RhoV2 criteria for Flare system

[ProcessNorway]

Rhov2 is a design limit for offshore flare systems in NORSOK P-001

But why is Rhov2 used?
NORSOK P-001 has the limit Rhov2 < 200000 kg/m/s2
What will physically happen if the limit is exceeded?

My knowledge far:
the momentum G =rho*v2
the dynamic pressure Pdynamic = rho*v2/2 by Bernoulli's eq
the axial force in a 90 deg bend F = massflow * velocity (SI units)
F may be written F=G*FlowCrossectionalArea
this gives that the bend forces(flow induced) are directly proportinal to rhov2.
(i'm not talking about pipe support forces, just internal flow induced bend forces)

Are there other resasons for limiting rhov2 ?
-vibrations?
-noise?
-acoustic fatigue?
-oscillations?
-erosion?
-pipe stress?
-slug forces?

 

[ione]

Take a look at what happened to the Salah gas flare header

Take a look also to this (there are interesting figures for limiting velocity):

www.standard.no/PageFiles/1134/P-001e5.pdf

 

[LSThill]

ProcessNorway (Petroleum)

Reference Review:

FREDERICK J. MOODY
ASME PD382 Hydraulic Loads on PVP
HOW TO PREDICT THERMAL-HYDRAULIC LOADS ON PRESSURE VESSELS AND PIPING

Introduction to Unsteady Thermofluid Mechanics, Frederick J. Moody

RECOMMENDED PRACTICE DET NORSKE VERITAS
DNV-RP-D101
STRUCTURAL ANALYSIS OF PIPING SYSTEMS OCTOBER 2008

Been their did that

L S THILL

 

[MortenA]

Interesting link ione - will have a lookat that!

Best regards

Morten

 

[ProcessNorway]

Thanks for your answers!

My main issue is to get the physical understanding of why Rhov2 is used as design criteria in flare systems.

I have worked with flare systems for 6 years (simulations, design, Norsok P-001, P-100, API 520, API521, Flarenet, Acoustic Fatigue, etc)

But still, I don't have the physically understanding of why Rhov2 is important.

 

[ione]

This is IMO a guideline to avoid issues related to acoustic fatigue, noise (also Mach number should not exceed 0.6) and problems related to dynamic loads (change of direction) which are proportional to rho*v2 and could lead to anchor’s failure.