Currently, we are analyzing 3 pumps for gasoline services @ 38 degrees Celsius (ambient=21 degrees). Only two were going to run simultaneously and the other as spare. 6" nozzle, 10" piping. all restraint=sliding plate.

Attached config always resulted in failure of the spare pump nozzle in Fx wether the other two is running or the spare is running with either of the two.

My question are:
1. does the arrangement of the spare piping affects the nozzle of the spare pump?

2. someone suggest an EJ in the spare pump only, is it advisable?

Though we tried to add flexibility near the header(for all three) still same result( a failure in Fx in spare pump).. and flexibity near the valve assemblies cannot be provided anymore.

Please advise. An EJ on one pump only, is it okay?


I think.
Spare is not always a good thing.
Life's a mess.

im not sure if i attached the pic.
send me your e mail. i'll send it.

Dear dark,

I am very interesting with your case. Please send me the input file and input echo to my email samsulpm@yahoo.com.

Arrangement of piping do affect flexibility of the system and therefore the nozzle of pumps attached to the piping.

Any one of the three pumps can be SPARE PUMP during operation. Would you be adding expansion joint to all the three pumps? Had i faced such problem, i would have focused on rerouting my piping instead of using EJs.

Dear dark,

Have you already considered?
Case 1: P1 on, P2 on, P3 off (spare)
Case 2: P1 on, P2 off (spare), P3 on
Case 3: P1 off (spare), P2 on, P3 on

As per your explanation, I guess you only did let say case 1. If you run all 3 case above, is it always fail for spare pump?

In my opinion Exp, joint is the last choice for the case. I ever did with Exp. joint. But it was connected to existing line, no space too crowded.

Its about space and economy.. rerouting might be an option BUT is it economical? If EJ, do what will be the cost of your maintenance?.

One thing,.. your operating temperature is just 38deg. C. the source of your failure might be in your connecting route because this temperature are low and you may eleminate this problem by adding/removing/relocating supports. but first checkk API 610 if you realy have to change those configuration because your pump might be at the range as stated in annex F for "API pumps".

Regards!

Dear Dark,

My answer to your query.

1.Yes, arrangement of the spare piping does affect the nozzle of the spare pump.
2.I will not recommend to use the EJ.

The spare pump could be any of the three pumps.

I had analyzed 3 pump system.It is always difficult to limit the nozzle loads within the allowable limits.
You should reroute the piping in such a way that pump piping of all the three pumps is symterical with respect to the piping header.Provide a line stop in the middle of the piping header & check if it helps.

Did you consider extra allowables for the spare pump?.
I believe you can consider extra allowable loads for the spare pump.In my system as per the project guidelines,I had considered 50 % extra nozzle loads for the spare pump as compared to the working pump.

Hope it will help.

Cheers
Saneh

Thanks for all the reply.

To samsul: i send you a picture only. i cannot send the input file. still i will try. case 1 2 & 3 is considered(and others as per advise). and yes only the spare pump is the problem. (spare pump is specific and identified).

To skyofstars: 2 headers and 3 pumps. third pump is spare only. we are working on rerouting the spare pump piping than EJs.

To bom: thanks! i'll check it(API 610).

To saneh: thanks for your reply and idea. i'll give it a thoughts.

Again, thanks to all!

Dark,

I would strongly advise that you get something very firm from the client regarding "spare pump is specific and identified". Typically, when you have three pumps where one is a common spare for the other two, identifying the "spare" pump means that it has been sized to handle whichever service has the higher flow requirements and is usually located in the middle.

But, I highly doubt that the client's intent is to just let that pump sit idle forever until one of the other two fails. Clients are going to want to provide more even wear by running the "spare" pump regularly. Plus, it's not going to be good for reliability to just leave the "spare" pump sitting idle for so long, just as you would not want to leave a car sitting for years and then expect it to just crank up and take off down the road.