배관 진동에 대한 정성적 평가 기준

배관 진동에 대한 정성적 평가 기준

Qualitative Assessment for Pipe vibration

 

설계 단계에서 New plant, Existing plant의 배관 시스템에 대한 잠재적인 진동 가진원을 평가하고, 정량적 평가(Likelihood of failure, LOF)에 대한 기초자료로 활용하기 위한 정량적 평가(Qualitative Assessment) 업무가 진행됩니다. Qualitative Assessment 평가 단계에서는 아래와 같은 배관 진동원의 가능성 유무를 판별합니다.

 

-       Flow induced turbulence

-       Flowinduced pulsation

-       High frequency acoustic excitation

-       Mechanical excitation

-       Pulsation from reciprocating compressor or pump

-       Pulsation from rotating stall

-       Cavitation and flashing

-       Surge and momentum changes

-       Vortes shedding from intrusive elements

 

[ Guideline for Qualitative Assessment for Piping System ]

Item	Aspect	Applicable process fluid(s)	Likelihood Classification			Potential excitation mechanism(s)
			Low	Medium	High
1	What is the maximum value of kinetic energy(pv2) of the process fluid within the system under consideration?	All				Flow induced turbulence(All fluids) refer to Scetion T2.2 Flow induced pulsation(Gases only) refer to Scetion T2.6
2	Is choked flow possible or are sonic flow velocities likely to be encountered?	Gas	No		Yes	High frequency acoustic excitation refer to Section T2.7
3	Is there any rotating or reciprocating machinery?	All	No	rotating equipment only	reciprocating equipment	Mechanical excitation refer to Section T2.3
4	Are there any positive displacement pumps or compressors?	All	No	Screw/gear type positive displacement machine	reciprocating type positive displacement machine	Pulsation - reciprocating refer to Section T2.4
5	Are there any centrifugal compressors which have the potential to operate under rotating stall conditions?	Gas	No	Compressor has stall charateristics but operational restraints in place to ensure that rotating stall is not encountered	Stall rotating condition unknown. Compressor has rotating stall charateristics and may operate at conditions that will give rise to stall conditions	Pulsation - rotating stall refer to Section T2.5
6	Are there any systems which may exhibit flashing or cavitation?	Liquid / Multiphase	No		Yes	Cavitation and Flashing refer to Section T2.9
7	Are there any systems with fast acting opening or closing valves?	All	No		Yes	Surge/Momentum changes refer to Section T2.8
8	Are there intrusive elements in the process stream?	Gas / Liquid	No		Yes	Vortex shedding from intrusive elements to refer to TM-04
9	Is there a possibility of slug flow?	Multiphase	No		Yes	Slug flow - seek specialist advice
10	Is there a history of pipework vibration issues, or are there any systems which are similar to those on another plant which have a known history of pipework vibration issues?	All	No	Yes: however, suitable corrective action in place and validated for the complete operating envelope.	Yes	Known vibration refer to Chapter4

(참고: Energy Instiude, Guidelines for the avoidance of vibration induced fatigue failure in process pipework, Jan. 2008)