Thanks for replies,
However to justify the MWS and Client, is there any reference to explain on the allowable distance, or it is only based on experience?
Case: Subsea Pipeline Detail Fatigue Analysis by Force Model (Direct Wave)
Ref.: DNV-RP-F105 (Feb 2006), sec. 5.3.2
Question: To calculate the in line stress range (due to drag and inertia loads) I do not know what boundary conditions to be considered? (e.g. pin-pin or fix-fix, or etc)
Dear DLITE30
If I Size control valve for 25% of flow which is maximum flow passing controlvalve during operation,how can I ensure that the valve con serve suitable for 100% of compressor capacity during shutdown case?
on the other hand, we need to achive to settle out condition after compressor...
thank you for your response to the questions .let me to describe the problem more detail.
we have 6 stages of compression from 2bara to 240 bara.
as you know,any stage have its own air cooler and the recycle btranch is located down stream of air cooler and return the compressed gas before K.O...
Refer to API 618 capacity of reciprocating compressors could be controlled by unloading device, clearance pocket and spillback control valve.
If five steps unloading (i.e. 0, 25, 50, 75 and 100% of full flow) are used in combination of spillback control valve, it is kindly requested to inform us...
Refer to API 618 capacity of reciprocating compressors could be controlled by unloading device, clearance pocket and spillback control valve.
If five steps unloading (i.e. 0, 25, 50, 75 and 100% of full flow) are used in combination of spillback control valve, it is kindly requested to inform us...
Case: Pipelaying by Barge Near an Existing Platform (the barge is anchor handling type)
Question: what is allowable lateral distance between pipelaying barge and existing platform?
Many thanks in advance.
Thanks for replies.
Re Question 1)
I know that wave and current effects in fatigue should be considered. My matter is mathematical as I do not know how to calculate dF(Uc) in Sec 4.2.1 or 4.2.2. (F(Uc) is cumulative weibull distribution of current) (d is differential)
However, I think...
Ref.: DNV-RP-F105 (Feb 2006)
•Question 1
Sec.: 4.2.1 & 4.2.2:
Could somebody literally explain the meaning of “integration over the long term distribution for current velocity represented by a Weibull distribution or histogram”. (If possible to provide a simple example, please)
•Question 2...
Thanks for reply,
In general fatigue is due to two effects, VIV and Direct Wave. VIV effect is named as Response Model and Direct Wave as Force Model (ref. DNV-RP-F105).
Stress Spectral Density in F105, Sec. 5.2.6 is for Force Model (i.e. Direct Wave fatigue), and based on your advice I...
Ref.: DNV-RP-F109 (Oct 2007), sec 3.4.5 (EQs 3.21 & 3.22)
My case: modeling of subsea pipeline in a trench
Question: I understand in case distance of pipeline from either trench sides/walls is more than 3D (D is pipe outside diameter) the load reduction due to trenching is not considered. Is...
Thanks,
Ref. DNV-RP-F204
You mean that EQ. A.3 is unit time fatigue damage for a sea state and based on wave probability and each sea state duration the cumulative damage fatigue should be calculated.
To extend my matter, to use EQ A.3 it is required the coefficients (i.e. m and sigma) are...
