Sources of Vibration in Control Valves

Compressible fluid flow through control valves will inevitably cause some form of flow induced vibration in the fluid system. Identifying the type and cause of the vibration requires detective work.


Control valve vibration may be caused by many factors, some generated internally by the process stream and others generated externally. Some of the different forms of flow induced vibration are enumerated as follows :

1. Process Stream Energy Release - a flowing process stream contains considerable energy, a portion of which is released during its journey through a valve. The released energy takes the form of fluid turbulence, viscous drag, generated noise flow instabilities, and other forms of released energy. This energy will also interact with the valve trim and may cause noticeable vibration.
2. Upstream Equipment Pulsations - Compressors, pumps and other upstream equipment generate mechanical vibrations and pressure pulsations that interact with other process equipment and piping in the system. The vibration energy is efficiently carried downstream by the piping system. In addition, pipe configurations such as elbows and tees upstream of the valve can create swirling flows and introduce turbulence, which may affect the valve.
3. Pipeline Resonance - Pipelines with long runs between supports can resonate at the first or second bending mode of the system, vibrating up and down in a "U" or "S" shape. Higher order pipe natural modes (radial and circumferential) may also be excited. These natural modes can be excited by other vibration levels to build up and affect process equipment and the supporting structure.
4. Support Structure Vibration - Some form of vibration is always present in a running plant, but normally, it is not severe enough to be problematic. However, if the support floor resonates in tune with this vibration, the amplitude can increase to the point where it may become destructive.
5. Acoustic Noise Creation - Very high sound power levels can release enough energy to create serious valve vibration and in extreme cases, cause metal fatigue.

Excerpted from "Control Valve Design" by Asher Glaun

Job Vacancy for MIESCOR

MIESCOR is currently building capability
on elevator, escalator and air conditioning installation,
repair and maintenance as well as on rail transport system construction,
repair and maintenance
and therefore in need of

Mechanical Engineers

with at least 1 year experience on related fields.

Interested parties may send their resume’s to hr@miescor.net .

Invitation to Join

We are inviting all professional mechanical engineers, licensed or unlicensed ME, CPM or ME student to join the Philippine Society of Mechanical Engineers (PSME)

Let me know if you are interested to join and I will send the membership application form by E-mail, especially for those in the Eastern Batangas area

Job Vacancy for FCP Group Philippines, Inc.

FCP Group Philippines is in need of competent and reliable people
for our new project in BAGUIO CITY starting this APRIL 2012.

BUILDINGS AND GROUNDS:
Registered Civil Engineer
Lead Fire Technician
Fire Alarm Technicians
Civil Works Staff (Carpenters)
Mechanics

HVAC PERSONNEL:
Registered Mechanical Engineer
HVAC Technician
Quality Assurance Officer

BRANCH OFFICE TECHNICIAN:
Multi-Skilled Technicians

Be part of
FCP Group Philippines, Inc.

Attractive Compensation Package and Benefits!
Submit your resume on or before
M a r c h 26, 2 0 1 2

Visit their website at www.fcpgroup.net
Or call them at telefax 894-0398 or 0922-8067365
Send resume to U514 Makati Executive Center
#114 Leviste cor Rufino Sts. Salcedo Vill., Makati City
or E-mail them at recruitment@fcpgroup.net

Flow - Psychology of Optimal Experience

Everyone wants to live a happy life. All other goals we make (for health, beauty, marriage, friendship, recognition, success, money or power) is based on the premise that it will give us happiness. Happiness is the ultimate goal. Yet many people put the other goals above all other and in the end could not find happiness.

When are people most happy ? Happiness is not a result of chance or good fortune. It results from people learning to control their inner experience when confronted by external events. Happiness results when people are in the state of flow. Though we also enjoy the calm and relaxing times, the best moments usually occur when one's mind or body is stretched to its limits in a voluntary effort to accomplish something difficult and worthwhile.

“Flow” is the way people describe their state of mind when consciousness is harmoniously ordered, and they want to pursue whatever they are doing for its
own sake. This state is characterized by the following :
1) Having a clear understanding of what you want to achieve
2) Being able to concentrate for a sustained period of time
3) Losing the feeling of consciousness of one's self including awareness of bodily needs
4) Finding that time passes quickly (it always does when you're having fun
5) Experiencing a balance between your ability level and the challenge at hand
6) Having a sense of personal control over the situation
7) Feeling that the activity is intrinsically rewarding
8) Joy and creativity at their peak
9) Being completely absorbed and totally involved in the activity itself

Flow MODEL

The flow model is shown as a two dimensional graph showing the emotional states between various levels of perceived skill level and challenge. For example, when the perceived challenge is too high compared to how their skill level, the result is worry or anxiety for the individual as he or she may feel not capable of successfully meeting the challenge. Whereas, if a person perceives his skill (knowledge or experience) as much higher than required for a certain challenge, the individual will either feel too relaxed or even bored with the activity.
I still recall an old professor during my college days. He is quite good at the subject matters he is teaching. Some of my classmates say he is very good at teaching and that they are able to learn much better than with the other teachers. However, for some reason some of us just makes one or so stupid mistakes during his test exams. It was really frustrating not getting a perfect score with such simple problems. It got to the point that I make it a point to avoid schedules when he is the subject instructor and chose those with "terror" reputation. Looking back, it was just as if my mind just goes to sleep after perceiving such a low challenge level. It took quite an effort to be able to bypass the apathy and concentrate on the test exam.
With the right challenge suited to your perceived skill level, you experience a state of mind called "Flow". It can be quite fullfilling to feel like doing something "significant".

For those who finds the challenge too high for them, the best way to improve would be :

1. Do a SWOT (Strength, Weakness, Opportunities, Threats) analysis - compare your skill levels to that needed for your desired conditions
2. Improve Yourself - make a development plan for upgrading your knowledge and skill level and implement it
3. Coaching - motivate yourself or get someone in your social network to do so and keep you on track with your development plan and reach your goals

Reference book : Flow - The Psychology of Optimal Experience by Mihaly Csikszentmihalyi

What is a Proactive Maintenance Technician ?

A proactive maintenance technician is a highly trained professional, with knowledge in many skills area (including safety and production) in addition to his own field of expertise. This professional knows and can implement proactive maintenance strategy for any piece of equipment, using his knowledge and experience to ensure the maintenance process is optimized by making constructive improvement recommendations to management.

He is characterize by the following :

1. Constantly reviews information to ensure procedures are accurate
2. Resolves issues quickly
3. Ensures the procedure is repeatable
4. Leads by example
5. Knows and follows best practices in his work
6. Has a suitable reference book on hand
7. Starts and Ends his work on time
8. Knows the planned and scheduled work for the week
9. Inspect the next day's tool and spares requirement beforehand
10. Makes recommendations for improvements
11. Makes sure area is clean and safe when completing his work
12. Proud of his work

What about your group of maintenance technicians ? Can you say they are a proactive bunch ?

Reference : A Day in the Life of a Maintenance Technician by Ricky Smith

Job Opportunities in Vetyard

For Local employment

(1) Senior licensed mechanical engineer - with experience in doing mechanical design elements for major projects. He should be able to work with the principal designers by attending meetings and manage the production of drawings and reports. Also, with experience in managing a project team and provide guidance to junior members of the team.

For overseas employment (US)

Repairs and Maintenance Manager – for a terminal container; at least 10 years experience, between 35 to 45 years old; can lead IT systems.

Send your updated resume to Julie Casis at email: jcasis@vetyard.com