Hi,

I just have some issue regauring the access distance
required for maintenance for pump discharge piping. As shown in the
attached drawing, there is a guide just after the pump nozzle in
discharge piping. the distance of guide from pump foundation is about
200 mm. I just read somewhere that minimum access of about 950 mm
around any rotating equipment. the distance available is 500 mm
instead of 950mm. All pumps and piping has already been installed. Do
u know any way to provide this access? We cannot move the pumps. This
has been been done by some previous designer. I need to provide any
alternative way around. i only way i think is to remove the guide
then access will be 1000 mm. But i think that guide is must after pump
discharge nozzle. What do u think? Du u have any alternative proposal
in that case based upon ur experiance?
The image is shown as per following link

http://www.4shared.com/photo/zU8AGtCN/PP_online.html

Thanks for help.

Waqas

I am very concerned about you having a "Guide" so close to the pump discharge nozzle but I could not open your drawing so I cannot comment on your arrangement. The following is some basic and very general guidelines I teach new pipers.

Pumps
Locate pumps close to the equipment from which they take suction. Normally, locate pumps in process units under pipeways.
Design piping to provide clearance for pump or driver removal. Similarly, on end suction pumps, piping should permit removing suction cover and pump impeller while the suction and discharge valves are in place.
Arrange suction lines to minimize offsets. The suction lines should be short and as direct as possible, and should step down from the equipment to the pump. Suction lines routed on sleeperways may rise to pump suction nozzle elevation.
Orient valve handwheels or handles so they will not interfere with pump maintenance or motor removal. Valve handwheels or handles should be readily operable from grade.
Maintenance and operating aisles with a minimum width of 2'-6" (800mm) should be provided on three sides of all pumps.

I will also offer "There is access and then there is access" By this I mean there is one level of access for normal operation and normal maintenance. However, if major maintenance is required then it is not unreasonable to require disassemble of some suction and discharge piping to allow greater access.

Thanks alot for the help.. THe discharge piping access is abut 500 mm from the both sides of the pump. Can we remove the support PS-002A so as to provide access. the link for the image is:

http://www.4shared.com/photo/LTM2VpcR/2 ... furl=d1url

Firstly I want to make it clear that I am not a stress engineer, I am however a designer and after many years we do develop a gut feel for the good and the bad when we see it. So, just to be clear, the following is my gut feel on your question about supporting and guiding, not the advice of a stress engineer, based on the piping arrangement that you provided in the following link - http://www.4shared.com/photo/LTM2VpcR/2 ... furl=d1url

Secondly, you refer to one support (PS-002A) in your posting, but actually we're talking about two supports: PS-001A and PS-002A and two pumps, an A and a B pump, so I'll speak to both. You can't remove the PS-001A (B pump discharge piping support) and PS-002A (A pump discharge piping support) supports because the weight of the pipe and the valves would put too much stress back on the pump discharge nozzle. You could make the tee supports cantilvers and thereby move the posts further away from the pumps, but that's about it. However, if I'm reading the mark-ups correctly, PS-001A can"t be moved because of an adjacent pipe and PS-002A can't be cantilvered for whatever reason. Probably because cantilevering would mean encroaching on walkway or other access adjacent to the pump (not visable in the piping arrangement you have provided). As to the guides you mention, which I take it are also on PS-001A and PS-002A, all they're doing is restricting the pipe movement and imposing unnecessary loads back on the pump nozzles. I can't see any purpose for them and they should probably be removed.

So, now I have some further observations and questions for you:
Why is everyone so concerned about these supports when access to the pumps isn't just restricted by these first supports only? The whole piping arrangement is in the way of pump access (BOP EL.101.203), so why focus on the supports? I also notice a PS-003 and PS-004, which I believe to be base ell supports and PS-005 and PS-006 tee post supports. One of these supports on each pump discharge piping is redundant; right now it's the tee posts. You can keep the base ell's and get rid of the tee supports or the other way around, but both are not needed.

My opinion is that if you really want to do something about the access around these pumps, you'll need to reconfigure the pump discharge piping. Put the check and gate valves in the vertical off of the pump discharge, rise vertically beyond head height, offset the piping so that you don't run pipe above the pump and then run horizontally to the tee'd connection between the pumps. You'll also have to redesign some of the supporting, but that's part of the fun.

Maybe this helps,
Best wishes.

I'm more concerned about the whole piping configuration; this system has both pumps "caged in"! HOW is a maintenance crew going to pull maintenance on these pumps when they are hard get too? I would have preferred the discharge piping to have been routed 180 Deg.s and parallel the suction ...pumps are exposed and maintenance now becomes easier. ...I won't even comment on the high school drafting mistakes I see in dimensioning!

Hi 11echo,
I agree with your response. For whatever reason, I was overlooking the fact that the suction piping does not need to come back on itself in my description of reconfiguration. Your solution is correct and would allow for the removal of not just pipe supports PS-001A and PS-002A, but also PS-005/6 and 7 and give all around access to the pumps, which is of course how the piping should have originally been designed.

In regards to your last comment on dimensioning; in the transition from manual drafting to 2D CAD and to 3D CAD, it appears that designers are no longer being educated on how to correctly dimension a piping drawing. The example before us demonstrates several poor dimensioning practices: no coordinates on the pumps nor the supports, reference to BOP instead of centerline elevations, and dimensions to what appears to be a face of concrete. Dimensioning practice on piping arrangements would be a good discussion topic.

Regards and best wishes.