Brighton,

I am starting this new thread, as suggested by Steven. I will try to answer your queries, but if I miss any, please point them out.
1. >snip> MY INTENTION IS TO SWAP OVER TO THE DUTY ONE AFTER A DAY OF RUNNING THE STANDBY ONE. Could you please verify if it is what you meant? Answer: Yes.
2. ,snip> The other thing is what is the maintenance strategy for more important equipments like compressore, compressor after coolers? Appreciate your advise greatly.>> Ans: If the comprssors are recips and have soft gland packings, a weekly chageover may be reqd to keep the glands lubricated. If they are centrifugal or screw or recips with mech seals, run them duty/standby like the pumps.
3 <snip> Could you please advise what servises we are able to get from him mechanicalwise? i.e services in order to improve mechanical equipment performance? > Ans: Thermography is useful in any situation where hot or cold spots can occur. Hot bearings, damaged insulation, steam traps, furnace tubes etc. are all possible areas of use, the list can go on.
4, ,snip> We are planning to do a shutdown shortly and then keep the plant run for three years. Does it affect the duty-standby philosophy of running pumps? > Ans: Not at all.

Before you apply any new strategies. please gain an understanding of why we should consider them. That is whole subject in itself and you need to read books, articles, papers etc. and talk to your operators, maintainers and to experts you have access to. Picking up strategies based on a website discussion is not optimal.

Just throwing in the ball

In the duty x standby mode, it is often required to have the back-up on "hot" standby. This strategy is equipment specific.
1) For instance a back-up compressor can go to unloaded operation, before going to "sleep" mode.
2) A backup boiler should be maintained above a certain pressure to be able to come in quick operation.
3) Refinery pumps for hot service with mechanical seals; sometimes there is a bypass leading from the pump suction to the discharge entering after a checkvalve in the discharge line. In the hot standby mode this valve must be cracked open to allow slow rotation of the pumpshaft.
Any comments on this Vee?

Steven,
In your cases 1 and 2, the hot standby is in fact a second mode of operation, on no load or light load. It is not the conventional duty-standby operation at all, in that its sees some, but not all of the degradation mechanisms in the hot standby mode. Compare this with a Cruise liner which sees relatively steady and light loads when cruising in calm weather, against an operating mode where it is berthing or sailing off from a port. The second mode sees high loading on all systems. When we analyse such dual mode situations, we consider the % time in each mode, and try to devise a suitable strategy. The conventional duty/standby strategies do not apply.
In your case 3, the motor is not running and there is no load on the pump. It is merely being kept warm. Sometimes it might be rotated with barring gear. This is in a standby mode, so the duty/standby strategies apply.

Thanks guys.
Unfortunately in the plan where I work they swap over pumps every week. Not good!
I have not gone through any vendor manual and I would like to bring this question here:
When you say run the duty one as much as possible; then how we van ensure the standby equipment integrity; i.e. ensure it can come online when needs be?

The other question is: we contracted a company to do vibration analysis (VA) every three months. I am not sure if it is ideal or not but could you please say what we can do in order to monitor the equipment in between any 2 VA surveys?

quote:

monitor the equipment in between 2 VA surveys

I thought the VA surveys are part of the monitoring.

Brighton,
Your quetsions have been addressed in earlier posts. Please take some time to review them, else we will keep repeating things.
I thought I explained how you maintain the start integrity a few days ago (horse and cart illustration). Did you see that one?

Vee, I remember you gave a good example of horse and cart; however I asked about info about different topic. We do not have any vib tech in our plant. I want to continusely have the condition of machines monitored, via plant techs, in between our three months vib survey.

1- What are the basic maintenance activity that our techs can do?

2- Suppose the vib guy takes the reading on a standby one and we swap over to duty machine. It would be an embarrassing situation if the day after we urgently need to operate standby one, due to an unexpected problem for duty, and it fails to start. I would like to know the activities we can do in order to ensure the stanby machine doesn't let us down when it is needed for service?

Thanks

quote:

What are the basic maintenance activity that our techs can do?

1) Keep the machine clean and lubricated, we call that preventive maintenance in our plant. There are a lot of things that must be done during a PM (check for lose bolts, check alignment, oil level, clogged filters, rubbing parts, strange noises, loose electrical connections etc.)
I have the strange feeling that you guys are waiting for the VIB club to come tell you what to do with your equipment

2)

quote:

It would be an embarrassing situation..

My boss always told me that if we screwed up a machine during repairs, he would not care, but he would fire us if the machine screwed up because we did nothing.

Steven,

Don't get me wrong. We obviously check the machine against the items you said; however I wanna know if there is any specific, tricky, thing there is we'd better to know.

Can you say for a standby pump, what is the internal of oil change?

If you are in a climate with very low humidity and have complete control over the back-up pump (that is you are sure that it is not running), no dirt ingress or product contamination, I would go for a one year change. If none of this conditions is met, I would just go for a 3 or 6 months interval, it is easier to administrate.

Brighton,

1. Please read the posts in the thread called Best Strategy, started by RCM2. There are a number of useful suggestions there.
2. Your starting point, that the vib people come in every 3 months needs review. Surely that cannot be what determines your strategy or workload. What you need to decide, if you agree to a duty/standby regime is how often you need to switch over. For reasons I wont repeat here, this can be 2 to 3 months, not more, as you need to ensure your standby will start on demand. The vib people must also come at this frequency. In my earlier post I tried (and obviously failed) to explain that the frequency of starts is the horse, the vib folk frequency is the cart.
3. Unless your vib people also do some maintenance interventions, your query about what your techs do is not clear. Surely they do all the PMs, non-vib PdMs such as lub oil sampling, thermography etc.? I am missing your point I think as these items have been discussed earlier.

No worries Vee. Could you please say what do you mean by MTBF in the below context?

the MTBF of pumps wil increase about 10% if...

Vee, as you recommended, I started reading the discussion "Best Strategy" but I might have some small questions that I will appreciate your patience in advance to answer.
Vee: There are certain maintenance activities, usually of low cost, which are worth carrying out whatever operating policy we follow, without the need for any special analysis. These include oil top-ups or changes, cleaning and taking vibration readings. These will fall under housekeeping or PM tasks. But intrusive work is only called for if a fault is found during a test start.

Could you say how often this test start can be? Could it be every three months when vib guys come on site?

Brighton,
Mean Time Between Failures. I(t is a commonly used measure of reliability. The higher the MTBF, the fewrer the failures, hence longer the runs and better avialability, lowers costs.

Brighton,

quote:

Could you say how often this test start can be? Could it be every three months when vib guys come on site?

I thought I had just finnished explaining that you need to test start every 2 months; in some cases you can go up to 3 months. To begin with, you are safer sticking to 2 monthly tests. If the tests are done every 2 months, then you HAVE TO take the vib readings at least every two months.

I do not undertsnd your fixation with your vibe folks. Why cant they come every two months? What is holy about their quarterlyy contract? Tear it up and write a new one if reqd. That old contract for vib readings CANNOT determine how often you test start your standby.

Brighton,
1) what type of plant is?
2) 24x7x360 or 5x8?
3) Are the vib guys paid per measuring point? , not that I have something against that, In fact if I was in their place, I would do the same, but if I have to pay the bill, I would rather base the pay on performance/reporting

"In my view, the duty/standby situation produces the highest reliability, highest availability, lowest cost option."

Vee, my understanding from your quote is run the duty until it busts; then you have to swap over to standby one. Can you please confirm? I admit I am learning things here; hence my apologies if I ask many questions; some preliminary though!

Rgds

quote:

my understanding from your quote is run the duty until it busts; then you have to swap over to standby one

Wrong!!

1) Run and monitor the condition of the duty pump, untill it is time to interfere (this will be determined by experience) there are well known established warning and absolute fault limits for equipment.
2) Test run the standby unit, in a manner that it can be evaluated under normal working conditions also.

This can be done in a 12 weeks on - 3 weeks off for the main pump, and a 12 weeks off - 3 weeks on for the backup pump.

This way we know all the time the condition of both pumps. Coincidentally , the back-up pump would be running when the main pump is down for service. Although the "service" can be done in one day, we will create time to evaluate the condition of the backup pump.

Frequent start-stop of most equipment will lead to premature failures.

The last thing we want is to run the main pump untill it explodes and discover that the backup has died silently long time ago.

This message has been edited. Last edited by: svanels,

Steven,

Thanks for your reply. 12 weeks on, 3 weeks off is like 80:20 which is not in compliance with the duty/standby or 90:10 policy that Vee introduced. Could you pls clarify?

Cheers