure. When a safety relief device is installed, it must not be lower than the bursting pressure of the rupture disc or the opening pressure of the safety valve. The calculation of pressure is mainly aimed at the various pressure-bearing components of the container, and is only used to determine the thickness required for the stability and rigidity of the container and the strength that each pressure-bearing component meets.
The calculated pressure of each pressure-bearing component of the container is determined based on the design pressure of each cavity of the container and the static pressure of the liquid column acting on it separately and in combination. For the pressure-bearing components in multi-chamber containers that are subjected to multi-chamber pressure, the calculated pressure should be determined based on the possible situations that may occur during production operations. For example, when determining the calculated pressure of the heat exchanger tube sheet, the situations where the tube side pressure acts alone, the shell side pressure acts alone, and they act together should be taken into consideration. When determining the calculated pressure of the pressure-bearing elements surrounded by the jacket on the inner container in a jacketed container, the situations where the inner container pressure acts alone, the jacket pressure acts alone, and they act together should be taken into account. At the same time, their stability under the jacket test pressure should also be considered. For single-chamber containers, when there is liquid in the medium, the calculated pressure of the pressure-bearing element subjected to the static pressure of the liquid column is the design pressure of the container plus the static pressure of the liquid column. When the medium is all gas, the calculated pressure of each pressure-bearing component on the container is the design pressure of the container.
Pressure vessel design and manufacturing license level:
Class A is classified as A1: ultra-high pressure vessels, high pressure vessels (single-layer, multi-layer);
A2: The third category of low and medium pressure vessels;
A3: Spherical container
A4: Non-metallic pressure vessels.
Class C is divided into C1: Railway tank cars;
C2: Automobile tank trucks, long tube trailers;
C3: Tank container.
Class D is divided into D1: Class I pressure vessels;
D2: The second type of pressure vessel.
SAD grade refers to the stress analysis design of pressure vessels.
The third category of pressure vessels shall be classified as such if they meet any of the following conditions:
High-pressure vessel
Medium-pressure vessels (only for media with extremely and highly hazardous toxicity levels);
Medium-pressure storage containers (only for flammable or moderately hazardous media with a pV product greater than or equal to 10MPa) 'm3);'
Medium-pressure reaction vessels (only for flammable or moderately toxic media with a pV product greater than or equal to 0.5Pa?) 'm3);'
Low-pressure vessels (only for media with extremely and highly hazardous toxicity levels, and the product is greater than or equal to 0.2MPa?) 'm3);'
High-pressure and medium-pressure shell-and-tube waste heat boilers
Medium-pressure glass-lined pressure vessel
Pressure vessels made of materials with a higher strength grade (referring to the lower limit of the tensile strength specified value in the corresponding standard being greater than or equal to 540MPa);
Mobile pressure vessels, including railway tank cars (with medium being liquefied gas or cryogenic liquid), tank trucks [liquefied gas transport (semi-trailer) cars, cryogenic liquid transport (semi-trailer) cars, permanent gas transport (semi-trailer) cars] and tank containers (with medium being liquefied gas or cryogenic liquid), etc.
Spherical storage tanks (with a volume of 50 cubic meters or more) Cryogenic liquid storage containers (with a volume greater than 5 cubic meters).
Cryogenic liquid storage containers (with a volume greater than 5 cubic meters)
2. For the second category of pressure vessels, any of the following conditions shall be classified as a second category pressure vessel:
Medium-pressure vessel
Low-pressure vessels (only for media with extremely and highly hazardous toxicity levels);
Low-pressure reaction vessels and low-pressure storage vessels (only for flammable media or media with moderate toxicity);
Low-pressure shell and tube waste heat boiler
Low-pressure glass-lined pressure vessel.
3. Class I pressure vessels: Low-pressure vessels other than those specified above are classified as Class I pressure vessels.
Classification and grading of pressure pipelines?
Answer: Classification and grading of pressure pipelines
By pressure:
1. The pressure of low-pressure pipeline engineering is less than 1.6MPa;
2. The pressure of medium-pressure pipeline engineering is 1.6-6.4MPa.
3. The pressure of high-pressure pipeline engineering is 6.4-10MPa.
4. The pressure of ultra-high pressure pipeline engineering is 10-20 mpa.
Pressure pipelines are classified as:
1) Long-distance pipelines are classified as GA type, and their grades are as follows:
1) Long-distance pipelines that meet one of the following conditions are classified as GAl grade:
(1) Pipelines for transporting toxic, flammable and explosive gas media with a design pressure P > 1.6 MPa;
(2) Pipelines for transporting toxic, flammable or explosive liquid media, with a transportation distance (the transportation distance refers to the direct distance between the production site, storage depot and users on the pipeline used for transporting commercial media) of no less than 200 kilometers and a nominal diameter DN of no less than 300mm.
(3) Pipelines for transporting slurry media with a transportation distance of no less than 50 kilometers and a nominal diameter DN of no less than 150mm.
2) Long-distance pipeline foot GA2 grade that meets one of the following conditions.
(1) Pipelines for transporting toxic, flammable and explosive gas media with a design pressure P≤ 1.6 PMa;
(2) Pipelines outside the scope of GAl(2);
(3) Pipelines outside the scope of GAl(3).
Ii. The common passageways are classified as GB class, and the level classification is as follows:
GBl: Gas Pipeline
GB2: Thermal pipelines.
Iii. Industrial pipelines are classified as GC, and the level classification is as follows:
Industrial pipelines that meet any of the following conditions are classified as GC1 grade:
(1) Pipelines transporting media with extremely hazardous toxicity as stipulated in GB5044 'Classification of Hazardous Levels of Occupational Exposure to Toxic Substances';
(2) Pipelines transporting flammable gases of Class A or B or flammable liquids of Class A as stipulated in GB50160 'Code for Fire Protection Design of Petrochemical Enterprises' and GBJl6 'Code for Fire Protection Design of Buildings', with a design pressure P≥ 4.0 MPa;
(3) Pipelines for transporting flammable and toxic fluid media, with a design pressure P≥ 4.0 MPa and a design temperature ≥400℃;
(4) Pipelines for transporting fluid media with a design pressure P≥ 10.0 MPa.
2) Industrial pipelines that meet any of the following conditions are classified as GC2 grade:
Pipelines transporting flammable gases of Class A or B or flammable liquids of Class A as stipulated in GB50160 'Code for Fire Protection Design of Petrochemical Enterprises' and GBJl6 'Code for Fire Protection Design of Buildings', with a design pressure P < 4.0 MPa;
(2) Pipelines for transporting flammable and toxic fluid media, with a design pressure P < 4.0 MPa and a design temperature ≥400℃;
(3) Pipelines for transporting non-flammable and non-toxic fluid media, with a design pressure P < 10MPa and a design temperature ≥400℃; (4) Pipelines for transporting fluid media with a design pressure P < 10MPa and a design temperature < 400℃.
3) GC2 grade pipelines that meet any of the following conditions are classified as GC3 grade:
(1) Pipelines for transporting flammable and toxic fluid media with a design pressure P < 1.0 MPa and a design temperature < 400℃; (2) Pipelines for transporting non-flammable and non-toxic fluid media, with a design pressure P < 4.0 MPa and a design temperature < 400℃.
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