Some standard content:
SY/T 10007--1996 Offshore Oil and Gas Industry Standard of the People's Republic of China
On-Bottom Stability Design of Submarine Pipeline1996-08-19 Issued
China National Offshore Oil Corporation
1996-08-19 Implemented
Symbol Table
Chapter 1
Chapter 2
Chapter 3
Chapter 1
Chapter 5
Chapter 6
Appendix A
Appendix B
Design Conditions
Design Methods
Design Criteria
Analysis Methods
References
Approximate Calculation Method of Boundary Layer Reduction Coefficient
In order to meet the needs of developing marine oil and gas resources in my country, our company adopts the 1988 edition of "Stability Design of Submarine Pipelines" of Norwegian Classification Society, namely DnV RPE305 On--Bottom Stability Design of Subnarine Pipeline 1988. It is published as the recommended standard of China National Offshore Oil Corporation.
If there is any objection to the translation of this standard, the original standard shall be used. In the design, construction and use of offshore oil and gas development equipment, when laws, regulations and provisions of the government or other competent authorities of the original standard are involved, they shall be implemented in accordance with the corresponding laws, regulations and provisions promulgated by the government of the People's Republic of China or the competent authorities of the government. The data or quantitative calculation methods of environmental conditions such as wind, waves, currents, ice, temperature, earthquakes, etc. in the original standard can be used as a reference if they are in line with my country's actual situation; otherwise, the original standard that meets my country's environmental conditions should be used. As actual data and quantitative calculation methods. Regarding the units of measurement, the legal units of measurement are mainly used, that is, the legal measurement unit value is in front, and the corresponding value of the imperial unit is marked in brackets. In order not to change the shape characteristics of the formulas and curves in the original standard, constants and coefficients, all those using imperial units shall continue to use imperial units. China National Offshore Oil Corporation
China National Offshore Oil Standardization Technical Committee 1993.11.15
C—Constant
D——Nominal outer diameter of pipe
Elastic modulus
Weight of one tangerine to soil (sand soil)
Symbol table
K-Keulegan Carpenter number, KU.· Tr./D1. 1. Pipe weight parameter
Ratio of flow velocity to wave velocity, M=Ua/Us
R-Reduction factor cited by the directionality and dispersion of waves
S-Shear strength parameter
T-Time parameter, 7=T,/T,
Trace radius of water particle velocity
As Effective acceleration
Cn-Drag coefficient
C —~Lift coefficient
Cu—-Inertia coefficient
Outer diameter of steel pipe including anti-corrosion coating
D-Inner diameter of pipe
Outer diameter of steel pipe
Inertia
Load coefficient (or calibration coefficient translator's note)
Effective wave height
Equivalent sand roughness parameter
S.—Safety factor
Wave spectrum (long-peak sea waves)
Horizontal velocity spectrum near the bottom
Undrained shear strength
Duration
Parameter, T,=Rd/g)
Peak period of sea surface wave spectrum
T—Average upper cross-peak period
Coefficient)
Flow velocity perpendicular to the pipe
·Vertical "Effective flow transfer of the pipe
Effective flow velocity perpendicular to the pipe (excluding reduction*
Friction velocity
Average velocity on the pipe diameter D
Reference steady-state flow velocity
Desired flow velocity
Underwater weight of the pipe
Design weight
l—-water depth
Average particle size
Underwater weight correction factor
Gravity acceleration
Ling——Wave number
me, ma—Spectral moment
Dispersion index
Steel pipe wall thickness
Elevation above seabed
Seabed roughness parameter
·Apparent roughness
Reference height above seabed
-Philliis Constant
3——The secondary wave direction around the main wave direction
-proportional lateral displacement
E,——upper strain and eigen strain
(.0)-—scatter function
Kurtosis parameter of Jonswan spectrum
vonkarmati number
soil friction coefficient
angular frequency
spectral peak angular frequency
P-concrete coating density
anti-corrosion coating density
P:--medium density in pipe
——sand density
P—rice material density
pa——water density
—spectral width parameter
8——phase angle of main wave direction
0-—square perpendicular to pipeline
Q/HS 7016—93
Chapter 1 Introduction
This recommended practice summarizes the basic issues that should be considered in the stability design of submarine pipelines. The main purpose of this recommended practice is to make the most advanced pipeline stability data available for effective application to submarine pipeline design and to provide a framework for further improvement of the stability design method as more data become available. This practice is based primarily on the results of the pipeline stability research project PIPESTAB (1983-1987) completed by SINTFF with support from EssoNorge A/S and Sta-1oil, see references [2]-[8]. Other research results can also be used for pipeline stability analysis on the seabed. Therefore, the author may revise the current recommended practice in conjunction with other research results and data to expand its scope of application. The design method recommended by the Society is applicable to the stability analysis of submarine pipelines on the seabed during their service life or before taking stability measures (such as trenching, burial or burial). The stability of the pipeline is directly related to the underwater weight of the arm, environmental load and the resistance between the pipeline and the soil. It can be seen that the purpose of stability design is to confirm whether the underwater weight of the pipeline can meet the stability principle.
Chapter 2 Design Conditions
Z.1 Basic Conditions
2.1.1 When conducting stability design of submarine pipelines on the seabed, the following basic conditions should be considered: 1 Environmental conditions: || tt||- Seabed geological conditions,
- Seabed geomorphic conditions (slope, rock outcropping, depressions): -- Bathymetry (water depth)
- Pipe data (diameter, wall thickness, concrete coating); Pipeline constraint locations (riser connections, intersections, etc.). 2.2 Return period
2.2.1 The stability design should adopt the return period of a given environmental condition close to the seabed and acting vertically on the pipeline. Usually, the water particle velocity close to the seabed caused by waves and the flow velocity close to the seabed should be considered at the same time. 2.2.2 If sufficient wave and current joint distribution probability data are available, the wave and steady-state sea The combination of currents should adopt a 100-year return period. Otherwise, for the ten operating conditions, the following return periods are recommended: If wave forces are dominant, then
Wave: The wave-induced water particle velocity of the vertically lowered pipeline close to the seabed with a return period of 100 years is used as the condition; Ocean current: The return period is 10 years.
If ocean current forces are dominant, then
Wave: The return period is 10 years:
Ocean current: The return period is 100 years.
2.2.3For temporary situations, the return period should be selected as follows: Operation period is less than 3 days: An environmental load can be determined based on reliable weather forecasts. Environmental parameters. If the operation period exceeds 3 years: (1) No harm to humans, the parameters with a return period of 1 year in the corresponding season can be used; (2) Endangering human survival, the environmental parameters should be determined according to the return period of 100 years in the corresponding season. However, the corresponding season should not be less than 2 months. 2.3 Environmental turbulencebzxZ.net
2.3.1 The following environmental conditions should be evaluated at several locations along the pipeline: - waves;
- current.
Q/HS7016--93
The number of locations required to fully determine the environmental parameters depends on factors such as pipeline length, water depth changes, seabed soil and meteorology. 2.3.2 Sufficient data for the relevant area can be obtained through measurement, hindcast model or visual observation, and on this basis, the environmental parameters used in the stability design can be established. If there is a lack of sufficient data in a specific area, reasonable conservative estimates can be made based on corresponding data from other adjacent areas.
2.3.3 Recognized statistical analysis methods should be used to describe the randomness of environmental conditions. Usually, sea conditions are defined by significant wave height Hp, spectral peak period T and corresponding recurrence period.
2.3.4 The wave data obtained can be the joint distribution probability of Hp and Tp with directionality, or the design value of significant wave height with no directionality and its corresponding estimation period. Its form depends on the quantity and quality of valid data obtained in the specific area in question. In the design method proposed in Chapter 3, wave data with different phase angles can be input: 2.3.5 Spectral peak period T is determined according to the wind zone, water depth range and the duration of the sea condition. For the lower peak period, if no other data are available, its upper limit can be determined by the following formula:
T: (2 500Hs/g)
If the joint distribution of H and Tp is available, the combination of Hs and T that gives the most extreme conditions close to the seabed should be selected. 2.3.6 When selecting the design velocity of water particles caused by waves, the directional distribution of waves can be considered. Usually, extreme sea conditions from different directions need to be considered. If the directional data of waves are not available, it should be assumed that extreme waves act perpendicularly to the axis of the pipeline. 2.3. When selecting the design velocity of water particles caused by waves, short-peak waves can be considered. If specific data on the site are not available, it can be assumed that the energy disk is diffused along the main direction of wave propagation. 2.3.8 The water particle velocity caused by waves used in the stability analysis is expressed by the effective value U close to the seabed and perpendicular to the pipeline and the corresponding average upper zero-crossing period T.
2.3.9 When calculating U/T:, the most appropriate water surface elevation spectrum expression should be used. For the North Sea, it is recommended to use the Jonswap spectrum. For long-peaked waves, the Jonswap spectrum is given by the following formula: Sp(w)=ag(w)-expi(w/w,)-4/y
j -(tu-w,)*
a=exp(
where: w—angular frequency:
is called the spectrum peak angular frequency;
is called the gravitational acceleration:
— phillips Constant;
—spectral width parameter:
If wsw-, then a=0.07;
If w>wp, then a=0.09;
—kurtosis parameter.
2.3.10U, and T can be calculated by converting the long-peak water surface elevation spectrum to the seabed, and using a reduction coefficient to consider the directionality of the wave relative to the tube. The expression of these short-peak wave spectra is as follows: Su(w)=[/sinh(kd) .S()
Where: 5()——water surface elevation spectrum (long peak); k——wave number (o=gktanh
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